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mariadb mariadb-tools mariadb-tools
=============
All of the helper and wrapper scripts we use for benchmarks and tests are available in the [mariadb.org-tools project on GitHub](https://github.com/MariaDB/mariadb.org-tools).
The MariaDB Server Tools package from the MariaDB Corporation is available for download [from the Downloads page](https://mariadb.com/downloads/tools/server-tools/) while the source is available from: [on GitHub](https://github.com/mariadb-corporation/mariadb-tools). Official documentation is viewable on the [GitHub Pages site from the source](https://mariadb-corporation.github.io/mariadb-tools/index.html).
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb mysql.password_reuse_check_history Table mysql.password\_reuse\_check\_history Table
===========================================
**MariaDB starting with [10.7.0](https://mariadb.com/kb/en/mariadb-1070-release-notes/)**The mysql.password\_reuse\_check\_history Table is installed as part of the [password\_reuse\_check plugin](../password_reuse_check-plugin/index), available from [MariaDB 10.7.0](https://mariadb.com/kb/en/mariadb-1070-release-notes/).
The `mysql.password_reuse_check_history` table stores old passwords, so that when a user sets a new password, it can be checked for purposes of preventing password reuse.
It contains the following fields:
| Field | Type | Null | Key | Default | Description |
| --- | --- | --- | --- | --- | --- |
| hash | binary(64) | NO | PRI | NULL | |
| time | timestamp | NO | MUL | current\_timestamp() | |
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb CONSTRAINT CONSTRAINT
==========
MariaDB supports the implementation of constraints at the table-level using either [CREATE TABLE](../create-table/index) or [ALTER TABLE](../alter-table/index) statements. A table constraint restricts the data you can add to the table. If you attempt to insert invalid data on a column, MariaDB throws an error.
Syntax
------
```
[CONSTRAINT [symbol]] constraint_expression
constraint_expression:
| PRIMARY KEY [index_type] (index_col_name, ...) [index_option] ...
| FOREIGN KEY [index_name] (index_col_name, ...)
REFERENCES tbl_name (index_col_name, ...)
[ON DELETE reference_option]
[ON UPDATE reference_option]
| UNIQUE [INDEX|KEY] [index_name]
[index_type] (index_col_name, ...) [index_option] ...
| CHECK (check_constraints)
index_type:
USING {BTREE | HASH | RTREE}
index_col_name:
col_name [(length)] [ASC | DESC]
index_option:
| KEY_BLOCK_SIZE [=] value
| index_type
| WITH PARSER parser_name
| COMMENT 'string'
| CLUSTERING={YES|NO}
reference_option:
RESTRICT | CASCADE | SET NULL | NO ACTION | SET DEFAULT
```
Description
-----------
Constraints provide restrictions on the data you can add to a table. This allows you to enforce data integrity from MariaDB, rather than through application logic. When a statement violates a constraint, MariaDB throws an error.
There are four types of table constraints:
| Constraint | Description |
| --- | --- |
| `PRIMARY KEY` | Sets the column for referencing rows. Values must be unique and not null. |
| `FOREIGN KEY` | Sets the column to reference the primary key on another table. |
| `UNIQUE` | Requires values in column or columns only occur once in the table. |
| `CHECK` | Checks whether the data meets the given condition. |
The [Information Schema TABLE\_CONSTRAINTS Table](../information-schema-table_constraints-table/index) contains information about tables that have constraints.
### FOREIGN KEY Constraints
[InnoDB](../innodb/index) supports [foreign key](../foreign-keys/index) constraints. The syntax for a foreign key constraint definition in InnoDB looks like this:
```
[CONSTRAINT [symbol]] FOREIGN KEY
[index_name] (index_col_name, ...)
REFERENCES tbl_name (index_col_name,...)
[ON DELETE reference_option]
[ON UPDATE reference_option]
reference_option:
RESTRICT | CASCADE | SET NULL | NO ACTION
```
The [Information Schema REFERENTIAL\_CONSTRAINTS](../information-schema-referential_constraints-table/index) table has more information about foreign keys.
### CHECK Constraints
**MariaDB starting with [10.2.1](https://mariadb.com/kb/en/mariadb-1021-release-notes/)**From [MariaDB 10.2.1](https://mariadb.com/kb/en/mariadb-1021-release-notes/), constraints are enforced. Before [MariaDB 10.2.1](https://mariadb.com/kb/en/mariadb-1021-release-notes/) constraint expressions were accepted in the syntax but ignored.
In [MariaDB 10.2.1](https://mariadb.com/kb/en/mariadb-1021-release-notes/) you can define constraints in 2 different ways:
* `CHECK(expression)` given as part of a column definition.
* `CONSTRAINT [constraint_name] CHECK (expression)`
Before a row is inserted or updated, all constraints are evaluated in the order they are defined. If any constraint expression returns false, then the row will not be inserted or updated. One can use most deterministic functions in a constraint, including [UDFs](../user-defined-functions/index).
```
CREATE TABLE t1 (a INT CHECK (a>2), b INT CHECK (b>2), CONSTRAINT a_greater CHECK (a>b));
```
If you use the second format and you don't give a name to the constraint, then the constraint will get an automatically generated name. This is done so that you can later delete the constraint with [ALTER TABLE DROP constraint\_name](../alter-table/index).
One can disable all constraint expression checks by setting the [check\_constraint\_checks](../server-system-variables/index#check_constraint_checks) variable to `OFF`. This is useful for example when loading a table that violates some constraints that you want to later find and fix in SQL.
### Replication
In [row-based](../binary-log-formats/index#row-based) [replication](../replication/index), only the master checks constraints, and failed statements will not be replicated. In [statement-based](../binary-log-formats/index#statement-based) replication, the slaves will also check constraints. Constraints should therefore be identical, as well as deterministic, in a replication environment.
### Auto\_increment
**MariaDB starting with [10.2.6](https://mariadb.com/kb/en/mariadb-1026-release-notes/)*** From [MariaDB 10.2.6](https://mariadb.com/kb/en/mariadb-1026-release-notes/), [auto\_increment](../auto_increment/index) columns are no longer permitted in check constraints. Previously they were permitted, but would not work correctly. See [MDEV-11117](https://jira.mariadb.org/browse/MDEV-11117).
Examples
--------
```
CREATE TABLE product (category INT NOT NULL, id INT NOT NULL,
price DECIMAL,
PRIMARY KEY(category, id)) ENGINE=INNODB;
CREATE TABLE customer (id INT NOT NULL,
PRIMARY KEY (id)) ENGINE=INNODB;
CREATE TABLE product_order (no INT NOT NULL AUTO_INCREMENT,
product_category INT NOT NULL,
product_id INT NOT NULL,
customer_id INT NOT NULL,
PRIMARY KEY(no),
INDEX (product_category, product_id),
FOREIGN KEY (product_category, product_id)
REFERENCES product(category, id)
ON UPDATE CASCADE ON DELETE RESTRICT,
INDEX (customer_id),
FOREIGN KEY (customer_id)
REFERENCES customer(id)) ENGINE=INNODB;
```
**MariaDB starting with [10.2.1](https://mariadb.com/kb/en/mariadb-1021-release-notes/)**The following examples will work from [MariaDB 10.2.1](https://mariadb.com/kb/en/mariadb-1021-release-notes/) onwards.
Numeric constraints and comparisons:
```
CREATE TABLE t1 (a INT CHECK (a>2), b INT CHECK (b>2), CONSTRAINT a_greater CHECK (a>b));
INSERT INTO t1(a) VALUES (1);
ERROR 4022 (23000): CONSTRAINT `a` failed for `test`.`t1`
INSERT INTO t1(a,b) VALUES (3,4);
ERROR 4022 (23000): CONSTRAINT `a_greater` failed for `test`.`t1`
INSERT INTO t1(a,b) VALUES (4,3);
Query OK, 1 row affected (0.04 sec)
```
Dropping a constraint:
```
ALTER TABLE t1 DROP CONSTRAINT a_greater;
```
Adding a constraint:
```
ALTER TABLE t1 ADD CONSTRAINT a_greater CHECK (a>b);
```
Date comparisons and character length:
```
CREATE TABLE t2 (name VARCHAR(30) CHECK (CHAR_LENGTH(name)>2), start_date DATE,
end_date DATE CHECK (start_date IS NULL OR end_date IS NULL OR start_date<end_date));
INSERT INTO t2(name, start_date, end_date) VALUES('Ione', '2003-12-15', '2014-11-09');
Query OK, 1 row affected (0.04 sec)
INSERT INTO t2(name, start_date, end_date) VALUES('Io', '2003-12-15', '2014-11-09');
ERROR 4022 (23000): CONSTRAINT `name` failed for `test`.`t2`
INSERT INTO t2(name, start_date, end_date) VALUES('Ione', NULL, '2014-11-09');
Query OK, 1 row affected (0.04 sec)
INSERT INTO t2(name, start_date, end_date) VALUES('Ione', '2015-12-15', '2014-11-09');
ERROR 4022 (23000): CONSTRAINT `end_date` failed for `test`.`t2`
```
A misplaced parenthesis:
```
CREATE TABLE t3 (name VARCHAR(30) CHECK (CHAR_LENGTH(name>2)), start_date DATE,
end_date DATE CHECK (start_date IS NULL OR end_date IS NULL OR start_date<end_date));
Query OK, 0 rows affected (0.32 sec)
INSERT INTO t3(name, start_date, end_date) VALUES('Io', '2003-12-15', '2014-11-09');
Query OK, 1 row affected, 1 warning (0.04 sec)
SHOW WARNINGS;
+---------+------+----------------------------------------+
| Level | Code | Message |
+---------+------+----------------------------------------+
| Warning | 1292 | Truncated incorrect DOUBLE value: 'Io' |
+---------+------+----------------------------------------+
```
Compare the definition of table *t2* to table *t3*. `CHAR_LENGTH(name)>2` is very different to `CHAR_LENGTH(name>2)` as the latter mistakenly performs a numeric comparison on the *name* field, leading to unexpected results.
See Also
--------
* [Foreign Keys](../foreign-keys/index)
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mariadb MariaDB Backups Overview for SQL Server Users MariaDB Backups Overview for SQL Server Users
=============================================
MariaDB has the following types of backups:
* Logical backups (dumps).
* Hot backups with Mariabackup.
* Snapshots.
* Incremental backups.
Logical Backups (Dumps)
-----------------------
A *dump*, also called a *logical backup*, consists of the SQL statements needed to recreate MariaDB databases and their data into another server. A dump is the slowest form of backup to restore, because it implies executing all the SQL statements needed to recreate data. However it is also the most flexible, because restoring will work on any MariaDB version, because the SQL syntax is usually compatible. It is even possible to restore a dump into an older version, though the incompatible syntax (new features) will be ignored. Under certain conditions, MariaDB dumps may also be restored on other DBMSs, including SQL Server.
The compatibility between different versions and technologies is achieved by using [executable comments](../comment-syntax/index), but we should be aware of how they work. If we use a feature introduced in version 10.1, for example, it will be included in the dump inside an executable comment. If we restore that backup on a server with [MariaDB 10.0](../what-is-mariadb-100/index), the 10.1 feature will be ignored. This is the only way to restore backups in older MariaDB versions.
### mysqldump
Logical backups are usually taken with [mysqldump](../mysqldump/index).
mysqldump allows to dump all databases, a single database, or a set of tables from a database. It is even possible to specify a `WHERE` clause, which under certain circumstances allows to obtain incremental dumps.
For consistency reasons, when using the default storage engine [InnoDB](../understanding-mariadb-architecture/index#innodb), it is important to use the `--single-transaction` option. This will read all data in a single transaction. It's important however to understand that long transactions may have a big impact on performance.
The `--master-data` option adds the statements to setup a slave to the dump.
MariaDB also supports statements which make easy to write applications to obtain custom types of dumps. For most `CREATE <object_type>` statement, a corresponding `SHOW CREATE <object_type>` exists. For example, [SHOW CREATE TABLE](../show-create-table/index) returns the `CREATE TABLE` statement that can be used to recreate a certain table, without data.
### mydumper
[mydumper](https://github.com/maxbube/mydumper) is a 3rd party tools to take dumps from MariaDB and MySQL databases. It is much faster than mysqldump because it takes backups with several parallel threads, usually one thread for each available CPU core. It produces several files, that can be used to restore a database using the related tool myloader.
Since is it a 3rd party tool, it could be incompatible with some present or future MariaDB features.
Hot Backups (mariabackup)
-------------------------
**MariaDB starting with [10.1.23](https://mariadb.com/kb/en/mariadb-10123-release-notes/)**[mariabackup](../mariabackup-overview/index) was first released in [MariaDB 10.1.23](https://mariadb.com/kb/en/mariadb-10123-release-notes/) and [MariaDB 10.2.7](https://mariadb.com/kb/en/mariadb-1027-release-notes/). It was first released as GA in [MariaDB 10.1.26](https://mariadb.com/kb/en/mariadb-10126-release-notes/) and [MariaDB 10.2.10](https://mariadb.com/kb/en/mariadb-10210-release-notes/).
**MariaDB until [10.1.23](https://mariadb.com/kb/en/mariadb-10123-release-notes/)**With older versions, it is possible to use Percona Xtrabackup. The problem with that tool is that it is written for MySQL, not MariaDB. When using MariaDB features not supported by MySQL it may break or produce unexpected results.
Mariabackup is a tool for taking a backup of MariaDB files while MariaDB is working. A lock is only held for a small amount of time, so it is suitable to backup a server without causing disruptions. It works by taking corrupted backups and then bringing them to a consistent state by using the [InnoDB undo log](../innodb-undo-log/index). Mariabackup also properly backups [MyRocks](../myrocks/index) tables and non-transactional storage engines.
Cold Backups and Snapshots
--------------------------
A copy of all MariaDB files is a working backup. Therefore, the easiest way to backup a dataset is to shutdown the server and copy all its files. It will be entirely possible to start another server with a copy of those files. This is often referred to as a *cold backup*. However, in most cases we don't want to do this, because it implies downtime for the server: it will not be working at least for the time necessary to copy the files.
Snapshots are usually a better idea, as they are a consistent copy of the files at a given moment in time, taken without stopping the normal operations.
A snapshot of the files can be taken at several levels: filesystem level, if the filesystem supports snapshots, for example zfs; Linux Logical Volume Manager (LVM) also supports snapshots; and virtual machines also allow one to take snapshots. Windows shadow copies are also snapshots, with a benefit: it is possible to restore a single file from a shadow copy. A snapshot is not an expensive operation, because it does not imply a copy of the files. The current files will not be modified anymore, and changes to them will be written in separate places.
The problem with snapshots is that they behave like a logical copy of the files as they are in a given point in time. But database files are not guaranteed to be consistent in every moment, because contents can be buffered before being flushed to the disk. You can think a database snapshot like a database after an operating system crash.
With non-transactional tables, some data is typically lost. Data changes that are present in a buffer before the snapshot, but not written on a disk, cannot be recovered in any way. Data changes in transactional tables, like InnoDB tables, can always be recovered after restoring a snapshot (or after a crash), as long as a commit was done. Tables will still need to be repaired, just like it happens after an SQL Server crash.
Snapshots can be taken while MariaDB is running. To restore them, stop MariaDB first - or kill the process, because you don't really care of the consequences in this case. Then restore a snapshot and start MariaDB again.
For more information about snapshots, check your filesystem, LVM or virtual machine documentation.
Incremental Backups
-------------------
The term incremental backup in MariaDB indicates what SQL Server calls a *[differential backup](https://docs.microsoft.com/en-us/sql/relational-databases/backup-restore/differential-backups-sql-server)*. An important difference is that in SQL Server such backups are based on the [transaction log](https://docs.microsoft.com/en-us/sql/relational-databases/backup-restore/transaction-log-backups-sql-server), which wouldn't be possible in MariaDB because transaction logs are handled at storage engine level.
As mentioned [here](../understanding-mariadb-architecture/index#the-binary-log), MariaDB can use the [binary log](../binary-log/index) instead for backup purposes. Such incremental backups can be done manually. This means that:
* The binary log files are copied just like any other regular file.
* To copy those files it is necessary to have the proper permissions at filesystem level, not in MariaDB.
* Backups do not expire until we delete the last needed complete backup.
### Replaying the Binary Log
The page [Using mysqlbinlog](../using-mysqlbinlog/index) shows how to use the mysqlbinlog utility to replay a binary log file.
The page also shows how to edit the binary log before replaying it. This allows one to undo an SQL statement that was executed by mistake, for example a `DROP TABLE` against a wrong table. The high level procedure is the following:
* Restore a backup that is older than the SQL statement to undo.
* Use `mysqlbinlog` to generate a file with the SQL statements that were executed after the backup.
* Edit the SQL file, erasing the unwanted statement.
* Run the SQL file.
### Incremental Backups with mariabackup
The simplest way to take an incremental backup is to use Mariabackup. This tool is able to take and restore incremental backups. For the complete procedure to use, see [Incremental Backup and Restore with Mariabackup](../incremental-backup-and-restore-with-mariabackup/index).
Mariabackup can run on both Linux and Windows systems.
### Flashback
**MariaDB starting with [10.2.4](https://mariadb.com/kb/en/mariadb-1024-release-notes/)**DML-only flashback was introduced in [MariaDB 10.2.4](https://mariadb.com/kb/en/mariadb-1024-release-notes/)
[Flashback](../flashback/index) is a feature that allows one to bring all databases, some databases or some tables back to a certain point in time. This can only be done if the binary log is enabled. Flashback is not a proper backup, but it can be used to restore a certain set of data.
### Copying Individual Tables
It is entirely possible to restore a single table from a physical backup, or to copy the table to another server.
With the [MyISAM](../myisam/index) storage engine it was very easy to move tables between different servers, as long as the MySQL or MariaDB version was the same.
[InnoDB](../innodb/index) is nowadays the default storage engine, and it is more complex, as it supports transactions for example. It still supports restoring a table from a physical file, this feature is called *transportable tablespaces*. There is a particular procedure to follow, and some limitations. This is basically the MariaDB equivalent of detaching and re-attaching tables in SQL Server.
For more information, see [InnoDB File-Per-Table Tablespaces](../innodb-file-per-table-tablespaces/index).
By default. all table files are located in the *data directory*, which is defined by the system variable [datadir](../server-system-variables/index#datadir). There may be exceptions, because a table's files can be located elsewhere using the [`DATA DIRECTORY` and `INDEX DIRECTORY`](../create-table/index#data-directoryindex-directory) options in `CREATE TABLE`.
Regardless of the storage engine used, each table's structure is generally stored in a file with the `.frm` extension.
The files used for [partitioned tables](../partitioning-tables/index) are different from the files used for non-partitioned tables. See [Partitions Files](../partitions-files/index) for details.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb Filesystem Optimizations Filesystem Optimizations
========================
Which filesystem is best?
-------------------------
The filesystem is not the most important aspect of MariaDB performance. Far more important are available RAM, drive speed, the system variable settings (see [Hardware Optimization](../hardware-optimization/index) and [System Variables](../system-variables/index)).
Optimizing the filesystem can however in some cases make a noticeable difference. Currently, the best Linux filesystems are generally regarded as ext4, XFS and Btrfs. They are all included in the mainline Linux kernel, and are widely supported and available on most Linux distributions. Red Hat though regards Brtfs as a technology preview, not yet ready for production systems.
The following theoretical file size and filesystem size limits apply to the three filesystems:
| | | | |
| --- | --- | --- | --- |
| | ext4 | XFS | Brtfs |
| Max file size | 16TB | 8EB | 16EB |
| Max filesystem size | 1 EB | 8EB | 16EB |
Each has unique characteristics that are worth understanding to get the most from.
Disabling access time
---------------------
It's unlikely you'll need to record file access time on a database server, and mounting your filesystem with this disabled can give an easy improvement in performance. To do so, use the `noatime` option.
If you want to keep access time for [log files](../log-files/index) or other system files, these can be stored on a separate drive.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb JSON_ARRAYAGG JSON\_ARRAYAGG
==============
**MariaDB starting with [10.5.0](https://mariadb.com/kb/en/mariadb-1050-release-notes/)**JSON\_ARRAYAGG was added in [MariaDB 10.5.0](https://mariadb.com/kb/en/mariadb-1050-release-notes/).
Syntax
------
```
JSON_ARRAYAGG(column_or_expression)
```
Description
-----------
`JSON_ARRAYAGG` returns a JSON array containing an element for each value in a given set of JSON or SQL values. It acts on a column or an expression that evaluates to a single value.
Returns NULL in the case of an error, or if the result contains no rows.
`JSON_ARRAYAGG` cannot currently be used as a [window function](../window-functions/index).
The full syntax is as follows:
```
JSON_ARRAYAGG([DISTINCT] expr [,expr ...]
[ORDER BY {unsigned_integer | col_name | expr}
[ASC | DESC] [,col_name ...]]
[LIMIT {[offset,] row_count | row_count OFFSET offset}])
```
Examples
--------
```
CREATE TABLE t1 (a INT, b INT);
INSERT INTO t1 VALUES (1, 1),(2, 1), (1, 1),(2, 1), (3, 2),(2, 2),(2, 2),(2, 2);
SELECT JSON_ARRAYAGG(a), JSON_ARRAYAGG(b) FROM t1;
+-------------------+-------------------+
| JSON_ARRAYAGG(a) | JSON_ARRAYAGG(b) |
+-------------------+-------------------+
| [1,2,1,2,3,2,2,2] | [1,1,1,1,2,2,2,2] |
+-------------------+-------------------+
SELECT JSON_ARRAYAGG(a), JSON_ARRAYAGG(b) FROM t1 GROUP BY b;
+------------------+------------------+
| JSON_ARRAYAGG(a) | JSON_ARRAYAGG(b) |
+------------------+------------------+
| [1,2,1,2] | [1,1,1,1] |
| [3,2,2,2] | [2,2,2,2] |
+------------------+------------------+
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb MariaDB Debian Live Images MariaDB Debian Live Images
==========================
**Note:** This page is obsolete. The information is old, outdated, or otherwise currently incorrect. We are keeping the page for historical reasons only. **Do not** rely on the information in this article.
A member of the MariaDB community, Mark `<ms (at) it-infrastrukturen (dot) org>`, has created some Debian "squeeze" 6.0.4 based, live iso images with [MariaDB 5.2](../what-is-mariadb-52/index) or 5.3 pre-installed on them and some Debian "squeeze" 6.0.5 based, live iso images with [MariaDB 5.5](../what-is-mariadb-55/index) pre-installed on them.
These live and install images can be used to quickly run a MariaDB server in live mode for learning or testing purposes, or to simplify and speed up off-line installations of Debian-based MariaDB servers onto harddisk.
To work in live mode the system boots from a usb stick (or CD/DVD) and runs in RAM without touching the system's harddisk drive.
The same usb stick (or CD/DVD media) can be used to install a complete server installation onto the harddisk drive using the included Debian installer.
All required MariaDB packages are included on the media, so there is no need for an Internet connection.
Three types of images are provided, text (command line), LXDE, and Gnome. The text-based live images can be used for testing or server off-line installations. The two gui types, LXDE and Gnome, can be used for testing/learning in live mode or for off-line desktop installations. Debian live images with LXDE (gnome, KDE or awesome) are pretty comfortable for daily work as a replacement for whatever desktop OS is installed on on the system.
There are three iso images for each type, one for 32-bit (i386) systems, one for 64-bit (amd64) systems, and one with both.
1. [MariaDB 5.2](../what-is-mariadb-52/index) Live iso images (text) for i386, amd64 or multi architectures.
* `[binary-hybrid-squeeze-i386-mariadb52-text.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-i386-mariadb52-text.iso)`
* `[binary-hybrid-squeeze-amd64-mariadb52-text.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-amd64-mariadb52-text.iso)`
* `[binary-hybrid-squeeze-i386-amd64-mariadb52-text.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-i386-amd64-mariadb52-text.iso)`
2. [MariaDB 5.3](../what-is-mariadb-53/index) Live iso images (text) for i386, amd64 or multi architectures.
* `[binary-hybrid-squeeze-i386-mariadb53-text.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-i386-mariadb53-text.iso)`
* `[binary-hybrid-squeeze-amd64-mariadb53-text.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-amd64-mariadb53-text.iso)`
* `[binary-hybrid-squeeze-i386-amd64-mariadb53-text.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-i386-amd64-mariadb53-text.iso)`
3. [MariaDB 5.3](../what-is-mariadb-53/index) Live iso images with LXDE for i386, amd64 or multi architectures.
* `[binary-hybrid-squeeze-i386-mariadb53-lxde.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-i386-mariadb53-lxde.iso)`
* `[binary-hybrid-squeeze-amd64-mariadb53-lxde.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-amd64-mariadb53-lxde.iso)`
* `[binary-hybrid-squeeze-i386-amd64-mariadb53-lxde.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-i386-amd64-mariadb53-lxde.iso)`
4. [MariaDB 5.3](../what-is-mariadb-53/index) Live iso images with Gnome for i386, amd64 or multi architectures.
* `[binary-hybrid-squeeze-i386-mariadb53-gnome.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-i386-mariadb53-gnome.iso)`
* `[binary-hybrid-squeeze-amd64-mariadb53-gnome.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-amd64-mariadb53-gnome.iso)`
* `[binary-hybrid-squeeze-i386-amd64-mariadb53-gnome.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-i386-amd64-mariadb53-gnome.iso)`
5. [MariaDB 5.5](../what-is-mariadb-55/index) Live images
* `[binary-hybrid-squeeze-amd64-mariadb55-text-bpo.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-amd64-mariadb55-text-bpo.iso)`
* `[binary-hybrid-squeeze-amd64-mariadb55-lxde-bpo.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-amd64-mariadb55-lxde-bpo.iso)`
* `[binary-hybrid-squeeze-amd64-mariadb55-gnome-bpo.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-amd64-mariadb55-gnome-bpo.iso)`
* `[binary-hybrid-squeeze-amd64-mariadb55-awesome-bpo.iso](http://rsync.it-infrastrukturen.org/public-mariadb/binary-hybrid-squeeze-amd64-mariadb55-awesome-bpo.iso)`
6. [MariaDB 5.5](../what-is-mariadb-55/index) Live images demonstration video
* `[README-mariadb-video.txt](http://rsync.it-infrastrukturen.org/public-mariadb/README-mariadb-video.txt)`
* `[video-mariadb5.5-live-images-on-USB.ogv](http://rsync.it-infrastrukturen.org/public-mariadb/video-mariadb5.5-live-images-on-USB.ogv)`
* `[video-mariadb5.5-live-images-on-USB.mp4](http://rsync.it-infrastrukturen.org/public-mariadb/video-mariadb5.5-live-images-on-USB.mp4)`
The LXDE and Gnome images contain documentation under `/srv/PDF`. Including instructions on how to create your own Debian live images in live mode (you need 16GB RAM or more to be able to do this). See the README, README.live, and live-manual.en.pdf files under `/srv/PDF` for details.
**Note:** Some HP notebooks are not able to boot binary hybrid iso images from a USB stick.
Downloads
---------
To get the iso images you can use rsync:
```
rsync -avP rsync://rsync.it-infrastrukturen.org/ftp/public-mariadb/<image_or_file_name_as_above> .
```
or just use the links above (or go to: <http://rsync.it-infrastrukturen.org/public-mariadb/> ).
Preparing of bootable media:
----------------------------
A USB stick or CD/DVD can be used as bootable media. The preferred way is a USB stick.
* for Linux: `dd if=./<image_name_as_above.iso> of=/dev/<USB-stick-ID_like_sdb_or_sdc>`
* for other systems: cygwin includes dd and some other linux/Unix tools.
The iso images have been successfully tested on:
* Acer ASPIRE @ne netbooks (1GB RAM)
* ThinkPad T60p and T61p notebooks (2 or 4GB RAM)
* Xeon E31270 / Asus P8BWS desktop (16GB ECC RAM)
* AMD FX-4100 / Asus M5A99X EVO desktop (16GB ECC RAM)
* HP DL385g7 Opteron 6170SE or 6180SE servers (32 or 64GB ECC RAM)
### Notes
It is possible to add some options on the bootline for special purposes like, for example, the installation of additional packages from a local repository on the image or assigning a static IP address and running sshd.
1. To configure a static IP use "`ip=`". For example: "`ip=eth0:192.168.1.53:255.255.255.0:192.168.1.1`"
* The full format of "`ip=`" is: "`ip=[interface]:[IP_address]:[netmask]:[gateway]`"
2. If you use an empty "`ip=`" value the content of `/etc/network/interfaces` and `/etc/resolv.conf` will be used. Without the "`ip=`" option, dhcp will be used to get an IP address.
3. For installing and running sshd (so that the image can act as a server in a test environment) use: "`sshd=on`"
* The live user is "sql" and the password is "live". Please change the password immediately after first login!
4. Depending on the image [MariaDB 5.2](../what-is-mariadb-52/index) or 5.3 server is installed. There is no root passord for the database set so please set a password immediately after first login!
5. Run `repo-off-line.sh` to activate local repositories on the image for apt-get (for off-line installations) or `repo-on-line.sh` for internet repositories.
6. The binary hybrid live iso images with multiple-choices inside the boot menu allow for the assignment of two different IPs. (e.g. for testing of clustered database operations)
Send any feedback or suggestions related to these images to:
* Mark `<ms (at) it-infrastrukturen (dot) org>`
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Threadpool Benchmarks Threadpool Benchmarks
=====================
Here are some benchmarks of some development threadpool code (the [5.5 threadpool](../thread-pool-in-mariadb/index)).
The benchmarks were run on three machines:
* facebook-maria1 (Linux, 16 cores)
* pitbull (Linux, 24 cores)
* windows (Windows, 8 cores)
Sysbench 0.4 was used to run some "unit" OLTP tests (point-select and update-nokey), as well as the "classic" OLTP-readonly and OLTP-readwrite. All tests were run with the number of concurrent clients ranging from 16 to 4096, with warm cache, with the sysbench table having 1M records.
The results are quite different on all of the machines tested (the machines are very different, in terms of cores, IO etc), yet threadpool has a positive effect on all 3 machines, and the positive effect seems to grow with the number of cores.
Some notes on how the benchmarks were run:
1. The benchmark client and server used different CPUs - ('taskset' (Linux), or 'start /affinity' (Windows) were used to run the benchmark client on `#CPUs/4`, the rest of CPUs were used by the server). On the Linux boxes, `--thread_pool_size=<N>` (where N is number of cores dedicated to the server) was used.
2. `innodb_flush_log_at_trx_commit=0` and `innodb_flush_method=ALL_O_DIRECT` was used to avoid extensive fsyncing, which is ok for the purposes of the testing for this.
3. Every "write" benchmark (`oltp_rw` and `update_nokey`) started with a new server (i.e. kill mysqld, remove innodb files, and restart mysqld for each test). Every "read" benchmark, on the other hand, reused the same running server instance. Starting afresh with a new server on write benchmarks is done mainly to eliminate the effects of the purge lag.
4. The results are in queries-per-second (QPS).
OLTP\_RO
--------
### OLTP\_RO facebook-maria1
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 3944 | 4725 | 4878 | 4863 | 4732 | 4554 | 4345 | 4103 | 1670 |
| threadpool | 3822 | 4955 | 4991 | 5017 | 4908 | 4716 | 4610 | 4307 | 2962 |
### OLTP\_RO pitbull
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 6754 | 7905 | 8152 | 7948 | 7924 | 7587 | 5313 | 3827 | 208 |
| threadpool | 6566 | 7725 | 8108 | 8079 | 7976 | 7793 | 7429 | 6523 | 4456 |
### OLTP\_RO Windows
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 1822 | 1831 | 1825 | 1829 | 1816 | 1879 | 1866 | 1783 | 987 |
| threadpool | 2019 | 2049 | 2024 | 1992 | 1924 | 1897 | 1855 | 1825 | 1403 |
OLTP\_RW
--------
### OLTP\_RW facebook-maria1
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 2833 | 3510 | 3545 | 3420 | 3259 | 2818 | 1788 | 820 | 113 |
| threadpool | 3163 | 3590 | 3498 | 3459 | 3354 | 3117 | 2190 | 1064 | 506 |
### OLTP\_RW pitbull
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 4561 | 5316 | 5332 | 3512 | 2874 | 2476 | 1380 | 265 | 53 |
| threadpool | 4504 | 5382 | 5694 | 5567 | 5302 | 4514 | 2548 | 1186 | 484 |
### OLTP\_RW Windows
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 1480 | 1498 | 1472 | 1477 | 1456 | 1371 | 731 | 328 | 82 |
| threadpool | 1449 | 1523 | 1527 | 1492 | 1443 | 1409 | 1365 | 1240 | 862 |
POINT\_SELECT
-------------
### POINT\_SELECT facebook-maria1
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 91322 | 113116 | 115418 | 114484 | 111169 | 104612 | 26902 | 12843 | 5038 |
| threadpool | 100359 | 115618 | 118115 | 120136 | 119165 | 113931 | 110787 | 109970 | 104985 |
### POINT\_SELECT pitbull
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 148673 | 161547 | 169747 | 172083 | 69036 | 42041 | 21775 | 4368 | 282 |
| threadpool | 143222 | 167069 | 167270 | 165977 | 164983 | 158410 | 148690 | 147107 | 143934 |
### POINT\_SELECT Windows
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 39734 | 42885 | 44448 | 44478 | 41720 | 38196 | 36844 | 35404 | 23306 |
| threadpool | 42143 | 45679 | 47066 | 47753 | 46720 | 44215 | 43677 | 43093 | 44364 |
UPDATE\_NOKEY
-------------
### UPDATE\_NOKEY facebook-maria1
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 60165 | 65761 | 67727 | 57232 | 47612 | 26341 | 8981 | 3265 | 389 |
| threadpool | 65092 | 68683 | 67053 | 64141 | 64815 | 63047 | 63346 | 63638 | 62843 |
### UPDATE\_NOKEY pitbull
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 65213 | 71680 | 19418 | 13008 | 11155 | 8742 | 5645 | 635 | 332 |
| threadpool | 64902 | 70236 | 70037 | 68926 | 69930 | 69929 | 67099 | 62376 | 17766 |
### UPDATE\_NOKEY Windows
| concurrent clients | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| thread per connection | 24790 | 25634 | 25639 | 25309 | 24754 | 19420 | 5249 | 2361 | 824 |
| threadpool | 25251 | 25259 | 25406 | 25327 | 24850 | 23818 | 23137 | 23003 | 22047 |
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Information Schema DISKS Table Information Schema DISKS Table
==============================
**MariaDB [10.1.32](https://mariadb.com/kb/en/mariadb-10132-release-notes/)**The `DISKS` table was introduced in [MariaDB 10.1.32](https://mariadb.com/kb/en/mariadb-10132-release-notes/), [MariaDB 10.2.14](https://mariadb.com/kb/en/mariadb-10214-release-notes/), and [MariaDB 10.3.6](https://mariadb.com/kb/en/mariadb-1036-release-notes/) as part of the `[DISKS](../disks-plugin/index)` plugin.
Description
-----------
The `DISKS` table is created when the [DISKS](../disks-plugin/index) plugin is enabled, and shows metadata about disks on the system.
Before [MariaDB 10.4.7](https://mariadb.com/kb/en/mariadb-1047-release-notes/), [MariaDB 10.3.17](https://mariadb.com/kb/en/mariadb-10317-release-notes/), [MariaDB 10.2.26](https://mariadb.com/kb/en/mariadb-10226-release-notes/) and [MariaDB 10.1.41](https://mariadb.com/kb/en/mariadb-10141-release-notes/), this plugin did **not** check [user privileges](../grant/index). When it is enabled, **any** user can query the `INFORMATION_SCHEMA.DISKS` table and see all the information it provides.
Since [MariaDB 10.4.7](https://mariadb.com/kb/en/mariadb-1047-release-notes/), [MariaDB 10.3.17](https://mariadb.com/kb/en/mariadb-10317-release-notes/), [MariaDB 10.2.26](https://mariadb.com/kb/en/mariadb-10226-release-notes/) and [MariaDB 10.1.41](https://mariadb.com/kb/en/mariadb-10141-release-notes/), it requires the [FILE privilege](../grant/index).
The plugin only works on Linux.
The table contains the following columns:
| Column | Description |
| --- | --- |
| `DISK` | Name of the disk itself. |
| `PATH` | Mount point of the disk. |
| `TOTAL` | Total space in KiB. |
| `USED` | Used amount of space in KiB. |
| `AVAILABLE` | Amount of space in KiB available to non-root users. |
Note that as the amount of space available to root (OS user) may be more that what is available to non-root users, 'available' + 'used' may be less than 'total'.
All paths to which a particular disk has been mounted are reported. The rationale is that someone might want to take different action e.g. depending on which disk is relevant for a particular path. This leads to the same disk being reported multiple times.
Example
-------
```
SELECT * FROM information_schema.DISKS;
+-----------+-------+----------+---------+-----------+
| Disk | Path | Total | Used | Available |
+-----------+-------+----------+---------+-----------+
| /dev/vda1 | / | 26203116 | 2178424 | 24024692 |
| /dev/vda1 | /boot | 26203116 | 2178424 | 24024692 |
| /dev/vda1 | /etc | 26203116 | 2178424 | 24024692 |
+-----------+-------+----------+---------+-----------+
```
See Also
--------
* [Disks Plugin](../disks-plugin/index) for details on installing, options
* [Plugin Overview](../plugin-overview/index) for details on managing plugins.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb Performance Schema events_waits_summary_by_user_by_event_name Table Performance Schema events\_waits\_summary\_by\_user\_by\_event\_name Table
==========================================================================
The [Performance Schema](../performance-schema/index) `events_waits_summary_by_user_by_event_name` table contains wait events summarized by user and event name. It contains the following columns:
| Column | Description |
| --- | --- |
| `USER` | User. Used together with `EVENT_NAME` for grouping events. |
| `EVENT_NAME` | Event name. Used together with `USER` for grouping events. |
| `COUNT_STAR` | Number of summarized events |
| `SUM_TIMER_WAIT` | Total wait time of the summarized events that are timed. |
| `MIN_TIMER_WAIT` | Minimum wait time of the summarized events that are timed. |
| `AVG_TIMER_WAIT` | Average wait time of the summarized events that are timed. |
| `MAX_TIMER_WAIT` | Maximum wait time of the summarized events that are timed. |
The `*_TIMER_WAIT` columns only calculate results for timed events, as non-timed events have a `NULL` wait time.
Example
-------
```
SELECT * FROM events_waits_summary_by_user_by_event_name\G
...
*************************** 916. row ***************************
USER: NULL
EVENT_NAME: wait/io/socket/sql/server_unix_socket
COUNT_STAR: 0
SUM_TIMER_WAIT: 0
MIN_TIMER_WAIT: 0
AVG_TIMER_WAIT: 0
MAX_TIMER_WAIT: 0
*************************** 917. row ***************************
USER: NULL
EVENT_NAME: wait/io/socket/sql/client_connection
COUNT_STAR: 0
SUM_TIMER_WAIT: 0
MIN_TIMER_WAIT: 0
AVG_TIMER_WAIT: 0
MAX_TIMER_WAIT: 0
*************************** 918. row ***************************
USER: NULL
EVENT_NAME: idle
COUNT_STAR: 0
SUM_TIMER_WAIT: 0
MIN_TIMER_WAIT: 0
AVG_TIMER_WAIT: 0
MAX_TIMER_WAIT: 0
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb MATCH AGAINST MATCH AGAINST
=============
Syntax
------
```
MATCH (col1,col2,...) AGAINST (expr [search_modifier])
```
Description
-----------
A special construct used to perform a fulltext search on a fulltext index.
See [Fulltext Index Overview](../fulltext-index-overview/index) for a full description, and [Full-text Indexes](../full-text-indexes/index) for more articles on the topic.
Examples
--------
```
CREATE TABLE ft_myisam(copy TEXT,FULLTEXT(copy)) ENGINE=MyISAM;
INSERT INTO ft_myisam(copy) VALUES ('Once upon a time'), ('There was a wicked witch'),
('Who ate everybody up');
SELECT * FROM ft_myisam WHERE MATCH(copy) AGAINST('wicked');
+--------------------------+
| copy |
+--------------------------+
| There was a wicked witch |
+--------------------------+
```
```
SELECT id, body, MATCH (title,body) AGAINST
('Security implications of running MySQL as root'
IN NATURAL LANGUAGE MODE) AS score
FROM articles WHERE MATCH (title,body) AGAINST
('Security implications of running MySQL as root'
IN NATURAL LANGUAGE MODE);
+----+-------------------------------------+-----------------+
| id | body | score |
+----+-------------------------------------+-----------------+
| 4 | 1. Never run mysqld as root. 2. ... | 1.5219271183014 |
| 6 | When configured properly, MySQL ... | 1.3114095926285 |
+----+-------------------------------------+-----------------+
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb mroonga_snippet_html mroonga\_snippet\_html
======================
Description
-----------
`mroonga_snippet_html` is a [user-defined function](../user-defined-functions/index) (UDF) included with the [Mroonga storage engine](../mroonga/index). It provides a keyword with surrounding text, or the keyword in context. It is still considered experimental. See [Creating Mroonga User-Defined Functions](../creating-mroonga-user-defined-functions/index) for details on creating this UDF if required.
See Also
--------
* [Creating Mroonga User-Defined Functions](../creating-mroonga-user-defined-functions/index)
* [mroonga\_snippet](../mroonga_snippet/index)
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Database Normalization Overview Database Normalization Overview
===============================
Developed in the 1970's by E.F. Codd, database normalization is standard requirement of many database designs. Normalization is a technique that can help you avoid data anomalies and other problems with managing your data. It consists of transforming a table through various stages: *1st normal form*, *2nd normal form*, *3rd normal form*, and beyond.
It aims to:
* Eliminate data redundancies (and therefore use less space)
* Make it easier to make changes to data, and avoid anomalies when doing so
* Make referential integrity constraints easier to enforce
* Produce an easily comprehensible structure that closely resembles the situation the data represents, and allows for growth
Let's begin by creating a sample set of data. You'll walk through the process of normalization first without worrying about the theory, to get an understanding of the reasons you'd want to normalize. Once you've done that, we'll introduce the theory and the various stages of normalization, which will make the whole process described below much simpler the next time you do it.
Imagine you are working on a system that records plants placed in certain locations, and the soil descriptions associated with them.
The location:
* Location Code: 11
* Location name: Kirstenbosch Gardens
contains the following three plants:
* Plant code: 431
* Plant name: Leucadendron
* Soil category: A
* Soil description: Sandstone
* Plant code: 446
* Plant name: Protea
* Soil category: B
* Soil description: Sandstone/Limestone
* Plant code: 482
* Plant name: Erica
* Soil category: C
* Soil description: Limestone
The location:
* Location Code: 12
* Location name: Karbonkelberg Mountains
contains the following two plants:
* Plant code: 431
* Plant name: Leucadendron
* Soil category: A
* Soil description: Sandstone
* Plant code: 449
* Plant name: Restio
* Soil category: B
* Soil description: Sandstone/Limestone
Tables in a relational database are in a grid, or table format (MariaDB, like most modern DBMSs is a relational database), so let's rearrange this data in the form of a tabular report:
### Plant data displayed as a tabular report
| Location code | Location name | Plant code | Plant name | Soil category | Soil description |
| --- | --- | --- | --- | --- | --- |
| 11 | Kirstenbosch Gardens | 431 | Leaucadendron | A | Sandstone |
| | | 446 | Protea | B | Sandstone/limestone |
| | | 482 | Erica | C | Limestone |
| 12 | Karbonkelberg Mountains | 431 | Leucadendron | A | Sandstone |
| | | 449 | Restio | B | Sandstone/limestone |
How are you to enter this data into a table in the database? You could try to copy the layout you see above, resulting in a table something like the below. The null fields reflect the fields where no data was entered.
### Trying to create a table with plant data
| Location code | Location name | Plant code | Plant name | Soil category | Soil description |
| --- | --- | --- | --- | --- | --- |
| 11 | Kirstenbosch Gardens | 431 | Leucadendron | A | Sandstone |
| NULL | NULL | 446 | Protea | B | Sandstone/limestone |
| NULL | NULL | 482 | Erica | C | Limestone |
| 1 2 | Karbonkelberg Mountains | 431 | Leucadendron | A | Sandstone |
| NULL | NULL | 449 | Restio | B | Sandstone/limestone |
This table is not much use, though. The first three rows are actually a group, all belonging to the same location. If you take the third row by itself, the data is incomplete, as you cannot tell the location the Erica is to be found. Also, with the table as it stands, you cannot use the location code, or any other fields, as a primary key (remember, a primary key is a field, or list of fields, that uniquely identify one record). There is not much use in having a table if you can't uniquely identify each record in it.
So, the solution is to make sure each table row can stand alone, and is not part of a group, or set. To achieve this, remove the groups, or sets of data, and make each row a complete record in its own right, which results in the table below.
### Each record stands alone
| Location code | Location name | Plant code | Plant name | Soil category | Soil description |
| --- | --- | --- | --- | --- | --- |
| 11 | Kirstenbosch Gardens | 431 | Leucadendron | A | Sandstone |
| 11 | Kirstenbosch Gardens | 446 | Protea | B | Sandstone/limestone |
| 11 | Kirstenbosch Gardens | 482 | Erica | C | Limestone |
| 12 | Karbonkelberg Mountains | 431 | Leucadendron | A | Sandstone |
| 12 | Karbonkelberg Mountains | 449 | Restio | B | Sandstone/limestone |
Notice that the location code cannot be a primary key on its own. It does not uniquely identify a row of data. So, the primary key must be a combination of *location code* and *plant code*. Together these two fields uniquely identify a row of data. Think about it. You would never add the same plant type more than once to a particular location. Once you have the fact that it occurs in that location, that's enough. If you want to record quantities of plants at a location - for this example, you're just interested in the spread of plants - you don't need to add an entire new record for each plant; rather, just add a quantity field. If for some reason you would be adding more than one instance of a plant/location combination, you'd need to add something else to the key to make it unique.
So, now the data can go in table format, but there are still problems with it. The table stores the information that code *11* refers to *Kirstenbosch Gardens* three times! Besides the waste of space, there is another serious problem. Look carefully at the data below.
### Data anomaly
| Location code | Location name | Plant code | Plant name | Soil category | Soil description |
| --- | --- | --- | --- | --- | --- |
| 11 | Kirstenbosch Gardens | 431 | Leucadendron | A | Sandstone |
| 11 | Kirstenbosh Gardens | 446 | Protea | B | Sandstone/limestone |
| 11 | Kirstenbosch Gardens | 482 | Erica | C | Limestone |
| 12 | Karbonkelberg Mountains | 431 | Leucadendron | A | Sandstone |
| 12 | Karbonkelberg Mountains | 449 | Restio | B | Sandstone/limestone |
Did you notice anything strange? Congratulations if you did! *Kirstenbosch* is misspelled in the second record. Now imagine trying to spot this error in a table with thousands of records! By using the structure in the table above, the chances of data anomalies increases dramatically.
The solution is simple. You remove the duplication. What you are doing is looking for partial dependencies - in other words, fields that are dependent on a part of a key and not the entire key. Because both the location code and the plant code make up the key, you look for fields that are dependent only on location code or on plant name.
There are quite a few fields where this is the case. Location name is dependent on location code (plant code is irrelevant in determining project name), and plant name, soil code, and soil name are all dependent on plant number. So, take out all these fields, as shown in the table below:
### Removing the fields not dependent on the entire key
| Location code | Plant code |
| --- | --- |
| 11 | 431 |
| 11 | 446 |
| 11 | 482 |
| 12 | 431 |
| 12 | 449 |
Clearly you can't remove the data and leave it out of your database completely. You take it out, and put it into a new table, consisting of the fields that have the partial dependency and the fields on which they are dependent. For each of the *key* fields in the partial dependency, you create a new table (in this case, both are already part of the primary key, but this doesn't always have to be the case). So, you identified *plant name*, *soil description* and *soil category* as being dependent on *plant code*. The new table will consist of *plant code*, as a key, as well as plant name, soil category and soil description, as shown below:
### Creating a new table with location data
| Plant code | Plant name | Soil category | Soil description |
| --- | --- | --- | --- |
| 431 | Leucadendron | A | Sandstone |
| 446 | Protea | B | Sandstone/limestone |
| 482 | Erica | C | Limestone |
| 431 | Leucadendron | A | Sandstone |
| 449 | Restio | B | Sandstone/limestone |
You do the same process with the location data, shown below:
### Creating a new table with location data
| Location code | Location name |
| --- | --- |
| 11 | Kirstenbosch Gardens |
| 12 | Karbonkelberg Mountains |
See how these tables remove the earlier duplication problem? There is only one record that contains *Kirstenbosch Gardens*, so the chances of noticing a misspelling are much higher. And you aren't wasting space storing the name in many different records. Notice that the location code and plant code fields are repeated in two tables. These are the fields that create the relation, allowing you to associate the various plants with the various locations. Obviously there is no way to remove the duplication of these fields without losing the relation altogether, but it is far more efficient storing a small code repeatedly than a large piece of text.
But the table is still not perfect. There is still a chance for anomalies to slip in. Examine the table below carefully:
### Another anomaly
| Plant code | Plant name | Soil category | Soil description |
| --- | --- | --- | --- |
| 431 | Leucadendron | A | Sandstone |
| 446 | Protea | B | Sandstone/limestone |
| 482 | Erica | C | Limestone |
| 431 | Leucadendron | A | Sandstone |
| 449 | Restio | B | Sandstone |
The problem in the table above is that the Restio has been associated with Sandstone, when in fact, having a soil category of B, it should be a mix of sandstone and limestone (the soil category determines the soil description in this example). Once again you're storing data redundantly. The *soil category* to *soil description* relationship is being stored in its entirety for each plant. As before, the solution is to take out this excess data and place it in its own table. What you are in fact doing at this stage is looking for transitive relationships, or relationships where a nonkey field is dependent on another nonkey field. *Soil description*, although in one sense dependent on plant code (it did seem to be a partial dependency when we looked at it in the previous step), is actually dependent on *soil category*. So, *soil description* must be removed. Once again, take it out and place it in a new table, along with its actual key (*soil category*) as shown in the tables below:
### Plant data after removing the soil description
| Plant code | Plant name | Soil category |
| --- | --- | --- |
| 431 | Leucadendron | A |
| 446 | Protea | B |
| 482 | Erica | C |
| 449 | Restio | B |
### Creating a new table with the soil description
| Soil category | Soil description |
| --- | --- |
| A | Sandstone |
| B | Sandstone/limestone |
| C | Limestone |
You've cut down on the chances of anomalies once again. It is now impossible to mistakenly assume soil category B is associated with anything but a mix of sandstone and limestone. The soil description to soil category relationships are stored in only one place - the new *soil* table, where you can be much more certain they are accurate.
Often, when you're designing a system you don't yet have a complete set of test data available, and it's not necessary if you understand how the data relates. This article has used the tables and their data to demonstrate the consequences of storing data in tables that were not normalized, but without them you have to rely on dependencies between fields, which is the key to database normalization.
The following articles will describe the process more formally, starting with moving from unnormalized data (or zero normal form) to first normal form.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb GRANT GRANT
=====
Syntax
------
```
GRANT
priv_type [(column_list)]
[, priv_type [(column_list)]] ...
ON [object_type] priv_level
TO user_specification [ user_options ...]
user_specification:
username [authentication_option]
authentication_option:
IDENTIFIED BY 'password'
| IDENTIFIED BY PASSWORD 'password_hash'
| IDENTIFIED {VIA|WITH} authentication_rule [OR authentication_rule ...]
authentication_rule:
authentication_plugin
| authentication_plugin {USING|AS} 'authentication_string'
| authentication_plugin {USING|AS} PASSWORD('password')
GRANT PROXY ON username
TO user_specification [, user_specification ...]
[WITH GRANT OPTION]
GRANT rolename TO grantee [, grantee ...]
[WITH ADMIN OPTION]
grantee:
rolename
username [authentication_option]
user_options:
[REQUIRE {NONE | tls_option [[AND] tls_option] ...}]
[WITH with_option [with_option] ...]
object_type:
TABLE
| FUNCTION
| PROCEDURE
| PACKAGE
priv_level:
*
| *.*
| db_name.*
| db_name.tbl_name
| tbl_name
| db_name.routine_name
with_option:
GRANT OPTION
| resource_option
resource_option:
MAX_QUERIES_PER_HOUR count
| MAX_UPDATES_PER_HOUR count
| MAX_CONNECTIONS_PER_HOUR count
| MAX_USER_CONNECTIONS count
| MAX_STATEMENT_TIME time
tls_option:
SSL
| X509
| CIPHER 'cipher'
| ISSUER 'issuer'
| SUBJECT 'subject'
```
Description
-----------
The `GRANT` statement allows you to grant privileges or [roles](#roles) to accounts. To use `GRANT`, you must have the `GRANT OPTION` privilege, and you must have the privileges that you are granting.
Use the [REVOKE](../revoke/index) statement to revoke privileges granted with the `GRANT` statement.
Use the [SHOW GRANTS](../show-grants/index) statement to determine what privileges an account has.
Account Names
-------------
For `GRANT` statements, account names are specified as the `username` argument in the same way as they are for [CREATE USER](../create-user/index) statements. See [account names](../create-user/index#account-names) from the `CREATE USER` page for details on how account names are specified.
Implicit Account Creation
-------------------------
The `GRANT` statement also allows you to implicitly create accounts in some cases.
If the account does not yet exist, then `GRANT` can implicitly create it. To implicitly create an account with `GRANT`, a user is required to have the same privileges that would be required to explicitly create the account with the `CREATE USER` statement.
If the `NO_AUTO_CREATE_USER` [SQL\_MODE](../sql-mode/index) is set, then accounts can only be created if authentication information is specified, or with a [CREATE USER](../create-user/index) statement. If no authentication information is provided, `GRANT` will produce an error when the specified account does not exist, for example:
```
show variables like '%sql_mode%' ;
+---------------+--------------------------------------------+
| Variable_name | Value |
+---------------+--------------------------------------------+
| sql_mode | NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+---------------+--------------------------------------------+
GRANT USAGE ON *.* TO 'user123'@'%' IDENTIFIED BY '';
ERROR 1133 (28000): Can't find any matching row in the user table
GRANT USAGE ON *.* TO 'user123'@'%'
IDENTIFIED VIA PAM using 'mariadb' require ssl ;
Query OK, 0 rows affected (0.00 sec)
select host, user from mysql.user where user='user123' ;
+------+----------+
| host | user |
+------+----------+
| % | user123 |
+------+----------+
```
Privilege Levels
----------------
Privileges can be set globally, for an entire database, for a table or routine, or for individual columns in a table. Certain privileges can only be set at certain levels.
* [Global privileges *priv\_type*](#global-privileges) are granted using `*.*` for *priv\_level*. Global privileges include privileges to administer the database and manage user accounts, as well as privileges for all tables, functions, and procedures. Global privileges are stored in the [mysql.user table](../mysqluser-table/index) prior to [MariaDB 10.4](../what-is-mariadb-104/index), and in [mysql.global\_priv table](../mysqlglobal_priv-table/index) afterwards.
* [Database privileges *priv\_type*](#database-privileges) are granted using `db_name.*` for *priv\_level*, or using just `*` to use default database. Database privileges include privileges to create tables and functions, as well as privileges for all tables, functions, and procedures in the database. Database privileges are stored in the [mysql.db table](../mysqldb-table/index).
* [Table privileges *priv\_type*](#table-privileges) are granted using `db_name.tbl_name` for *priv\_level*, or using just `tbl_name` to specify a table in the default database. The `TABLE` keyword is optional. Table privileges include the ability to select and change data in the table. Certain table privileges can be granted for individual columns.
* [Column privileges *priv\_type*](#column-privileges) are granted by specifying a table for *priv\_level* and providing a column list after the privilege type. They allow you to control exactly which columns in a table users can select and change.
* [Function privileges *priv\_type*](#function-privileges) are granted using `FUNCTION db_name.routine_name` for *priv\_level*, or using just `FUNCTION routine_name` to specify a function in the default database.
* [Procedure privileges *priv\_type*](#procedure-privileges) are granted using `PROCEDURE db_name.routine_name` for *priv\_level*, or using just `PROCEDURE routine_name` to specify a procedure in the default database.
### The `USAGE` Privilege
The `USAGE` privilege grants no real privileges. The [SHOW GRANTS](../show-grants/index) statement will show a global `USAGE` privilege for a newly-created user. You can use `USAGE` with the `GRANT` statement to change options like `GRANT OPTION` and `MAX_USER_CONNECTIONS` without changing any account privileges.
### The `ALL PRIVILEGES` Privilege
The `ALL PRIVILEGES` privilege grants all available privileges. Granting all privileges only affects the given privilege level. For example, granting all privileges on a table does not grant any privileges on the database or globally.
Using `ALL PRIVILEGES` does not grant the special `GRANT OPTION` privilege.
You can use `ALL` instead of `ALL PRIVILEGES`.
### The `GRANT OPTION` Privilege
Use the `WITH GRANT OPTION` clause to give users the ability to grant privileges to other users at the given privilege level. Users with the `GRANT OPTION` privilege can only grant privileges they have. They cannot grant privileges at a higher privilege level than they have the `GRANT OPTION` privilege.
The `GRANT OPTION` privilege cannot be set for individual columns. If you use `WITH GRANT OPTION` when specifying [column privileges](#column-privileges), the `GRANT OPTION` privilege will be granted for the entire table.
Using the `WITH GRANT OPTION` clause is equivalent to listing `GRANT OPTION` as a privilege.
### Global Privileges
The following table lists the privileges that can be granted globally. You can also grant all database, table, and function privileges globally. When granted globally, these privileges apply to all databases, tables, or functions, including those created later.
To set a global privilege, use `*.*` for *priv\_level*.
#### BINLOG ADMIN
Enables administration of the [binary log](../binary-log/index), including the [PURGE BINARY LOGS](../purge-binary-logs/index) statement and setting the system variables:
* [binlog\_annotate\_row\_events](../replication-and-binary-log-system-variables/index#binlog_annotate_row_events)
* [binlog\_cache\_size](../replication-and-binary-log-system-variables/index#binlog_cache_size)
* [binlog\_commit\_wait\_count](../replication-and-binary-log-system-variables/index#binlog_commit_wait_count)
* [binlog\_commit\_wait\_usec](../replication-and-binary-log-system-variables/index#binlog_commit_wait_usec)
* [binlog\_direct\_non\_transactional\_updates](../replication-and-binary-log-system-variables/index#binlog_direct_non_transactional_updates)
* [binlog\_expire\_logs\_seconds](../replication-and-binary-log-system-variables/index#binlog_expire_logs_seconds)
* [binlog\_file\_cache\_size](../replication-and-binary-log-system-variables/index#binlog_file_cache_size)
* [binlog\_format](../replication-and-binary-log-system-variables/index#binlog_format)
* [binlog\_row\_image](../replication-and-binary-log-system-variables/index#binlog_row_image)
* [binlog\_row\_metadata](../replication-and-binary-log-system-variables/index#binlog_row_metadata)
* [binlog\_stmt\_cache\_size](../replication-and-binary-log-system-variables/index#binlog_stmt_cache_size)
* [expire\_logs\_days](../replication-and-binary-log-system-variables/index#expire_logs_days)
* [log\_bin\_compress](../replication-and-binary-log-system-variables/index#log_bin_compress)
* [log\_bin\_compress\_min\_len](../replication-and-binary-log-system-variables/index#log_bin_compress_min_len)
* [log\_bin\_trust\_function\_creators](../replication-and-binary-log-system-variables/index#log_bin_trust_function_creators)
* [max\_binlog\_cache\_size](../replication-and-binary-log-system-variables/index#max_binlog_cache_size)
* [max\_binlog\_size](../replication-and-binary-log-system-variables/index#max_binlog_size)
* [max\_binlog\_stmt\_cache\_size](../replication-and-binary-log-system-variables/index#max_binlog_stmt_cache_size)
* [sql\_log\_bin](../replication-and-binary-log-system-variables/index#sql_log_bin) and
* [sync\_binlog](../replication-and-binary-log-system-variables/index#sync_binlog).
Added in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/).
#### BINLOG MONITOR
New name for [REPLICATION CLIENT](#replication-client) from [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/), (`REPLICATION CLIENT` still supported as an alias for compatibility purposes). Permits running SHOW commands related to the [binary log](../binary-log/index), in particular the [SHOW BINLOG STATUS](../show-binlog-status/index) and [SHOW BINARY LOGS](../show-binary-logs/index) statements. Unlike [REPLICATION CLIENT](#replication-client) prior to [MariaDB 10.5](../what-is-mariadb-105/index), [SHOW REPLICA STATUS](../show-replica-status/index) isn't included in this privilege, and [REPLICA MONITOR](#replica-monitor) is required.
#### BINLOG REPLAY
Enables replaying the binary log with the [BINLOG](../binlog/index) statement (generated by [mariadb-binlog](../mysqlbinlog/index)), executing [SET timestamp](../server-system-variables/index#timestamp) when [secure\_timestamp](../server-system-variables/index#secure_timestamp) is set to `replication`, and setting the session values of system variables usually included in BINLOG output, in particular:
* [gtid\_domain\_id](../gtid/index#gtid_domain_id)
* [gtid\_seq\_no](../gtid/index#gtid_seq_no)
* [pseudo\_thread\_id](../server-system-variables/index#pseudo_thread_id)
* [server\_id](../replication-and-binary-log-system-variables/index#server_id).
Added in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/)
#### CONNECTION ADMIN
Enables administering connection resource limit options. This includes ignoring the limits specified by:
* [max\_connections](../server-system-variables/index#max_connections)
* [max\_user\_connections](../server-system-variables/index#max_user_connections) and
* [max\_password\_errors](../server-system-variables/index#max_password_errors).
The statements specified in [init\_connect](../server-system-variables/index#init_connect) are not executed, [killing connections and queries](../kill/index) owned by other users is permitted. The following connection-related system variables can be changed:
* [connect\_timeout](../server-system-variables/index#connect_timeout)
* [disconnect\_on\_expired\_password](../server-system-variables/index#disconnect_on_expired_password)
* [extra\_max\_connections](../thread-pool-system-status-variables/index#extra_max_connections)
* [init\_connect](../server-system-variables/index#init_connect)
* [max\_connections](../server-system-variables/index#max_connections)
* [max\_connect\_errors](../server-system-variables/index#max_connect_errors)
* [max\_password\_errors](../server-system-variables/index#max_password_errors)
* [proxy\_protocol\_networks](../server-system-variables/index#proxy_protocol_networks)
* [secure\_auth](../server-system-variables/index#secure_auth)
* [slow\_launch\_time](../server-system-variables/index#slow_launch_time)
* [thread\_pool\_exact\_stats](../thread-pool-system-status-variables/index#thread_pool_exact_stats)
* [thread\_pool\_dedicated\_listener](../thread-pool-system-status-variables/index#thread_pool_dedicated_listener)
* [thread\_pool\_idle\_timeout](../thread-pool-system-status-variables/index#thread_pool_idle_timeout)
* [thread\_pool\_max\_threads](../thread-pool-system-status-variables/index#thread_pool_max_threads)
* [thread\_pool\_min\_threads](../thread-pool-system-status-variables/index#thread_pool_min_threads)
* [thread\_pool\_oversubscribe](../thread-pool-system-status-variables/index#thread_pool_oversubscribe)
* [thread\_pool\_prio\_kickup\_timer](../thread-pool-system-status-variables/index#thread_pool_prio_kickup_timer)
* [thread\_pool\_priority](../thread-pool-system-status-variables/index#thread_pool_priority)
* [thread\_pool\_size](../thread-pool-system-status-variables/index#thread_pool_size), and
* [thread\_pool\_stall\_limit](../thread-pool-system-status-variables/index#thread_pool_stall_limit).
Added in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/).
#### CREATE USER
Create a user using the [CREATE USER](../create-user/index) statement, or implicitly create a user with the `GRANT` statement.
#### FEDERATED ADMIN
Execute [CREATE SERVER](../create-server/index), [ALTER SERVER](../alter-server/index), and [DROP SERVER](../drop-server/index) statements. Added in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/).
#### FILE
Read and write files on the server, using statements like [LOAD DATA INFILE](../load-data-infile/index) or functions like [LOAD\_FILE()](../load_file/index). Also needed to create [CONNECT](../connect/index) outward tables. MariaDB server must have the permissions to access those files.
#### GRANT OPTION
Grant global privileges. You can only grant privileges that you have.
#### PROCESS
Show information about the active processes, for example via [SHOW PROCESSLIST](../show-processlist/index) or [mysqladmin processlist](../mysqladmin/index). If you have the PROCESS privilege, you can see all threads. Otherwise, you can see only your own threads (that is, threads associated with the MariaDB account that you are using).
#### READ\_ONLY ADMIN
User can set the [read\_only](../server-system-variables/index#read_only) system variable and allows the user to perform write operations, even when the `read_only` option is active. Added in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/).
#### RELOAD
Execute [FLUSH](../flush/index) statements or equivalent [mariadb-admin/mysqladmin](../mysqladmin/index) commands.
#### REPLICATION CLIENT
Execute [SHOW MASTER STATUS](../show-master-status/index) and [SHOW BINARY LOGS](../show-binary-logs/index) informative statements. Renamed to [BINLOG MONITOR](#binlog-monitor) in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/) (but still supported as an alias for compatibility reasons). [SHOW SLAVE STATUS](../show-slave-status/index) was part of [REPLICATION CLIENT](#replication-client) prior to [MariaDB 10.5](../what-is-mariadb-105/index).
#### REPLICATION MASTER ADMIN
Permits administration of primary servers, including the [SHOW REPLICA HOSTS](../show-replica-hosts/index) statement, and setting the [gtid\_binlog\_state](../gtid/index#gtid_binlog_state), [gtid\_domain\_id](../gtid/index#gtid_domain_id), [master\_verify\_checksum](../replication-and-binary-log-system-variables/index#master_verify_checksum) and [server\_id](../replication-and-binary-log-system-variables/index#server_id) system variables. Added in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/).
#### REPLICA MONITOR
Permit [SHOW REPLICA STATUS](../show-replica-status/index) and [SHOW RELAYLOG EVENTS](../show-relaylog-events/index). From [MariaDB 10.5.9](https://mariadb.com/kb/en/mariadb-1059-release-notes/).
When a user would upgrade from an older major release to a [MariaDB 10.5](../what-is-mariadb-105/index) minor release prior to [MariaDB 10.5.9](https://mariadb.com/kb/en/mariadb-1059-release-notes/), certain user accounts would lose capabilities. For example, a user account that had the REPLICATION CLIENT privilege in older major releases could run [SHOW REPLICA STATUS](../show-replica-status/index), but after upgrading to a [MariaDB 10.5](../what-is-mariadb-105/index) minor release prior to [MariaDB 10.5.9](https://mariadb.com/kb/en/mariadb-1059-release-notes/), they could no longer run [SHOW REPLICA STATUS](../show-replica-status/index), because that statement was changed to require the REPLICATION REPLICA ADMIN privilege.
This issue is fixed in [MariaDB 10.5.9](https://mariadb.com/kb/en/mariadb-1059-release-notes/) with this new privilege, which now grants the user the ability to execute SHOW [ALL] (SLAVE | REPLICA) STATUS.
When a database is upgraded from an older major release to MariaDB Server 10.5.9 or later, any user accounts with the REPLICATION CLIENT or REPLICATION SLAVE privileges will automatically be granted the new REPLICA MONITOR privilege. The privilege fix occurs when the server is started up, not when mariadb-upgrade is performed.
However, when a database is upgraded from an early 10.5 minor release to 10.5.9 and later, the user will have to fix any user account privileges manually.
#### REPLICATION REPLICA
Synonym for [REPLICATION SLAVE](#replication-slave). From [MariaDB 10.5.1](https://mariadb.com/kb/en/mariadb-1051-release-notes/).
#### REPLICATION SLAVE
Accounts used by replica servers on the primary need this privilege. This is needed to get the updates made on the master. From [MariaDB 10.5.1](https://mariadb.com/kb/en/mariadb-1051-release-notes/), [REPLICATION REPLICA](#replication-replica) is an alias for `REPLICATION SLAVE`.
#### REPLICATION SLAVE ADMIN
Permits administering replica servers, including [START REPLICA/SLAVE](../start-replica/index), [STOP REPLICA/SLAVE](../stop-replica/index), [CHANGE MASTER](../change-master-to/index), [SHOW REPLICA/SLAVE STATUS](../show-replica-status/index), [SHOW RELAYLOG EVENTS](../show-relaylog-events/index) statements, replaying the binary log with the [BINLOG](../binlog/index) statement (generated by [mariadb-binlog](../mysqlbinlog/index)), and setting the system variables:
* [gtid\_cleanup\_batch\_size](../gtid/index#gtid_cleanup_batch_size)
* [gtid\_ignore\_duplicates](../gtid/index#gtid_ignore_duplicates)
* [gtid\_pos\_auto\_engines](../gtid/index#gtid_pos_auto_engines)
* [gtid\_slave\_pos](../gtid/index#gtid_slave_pos)
* [gtid\_strict\_mode](../gtid/index#gtid_strict_mode)
* [init\_slave](../replication-and-binary-log-system-variables/index#init_slave)
* [read\_binlog\_speed\_limit](../replication-and-binary-log-system-variables/index#read_binlog_speed_limit)
* [relay\_log\_purge](../replication-and-binary-log-system-variables/index#relay_log_purge)
* [relay\_log\_recovery](../replication-and-binary-log-system-variables/index#relay_log_recovery)
* [replicate\_do\_db](../replication-and-binary-log-system-variables/index#replicate_do_db)
* [replicate\_do\_table](../replication-and-binary-log-system-variables/index#replicate_do_table)
* [replicate\_events\_marked\_for\_skip](../replication-and-binary-log-system-variables/index#replicate_events_marked_for_skip)
* [replicate\_ignore\_db](../replication-and-binary-log-system-variables/index#replicate_ignore_db)
* [replicate\_ignore\_table](../replication-and-binary-log-system-variables/index#replicate_ignore_table)
* [replicate\_wild\_do\_table](../replication-and-binary-log-system-variables/index#replicate_wild_do_table)
* [replicate\_wild\_ignore\_table](../replication-and-binary-log-system-variables/index#replicate_wild_ignore_table)
* [slave\_compressed\_protocol](../replication-and-binary-log-system-variables/index#slave_compressed_protocol)
* [slave\_ddl\_exec\_mode](../replication-and-binary-log-system-variables/index#slave_ddl_exec_mode)
* [slave\_domain\_parallel\_threads](../replication-and-binary-log-system-variables/index#slave_domain_parallel_threads)
* [slave\_exec\_mode](../replication-and-binary-log-system-variables/index#slave_exec_mode)
* [slave\_max\_allowed\_packet](../replication-and-binary-log-system-variables/index#slave_max_allowed_packet)
* [slave\_net\_timeout](../replication-and-binary-log-system-variables/index#slave_net_timeout)
* [slave\_parallel\_max\_queued](../replication-and-binary-log-system-variables/index#slave_parallel_max_queued)
* [slave\_parallel\_mode](../replication-and-binary-log-system-variables/index#slave_parallel_mode)
* [slave\_parallel\_threads](../replication-and-binary-log-system-variables/index#slave_parallel_threads)
* [slave\_parallel\_workers](../replication-and-binary-log-system-variables/index#slave_parallel_workers)
* [slave\_run\_triggers\_for\_rbr](../replication-and-binary-log-system-variables/index#slave_run_triggers_for_rbr)
* [slave\_sql\_verify\_checksum](../replication-and-binary-log-system-variables/index#slave_sql_verify_checksum)
* [slave\_transaction\_retry\_interval](../replication-and-binary-log-system-variables/index#slave_transaction_retry_interval)
* [slave\_type\_conversions](../replication-and-binary-log-system-variables/index#slave_type_conversions)
* [sync\_master\_info](../replication-and-binary-log-system-variables/index#sync_master_info)
* [sync\_relay\_log](../replication-and-binary-log-system-variables/index#sync_relay_log), and
* [sync\_relay\_log\_info](../replication-and-binary-log-system-variables/index#sync_relay_log_info).
Added in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/).
#### SET USER
Enables setting the `DEFINER` when creating [triggers](../triggers/index), [views](../views/index), [stored functions](../stored-functions/index) and [stored procedures](../stored-procedures/index). Added in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/).
#### SHOW DATABASES
List all databases using the [SHOW DATABASES](../show-databases/index) statement. Without the `SHOW DATABASES` privilege, you can still issue the `SHOW DATABASES` statement, but it will only list databases containing tables on which you have privileges.
#### SHUTDOWN
Shut down the server using [SHUTDOWN](../shutdown/index) or the [mysqladmin shutdown](../mysqladmin/index) command.
#### SUPER
Execute superuser statements: [CHANGE MASTER TO](../change-master-to/index), [KILL](../kill/index) (users who do not have this privilege can only `KILL` their own threads), [PURGE LOGS](../purge-binary-logs/index), [SET global system variables](../set/index), or the [mysqladmin debug](../mysqladmin/index) command. Also, this permission allows the user to write data even if the [read\_only](../server-system-variables/index#read_only) startup option is set, enable or disable logging, enable or disable replication on replica, specify a `DEFINER` for statements that support that clause, connect once reaching the `MAX_CONNECTIONS`. If a statement has been specified for the [init-connect](../server-system-variables/index#init_connect) `mysqld` option, that command will not be executed when a user with `SUPER` privileges connects to the server.
The SUPER privilege has been split into multiple smaller privileges from [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/) to allow for more fine-grained privileges, although it remains an alias for these smaller privileges.
### Database Privileges
The following table lists the privileges that can be granted at the database level. You can also grant all table and function privileges at the database level. Table and function privileges on a database apply to all tables or functions in that database, including those created later.
To set a privilege for a database, specify the database using `db_name.*` for *priv\_level*, or just use `*` to specify the default database.
| Privilege | Description |
| --- | --- |
| `CREATE` | Create a database using the [CREATE DATABASE](../create-database/index) statement, when the privilege is granted for a database. You can grant the `CREATE` privilege on databases that do not yet exist. This also grants the `CREATE` privilege on all tables in the database. |
| `CREATE ROUTINE` | Create Stored Programs using the [CREATE PROCEDURE](../create-procedure/index) and [CREATE FUNCTION](../create-function/index) statements. |
| `CREATE TEMPORARY TABLES` | Create temporary tables with the [CREATE TEMPORARY TABLE](../create-table/index) statement. This privilege enable writing and dropping those temporary tables |
| `DROP` | Drop a database using the [DROP DATABASE](../drop-database/index) statement, when the privilege is granted for a database. This also grants the `DROP` privilege on all tables in the database. |
| `EVENT` | Create, drop and alter `EVENT`s. |
| `GRANT OPTION` | Grant database privileges. You can only grant privileges that you have. |
| `LOCK TABLES` | Acquire explicit locks using the [LOCK TABLES](../lock-tables/index) statement; you also need to have the `SELECT` privilege on a table, in order to lock it. |
### Table Privileges
| Privilege | Description |
| --- | --- |
| `ALTER` | Change the structure of an existing table using the [ALTER TABLE](../alter-table/index) statement. |
| `CREATE` | Create a table using the [CREATE TABLE](../create-table/index) statement. You can grant the `CREATE` privilege on tables that do not yet exist. |
| `CREATE VIEW` | Create a view using the [CREATE\_VIEW](../create-view/index) statement. |
| `DELETE` | Remove rows from a table using the [DELETE](../delete/index) statement. |
| `DELETE HISTORY` | Remove [historical rows](../system-versioned-tables/index) from a table using the [DELETE HISTORY](../delete/index) statement. Displays as `DELETE VERSIONING ROWS` when running [SHOW GRANTS](../show-grants/index) until [MariaDB 10.3.15](https://mariadb.com/kb/en/mariadb-10315-release-notes/) and until [MariaDB 10.4.5](https://mariadb.com/kb/en/mariadb-1045-release-notes/) ([MDEV-17655](https://jira.mariadb.org/browse/MDEV-17655)), or when running SHOW PRIVILEGES until [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/), [MariaDB 10.4.13](https://mariadb.com/kb/en/mariadb-10413-release-notes/) and [MariaDB 10.3.23](https://mariadb.com/kb/en/mariadb-10323-release-notes/) ([MDEV-20382](https://jira.mariadb.org/browse/MDEV-20382)). From [MariaDB 10.3.4](https://mariadb.com/kb/en/mariadb-1034-release-notes/). From [MariaDB 10.3.5](https://mariadb.com/kb/en/mariadb-1035-release-notes/), if a user has the `SUPER` privilege but not this privilege, running [mysql\_upgrade](../mysql_upgrade/index) will grant this privilege as well. |
| `DROP` | Drop a table using the [DROP TABLE](../drop-table/index) statement or a view using the [DROP VIEW](../drop-view/index) statement. Also required to execute the [TRUNCATE TABLE](../truncate-table/index) statement. |
| `GRANT OPTION` | Grant table privileges. You can only grant privileges that you have. |
| `INDEX` | Create an index on a table using the [CREATE INDEX](../create-index/index) statement. Without the `INDEX` privilege, you can still create indexes when creating a table using the [CREATE TABLE](../create-table/index) statement if the you have the `CREATE` privilege, and you can create indexes using the [ALTER TABLE](../alter-table/index) statement if you have the `ALTER` privilege. |
| `INSERT` | Add rows to a table using the [INSERT](../insert/index) statement. The `INSERT` privilege can also be set on individual columns; see [Column Privileges](#column-privileges) below for details. |
| `REFERENCES` | Unused. |
| `SELECT` | Read data from a table using the [SELECT](../select/index) statement. The `SELECT` privilege can also be set on individual columns; see [Column Privileges](#column-privileges) below for details. |
| `SHOW VIEW` | Show the [CREATE VIEW](../create-view/index) statement to create a view using the [SHOW CREATE VIEW](../show-create-view/index) statement. |
| `TRIGGER` | Execute triggers associated to tables you update, execute the [CREATE TRIGGER](../create-trigger/index) and [DROP TRIGGER](../drop-trigger/index) statements. You will still be able to see triggers. |
| `UPDATE` | Update existing rows in a table using the [UPDATE](../update/index) statement. `UPDATE` statements usually include a `WHERE` clause to update only certain rows. You must have `SELECT` privileges on the table or the appropriate columns for the `WHERE` clause. The `UPDATE` privilege can also be set on individual columns; see [Column Privileges](#column-privileges) below for details. |
### Column Privileges
Some table privileges can be set for individual columns of a table. To use column privileges, specify the table explicitly and provide a list of column names after the privilege type. For example, the following statement would allow the user to read the names and positions of employees, but not other information from the same table, such as salaries.
```
GRANT SELECT (name, position) on Employee to 'jeffrey'@'localhost';
```
| Privilege | Description |
| --- | --- |
| `INSERT (column_list)` | Add rows specifying values in columns using the [INSERT](../insert/index) statement. If you only have column-level `INSERT` privileges, you must specify the columns you are setting in the `INSERT` statement. All other columns will be set to their default values, or `NULL`. |
| `REFERENCES (column_list)` | Unused. |
| `SELECT (column_list)` | Read values in columns using the [SELECT](../select/index) statement. You cannot access or query any columns for which you do not have `SELECT` privileges, including in `WHERE`, `ON`, `GROUP BY`, and `ORDER BY` clauses. |
| `UPDATE (column_list)` | Update values in columns of existing rows using the [UPDATE](../update/index) statement. `UPDATE` statements usually include a `WHERE` clause to update only certain rows. You must have `SELECT` privileges on the table or the appropriate columns for the `WHERE` clause. |
### Function Privileges
| Privilege | Description |
| --- | --- |
| `ALTER ROUTINE` | Change the characteristics of a stored function using the [ALTER FUNCTION](../alter-function/index) statement. |
| `EXECUTE` | Use a stored function. You need `SELECT` privileges for any tables or columns accessed by the function. |
| `GRANT OPTION` | Grant function privileges. You can only grant privileges that you have. |
### Procedure Privileges
| Privilege | Description |
| --- | --- |
| `ALTER ROUTINE` | Change the characteristics of a stored procedure using the [ALTER PROCEDURE](../alter-procedure/index) statement. |
| `EXECUTE` | Execute a [stored procedure](../stored-procedures/index) using the [CALL](../call/index) statement. The privilege to call a procedure may allow you to perform actions you wouldn't otherwise be able to do, such as insert rows into a table. |
| `GRANT OPTION` | Grant procedure privileges. You can only grant privileges that you have. |
```
GRANT EXECUTE ON PROCEDURE mysql.create_db TO maintainer;
```
### Proxy Privileges
| Privilege | Description |
| --- | --- |
| `PROXY` | Permits one user to be a proxy for another. |
The `PROXY` privilege allows one user to proxy as another user, which means their privileges change to that of the proxy user, and the [CURRENT\_USER()](../current_user/index) function returns the user name of the proxy user.
The `PROXY` privilege only works with authentication plugins that support it. The default [mysql\_native\_password](../authentication-plugin-mysql_native_password/index) authentication plugin does not support proxy users.
The [pam](../authentication-plugin-pam/index) authentication plugin is the only plugin included with MariaDB that currently supports proxy users. The `PROXY` privilege is commonly used with the [pam](../authentication-plugin-pam/index) authentication plugin to enable [user and group mapping with PAM](../user-and-group-mapping-with-pam/index).
For example, to grant the `PROXY` privilege to an [anonymous account](../create-user/index#anonymous-accounts) that authenticates with the [pam](../authentication-plugin-pam/index) authentication plugin, you could execute the following:
```
CREATE USER 'dba'@'%' IDENTIFIED BY 'strongpassword';
GRANT ALL PRIVILEGES ON *.* TO 'dba'@'%' ;
CREATE USER ''@'%' IDENTIFIED VIA pam USING 'mariadb';
GRANT PROXY ON 'dba'@'%' TO ''@'%';
```
A user account can only grant the `PROXY` privilege for a specific user account if the granter also has the `PROXY` privilege for that specific user account, and if that privilege is defined `WITH GRANT OPTION`. For example, the following example fails because the granter does not have the `PROXY` privilege for that specific user account at all:
```
SELECT USER(), CURRENT_USER();
+-----------------+-----------------+
| USER() | CURRENT_USER() |
+-----------------+-----------------+
| alice@localhost | alice@localhost |
+-----------------+-----------------+
SHOW GRANTS;
+-----------------------------------------------------------------------------------------------------------------------+
| Grants for alice@localhost |
+-----------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'alice'@'localhost' IDENTIFIED BY PASSWORD '*2470C0C06DEE42FD1618BB99005ADCA2EC9D1E19' |
+-----------------------------------------------------------------------------------------------------------------------+
GRANT PROXY ON 'dba'@'localhost' TO 'bob'@'localhost';
ERROR 1698 (28000): Access denied for user 'alice'@'localhost'
```
And the following example fails because the granter does have the `PROXY` privilege for that specific user account, but it is not defined `WITH GRANT OPTION`:
```
SELECT USER(), CURRENT_USER();
+-----------------+-----------------+
| USER() | CURRENT_USER() |
+-----------------+-----------------+
| alice@localhost | alice@localhost |
+-----------------+-----------------+
SHOW GRANTS;
+-----------------------------------------------------------------------------------------------------------------------+
| Grants for alice@localhost |
+-----------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'alice'@'localhost' IDENTIFIED BY PASSWORD '*2470C0C06DEE42FD1618BB99005ADCA2EC9D1E19' |
| GRANT PROXY ON 'dba'@'localhost' TO 'alice'@'localhost' |
+-----------------------------------------------------------------------------------------------------------------------+
GRANT PROXY ON 'dba'@'localhost' TO 'bob'@'localhost';
ERROR 1698 (28000): Access denied for user 'alice'@'localhost'
```
But the following example succeeds because the granter does have the `PROXY` privilege for that specific user account, and it is defined `WITH GRANT OPTION`:
```
SELECT USER(), CURRENT_USER();
+-----------------+-----------------+
| USER() | CURRENT_USER() |
+-----------------+-----------------+
| alice@localhost | alice@localhost |
+-----------------+-----------------+
SHOW GRANTS;
+-----------------------------------------------------------------------------------------------------------------------------------------+
| Grants for alice@localhost |
+-----------------------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'alice'@'localhost' IDENTIFIED BY PASSWORD '*2470C0C06DEE42FD1618BB99005ADCA2EC9D1E19' WITH GRANT OPTION |
| GRANT PROXY ON 'dba'@'localhost' TO 'alice'@'localhost' WITH GRANT OPTION |
+-----------------------------------------------------------------------------------------------------------------------------------------+
GRANT PROXY ON 'dba'@'localhost' TO 'bob'@'localhost';
```
A user account can grant the `PROXY` privilege for any other user account if the granter has the `PROXY` privilege for the `''@'%'` anonymous user account, like this:
```
GRANT PROXY ON ''@'%' TO 'dba'@'localhost' WITH GRANT OPTION;
```
For example, the following example succeeds because the user can grant the `PROXY` privilege for any other user account:
```
SELECT USER(), CURRENT_USER();
+-----------------+-----------------+
| USER() | CURRENT_USER() |
+-----------------+-----------------+
| alice@localhost | alice@localhost |
+-----------------+-----------------+
SHOW GRANTS;
+-----------------------------------------------------------------------------------------------------------------------------------------+
| Grants for alice@localhost |
+-----------------------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'alice'@'localhost' IDENTIFIED BY PASSWORD '*2470C0C06DEE42FD1618BB99005ADCA2EC9D1E19' WITH GRANT OPTION |
| GRANT PROXY ON ''@'%' TO 'alice'@'localhost' WITH GRANT OPTION |
+-----------------------------------------------------------------------------------------------------------------------------------------+
GRANT PROXY ON 'app1_dba'@'localhost' TO 'bob'@'localhost';
Query OK, 0 rows affected (0.004 sec)
GRANT PROXY ON 'app2_dba'@'localhost' TO 'carol'@'localhost';
Query OK, 0 rows affected (0.004 sec)
```
The default `root` user accounts created by [mysql\_install\_db](../mysql_install_db/index) have this privilege. For example:
```
GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION;
GRANT PROXY ON ''@'%' TO 'root'@'localhost' WITH GRANT OPTION;
```
This allows the default `root` user accounts to grant the `PROXY` privilege for any other user account, and it also allows the default `root` user accounts to grant others the privilege to do the same.
Authentication Options
----------------------
The authentication options for the `GRANT` statement are the same as those for the [CREATE USER](../create-user/index) statement.
### IDENTIFIED BY 'password'
The optional `IDENTIFIED BY` clause can be used to provide an account with a password. The password should be specified in plain text. It will be hashed by the [PASSWORD](../password/index) function prior to being stored.
For example, if our password is `mariadb`, then we can create the user with:
```
GRANT USAGE ON *.* TO foo2@test IDENTIFIED BY 'mariadb';
```
If you do not specify a password with the `IDENTIFIED BY` clause, the user will be able to connect without a password. A blank password is not a wildcard to match any password. The user must connect without providing a password if no password is set.
If the user account already exists and if you provide the `IDENTIFIED BY` clause, then the user's password will be changed. You must have the privileges needed for the [SET PASSWORD](../set-password/index) statement to change a user's password with `GRANT`.
The only [authentication plugins](../authentication-plugins/index) that this clause supports are [mysql\_native\_password](../authentication-plugin-mysql_native_password/index) and [mysql\_old\_password](../authentication-plugin-mysql_old_password/index).
### IDENTIFIED BY PASSWORD 'password\_hash'
The optional `IDENTIFIED BY PASSWORD` clause can be used to provide an account with a password that has already been hashed. The password should be specified as a hash that was provided by the [PASSWORD](../password/index) function. It will be stored as-is.
For example, if our password is `mariadb`, then we can find the hash with:
```
SELECT PASSWORD('mariadb');
+-------------------------------------------+
| PASSWORD('mariadb') |
+-------------------------------------------+
| *54958E764CE10E50764C2EECBB71D01F08549980 |
+-------------------------------------------+
1 row in set (0.00 sec)
```
And then we can create a user with the hash:
```
GRANT USAGE ON *.* TO foo2@test IDENTIFIED BY
PASSWORD '*54958E764CE10E50764C2EECBB71D01F08549980';
```
If you do not specify a password with the `IDENTIFIED BY` clause, the user will be able to connect without a password. A blank password is not a wildcard to match any password. The user must connect without providing a password if no password is set.
If the user account already exists and if you provide the `IDENTIFIED BY` clause, then the user's password will be changed. You must have the privileges needed for the [SET PASSWORD](../set-password/index) statement to change a user's password with `GRANT`.
The only [authentication plugins](../authentication-plugins/index) that this clause supports are [mysql\_native\_password](../authentication-plugin-mysql_native_password/index) and [mysql\_old\_password](../authentication-plugin-mysql_old_password/index).
### IDENTIFIED {VIA|WITH} authentication\_plugin
The optional `IDENTIFIED VIA authentication_plugin` allows you to specify that the account should be authenticated by a specific [authentication plugin](../authentication-plugins/index). The plugin name must be an active authentication plugin as per [SHOW PLUGINS](../show-plugins/index). If it doesn't show up in that output, then you will need to install it with [INSTALL PLUGIN](../install-plugin/index) or [INSTALL SONAME](../install-soname/index).
For example, this could be used with the [PAM authentication plugin](../authentication-plugin-pam/index):
```
GRANT USAGE ON *.* TO foo2@test IDENTIFIED VIA pam;
```
Some authentication plugins allow additional arguments to be specified after a `USING` or `AS` keyword. For example, the [PAM authentication plugin](../authentication-plugin-pam/index) accepts a [service name](../authentication-plugin-pam/index#configuring-the-pam-service):
```
GRANT USAGE ON *.* TO foo2@test IDENTIFIED VIA pam USING 'mariadb';
```
The exact meaning of the additional argument would depend on the specific authentication plugin.
**MariaDB starting with [10.4.0](https://mariadb.com/kb/en/mariadb-1040-release-notes/)**The `USING` or `AS` keyword can also be used to provide a plain-text password to a plugin if it's provided as an argument to the [PASSWORD()](../password/index) function. This is only valid for [authentication plugins](../authentication-plugins/index) that have implemented a hook for the [PASSWORD()](../password/index) function. For example, the [ed25519](../authentication-plugin-ed25519/index) authentication plugin supports this:
```
CREATE USER safe@'%' IDENTIFIED VIA ed25519
USING PASSWORD('secret');
```
**MariaDB starting with [10.4.3](https://mariadb.com/kb/en/mariadb-1043-release-notes/)**One can specify many authentication plugins, they all work as alternatives ways of authenticating a user:
```
CREATE USER safe@'%' IDENTIFIED VIA ed25519
USING PASSWORD('secret') OR unix_socket;
```
By default, when you create a user without specifying an authentication plugin, MariaDB uses the [mysql\_native\_password](../authentication-plugin-mysql_native_password/index) plugin.
Resource Limit Options
----------------------
**MariaDB starting with [10.2.0](https://mariadb.com/kb/en/mariadb-1020-release-notes/)**[MariaDB 10.2.0](https://mariadb.com/kb/en/mariadb-1020-release-notes/) introduced a number of resource limit options.
It is possible to set per-account limits for certain server resources. The following table shows the values that can be set per account:
| Limit Type | Decription |
| --- | --- |
| `MAX_QUERIES_PER_HOUR` | Number of statements that the account can issue per hour (including updates) |
| `MAX_UPDATES_PER_HOUR` | Number of updates (not queries) that the account can issue per hour |
| `MAX_CONNECTIONS_PER_HOUR` | Number of connections that the account can start per hour |
| `MAX_USER_CONNECTIONS` | Number of simultaneous connections that can be accepted from the same account; if it is 0, `max_connections` will be used instead; if `max_connections` is 0, there is no limit for this account's simultaneous connections. |
| `MAX_STATEMENT_TIME` | Timeout, in seconds, for statements executed by the user. See also [Aborting Statements that Exceed a Certain Time to Execute](../aborting-statements/index). |
If any of these limits are set to `0`, then there is no limit for that resource for that user.
To set resource limits for an account, if you do not want to change that account's privileges, you can issue a `GRANT` statement with the `USAGE` privilege, which has no meaning. The statement can name some or all limit types, in any order.
Here is an example showing how to set resource limits:
```
GRANT USAGE ON *.* TO 'someone'@'localhost' WITH
MAX_USER_CONNECTIONS 0
MAX_QUERIES_PER_HOUR 200;
```
The resources are tracked per account, which means `'user'@'server'`; not per user name or per connection.
The count can be reset for all users using [FLUSH USER\_RESOURCES](../flush/index), [FLUSH PRIVILEGES](../flush/index) or [mysqladmin reload](../mysqladmin/index).
Users with the `CONNECTION ADMIN` privilege (in [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/) and later) or the `SUPER` privilege are not restricted by `max_user_connections`, `max_connections`, or `max_password_errors`.
Per account resource limits are stored in the [user](../mysqluser-table/index) table, in the [mysql](../the-mysql-database-tables/index) database. Columns used for resources limits are named `max_questions`, `max_updates`, `max_connections` (for `MAX_CONNECTIONS_PER_HOUR`), and `max_user_connections` (for `MAX_USER_CONNECTIONS`).
TLS Options
-----------
By default, MariaDB transmits data between the server and clients without encrypting it. This is generally acceptable when the server and client run on the same host or in networks where security is guaranteed through other means. However, in cases where the server and client exist on separate networks or they are in a high-risk network, the lack of encryption does introduce security concerns as a malicious actor could potentially eavesdrop on the traffic as it is sent over the network between them.
To mitigate this concern, MariaDB allows you to encrypt data in transit between the server and clients using the Transport Layer Security (TLS) protocol. TLS was formerly known as Secure Socket Layer (SSL), but strictly speaking the SSL protocol is a predecessor to TLS and, that version of the protocol is now considered insecure. The documentation still uses the term SSL often and for compatibility reasons TLS-related server system and status variables still use the prefix ssl\_, but internally, MariaDB only supports its secure successors.
See [Secure Connections Overview](../secure-connections-overview/index) for more information about how to determine whether your MariaDB server has TLS support.
You can set certain TLS-related restrictions for specific user accounts. For instance, you might use this with user accounts that require access to sensitive data while sending it across networks that you do not control. These restrictions can be enabled for a user account with the [CREATE USER](../create-user/index), [ALTER USER](../alter-user/index), or [GRANT](index) statements. The following options are available:
| Option | Description |
| --- | --- |
| `REQUIRE NONE` | TLS is not required for this account, but can still be used. |
| `REQUIRE SSL` | The account must use TLS, but no valid X509 certificate is required. This option cannot be combined with other TLS options. |
| `REQUIRE X509` | The account must use TLS and must have a valid X509 certificate. This option implies `REQUIRE SSL`. This option cannot be combined with other TLS options. |
| `REQUIRE ISSUER 'issuer'` | The account must use TLS and must have a valid X509 certificate. Also, the Certificate Authority must be the one specified via the string `issuer`. This option implies `REQUIRE X509`. This option can be combined with the `SUBJECT`, and `CIPHER` options in any order. |
| `REQUIRE SUBJECT 'subject'` | The account must use TLS and must have a valid X509 certificate. Also, the certificate's Subject must be the one specified via the string `subject`. This option implies `REQUIRE X509`. This option can be combined with the `ISSUER`, and `CIPHER` options in any order. |
| `REQUIRE CIPHER 'cipher'` | The account must use TLS, but no valid X509 certificate is required. Also, the encryption used for the connection must use a specific cipher method specified in the string `cipher`. This option implies `REQUIRE SSL`. This option can be combined with the `ISSUER`, and `SUBJECT` options in any order. |
The `REQUIRE` keyword must be used only once for all specified options, and the `AND` keyword can be used to separate individual options, but it is not required.
For example, you can create a user account that requires these TLS options with the following:
```
GRANT USAGE ON *.* TO 'alice'@'%'
REQUIRE SUBJECT '/CN=alice/O=My Dom, Inc./C=US/ST=Oregon/L=Portland'
AND ISSUER '/C=FI/ST=Somewhere/L=City/ O=Some Company/CN=Peter Parker/[email protected]'
AND CIPHER 'SHA-DES-CBC3-EDH-RSA';
```
If any of these options are set for a specific user account, then any client who tries to connect with that user account will have to be configured to connect with TLS.
See [Securing Connections for Client and Server](../securing-connections-for-client-and-server/index) for information on how to enable TLS on the client and server.
Roles
-----
### Syntax
```
GRANT role TO grantee [, grantee ... ]
[ WITH ADMIN OPTION ]
grantee:
rolename
username [authentication_option]
```
The GRANT statement is also used to grant the use a [role](../roles/index) to one or more users or other roles. In order to be able to grant a role, the grantor doing so must have permission to do so (see WITH ADMIN in the [CREATE ROLE](../create-role/index) article).
Specifying the `WITH ADMIN OPTION` permits the grantee to in turn grant the role to another.
For example, the following commands show how to grant the same role to a couple different users.
```
GRANT journalist TO hulda;
GRANT journalist TO berengar WITH ADMIN OPTION;
```
If a user has been granted a role, they do not automatically obtain all permissions associated with that role. These permissions are only in use when the user activates the role with the [SET ROLE](../set-role/index) statement.
Grant Examples
--------------
### Granting Root-like Privileges
You can create a user that has privileges similar to the default `root` accounts by executing the following:
```
CREATE USER 'alexander'@'localhost';
GRANT ALL PRIVILEGES ON *.* to 'alexander'@'localhost' WITH GRANT OPTION;
```
See Also
--------
* [Troubleshooting Connection Issues](../troubleshooting-connection-issues/index)
* [--skip-grant-tables](../mysqld-options/index#-skip-grant-tables) allows you to start MariaDB without `GRANT`. This is useful if you lost your root password.
* [CREATE USER](../create-user/index)
* [ALTER USER](../alter-user/index)
* [DROP USER](../drop-user/index)
* [SET PASSWORD](../set-password/index)
* [SHOW CREATE USER](../show-create-user/index)
* [mysql.global\_priv table](../mysqlglobal_priv-table/index)
* [mysql.user table](../mysqluser-table/index)
* [Password Validation Plugins](../password-validation-plugins/index) - permits the setting of basic criteria for passwords
* [Authentication Plugins](../authentication-plugins/index) - allow various authentication methods to be used, and new ones to be developed.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb ST_LineFromText ST\_LineFromText
================
Syntax
------
```
ST_LineFromText(wkt[,srid])
ST_LineStringFromText(wkt[,srid])
LineFromText(wkt[,srid])
LineStringFromText(wkt[,srid])
```
Description
-----------
Constructs a [LINESTRING](../linestring/index) value using its [WKT](../wkt-definition/index) representation and [SRID](../srid/index).
`ST_LineFromText()`, `ST_LineStringFromText()`, `ST_LineFromText()` and `ST_LineStringFromText()` are all synonyms.
Examples
--------
```
CREATE TABLE gis_line (g LINESTRING);
SHOW FIELDS FROM gis_line;
INSERT INTO gis_line VALUES
(LineFromText('LINESTRING(0 0,0 10,10 0)')),
(LineStringFromText('LINESTRING(10 10,20 10,20 20,10 20,10 10)')),
(LineStringFromWKB(AsWKB(LineString(Point(10, 10), Point(40, 10)))));
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Buildbot Setup for Virtual Machines - Debian 7 "wheezy" Buildbot Setup for Virtual Machines - Debian 7 "wheezy"
=======================================================
Base install
------------
```
qemu-img create -f qcow2 /kvm/vms/vm-wheezy-amd64-serial.qcow2 10G
qemu-img create -f qcow2 /kvm/vms/vm-wheezy-i386-serial.qcow2 10G
```
Start each VM booting from the server install iso one at a time and perform the following install steps:
```
kvm -m 1024 -hda /kvm/vms/vm-wheezy-amd64-serial.qcow2 -cdrom /kvm/iso/debian-testing-amd64-CD-1.iso -redir tcp:2269::22 -boot d -smp 2 -cpu qemu64 -net nic,model=virtio -net user
kvm -m 1024 -hda /kvm/vms/vm-wheezy-i386-serial.qcow2 -cdrom /kvm/iso/debian-testing-i386-CD-1.iso -redir tcp:2270::22 -boot d -smp 2 -cpu qemu64 -net nic,model=virtio -net user
```
Once running you can connect to the VNC server from your local host with:
```
vncviewer -via ${remote-host} localhost
```
Replace ${remote-host} with the host the vm is running on.
**Note:** When you activate the install, vncviewer may disconnect with a complaint about the rect being too large. This is fine. Debian has just resized the vnc screen. Simply reconnect.
Install, picking default options mostly, with the following notes:
* Set the hostname to debian7-wheezy-amd64 or debian7-wheezy-i386
* When partitioning disks, choose "Guided - use entire disk" (we do not want LVM)
+ Partitioning Scheme: All files one partition
* No additional CDs
* Set up network mirror
* Software Selection Screen
+ Uncheck "Debian desktop environment"
+ Uncheck "Print server"
+ Keep "SSH server" and "Standard system utilities"
When the install is finished the installer will attempt to reboot and then fail. This is OK, just kill the kvm process on the host server.
Now that the VM is installed, it's time to configure it. If you have the memory you can do the following simultaneously:
```
kvm -m 1024 -hda /kvm/vms/vm-wheezy-amd64-serial.qcow2 -redir tcp:2269::22 -boot c -smp 2 -cpu qemu64 -net nic,model=virtio -net user -nographic
kvm -m 1024 -hda /kvm/vms/vm-wheezy-i386-serial.qcow2 -redir tcp:2270::22 -boot c -smp 2 -cpu qemu64 -net nic,model=virtio -net user -nographic
ssh -p 2269 localhost
# edit /boot/grub/menu.lst and visudo, see below
ssh -p 2270 localhost
# edit /boot/grub/menu.lst and visudo, see below
ssh -t -p 2269 localhost "mkdir -v .ssh"
ssh -t -p 2270 localhost "mkdir -v .ssh"
scp -P 2269 /kvm/vms/authorized_keys localhost:.ssh/
scp -P 2270 /kvm/vms/authorized_keys localhost:.ssh/
echo $'Buildbot\n\n\n\n\ny' | ssh -p 2269 localhost 'chmod -vR go-rwx .ssh; sudo adduser --disabled-password buildbot; sudo addgroup buildbot sudo; sudo mkdir ~buildbot/.ssh; sudo cp -vi .ssh/authorized_keys ~buildbot/.ssh/; sudo chown -vR buildbot:buildbot ~buildbot/.ssh; sudo chmod -vR go-rwx ~buildbot/.ssh'
echo $'Buildbot\n\n\n\n\ny' | ssh -p 2270 localhost 'chmod -vR go-rwx .ssh; sudo adduser --disabled-password buildbot; sudo addgroup buildbot sudo; sudo mkdir ~buildbot/.ssh; sudo cp -vi .ssh/authorized_keys ~buildbot/.ssh/; sudo chown -vR buildbot:buildbot ~buildbot/.ssh; sudo chmod -vR go-rwx ~buildbot/.ssh'
scp -P 2269 /kvm/vms/ttyS0.conf buildbot@localhost:
scp -P 2270 /kvm/vms/ttyS0.conf buildbot@localhost:
ssh -p 2269 buildbot@localhost 'sudo cp -vi ttyS0.conf /etc/init/; rm -v ttyS0.conf; sudo shutdown -h now'
ssh -p 2270 buildbot@localhost 'sudo cp -vi ttyS0.conf /etc/init/; rm -v ttyS0.conf; sudo shutdown -h now'
```
Enabling passwordless sudo:
```
su -
vi /etc/apt/sources.list #comment out the deb cdrom line
apt-get update
apt-get install sudo vim tree
update-alternatives --config editor # select vim.basic
visudo # comment out existing %sudo line and add: %sudo ALL=NOPASSWD: ALL
usermod -a -G sudo ${username}
```
Editing /boot/grub/menu.lst:
```
vi /etc/default/grub
# Add/edit these entries:
GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=ttyS0,115200n8"
GRUB_TERMINAL="serial"
GRUB_SERIAL_COMMAND="serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1"
update-grub
# exit back to the host server
```
VMs for building .debs
----------------------
```
for i in '/kvm/vms/vm-wheezy-amd64-serial.qcow2 2269 qemu64' '/kvm/vms/vm-wheezy-i386-serial.qcow2 2270 qemu64' ; do \
set $i; \
runvm --user=buildbot --logfile=kernel_$2.log --base-image=$1 --port=$2 --cpu=$3 "$(echo $1 | sed -e 's/serial/build/')" \
"= scp -P $2 -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no /kvm/boost_1_49_0.tar.gz buildbot@localhost:/dev/shm/" \
"sudo DEBIAN_FRONTEND=noninteractive apt-get update" \
"sudo DEBIAN_FRONTEND=noninteractive apt-get -y build-dep mysql-server-5.5" \
"sudo DEBIAN_FRONTEND=noninteractive apt-get install -y devscripts hardening-wrapper fakeroot doxygen texlive-latex-base ghostscript libevent-dev libssl-dev zlib1g-dev libpam0g-dev libreadline-gplv2-dev autoconf automake automake1.9 dpatch ghostscript-x libfontenc1 libjpeg62 libltdl-dev libltdl7 libmail-sendmail-perl libxfont1 lmodern texlive-latex-base-doc ttf-dejavu ttf-dejavu-extra libaio-dev xfonts-encodings xfonts-utils libxml2-dev unixodbc-dev" \
"cd /usr/local/src;sudo tar zxf /dev/shm/boost_1_49_0.tar.gz;cd /usr/local/include/;sudo ln -vs ../src/boost_1_49_0/boost ." ; \
done
```
VMs for install testing.
------------------------
See [Buildbot Setup for Virtual Machines - General Principles](../buildbot-setup-for-virtual-machines-general-principles/index) for how to obtain `my.seed` and `sources.append`.
```
for i in '/kvm/vms/vm-wheezy-amd64-serial.qcow2 2269 qemu64' '/kvm/vms/vm-wheezy-i386-serial.qcow2 2270 qemu64' ; do \
set $i; \
runvm --user=buildbot --logfile=kernel_$2.log --base-image=$1 --port=$2 --cpu=$3 "$(echo $1 | sed -e 's/serial/install/')" \
"sudo DEBIAN_FRONTEND=noninteractive apt-get update" \
"sudo DEBIAN_FRONTEND=noninteractive apt-get install -y patch libaio1 debconf-utils unixodbc libxml2" \
"= scp -P $2 /kvm/vms/my.seed /kvm/vms/sources.append buildbot@localhost:/tmp/" \
"sudo debconf-set-selections /tmp/my.seed" \
"sudo sh -c 'cat /tmp/sources.append >> /etc/apt/sources.list'"; \
done
```
VMs for MySQL upgrade testing
-----------------------------
2013-12-05 recreated the upgrade VMs, this time based off of the serial VM (which is better, maintenance-wise).
```
for i in '/kvm/vms/vm-wheezy-amd64-serial.qcow2 2269 qemu64' '/kvm/vms/vm-wheezy-i386-serial.qcow2 2270 qemu64' ; do \
set $i; \
runvm --user=buildbot --logfile=kernel_$2.log --base-image=$1 --port=$2 --cpu=$3 "$(echo $1 | sed -e 's/serial/upgrade/')" \
"sudo DEBIAN_FRONTEND=noninteractive apt-get update" \
"sudo DEBIAN_FRONTEND=noninteractive apt-get install -y patch libaio1 debconf-utils unixodbc libxml2" \
"= scp -P $2 /kvm/vms/my.seed /kvm/vms/sources.append buildbot@localhost:/tmp/" \
"sudo debconf-set-selections /tmp/my.seed" \
"sudo sh -c 'cat /tmp/sources.append >> /etc/apt/sources.list'" \
'sudo DEBIAN_FRONTEND=noninteractive apt-get install -y libaio1 mysql-server-5.5' \
'mysql -uroot -prootpass -e "create database mytest; use mytest; create table t(a int primary key); insert into t values (1); select * from t"' ;\
done
```
This was how the original upgrade VMs were created:
```
for i in '/kvm/vms/vm-wheezy-amd64-install.qcow2 2269 qemu64' '/kvm/vms/vm-wheezy-i386-install.qcow2 2270 qemu64' ; do \
set $i; \
runvm --user=buildbot --logfile=kernel_$2.log --base-image=$1 --port=$2 --cpu=$3 "$(echo $1 | sed -e 's/install/upgrade/')" \
'sudo DEBIAN_FRONTEND=noninteractive apt-get install -y libaio1 mysql-server-5.5' \
'mysql -uroot -prootpass -e "create database mytest; use mytest; create table t(a int primary key); insert into t values (1); select * from t"' ;\
done
```
VMs for MariaDB upgrade testing
-------------------------------
*The steps below are based on the Natty steps on [Installing VM images for testing .deb upgrade between versions](../installing-vm-images-for-testing-deb-upgrade-between-versions/index).*
```
for i in '/kvm/vms/vm-wheezy-amd64-serial.qcow2 2269 qemu64' '/kvm/vms/vm-wheezy-i386-serial.qcow2 2270 qemu64' ; do \
set $i; \
runvm --user=buildbot --logfile=kernel_$2.log --base-image=$1 --port=$2 --cpu=$3 "$(echo $1 | sed -e 's/serial/upgrade2/')" \
"= scp -P $2 -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no /kvm/vms/mariadb-wheezy.list buildbot@localhost:/tmp/tmp.list" \
'sudo mv -vi /tmp/tmp.list /etc/apt/sources.list.d/' \
'sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 1BB943DB' \
'sudo apt-get update' \
'sudo DEBIAN_FRONTEND=noninteractive apt-get install -y --allow-unauthenticated mariadb-server mariadb-server-5.5 mariadb-client mariadb-client-5.5 mariadb-test libmariadbclient-dev' \
'sudo apt-get -f install' \
'sudo mysqladmin -u root password "rootpass"' \
'sudo /etc/init.d/mysql restart' \
'mysql -uroot -prootpass -e "create database mytest; use mytest; create table t(a int primary key); insert into t values (1); select * from t"' \
'sudo rm -v /etc/apt/sources.list.d/tmp.list' \
'sudo apt-get update' \
'sudo DEBIAN_FRONTEND=noninteractive apt-get install -y libaio1' \
'sudo DEBIAN_FRONTEND=noninteractive apt-get upgrade -y'; \
done
```
Add Key to known\_hosts
-----------------------
Do the following on each build host server to add the VMs to known\_hosts.
```
# wheezy-amd64
cp -avi /kvm/vms/vm-wheezy-amd64-install.qcow2 /kvm/vms/vm-wheezy-amd64-test.qcow2
kvm -m 1024 -hda /kvm/vms/vm-wheezy-amd64-test.qcow2 -redir tcp:2269::22 -boot c -smp 2 -cpu qemu64 -net nic,model=virtio -net user -nographic
sudo su - buildbot
ssh -p 2269 buildbot@localhost sudo shutdown -h now
rm -v /kvm/vms/vm-wheezy-amd64-test.qcow2
# wheezy-i386
cp -avi /kvm/vms/vm-wheezy-i386-install.qcow2 /kvm/vms/vm-wheezy-i386-test.qcow2
kvm -m 1024 -hda /kvm/vms/vm-wheezy-i386-test.qcow2 -redir tcp:2270::22 -boot c -smp 2 -cpu qemu64 -net nic,model=virtio -net user -nographic
sudo su - buildbot
ssh -p 2270 buildbot@localhost sudo shutdown -h now
rm -v /kvm/vms/vm-wheezy-i386-test.qcow2
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Information Schema SCHEMATA Table Information Schema SCHEMATA Table
=================================
The [Information Schema](../information_schema/index) `SCHEMATA` table stores information about databases on the server.
It contains the following columns:
| Column | Description |
| --- | --- |
| `CATALOG_NAME` | Always `def`. |
| `SCHEMA_NAME` | Database name. |
| `DEFAULT_CHARACTER_SET_NAME` | Default [character set](../data-types-character-sets-and-collations/index) for the database. |
| `DEFAULT_COLLATION_NAME` | Default [collation](../data-types-character-sets-and-collations/index). |
| `SQL_PATH` | Always `NULL`. |
| `SCHEMA_COMMENT` | Database comment. From [MariaDB 10.5.0](https://mariadb.com/kb/en/mariadb-1050-release-notes/). |
Example
-------
```
SELECT * FROM INFORMATION_SCHEMA.SCHEMATA\G
*************************** 1. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: information_schema
DEFAULT_CHARACTER_SET_NAME: utf8
DEFAULT_COLLATION_NAME: utf8_general_ci
SQL_PATH: NULL
*************************** 2. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: mysql
DEFAULT_CHARACTER_SET_NAME: latin1
DEFAULT_COLLATION_NAME: latin1_swedish_ci
SQL_PATH: NULL
*************************** 3. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: performance_schema
DEFAULT_CHARACTER_SET_NAME: utf8
DEFAULT_COLLATION_NAME: utf8_general_ci
SQL_PATH: NULL
*************************** 4. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: test
DEFAULT_CHARACTER_SET_NAME: latin1
DEFAULT_COLLATION_NAME: latin1_swedish_ci
SQL_PATH: NULL
...
```
From [MariaDB 10.5.0](https://mariadb.com/kb/en/mariadb-1050-release-notes/):
```
SELECT * FROM INFORMATION_SCHEMA.SCHEMATA\G
...
*************************** 2. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: presentations
DEFAULT_CHARACTER_SET_NAME: latin1
DEFAULT_COLLATION_NAME: latin1_swedish_ci
SQL_PATH: NULL
SCHEMA_COMMENT: Presentations for conferences
...
```
See Also
--------
* [CREATE DATABASE](../create-database/index)
* [ALTER DATABASE](../alter-database/index)
* [DROP DATABASE](../drop-database/index)
* [SHOW CREATE DATABASE](../show-create-database/index)
* [SHOW DATABASES](../show-databases/index)
* [Character Sets and Collations](../character-sets-and-collations/index)
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Spider Feature Matrix Spider Feature Matrix
=====================
Not complete yet - still being updated
F(\*) Federation only , P(\*)partioning only . Spider column is for SpiderForMySQL found on the Spider web sIte.
| Feature | Spider | 10.0 |
| --- | --- | --- |
| **Clustering and High Availability** | | |
| Commit, Rollback transactions on multiple backend | Yes | Yes |
| Multiplexing to a number of replicas using xa protocol 2PC | Yes | Yes |
| Split brain resolution based on a majority decision, failed node is remove from the list of replicas | Yes | Yes |
| Enable a failed backend to re enter the cluster transparently | No | No |
| Synchronize DDL to backend, table modification, schema changes | No | No |
| Synchronize DDL to other Spider | No | No |
| GTID tracking per table on XA error | No | Yes |
| Transparent partitioning | No | No |
| Covered by generic SQL test case | Yes | Yes |
| **Heterogenous Backends** | | |
| MariaDB and MySQL database backend | Yes | Yes |
| Oracle database backend, if build from source against the client library 'ORACLE\_HOME' | Yes | Yes |
| Local table attachment | Yes | Yes |
| **Performance** | | |
| Index Condition Pushdown | No | No |
| Engine Condition Pushdown | Yes | Yes |
| Concurrent backend scan | Yes | No |
| Concurrent partition scan | Yes | No |
| Batched key access | Yes | Yes |
| Block hash join | No | Yes |
| HANDLER backend propagation | Yes | Yes |
| HANDLER backend translation from SQL | Yes | Yes |
| HANDLER OPEN cache per connection | No | Yes |
| HANDLER use prepared statement | No | Yes |
| HANDLER\_SOCKET protocol backend propagation | Yes | Yes |
| HANDLER\_SOCKET backend translation from SQL | No | No |
| Map reduce for `ORDER BY` ... LIMIT | Yes | Yes |
| Map reduce for `MAX & MIN & SUM` | Yes | Yes |
| Map reduce for some `GROUP BY` | Yes | Yes |
| Batch multiple WRITES in auto commit to reduce network round trip | Yes | Yes |
| Relaxing backend consistency | Yes | Yes |
| **Execution Control** | | |
| Configuration at table and partition level, settings can change per data collection | Yes | Yes |
| Configurable empty result set on errors. For API that does not have transactions replay | Yes | Yes |
| Query Cache tuning per table of the on remote backend | Yes | Yes |
| Index Hint per table imposed on remote backend | Yes | Yes |
| SSL connections to remote backend connections | Yes | Yes |
| Table definition discovery from remote backend | Yes | F(\*) |
| Direct SQL execution to backend via UDF | Yes | Yes |
| Table re synchronization between backends via UDF | Yes | Yes |
| Maintain Index and Table Statistics of remote backends | Yes | Yes |
| Can use Independent Index and Table Statistics | No | Yes |
| Maintain local or remote table increments | Yes | Yes |
| LOAD DATA INFILE translate to bulk inserting | Yes | Yes |
| Performance Schema Probes | Yes | Yes |
| Load Balance Reads to replicate weight control | Yes | Yes |
| Fine tuning tcp timeout, connections retry | Yes | Yes |
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb MariaDB Plans - Online Operations MariaDB Plans - Online Operations
=================================
**Note:** This page is obsolete. The information is old, outdated, or otherwise currently incorrect. We are keeping the page for historical reasons only. **Do not** rely on the information in this article.
Notes from the Online Operations team.
Extention to bigger datatype
(var)char(n) (n+x)
numerique (datatype >)
Extend ENUM done need more visibility
Alter comment
Add and drop index
OPTIMIZE
ANALYSE
COMPATIBILITY & USABILITY
Date & time embeded timezone
IPV6
Fonctions
Datatype
Extended timestamp > 2038
1M tables Information schema
mysql.\* in any engine
1M users requirements
LOG tables in a log\_schema schema
User Ldap Authentification like Drizzle
Link against openssl
Query logging tracking per user
flush and reload variables from my.cnf
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Installing and Using MariaDB via Docker Installing and Using MariaDB via Docker
=======================================
Sometimes we want to install a specific version of MariaDB, [MariaDB ColumnStore](../mariadb-columnstore/index), or [MaxScale](../mariadb-maxscale/index) on a certain system, but no packages are available. Or maybe, we simply want to isolate MariaDB from the rest of the system, to be sure that we won't cause any damage.
A virtual machine would certainly serve the scope. However, this means installing a system on the top of another system. It requires a lot of resources.
In many cases, the best solution is using containers. Docker is a framework that runs containers. A container is meant to run a specific daemon, and the software that is needed for that daemon to properly work. Docker does not virtualize a whole system; a container only includes the packages that are not included in the underlying system.
Docker requires a very small amount of resources. It can run on a virtualized system. It is used both in development and in production environments. Docker is an open source project, released under the Apache License, version 2.
Note that, while your package repositories could have a package called `docker`, it is probably not the Docker we are talking about. The Docker package could be called `docker.io` or `docker-engine`.
For information about installing Docker, see [Get Docker](https://docs.docker.com/get-docker/) in Docker documentation.
Installing Docker on Your System with the Universal Installation Script
-----------------------------------------------------------------------
The script below will install the Docker repositories, required kernel modules and packages on the most common Linux distributions:
```
curl -sSL https://get.docker.com/ | sh
```
### Starting dockerd
On some systems you may have to start the `dockerd daemon` yourself:
```
sudo systemctl start docker
sudo gpasswd -a "${USER}" docker
```
If you don't have `dockerd` running, you will get the following error for most `docker` commands: installing-and-using-mariadb-via-docker Cannot connect to the Docker daemon at unix:*/var/run/docker.sock. Is the docker daemon running? <</code>>*
Using MariaDB Images
--------------------
The easiest way to use MariaDB on Docker is choosing a MariaDB image and creating a container.
### Downloading an Image
You can download a MariaDB image for Docker from the [Offical Docker MariaDB](https://hub.docker.com/_/mariadb/), or choose another image that better suits your needs. You can search Docker Hub (the official set of repositories) for an image with this command:
```
docker search mariadb
```
Once you have found an image that you want to use, you can download it via Docker. Some layers including necessary dependencies will be downloaded too. Note that, once a layer is downloaded for a certain image, Docker will not need to download it again for another image.
For example, if you want to install the default MariaDB image, you can type:
```
docker pull mariadb:10.4
```
This will install the 10.4 version. Versions 10.2, 10.3, 10.5 are also valid choices.
You will see a list of necessary layers. For each layer, Docker will say if it is already present, or its download progress.
To get a list of installed images:
```
docker images
```
### Creating a Container
An image is not a running process; it is just the software needed to be launched. To run it, we must create a container first. The command needed to create a container can usually be found in the image documentation. For example, to create a container for the official MariaDB image:
```
docker run --name mariadbtest -e MYSQL_ROOT_PASSWORD=mypass -p 3306:3306 -d docker.io/library/mariadb:10.3
```
`mariadbtest` is the name we want to assign the container. If we don't specify a name, an id will be automatically generated.
10.2 and 10.5 are also valid target versions:
```
docker run --name mariadbtest -e MYSQL_ROOT_PASSWORD=mypass -p 3306:3306 -d docker.io/library/mariadb:10.2
```
```
docker run --name mariadbtest -e MYSQL_ROOT_PASSWORD=mypass -p 3306:3306 -d docker.io/library/mariadb:10.5
```
Optionally, after the image name, we can specify some [options for mysqld](../mysqld-options/index). For example:
```
docker run --name mariadbtest -e MYSQL_ROOT_PASSWORD=mypass -p 3306:3306 -d mariadb:10.3 --log-bin --binlog-format=MIXED
```
Docker will respond with the container's id. But, just to be sure that the container has been created and is running, we can get a list of running containers in this way:
```
docker ps
```
We should get an output similar to this one:
```
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
819b786a8b48 mariadb "/docker-entrypoint. 4 minutes ago Up 4 minutes 3306/tcp mariadbtest
```
### Running and Stopping the Container
Docker allows us to restart a container with a single command:
```
docker restart mariadbtest
```
The container can also be stopped like this:
```
docker stop mariadbtest
```
The container will not be destroyed by this command. The data will still live inside the container, even if MariaDB is not running. To restart the container and see our data, we can issue:
```
docker start mariadbtest
```
With `docker stop`, the container will be gracefully terminated: a `SIGTERM` signal will be sent to the `mysqld` process, and Docker will wait for the process to shutdown before returning the control to the shell. However, it is also possible to set a timeout, after which the process will be immediately killed with a `SIGKILL`. Or it is possible to immediately kill the process, with no timeout.
```
docker stop --time=30 mariadbtest
docker kill mariadbtest
```
In case we want to destroy a container, perhaps because the image does not suit our needs, we can stop it and then run:
```
docker rm mariadbtest
```
Note that the command above does not destroy the data volume that Docker has created for /var/lib/mysql. If you want to destroy the volume as well, use:
```
docker rm -v mariadbtest
```
#### Automatic Restart
When we start a container, we can use the `--restart` option to set an automatic restart policy. This is useful in production.
Allowed values are:
* `no`: No automatic restart.
* `on-failure`: The container restarts if it exits with a non-zero exit code.
* `unless-stopped`: Always restart the container, unless it was explicitly stopped as shown above.
* `always`: Similar to `unless-stopped`, but when Docker itself restarts, even containers that were explicitly stopped will restart.
It is possible to change the restart policy of existing, possibly running containers:
```
docker update --restart always mariadb
# or, to change the restart policy of all containers:
docker update --restart always $(docker ps -q)
```
A use case for changing the restart policy of existing containers is performing maintenance in production. For example, before upgrading the Docker version, we may want to change all containers restart policy to `always`, so they will restart as soon as the new version is up and running. However, if some containers are stopped and not needed at the moment, we can change their restart policy to `unless-stopped`.
#### Pausing Containers
A container can also be frozen with the `pause` command. Docker will freeze the process using croups. MariaDB will not know that it is being frozen and, when we `unpause` it, MariaDB will resume its work as expected.
Both `pause` and `unpause` accept one or more container names. So, if we are running a cluster, we can freeze and resume all nodes simultaneously:
```
docker pause node1 node2 node3
docker unpause node1 node2 node3
```
Pausing a container is very useful when we need to temporarily free our system's resources. If the container is not crucial at this moment (for example, it is performing some batch work), we can free it to allow other programs to run faster.
### Troubleshooting a Container
If the container doesn't start, or is not working properly, we can investigate with the following command:
```
docker logs mariadbtest
```
This command shows what the daemon sent to the stdout since the last attempt of starting - the text that we typically see when we invoke `mysqld` from the command line.
On some systems, commands such as `docker stop mariadbtest` and `docker restart mariadbtest` may fail with a permissions error. This can be caused by AppArmor, and even `sudo` won't allow you to execute the command. In this case, you will need to find out which profile is causing the problem and correct it, or disable it. **Disabling AppArmor altogether is not recommended, especially in production.**
To check which operations were prevented by AppArmor, see [AppArmor Failures](https://gitlab.com/apparmor/apparmor/-/wikis/AppArmor_Failures) in AppArmor documentation.
To disable a profile, create a symlink with the profile name (in this example, `mysqld`) to `etc/apparmor.d/disable`, and then reload profiles:
```
ln -s /etc/apparmor.d/usr.sbin.mysqld /etc/apparmor.d/disable/
sudo apparmor_parser -R /etc/apparmor.d/usr.sbin.mysqld
```
For more information, see [Policy Layout](https://gitlab.com/apparmor/apparmor/-/wikis/Policy_Layout) in AppArmor documentation.
After disabling the profile, you may need to run:
```
sudo service docker restart
docker system prune --all --volumes
```
Restarting the system will then allow Docker to operate normally.
### Accessing the Container
To access the container via Bash, we can run this command:
```
docker exec -it mariadbtest bash
```
Now we can use normal Linux commands like *cd*, *ls*, etc. We will have root privileges. We can even install our favorite file editor, for example:
```
apt-get update
apt-get install vim
```
In some images, no repository is configured by default, so we may need to add them.
Note that if we run [mysqladmin shutdown](../mysqladmin/index#mysqladmin-commands) or the [SHUTDOWN](../shutdown/index) command to stop the container, the container will be deactivated, and we will automatically exit to our system.
### Connecting to MariaDB from Outside the Container
If we try to connect to the MariaDB server on `localhost`, the client will bypass networking and attempt to connect to the server using a socket file in the local filesystem. However, this doesn't work when MariaDB is running inside a container because the server's filesystem is isolated from the host. The client can't access the socket file which is inside the container, so it fails to connect.
Therefore connections to the MariaDB server must be made using TCP, even when the client is running on the same machine as the server container.
Find the IP address that has been assigned to the container:
```
docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' mariadbtest
```
You can now connect to the MariaDB server using a TCP connection to that IP address.
#### Forcing a TCP Connection
After enabling network connections in MariaDB as described above, we will be able to connect to the server from outside the container.
On the host, run the client and set the server address ("-h") to the container's IP address that you found in the previous step:
```
mysql -h 172.17.0.2 -u root -p
```
This simple form of the connection should work in most situations. Depending on your configuration, it may also be necessary to specify the port for the server or to force TCP mode:
```
mysql -h 172.17.0.2 -P 3306 --protocol=TCP -u root -p
```
#### Port Configuration for Clustered Containers and Replication
Multiple MariaDB servers running in separate Docker containers can connect to each other using TCP. This is useful for forming a Galera cluster or for replication.
When running a cluster or a replication setup via Docker, we will want the containers to use different ports. The fastest way to achieve this is mapping the containers ports to different port on our system. We can do this when creating the containers (`docker run` command), by using the `-p` option, several times if necessary. For example, for Galera nodes we will use a mapping similar to this one:
```
-p 4306:3306 -p 5567:5567 -p 5444:5444 -p 5568:5568
```
Installing MariaDB on Another Image
-----------------------------------
It is possible to download a Linux distribution image, and to install MariaDB on it. This is not much harder than installing MariaDB on a regular operating system (which is easy), but it is still the hardest option. Normally we will try existing images first. However, it is possible that no image is available for the exact version we want, or we want a custom installation, or perhaps we want to use a distribution for which no images are available. In these cases, we will install MariaDB in an operating system image.
### Daemonizing the Operating System
First, we need the system image to run as a daemon. If we skip this step, MariaDB and all databases will be lost when the container stops.
To demonize an image, we need to give it a command that never ends. In the following example, we will create a Debian Jessie daemon that constantly pings the 8.8.8.8 special address:
```
docker run --name debian -p 3306:3306 -d debian /bin/sh -c "while true; do ping 8.8.8.8; done"
```
### Installing MariaDB
At this point, we can enter the shell and issue commands. First we will need to update the repositories, or no packages will be available. We can also update the packages, in case some of them are newer than the image. Then, we will need to install a text editor; we will need it to edit configuration files. For example:
```
# start an interactive Bash session in the container
docker exec -ti debian bash
apt-get -y update
apt-get -y upgrade
apt-get -y install vim
```
Now we are ready to [install MariaDB](../getting-installing-and-upgrading-mariadb/index) in the way we prefer.
See Also
--------
* [Official MariaDB Docker Images Webinar](https://go.mariadb.com/GLBL-WBN_2018-10-09-MariaDB_Containers.html).
* [Docker official site](https://www.docker.com/).
* [Docker Hub](https://hub.docker.com/).
* [Docker documentation](https://docs.docker.com/).
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb SUBTIME SUBTIME
=======
Syntax
------
```
SUBTIME(expr1,expr2)
```
Description
-----------
SUBTIME() returns `expr1` - `expr2` expressed as a value in the same format as `expr1`. `expr1` is a time or datetime expression, and expr2 is a time expression.
Examples
--------
```
SELECT SUBTIME('2007-12-31 23:59:59.999999','1 1:1:1.000002');
+--------------------------------------------------------+
| SUBTIME('2007-12-31 23:59:59.999999','1 1:1:1.000002') |
+--------------------------------------------------------+
| 2007-12-30 22:58:58.999997 |
+--------------------------------------------------------+
SELECT SUBTIME('01:00:00.999999', '02:00:00.999998');
+-----------------------------------------------+
| SUBTIME('01:00:00.999999', '02:00:00.999998') |
+-----------------------------------------------+
| -00:59:59.999999 |
+-----------------------------------------------+
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb DIMENSION DIMENSION
=========
A synonym for [ST\_DIMENSION](../st_dimension/index).
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Installing and Configuring a ColumnStore System using the Google Cloud Installing and Configuring a ColumnStore System using the Google Cloud
======================================================================
### Introduction
MariaDB ColumnStore can be used a Single Node or a Multi-Node system in the Google Cloud environment. You would follow the setup procedure from the Setup document. This document shows how to set Google Cloud Instances.
You will need to have an Google Google account setup to access plus some basic knowledge of accessing and launching Google Cloud Instances.
These are the support configuration options:
1. Single-Node install
2. Multi-Node Install
* Setup with User Module and Performance Module functionality on the same Instance(s)
* Setup with User Module and Performance Module functionality on different Instance(s)
### Google Cloud Platform page
1. Create a Project
2. Go to Compute Engine Page
3. Go to Images page and select and Create an image, recommend Centos 7 is you don't have a preference. If planning a multi-node system, create # number of instances you need for your system. A 1um and 2 pm (3 instances) is a typical setup.
a. Machine type - Minimum for testing would be 8 vCPU's, the more cpu and memory you have the better the performance will be.
b. SSD disk, minimum 100gb. But this again is based on the size you would need for your database
### SSH into Instance(s)
Check the Google Cloud Document on the different ways to access the instances using ssh.
<https://cloud.google.com/compute/docs/instances/connecting-to-instance>
Here is a link to the initial setup document that you will need to follow:
[https://mariadb.com/kb/en/mariadb/preparing-for-columnstore-installation](../mariadb/preparing-for-columnstore-installation)
1. Setup on each instance
a. It is recommended that ssh-keys be setup for multi-node installs, so that would need to be done on all nodes. 'ssh' is used during the installation process.
b. Installed MariaDB ColumnStore dependent packages
c. make sure the firewalls are disabled as stated in the Prepare Document.
2. On just one of the instance, which will be used as pm1
a. Installed MariaDB ColumnStore
b. Run postConfigure and configured pm1
NOTE: Can you follow the postConfigure install instructions from the Single-Server Install document and the Multi-server Install Document.
[https://mariadb.com/kb/en/mariadb/installing-and-configuring-mariadb-columnstore](../mariadb/installing-and-configuring-mariadb-columnstore)
[https://mariadb.com/kb/en/mariadb/installing-and-configuring-a-multi-server-columnstore-system](../mariadb/installing-and-configuring-a-multi-server-columnstore-system)
NOTE: When configuring the nodes, use the Internal IP addresses.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Building the Galera wsrep Package on Ubuntu and Debian Building the Galera wsrep Package on Ubuntu and Debian
======================================================
The instructions on this page were used to create the *galera* package on the Ubuntu and Debian Linux distributions. This package contains the wsrep provider for [MariaDB Galera Cluster](../galera/index).
**MariaDB Galera Cluster starting with 5.5.35**Starting with MariaDB Galera Cluster 5.5.35, the version of the wsrep provider is **25.3.5**. We also provide **25.2.9** for those that need or want it.
Prior to that, the wsrep version was 23.2.7.
1. Install prerequisites:
```
sudo apt-get update
sudo apt-get upgrade
sudo apt-get -y install check debhelper libasio-dev libboost-dev libboost-program-options-dev libssl-dev scons
```
2. Clone [galera.git](https://github.com/mariadb/galera) from [github.com/mariadb](https://github.com/mariadb) and checkout mariadb-3.x banch:
```
git init repo
cd repo
git clone -b mariadb-3.x https://github.com/MariaDB/galera.git
```
3. Build the packages by executing `build.sh` under scripts/ directory with `-p` switch:
```
cd galera
./scripts/build.sh -p
```
When finished, you will have the Debian packages for galera library and arbitrator in the parent directory.
Running galera test suite
-------------------------
If you want to run the `galera` test suite (`mysql-test-run --suite=galera`), you need to install the galera library as either `/usr/lib/galera/libgalera_smm.so` or `/usr/lib64/galera/libgalera_smm.so`
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb mariadbd-safe mariadbd-safe
=============
**MariaDB starting with [10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/)**From [MariaDB 10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/), `mariadbd-safe` is a symlink to `mysqld_safe`, the tool for starting mysqld on Linux and Unix distributions that do not support [systemd](../systemd/index).
**MariaDB starting with [10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/)**From [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/), `mariadbd-safe` is the name of the binary, with `mysqld_safe` a symlink .
See [mysqld\_safe](../mysqld_safe/index) for details.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Installing and Configuring a ColumnStore System using the Amazon AMI Installing and Configuring a ColumnStore System using the Amazon AMI
====================================================================
MariaDB ColumnStore AMI
-----------------------
The MariaDB ColumnStore AMI is CentOS 7 based with MariaDB ColumnStore GA packages.
The MariaDB Columnstore CentOS 7 binary package is installed in the user account:.
* ‘mariadb-user’ on MariaDB ColumnStore 1.2.0 and before releases
* 'mysql' on MariaDB ColumnStore 1.2.1 and later releases
The user account will be referred to as <USER> within this document.
This is a non-root install where the user will access and run all the commands via the user <USER>. The <USER> has been given 'sudo' privileges to run root level commands, which is required due to the fact that the MariaDB ColumnStore applications run some of these commands internally.
MariaDB ColumnStore can be used a Single Node or a Multi-Node system. And it supports using both local storage and EBS storage's.
You will need to have an AWS account setup to access and use the MariaDB ColumnStore AMI, plus some basic knowledge of accessing and launching AMI's and Instances.
These are the support configuration options:
1. Single-Node install with or without EBS Storages
2. Multi-Node Install with or without EBS Storages
* Setup with User Module and Performance Module functionality on the same Instance(s)
* Setup with User Module and Performance Module functionality on different Instance(s)
Also of note, MariaDB ColumnStore product also allows the user to install the RPMs and Binary packages on Amazon EC2 instances to create a system that performs like a standard hardware install. It's not required to run MariaDB ColumnStore via the use of this AMI. To do so, just follow the install instructions from the Single Serve and Multi Server install guides.
### New Installation and upgrades
The AMI is used for creating a new MariaDB ColumnStore. It will either create the Instances and EBS storages needed during startup, or use ones that you have already created and want to utilize.
On doing upgrades, you would follow the procedure that is shown in the associated Upgrade Document.
### Amazon AWS-CLI Tool Set
The MariaDB ColumnStore AMI comes installed with the Amazon AWS-CLI Tool set package, version 1.11.36. The Amazon AWS-CLI Tools provides the capability to the MariaDB ColumnStore to create EC2 Instances and EBS storages. It allows allows for EC2 Instance/node failover, meaning if an EC2 Instance goes down or stops communicating, MariaDB ColumnStore will handle that problem keeping the system functional. This might consist of re-attaching an EBS storage device from the problem EC2 Performance Module to an another Performance Module in the system. Also if a EC2 Instance was to terminate, MariaDB ColumnStore will launch another EC2 Instance in its place.
Even though this AMI has the Amazon AWS-CLI Tool set installed, the user has the option to Setup and Configure a MariaDB ColumnStore System using this AMI without the use of these tools and having them disabled. That is discussed later.
Here is a complete list of these commands:
<http://docs.aws.amazon.com/cli/latest/reference/ec2/index.html#cli-aws-ec2>
Here is the EC2 API Tools commands that the MariaDB ColumnStore Software calls:
1. ec2-describe-instances
2. ec2-run-instances
3. ec2-terminate-instances
4. ec2-stop-instances
5. ec2-start-instances
6. ec2-associate-address
7. ec2-disassociate-address
8. ec2-create-volume
9. ec2-describe-volumes
10. ec2-detach-volume
11. ec2-attach-volume
12. ec2-delete-volume
13. ec2-create-tags
Features in the AMI using MariaDB ColumnStore install script (postConfigure) and mcsadmin
* Both can create the additional Instances and EBS storage's that are used in the system. mcsadmin via the addModule/addDbroot commands.
* Both will allow user to enter EC2 Instance IDs and EBS Volume IDs, if you want to utilize AWS devices you have already created.
* You can also install via postConfigure and have the Amazon AMI tools functionality disabled, meaning you can install like like a regular hardware setup by providing host-names and IP Addresses during the configuration process.
To do this, you would enter 'n' at this prompt:
```
Do you want to have ColumnStore use the Amazon AWS CLI Tools [y,n] (y) >
```
### Amazon AWS setup and AMI Launching
The MariaDB ColumnStore AMI Instance uses 'iops' EBS storage for improved performance over the standard storage type. But it also means that based on the number of Instances/Module you plan to launch, you will need to check your account to make sure you have the permissions to create enough 'iops' storages. Amazon does have a limit on this.
Recommend use Instance Type of "m4.4xlarge" or large. Need to have high performance network.
#### AWS Certifications Keys - Access and Secret Keys
If you are doing a Amazon Multi-Node install and you want the ColumnStore processes to utilize the Amazon API Tool, you will need to either Provide an IAM role that has the Certifications Keys associated with it or you can update a file locally in the AMI Instance. To add it in the local file, you will need to do the following once the AMI Instance is launched and you are logged in using the <USER> user.
```
# cd .aws
# mv credentials.template credentials
// edit the file and add in the your access and secret key that was created for your User account
aws_access_key_id = xxxxxxxxxxxxxx
aws_secret_access_key = xxxxxxxxxxx
```
These keys aren't required for a single-node install.
<https://aws.amazon.com/developers/access-keys/>
### Amazon IAM Role
If you want to setup an IAM role where it passes in the credentials, here is some information on how to do that. Part of setting up the IAm role is you will be required also to Grant permissions to allow this role access to the EC2 command set.
Here is some links to Amazon on what the IAM is and how to set it up.
<http://docs.aws.amazon.com/IAM/latest/UserGuide/introduction.html>
<http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-policies-for-amazon-ec2.html>
### AWS Management Console page
1. Create and download a Key-Pair, this is used to log into the AMI Instance 2. Create a VPC Security Group with the following Inbound Rules.
NOTE: XXX.XXX.XXX.XXX is the VPC is the default subnet used in your account. So you will need to put the VPC IP Address for your account. The IP Address can be found via the VPC Dashboard
* SSH - Source = Your Public IP address
* SSH - AMI subnet XXX.XXX.XXX.XXX/16
* All ICMP
* Custom TCP rule - port range 8600-8800, subnet XXX.XXX.XXX.XXX/16
* MYSQL TCP (port 3306) - subnet XXX.XXX.XXX.XXX/16
* MYSQL TCP (port 3306) - Any other Public IP where you what to access the console 3. Select and Launch the MariaDB ColumnStore AMI:
* From AWS Console on the Instance page:
+ Press 'Launch Instance' button
+ Select "Community AMIs" and search for "MariaDB-ColumnStore-1.0.7" and select
+ Select Size : Recommend using Instance type of "m4.2xlarge" type to get optimal performance.
+ Press "Next: Configure Instance Details" Button
- Select VPC/Subnet and optional provide an "IAM role"
+ Press "Next: Add Storage" button
+ Storage size = default is 100 gb, can be increased if using local storage
+ Press "Next: Add Tags"
+ Value = Name of Instance, which is systemName-pm1. I.E. columnstore-1-pm1
+ Press "Next: Configure Security Group" button
+ Either select Security Group or create one with the ColumnStore setup
+ Press "Review and Launch" button
+ Select you Key Pair name and Launch Instance
#### Amazon AMI EC2 Instance user and password setup
The MariaDB ColumnStore AMI is setup to be accessed and run from the <USER> account
It comes with ssh-keys setup and these used during the install process.
### Access to Launched AMI Instance
Log into the instance as user <USER> or 'mysql'. If the connection link has 'root' user, you will need to change that to <USER> or 'mysql'. Here is an example:
Link from the AWS Console:
```
ssh -i "xxxxx.pem" [email protected]
```
Change to on MariaDB ColumnStore 1.2.0 and before releases
```
ssh -i "xxxxx.pem" [email protected]
```
Change to on MariaDB ColumnStore 1.2.1 and later releases
```
ssh -i "xxxxx.pem" [email protected]
```
### MariaDB ColumnStore System installation
There are 2 methods for perform the System Configuration and Installation:
* MariaDB ColumnStore One Step Quick Installer Script - Release 1.1.6 and later
* MariaDB ColumnStore Post Install Script
#### MariaDB ColumnStore One Step Quick Installer Script, quick\_installer\_amazon.sh
MariaDB ColumnStore One Step Quick Installer Script, quick\_installer\_amazon.sh, is used to perform a simple 1 command run to perform the configuration and startup of MariaDB ColumnStore package on a Aamazon AMI system setup. Available in Release 1.1.6 and later.
The script has 4 parameters.
* --pm-count=x Number of pm instances to create
* --um-count=x Number of um instances to create, optional
* --system-name=nnnn System Name, optional
It will perform an install with these defaults:
* System-Name = columnstore-1, when not specified
* Multi-Server Install
+ with X Number of PMs when only PM IP count are provided
+ with X Number of UMs when UM IP count are provided and X Number of UMs when PM IP count are provided
* Storage - Internal
* DBRoot - 1 DBroot per 1 Performance Module
* Local Query is disabled on um/pm install
* MariaDB Replication is enabled
##### Running quick\_installer\_multi\_server.sh help as non-root <USER> user
```
/home/<USER>/mariadb/columnstore/bin/quick_installer_amazon.sh --help
Usage ./quick_installer_amazon.sh [OPTION]
Quick Installer for an Amazon MariaDB ColumnStore Install
This requires to be run on a MariaDB ColumnStore AMI
Performace Module (pm) number is required
User Module (um) number is option
When only pm counts provided, system is combined setup
When both pm/um counts provided, system is seperate setup
--pm-count=x Number of pm instances to create
--um-count=x Number of um instances to create, optional
--system-name=nnnn System Name, optional
```
##### Running quick\_installer\_multi\_server.sh 1um/2pm setup as non-root <USER> user
```
$ ./mariadb/columnstore/bin/quick_installer_amazon.sh --pm-count=2 --um-count=1
NOTE: Performing a Multi-Server Seperate install with um and pm running on seperate servers
Run post-install script
The next steps are:
If installing on a pm1 node:
export COLUMNSTORE_INSTALL_DIR=/home/<USER>/mariadb/columnstore
export LD_LIBRARY_PATH=:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib
/home/<USER>/mariadb/columnstore/bin/postConfigure -i /home/<USER>/mariadb/columnstore -d
If installing on a non-pm1 using the non-distributed option:
export COLUMNSTORE_INSTALL_DIR=/home/<USER>/mariadb/columnstore
export LD_LIBRARY_PATH=:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib:/home/<USER>/mariadb/columnstore/lib:/home/<USER>/mariadb/columnstore/mysql/lib
/home/<USER>/mariadb/columnstore/bin/columnstore start
Run postConfigure script
This is the MariaDB ColumnStore System Configuration and Installation tool.
It will Configure the MariaDB ColumnStore System and will perform a Package
Installation of all of the Servers within the System that is being configured.
IMPORTANT: This tool requires to run on the Performance Module #1
With the no-Prompting Option being specified, you will be required to have the following:
1. Root user ssh keys setup between all nodes in the system or
use the password command line option.
2. A Configure File to use to retrieve configure data, default to Columnstore.xml.rpmsave
or use the '-c' option to point to a configuration file.
===== Quick Install Amazon Configuration =====
===== Setup System Module Type Configuration =====
There are 2 options when configuring the System Module Type: separate and combined
'separate' - User and Performance functionality on separate servers.
'combined' - User and Performance functionality on the same server
Select the type of System Module Install [1=separate, 2=combined] (1) >
Seperate Server Installation will be performed.
NOTE: Local Query Feature allows the ability to query data from a single Performance
Module. Check MariaDB ColumnStore Admin Guide for additional information.
Enable Local Query feature? [y,n] (n) >
NOTE: The MariaDB ColumnStore Schema Sync feature will replicate all of the
schemas and InnoDB tables across the User Module nodes. This feature can be enabled
or disabled, for example, if you wish to configure your own replication post installation.
MariaDB ColumnStore Schema Sync feature is Enabled, do you want to leave enabled? [y,n] (y) >
NOTE: Configured to have ColumnStore use the Amazon AWS CLI Tools
NOTE: MariaDB ColumnStore Replication Feature is enabled
Enter System Name (columnstore-1) >
===== Setup Storage Configuration =====
----- Setup User Module MariaDB ColumnStore Data Storage Mount Configuration -----
There are 2 options when configuring the storage: internal and external
'internal' - This is specified when a local disk is used for the Data storage.
'external' - This is specified when the MariaDB ColumnStore Data directory is externally mounted.
Select the type of Data Storage [1=internal, 2=external] (1) >
----- Setup Performance Module DBRoot Data Storage Mount Configuration -----
There are 2 options when configuring the storage: internal or external
'internal' - This is specified when a local disk is used for the DBRoot storage.
High Availability Server Failover is not Supported in this mode
'external' - This is specified when the DBRoot directories are mounted.
High Availability Server Failover is Supported in this mode.
Select the type of Data Storage [1=internal, 2=external] (1) >
===== Setup Memory Configuration =====
NOTE: Setting 'NumBlocksPct' to 70%
Setting 'TotalUmMemory' to 50%
===== Setup the Module Configuration =====
Amazon Install: For Module Configuration, you have the option to provide the
existing Instance IDs or have the Instances created.
You will be prompted during the Module Configuration setup section.
----- User Module Configuration -----
Enter number of User Modules [1,1024] (1) >
*** User Module #1 Configuration ***
Launched Instance for um1: i-0eac6a122c640e46c
Getting Private IP Address for Instance i-0eac6a122c640e46c, please wait...
Private IP Address of i-0eac6a122c640e46c is 172.31.33.235
----- Performance Module Configuration -----
Enter number of Performance Modules [1,1024] (2) >
*** Parent OAM Module Performance Module #1 Configuration ***
EC2 Instance ID for pm1: i-0b309a68398cf9302
Getting Private IP Address for Instance i-0b309a68398cf9302, please wait...
Private IP Address of i-0b309a68398cf9302 is 172.31.44.176
Enter the list (Nx,Ny,Nz) or range (Nx-Nz) of DBRoot IDs assigned to module 'pm1' (1) >
*** Performance Module #2 Configuration ***
Launched Instance for pm2: i-088f06a60d267e517
Getting Private IP Address for Instance i-088f06a60d267e517, please wait...
Private IP Address of i-088f06a60d267e517 is 172.31.40.50
Enter the list (Nx,Ny,Nz) or range (Nx-Nz) of DBRoot IDs assigned to module 'pm2' (2) >
Next step is to enter the password to access the other Servers.
This is either your password or you can default to using a ssh key
If using a password, the password needs to be the same on all Servers.
Enter password, hit 'enter' to default to using a ssh key, or 'exit' >
===== System Installation =====
System Configuration is complete.
Performing System Installation.
Performing a MariaDB ColumnStore System install using a Binary package
located in the /home/<USER> directory.
----- Performing Install on 'um1 / i-0eac6a122c640e46c' -----
Install log file is located here: /tmp/um1_binary_install.log
----- Performing Install on 'pm2 / i-088f06a60d267e517' -----
Install log file is located here: /tmp/pm2_binary_install.log
MariaDB ColumnStore Package being installed, please wait ... DONE
===== Checking MariaDB ColumnStore System Logging Functionality =====
The MariaDB ColumnStore system logging is setup and working on local server
===== MariaDB ColumnStore System Startup =====
System Configuration is complete.
Performing System Installation.
----- Starting MariaDB ColumnStore on local server -----
MariaDB ColumnStore successfully started
MariaDB ColumnStore Database Platform Starting, please wait ........... DONE
System Catalog Successfully Created
Run MariaDB ColumnStore Replication Setup.. DONE
MariaDB ColumnStore Install Successfully Completed, System is Active
Enter the following command to define MariaDB ColumnStore Alias Commands
. /etc/profile.d/columnstoreEnv.sh
. /etc/profile.d/columnstoreAlias.sh
Enter 'mcsmysql' to access the MariaDB ColumnStore SQL console
Enter 'mcsadmin' to access the MariaDB ColumnStore Admin console
NOTE: The MariaDB ColumnStore Alias Commands are in /etc/profile.d/columnstoreAlias.sh
```
#### MariaDB ColumnStore Post Install Script, postConfigure
Follow the instructions from the README file to setup and install MariaDB Columnstore
The Instance that was launched is ColumnStore Performance Module #1. This is the primary "pm" where the install process will always start. The install and configuration script, postConfigure is run to initiate the install process.
If you are installing as a Single-Node system, you can follow install instructions on how to run postConfigure in the follow document for non-root user:
[Installing and Configuring MariaDB ColumnStore](../installing-and-configuring-mariadb-columnstore/index)
The following is a transcript of a typical run of the MariaDB ColumnStore configuration script. Plain-text formatting indicates output from the script and bold text indicates responses to questions. After each question there is a short discussion of what the question is asking and what some typical answers might be. You will not see these discussions the running the actual configuration script.
###### Common Installation Examples
During postConfigure, there are 2 questions that are asked where the answer given determines the path that postConfigure takes in configuring the system. Those 2 questions are as follows:
```
Select the type of server install [1=single, 2=multi] (2) >
```
and
```
Select the Type of Module Install being performed:
1. Separate - User and Performance functionalities on separate servers
2. Combined - User and Performance functionalities on the same server
Enter Server Type ID [1-2] (1) >
```
The following examples illustrates some common configurations and helps to provide answers to the above questions:
* Single Node - User and Performance running on 1 server - single / combined
* Mutli-Node #1 - User and Performance running on some server - multi / combined
* Mutli-Node #2 - User and Performance running on separate servers - multi / separate
Run the postConfigure script first:
```
/home/<USER>/mariadb/columnstore/bin/postConfigure -i /home/<USER>/mariadb/columnstore -d
```
```
This is the MariaDB Columnstore System Configuration and Installation tool.
It will Configure the MariaDB Columnstore System and will perform a Package
Installation of all of the Servers within the System that is being configured.
IMPORTANT: This tool should only be run on the Parent OAM Module
which is a Performance Module, preferred Module #1
Prompting instructions:
Press 'enter' to accept a value in (), if available or
Enter one of the options within [], if available, or
Enter a new value
===== Setup System Server Type Configuration =====
There are 2 options when configuring the System Server Type: single and multi
'single' - Single-Server install is used when there will only be 1 server configured
on the system. It can also be used for production systems, if the plan is
to stay single-server.
'multi' - Multi-Server install is used when you want to configure multiple servers now or
in the future. With Multi-Server install, you can still configure just 1 server
now and add on addition servers/modules in the future.
Select the type of System Server install [1=single, 2=multi] (2) > <Enter>
===== Setup System Module Type Configuration =====
There are 2 options when configuring the System Module Type: separate and combined
'separate' - User and Performance functionality on separate servers.
'combined' - User and Performance functionality on the same server
Select the type of System Module Install [1=separate, 2=combined] (2) > 1
Separate Server Installation will be performed.
NOTE: Local Query Feature allows the ability to query data from a single Performance
Module. Check MariaDB Columnstore Admin Guide for additional information.
Enable Local Query feature? [y,n] (n) > <Enter>
NOTE: The MariaDB ColumnStore Schema Sync feature will replicate all of the
schemas and InnoDB tables across the User Module nodes. This feature can be enabled
or disabled, for example, if you wish to configure your own replication post installation.
MariaDB ColumnStore Schema Sync feature, do you want to enable? [y,n] (y) >
NOTE: Amazon AWS CLI Tools are installed and allow MariaDB ColumnStore to create Instances and ABS Volumes
Do you want to have ColumnStore use the Amazon AWS CLI Tools [y,n] (y) >
Enter System Name (columnstore-1) > mycs1
```
Notes: You should give this system a name that will appear in various Admin utilities, etc. The name can be composed of any number of printable characters and spaces.
```
===== Setup Storage Configuration =====
----- Setup User Module MariaDB Columnstore Data Storage Mount Configuration -----
There are 2 options when configuring the storage: internal and external
'internal' - This is specified when a local disk is used for the Data storage.
'external' - This is specified when the MariaDB Columnstore Data directory is externally mounted.
Select the type of Data Storage [1=internal, 2=external] (1) > <Enter>
```
Notes: Enter 2 if you want to create a EBS storage for the mysql schema's to be stored.
```
----- Setup Performance Module DBRoot Data Storage Mount Configuration -----
There are 2 options when configuring the storage: internal or external
'internal' - This is specified when a local disk is used for the DBRoot storage.
High Availability Server Failover is not Supported in this mode
'external' - This is specified when the DBRoot directories are mounted.
High Availability Server Failover is Supported in this mode.
Select the type of Data Storage [1=internal, 2=external] (1) > 2
```
Notes: Enter 2 if you want to create a EBS storage for the MariaDB ColumnStore DBRoot Data to be stored. When using option 2, this will allow this EBS volume to be reattached to other Performance Modules during failover situations
```
Enter EBS Volume Type (standard, gp2, io1) : (standard) > <Enter>
Enter EBS Volume storage size in GB: [1,16384] (100) > <Enter>
===== Setup Memory Configuration =====
NOTE: Setting 'NumBlocksPct' to 70%
Setting 'TotalUmMemory' to 50%
===== Setup the Module Configuration =====
Amazon Install: For Module Configuration, you have the option to provide the
existing Instance IDs or have the Instances created.
You will be prompted during the Module Configuration setup section.
----- User Module Configuration -----
Enter number of User Modules [1,1024] (1) > <Enter>
*** User Module #1 Configuration ***
Create Instance for um1 [y,n] (y) > <Enter>
```
Notes: By entering 'y', Instances will automatically be created. If there are Instances already created that you want to use, then enter 'n' and you will be prompted for the Instance ID.
```
Launched Instance for um1: i-05ab2990
Getting Private IP Address for Instance i-05ab2990, please wait...
Private IP Address of i-05ab2990 is 172.30.0.110
----- Performance Module Configuration -----
Enter number of Performance Modules [1,1024] (1) > 2
*** Parent OAM Module Performance Module #1 Configuration ***
EC2 Instance ID for pm1: i-a3a82a36
Getting Private IP Address for Instance i-a3a82a36, please wait...
Private IP Address of i-a3a82a36 is 172.30.0.107
Enter the list (Nx,Ny,Nz) or range (Nx-Nz) of DBRoot IDs assigned to module 'pm1' (1) > <Enter>
*** Setup External EBS Volume for DBRoot #1 ***
*** NOTE: You have the option to provide an
existing EBS Volume ID or have a Volume created
Create a new EBS volume for DBRoot #1 ? [y,n] (y) > <Enter>
Create AWS Volume for DBRoot #1
Formatting DBRoot #1, please wait...
```
Notes: By entering 'y', EBS Volumnes will automatically be created. If there are EBS Volumnes already created that you want to use, then enter 'n' and you will be prompted for the Volumne ID.
```
*** Performance Module #2 Configuration ***
Create Instance for pm2 [y,n] (y) > <Enter>
Launched Instance for pm2: i-1ca82a89
Getting Private IP Address for Instance i-1ca82a89, please wait...
Private IP Address of i-1ca82a89 is 172.30.0.238
Enter the list (Nx,Ny,Nz) or range (Nx-Nz) of DBRoot IDs assigned to module 'pm2' () > 2
*** Setup External EBS Volume for DBRoot #2 ***
*** NOTE: You have the option to provide an
existing EBS Volume ID or have a Volume created
Create a new EBS volume for DBRoot #2 ? [y,n] (y) > <Enter>
Create AWS Volume for DBRoot #2
Formatting DBRoot #2, please wait...
===== System Installation =====
System Configuration is complete.
Performing System Installation.
Performing an MariaDB Columnstore System install using a Binary package located in the /home/<USER> directory.
Next step is to enter the password to access the other Servers.
This is either your password or you can default to using a ssh key
If using a password, the password needs to be the same on all Servers.
Enter password, hit 'enter' to default to using a ssh key, or 'exit' > <Enter>
```
Notes: Hit Enter since ssh-keys are setup
```
----- Performing Install on 'um1 / i-05ab2990' -----
Install log file is located here: /tmp/um1_binary_install.log
----- Performing Install on 'pm2 / i-1ca82a89' -----
Install log file is located here: /tmp/pm2_binary_install.log
MariaDB Columnstore Package being installed, please wait ... DONE
===== Checking MariaDB Columnstore System Logging Functionality =====
The MariaDB Columnstore system logging is setup and working on local server
MariaDB Columnstore System Configuration and Installation is Completed
===== MariaDB Columnstore System Startup =====
System Installation is complete. If any part of the install failed,
the problem should be investigated and resolved before continuing.
Would you like to startup the MariaDB Columnstore System? [y,n] (y) > <Enter>
----- Starting MariaDB Columnstore on 'um1' -----
MariaDB Columnstore successfully started
----- Starting MariaDB Columnstore on 'pm2' -----
MariaDB Columnstore successfully started
----- Starting MariaDB Columnstore on local server -----
MariaDB Columnstore successfully started
MariaDB Columnstore Database Platform Starting, please wait ....... DONE
System Catalog Successfully Created
MariaDB Columnstore Install Successfully Completed, System is Active
Enter the following command to define MariaDB Columnstore Alias Commands
. /home/<USER>/mariadb/columnstore/bin/columnstoreAlias
Enter 'mcsmysql' to access the MariaDB Columnstore SQL console
Enter 'mcsadmin' to access the MariaDB Columnstore Admin console
```
MariaDB Columnstore Memory Configuration
----------------------------------------
During the installation process, postConfigure will set the 2 main Memory configuration settings based on the size of memory detected on the local node.
```
'NumBlocksPct' - Performance Module Data cache memory setting
TotalUmMemory - User Module memory setting, used as temporary memory for joins
```
On a system that has the Performance Module and User Module functionality combined on the same server, this is the default settings:
```
NumBlocksPct - 50% of total memory
TotalUmMemory - 25% of total memory, default maximum the percentage equal to 16G
```
On a system that has the Performance Module and User Module functionality on different servers, this is the default settings:
```
NumBlocksPct - This setting is NOT configured, and the default that the applications will then use is 70%
TotalUmMemory - 50% of total memory
```
The user can choose to change these settings after the install is completed, if for instance they want to setup more memory for Joins to utilize. On a single server or combined UM/PM server, it is recommended to not have the combination of these 2 settings over 75% of total memory
MariaDB Columnstore System Configuration settings
-------------------------------------------------
### vm.swappiness
The default setting for vm.swappiness is set to 30. This setting can be overridden by user on each instance.
To change the system swappiness value, open /etc/sysctl.conf as root. Then, change or add this line to the file:
vm.swappiness = 1
Reboot for the change to take effect
You can also change the value while your system is still running
sysctl vm.swappiness=1
#### Set the user file limits (by root user)
ColumnStore needs the open file limit to be increased for the specified user. To do this edit the /etc/security/limits.conf file and make the following additions at the end of the file:
```
<USER> hard nofile 65536
<USER> soft nofile 65536
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb Obsolete Installation Information Obsolete Installation Information
==================================
This section is for installation-related items that are obsolete.
| Title | Description |
| --- | --- |
| [MariaDB Debian Live Images](../mariadb-debian-live-images/index) | Debian live iso images with pre-installed MariaDB (obsolete) |
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Performance Schema mutex_instances Table Performance Schema mutex\_instances Table
=========================================
Description
-----------
The `mutex_instances` table lists all mutexes that the Performance Schema seeing while the server is executing.
A mutex is a code mechanism for ensuring that threads can only access resources one at a time. A second thread attempting to access a resource will find it protected by a mutex, and will wait for it to be unlocked.
The [performance\_schema\_max\_mutex\_instances](../performance-schema-system-variables/index#performance_schema_max_mutex_instances) system variable specifies the maximum number of instrumented mutex instances.
| Column | Description |
| --- | --- |
| `NAME` | Instrument name associated with the mutex. |
| `OBJECT_INSTANCE_BEGIN` | Memory address of the instrumented mutex. |
| `LOCKED_BY_THREAD_ID` | The `THREAD_ID` of the locking thread if a thread has a mutex locked, otherwise `NULL`. |
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb MultiLineStringFromWKB MultiLineStringFromWKB
======================
A synonym for [MLineFromWKB()](../mlinefromwkb/index).
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb 10.0.36 Release Upgrade Tests 10.0.36 Release Upgrade Tests
=============================
### Tested revision
e023f9a4d5a620b54d7f7132567150d80b630692
### Test date
2018-08-05 19:08:18
### Summary
Two tests failed due to problems in previous versions (unrelated to the release)
### Details
| type | pagesize | OLD version | file format | encrypted | compressed | | NEW version | file format | encrypted | compressed | readonly | result | notes |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| undo-recovery | 4 | 10.0.36 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo-recovery | 8 | 10.0.36 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo-recovery | 16 | 10.0.36 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| recovery | 16 | 10.0.36 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| recovery | 4 | 10.0.36 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| recovery | 8 | 10.0.36 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash | 4 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash | 8 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash | 16 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 16 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 4 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 8 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo | 16 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo | 4 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo | 8 | 10.0.35 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash | 4 | 10.0.14 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash | 8 | 10.0.14 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash | 16 | 10.0.14 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 16 | 10.0.14 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 4 | 10.0.14 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 8 | 10.0.14 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo | 16 | 10.0.18 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo | 4 | 10.0.18 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo | 8 | 10.0.18 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | **FAIL** | TEST\_FAILURE |
| crash | 4 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash | 8 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash | 16 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 16 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 4 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| normal | 8 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo | 16 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | **FAIL** | TEST\_FAILURE |
| undo | 4 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| undo | 8 | 5.6.41 (inbuilt) | | - | - | => | 10.0.36 (inbuilt) | | - | - | - | OK | |
| crash-downgrade | 4 | 10.0.36 (inbuilt) | | - | - | => | 10.0.35 (inbuilt) | | - | - | - | OK | |
| crash-downgrade | 8 | 10.0.36 (inbuilt) | | - | - | => | 10.0.35 (inbuilt) | | - | - | - | OK | |
| crash-downgrade | 16 | 10.0.36 (inbuilt) | | - | - | => | 10.0.35 (inbuilt) | | - | - | - | OK | |
| downgrade | 16 | 10.0.36 (inbuilt) | | - | - | => | 10.0.35 (inbuilt) | | - | - | - | OK | |
| downgrade | 4 | 10.0.36 (inbuilt) | | - | - | => | 10.0.35 (inbuilt) | | - | - | - | OK | |
| downgrade | 8 | 10.0.36 (inbuilt) | | - | - | => | 10.0.35 (inbuilt) | | - | - | - | OK | |
| crash-downgrade | 4 | 10.0.36 (inbuilt) | | - | - | => | 10.0.14 (inbuilt) | | - | - | - | OK | |
| crash-downgrade | 8 | 10.0.36 (inbuilt) | | - | - | => | 10.0.14 (inbuilt) | | - | - | - | OK | |
| crash-downgrade | 16 | 10.0.36 (inbuilt) | | - | - | => | 10.0.14 (inbuilt) | | - | - | - | OK | |
| downgrade | 16 | 10.0.36 (inbuilt) | | - | - | => | 10.0.14 (inbuilt) | | - | - | - | OK | |
| downgrade | 4 | 10.0.36 (inbuilt) | | - | - | => | 10.0.14 (inbuilt) | | - | - | - | OK | |
| downgrade | 8 | 10.0.36 (inbuilt) | | - | - | => | 10.0.14 (inbuilt) | | - | - | - | OK | |
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Table Discovery (before 10.0.2) Table Discovery (before 10.0.2)
===============================
This page describes the **old** discovery API, created in MySQL for NDB Cluster. It no longer works in MariaDB. New table discovery API is documented [here](../table-discovery/index).
There are four parts of it.
First, when a server finds that a table (for example, mentioned in the `SELECT` query) does not exist, it asks every engine whether it knows anything about this table. For this it uses **discover()** method of the handlerton. The method is defined as
```
int discover(handlerton *hton, THD* thd, const char *db, const char *name,
unsigned char **frmblob, size_t *frmlen);
```
It takes the database and a table name as arguments and is returns 0 if the table exists in the engine and 1 otherwise. If it returned 0, it is supposed to allocate (with `my_malloc()`) a buffer and store the complete binary image of the `.frm` file of that table. The server will write it down to disk, creating table's `.frm`. The output parameters `frmblob` and `frmlen` are used to return the information about the buffer to the caller. The caller is responsible for freeing the buffer with `my_free()`.
Second, in some cases the server only wants to know if the table exists, but it does not really need to open it and will not use its `.frm` file image. Then using the `discover()` method would be an overkill, and the server uses a lightweight **table\_exists\_in\_engine()** method. This method is defined as
```
int table_exists_in_engine(handlerton *hton, THD* thd,
const char *db, const char *name);
```
and it returns one of the `HA_ERR_` codes, typically `HA_ERR_NO_SUCH_TABLE` or `HA_ERR_TABLE_EXIST`.
Third, there can be a situation when the server thinks that the table exists (it found and successfully read the `.frm` file), but from the engine point of view the `.frm` file is incorrect. For example, the table was already deleted from the engine, or its definition was modified (again, modified only in the engine). In this case the `.frm` file is outdated, and the server needs to re-discover the table. The engine conveys this to the server by returning `HA_ERR_TABLE_DEF_CHANGED` error code from the handler's **open()** method. On receiving this error the server will use the `discover()` method to get the new `.frm` image. This also means that *after* the table is opened, the server does not expect its metadata to change. The engine thus should ensure (with some kind of locking, perhaps) that a table metadata cannot be modified, as long as the table stays opened.
And fourth, a user might want to retrieve a list of tables in a specific database. With `SHOW TABLES` or by quering `INFORMATION_SCHEMA` tables. The user expects to see all tables, but the server cannot discover them one by one, because it doesnt know table names. In this case, the server uses a special discovery technique. It is **find\_files()** method in the handlerton, defines as
```
int find_files(handlerton *hton, THD *thd,
const char *db, const char *path,
const char *wild, bool dir, List<LEX_STRING> *files);
```
and it, typically for Storage Engine API, returns 0 on success and 1 on failure. The arguments mean `db` - the name of the database, `path` - the path to it, `wild` an SQL wildcard pattern (for example, from `SHOW TABLES LIKE '...'`, and `dir`, if set, means to discover *databases* instead of *tables*.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb SSL/TLS Status Variables SSL/TLS Status Variables
========================
The status variables listed on this page relate to encrypting data during transfer with the Transport Layer Security (TLS) protocol. Often, the term Secure Socket Layer (SSL) is used interchangeably with TLS, although strictly speaking, the SSL protocol is a predecessor to TLS and is no longer considered secure.
For compatibility reasons, the TLS status variables in MariaDB still use the `Ssl_` prefix, but MariaDB only supports its more secure successors. For more information on SSL/TLS in MariaDB, see [Secure Connections Overview](../secure-connections-overview/index).
Variables
---------
#### `Ssl_accept_renegotiates`
* **Description:** Number of negotiations needed to establish the TLS connection. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_accepts`
* **Description:** Number of accepted TLS handshakes. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_callback_cache_hits`
* **Description:** Number of sessions retrieved from the session cache. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_cipher`
* **Description:** The TLS cipher currently in use.
* **Scope:** Global, Session
* **Data Type:** `string`
---
#### `Ssl_cipher_list`
* **Description:** List of the available TLS ciphers.
* **Scope:** Global, Session
* **Data Type:** `string`
---
#### `Ssl_client_connects`
* **Description:** Number of TLS handshakes started in client mode. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_connect_renegotiates`
* **Description:** Number of negotiations needed to establish the connection to a TLS-enabled master. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_ctx_verify_depth`
* **Description:** Number of tested TLS certificates in the chain. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_ctx_verify_mode`
* **Description:** Mode used for TLS context verification.The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_default_timeout`
* **Description:** Default timeout for TLS, in seconds.
* **Scope:** Global, Session
* **Data Type:** `numeric`
---
#### `Ssl_finished_accepts`
* **Description:** Number of successful TLS sessions in server mode. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_finished_connects`
* **Description:** Number of successful TLS sessions in client mode. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_server_not_after`
* **Description:** Last valid date for the TLS certificate.
* **Scope:** Global, Session
* **Data Type:** `numeric`
* **Introduced:** `[MariaDB 10.0](../what-is-mariadb-100/index)`
---
#### `Ssl_server_not_before`
* **Description:** First valid date for the TLS certificate.
* **Scope:** Global, Session
* **Data Type:** `numeric`
* **Introduced:** `[MariaDB 10.0](../what-is-mariadb-100/index)`
---
#### `Ssl_session_cache_hits`
* **Description:** Number of TLS sessions found in the session cache. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_session_cache_misses`
* **Description:** Number of TLS sessions not found in the session cache. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_session_cache_mode`
* **Description:** Mode used for TLS caching by the server.
* **Scope:** Global
* **Data Type:** `string`
---
#### `Ssl_session_cache_overflows`
* **Description:** Number of sessions removed from the session cache because it was full. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_session_cache_size`
* **Description:** Size of the session cache. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_session_cache_timeouts`
* **Description:** Number of sessions which have timed out. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_sessions_reused`
* **Description:** Number of sessions reused. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global, Session
* **Data Type:** `numeric`
---
#### `Ssl_used_session_cache_entries`
* **Description:** Current number of sessions in the session cache. The global value can be flushed by `[FLUSH STATUS](../flush/index)`.
* **Scope:** Global
* **Data Type:** `numeric`
---
#### `Ssl_verify_depth`
* **Description:** TLS verification depth.
* **Scope:** Global, Session
* **Data Type:** `numeric`
---
#### `Ssl_verify_mode`
* **Description:** TLS verification mode.
* **Scope:** Global, Session
* **Data Type:** `numeric`
---
#### `Ssl_version`
* **Description:** TLS version in use.
* **Scope:** Global, Session
* **Data Type:** `string`
---
See Also
--------
* [Server Status Variables](../server-status-variables/index) - complete list of status variables.
* [Full list of MariaDB options, system and status variables](../full-list-of-mariadb-options-system-and-status-variables/index)
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mariadb Lateral Derived Optimization Lateral Derived Optimization
============================
**MariaDB starting with [10.3](../what-is-mariadb-103/index)**Starting from [MariaDB 10.3](../what-is-mariadb-103/index), MariaDB has Lateral Derived optimization, also referred to as "Split Grouping Optimization" or "Split Materialized Optimization" in some sources.
Description
-----------
The optimization's use case is
* The query uses a derived table (or a VIEW, or a non-recursive CTE)
* The derived table/View/CTE has a GROUP BY operation as its top-level operation
* The query only needs data from a few GROUP BY groups
An example of this: consider a VIEW that computes totals for each customer in October:
```
create view OCT_TOTALS as
select
customer_id,
SUM(amount) as TOTAL_AMT
from orders
where
order_date BETWEEN '2017-10-01' and '2017-10-31'
group by
customer_id;
```
And a query that does a join with the customer table to get October totals for "Customer#1" and Customer#2:
```
select *
from
customer, OCT_TOTALS
where
customer.customer_id=OCT_TOTALS.customer_id and
customer.customer_name IN ('Customer#1', 'Customer#2')
```
Before Lateral Derived optimization, MariaDB would execute the query as follows:
1. Materialize the view OCT\_TOTALS. This essentially computes OCT\_TOTALS for all customers.
2. Join it with table customer.
The EXPLAIN would look like so:
```
+------+-------------+------------+-------+---------------+-----------+---------+---------------------------+-------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+------------+-------+---------------+-----------+---------+---------------------------+-------+--------------------------+
| 1 | PRIMARY | customer | range | PRIMARY,name | name | 103 | NULL | 2 | Using where; Using index |
| 1 | PRIMARY | <derived2> | ref | key0 | key0 | 4 | test.customer.customer_id | 36 | |
| 2 | DERIVED | orders | index | NULL | o_cust_id | 4 | NULL | 36738 | Using where |
+------+-------------+------------+-------+---------------+-----------+---------+---------------------------+-------+--------------------------+
```
It is obvious that Step #1 is very inefficient: we compute totals for all customers in the database, while we will only need them for two customers. (If there are 1000 customers, we are doing 500x more work than needed here)
Lateral Derived optimization addresses this case. It turns the computation of OCT\_TOTALS into what SQL Standard refers to as "LATERAL subquery": a subquery that may have dependencies on the outside tables. This allows pushing the equality `customer.customer_id=OCT_TOTALS.customer_id` down into the derived table/view, where it can be used to limit the computation to compute totals only for the customer of interest.
The query plan will look as follows:
1. Scan table `customer` and find `customer_id` for Customer#1 and Customer#2.
2. For each customer\_id, compute the October totals, for this specific customer.
The EXPLAIN output will look like so:
```
+------+-----------------+------------+-------+---------------+-----------+---------+---------------------------+------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-----------------+------------+-------+---------------+-----------+---------+---------------------------+------+--------------------------+
| 1 | PRIMARY | customer | range | PRIMARY,name | name | 103 | NULL | 2 | Using where; Using index |
| 1 | PRIMARY | <derived2> | ref | key0 | key0 | 4 | test.customer.customer_id | 2 | |
| 2 | LATERAL DERIVED | orders | ref | o_cust_id | o_cust_id | 4 | test.customer.customer_id | 1 | Using where |
+------+-----------------+------------+-------+---------------+-----------+---------+---------------------------+------+--------------------------+
```
Note the line with `id=2`: select\_type is `LATERAL DERIVED`. And table customer uses ref access referring to `customer.customer_id`, which is normally not allowed for derived tables.
In `EXPLAIN FORMAT=JSON` output, the optimization is shown like so:
```
...
"table": {
"table_name": "<derived2>",
"access_type": "ref",
...
"materialized": {
"lateral": 1,
```
Note the `"lateral": 1` member.
Controlling the Optimization
----------------------------
Lateral Derived is enabled by default, the optimizer will make a cost-based decision whether the optimization should be used.
If you need to disable the optimization, it has an [optimizer\_switch](../optimizer-switch/index) flag. It can be disabled like so:
```
set optimizer_switch='split_materialized=off'
```
References
----------
* Jira task: <https://jira.mariadb.org/browse/MDEV-13369>
* Commit: <https://github.com/MariaDB/server/commit/b14e2b044b>
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| programming_docs |
mariadb Conversion of Big IN Predicates Into Subqueries Conversion of Big IN Predicates Into Subqueries
===============================================
Starting from [MariaDB 10.3](../what-is-mariadb-103/index), the optimizer converts certain big IN predicates into IN subqueries.
That is, an IN predicate in the form
```
column [NOT] IN (const1, const2, .... )
```
is converted into an equivalent IN-subquery:
```
column [NOT] IN (select ... from temporary_table)
```
which opens new opportunities for the query optimizer.
The conversion happens if the following conditions are met:
* the IN list has more than 1000 elements (One can control it through the [in\_predicate\_conversion\_threshold](../server-system-variables/index#in_predicate_conversion_threshold) parameter).
* the [NOT] IN condition is at the top level of the WHERE/ON clause.
Controlling the Optimization
----------------------------
* The optimization is on by default. [MariaDB 10.3.18](https://mariadb.com/kb/en/mariadb-10318-release-notes/) (and debug builds prior to that) introduced the [in\_predicate\_conversion\_threshold](../server-system-variables/index#in_predicate_conversion_threshold) variable. Set to `0` to disable the optimization.
Benefits of the Optimization
----------------------------
If `column` is a key-prefix, MariaDB optimizer will process the condition
```
column [NOT] IN (const1, const2, .... )
```
by trying to construct a range access. If the list is large, the analysis may take a lot of memory and CPU time. The problem gets worse when `column` is a part of a multi-column index and the query has conditions on other parts of the index.
Conversion of IN predicates into a subqueries bypass the range analysis, which means the query optimization phase will use less CPU and memory.
Possible disadvantages of the conversion are are:
* The optimization may convert 'IN LIST elements' key accesses to a table scan (if there is no other usable index for the table)
* The estimates for the number of rows matching the `IN (...)` are less precise.
See Also
--------
* [IN operator](../in/index)
Links
-----
<https://jira.mariadb.org/browse/MDEV-12176>
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mariadb ALTER TABLESPACE ALTER TABLESPACE
================
The `ALTER TABLESPACE` statement is not supported by MariaDB. It was originally inherited from MySQL NDB Cluster. In MySQL 5.7 and later, the statement is also supported for InnoDB. However, MariaDB has chosen not to include that specific feature. See [MDEV-19294](https://jira.mariadb.org/browse/MDEV-19294) for more information.
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mariadb Information Schema SCHEMA_PRIVILEGES Table Information Schema SCHEMA\_PRIVILEGES Table
===========================================
The [Information Schema](../information_schema/index) `SCHEMA_PRIVILEGES` table contains information about [database privileges](../grant/index#database-privileges).
It contains the following columns:
| Column | Description |
| --- | --- |
| `GRANTEE` | Account granted the privilege in the format `user_name@host_name`. |
| `TABLE_CATALOG` | Always `def` |
| `TABLE_SCHEMA` | Database name. |
| `PRIVILEGE_TYPE` | The granted privilege. |
| `IS_GRANTABLE` | Whether the privilege can be granted. |
The same information in a different format can be found in the `[mysql.db](../mysqldb-table/index)` table.
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mariadb PERIOD_ADD PERIOD\_ADD
===========
Syntax
------
```
PERIOD_ADD(P,N)
```
Description
-----------
Adds `N` months to period `P`. `P` is in the format YYMM or YYYYMM, and is not a date value. If `P` contains a two-digit year, values from 00 to 69 are converted to from 2000 to 2069, while values from 70 are converted to 1970 upwards.
Returns a value in the format YYYYMM.
Examples
--------
```
SELECT PERIOD_ADD(200801,2);
+----------------------+
| PERIOD_ADD(200801,2) |
+----------------------+
| 200803 |
+----------------------+
SELECT PERIOD_ADD(6910,2);
+--------------------+
| PERIOD_ADD(6910,2) |
+--------------------+
| 206912 |
+--------------------+
SELECT PERIOD_ADD(7010,2);
+--------------------+
| PERIOD_ADD(7010,2) |
+--------------------+
| 197012 |
+--------------------+
```
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mariadb CONVERT CONVERT
=======
Syntax
------
```
CONVERT(expr,type), CONVERT(expr USING transcoding_name)
```
Description
-----------
The `CONVERT()` and [CAST()](../cast/index) functions take a value of one type and produce a value of another type.
The type can be one of the following values:
* [BINARY](../binary/index)
* [CHAR](../char/index)
* [DATE](../date/index)
* [DATETIME](../datetime/index)
* [DECIMAL[(M[,D])](../decimal/index)]
* [DOUBLE](../double/index)
* [FLOAT](../float/index) (from [MariaDB 10.4.5](https://mariadb.com/kb/en/mariadb-1045-release-notes/))
* [INTEGER](../int/index)
+ Short for `SIGNED INTEGER`
* SIGNED [INTEGER]
* UNSIGNED [INTEGER]
* [TIME](../time/index)
* [VARCHAR](../varchar/index) (in [Oracle mode](../sql_modeoracle/index), from [MariaDB 10.3](../what-is-mariadb-103/index))
Note that in MariaDB, `INT` and `INTEGER` are the same thing.
`BINARY` produces a string with the [BINARY](../binary/index) data type. If the optional length is given, `BINARY(N)` causes the cast to use no more than `N` bytes of the argument. Values shorter than the given number in bytes are padded with 0x00 bytes to make them equal the length value.
`CHAR(N)` causes the cast to use no more than the number of characters given in the argument.
The main difference between the [CAST()](../cast/index) and `CONVERT()` is that `CONVERT(expr,type)` is ODBC syntax while [CAST(expr as type)](../cast/index) and `CONVERT(... USING ...)` are SQL92 syntax.
`CONVERT()` with `USING` is used to convert data between different [character sets](../data-types-character-sets-and-collations/index). In MariaDB, transcoding names are the same as the corresponding character set names. For example, this statement converts the string 'abc' in the default character set to the corresponding string in the utf8 character set:
```
SELECT CONVERT('abc' USING utf8);
```
Examples
--------
```
SELECT enum_col FROM tbl_name
ORDER BY CAST(enum_col AS CHAR);
```
Converting a [BINARY](../binary/index) to string to permit the [LOWER](../lower/index) function to work:
```
SET @x = 'AardVark';
SET @x = BINARY 'AardVark';
SELECT LOWER(@x), LOWER(CONVERT (@x USING latin1));
+-----------+----------------------------------+
| LOWER(@x) | LOWER(CONVERT (@x USING latin1)) |
+-----------+----------------------------------+
| AardVark | aardvark |
+-----------+----------------------------------+
```
See Also
--------
* [Character Sets and Collations](../data-types-character-sets-and-collations/index)
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mariadb PROCEDURE ANALYSE PROCEDURE ANALYSE
=================
Syntax
------
```
analyse([max_elements[,max_memory]])
```
Description
-----------
This procedure is defined in the sql/sql\_analyse.cc file. It examines the result from a query and returns an analysis of the results that suggests optimal data types for each column. To obtain this analysis, append PROCEDURE ANALYSE to the end of a [SELECT](../select/index) statement:
```
SELECT ... FROM ... WHERE ... PROCEDURE ANALYSE([max_elements,[max_memory]])
```
For example:
```
SELECT col1, col2 FROM table1 PROCEDURE ANALYSE(10, 2000);
```
The results show some statistics for the values returned by the query, and propose an optimal data type for the columns. This can be helpful for checking your existing tables, or after importing new data. You may need to try different settings for the arguments so that PROCEDURE ANALYSE() does not suggest the ENUM data type when it is not appropriate.
The arguments are optional and are used as follows:
* max\_elements (default 256) is the maximum number of distinct values that analyse notices per column. This is used by analyse to check whether the optimal data type should be of type ENUM; if there are more than max\_elements distinct values, then ENUM is not a suggested type.
* max\_memory (default 8192) is the maximum amount of memory that analyse should allocate per column while trying to find all distinct values.
See Also
--------
* [PROCEDURE](../procedure/index)
* [SELECT](../select/index)
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mariadb MyRocks and Index-Only Scans MyRocks and Index-Only Scans
============================
This article is about [MyRocks](../myrocks/index) and index-only scans on secondary indexes. It applies to MariaDB's MyRocks, Facebook's MyRocks, and other variants.
Secondary Keys Only
-------------------
The primary key in MyRocks is always the clustered key, that is, the index record is THE table record and so it's not possible to do "index only" because there isn't anything that is not in the primary key's (Key,Value) pair.
Secondary keys may or may not support index-only scans, depending on the datatypes of the columns that the query is trying to read.
Background: Mem-Comparable Keys
-------------------------------
MyRocks indexes store "mem-comparable keys" (that is, the key values are compared with `memcmp`). For some datatypes, it is easily possible to convert between the column value and its mem-comparable form, while for others the conversion is one-way.
For example, in case-insensitive collations capital and regular letters are considered identical, i.e. 'c' ='C'. For some datatypes, MyRocks stores some extra data which allows it to restore the original value back. (For the `latin1_general_ci` [collation](../character-sets/index) and character 'c', for example, it will store one bit which says whether the original value was a small 'c' or a capital letter 'C'). This doesn't work for all datatypes, though.
Index-Only Support for Various Datatypes
----------------------------------------
Index-only scans are supported for numeric and date/time datatypes. For CHAR and VAR[CHAR], it depends on which collation is used, see below for details.
Index-only scans are currently not supported for less frequently used datatypes, like
* `[BIT(n)](../bit/index)`
* `[SET(...)](../set-data-type/index)`
* `[ENUM(...)](../enum/index)` *It is actually possible to add support for those, feel free to write a patch or at least make a case why a particular datatype is important*
Index-Only Support for Various Collations
-----------------------------------------
As far as Index-only support is concerned, MyRocks distinguishes three kinds of collations:
### 1. Binary (Reversible) Collations
These are `binary`, `latin1_bin`, and `utf8_bin`.
For these collations, it is possible to convert a value back from its mem-comparable form. Hence, one can restore the original value back from its index record, and index-only scans are supported.
### 2. Restorable Collations
These are collations where one can store some extra information which helps to restore the original value.
Criteria (from storage/rocksdb/rdb\_datadic.cc, rdb\_is\_collation\_supported()) are:
* The charset should use 1-byte characters (so, unicode-based collations are not included)
* strxfrm(1 byte) = {one 1-byte weight value always}
* no binary sorting
* PAD attribute
The examples are: `latin1_general_ci`, `latin1_general_cs`, `latin1_swedish_ci`, etc.
Index-only scans are supported for these collations.
### 3. All Other Collations
For these collations, there is no known way to restore the value from its mem-comparable form, and so index-only scans are not supported.
MyRocks needs to fetch the clustered PK record to get the field value.
Covering Secondary Key Lookups for VARCHARs
-------------------------------------------
TODO: there is also this optimization:
<https://github.com/facebook/mysql-5.6/issues/303> <https://github.com/facebook/mysql-5.6/commit/f349c95848e92b5b27b44f0e57194100eb0997e7>
document it.
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mariadb CONNECT JDBC Table Type: Accessing Tables from Another DBMS CONNECT JDBC Table Type: Accessing Tables from Another DBMS
===========================================================
The JDBC table type should be distributed with all recent versions of MariaDB. However, if the automatic compilation of it is possible after the java JDK was installed, the complete distribution of it is not fully implemented in older versions. The distributed JdbcInterface.jar file contains the JdbcInterface wrapper only. New versions distribute a JavaWrappers.jar that contains all currently existing wrappers.
This will require that:
1. The Java SDK is installed on your system.
2. The java wrapper class files are available on your system.
3. And of course, some JDBC drivers exist to be used with the matching DBMS.
Point 2 was made automatic in the newest versions of MariaDB.
Compiling From Source Distribution
----------------------------------
Even when the Java JDK has been installed, CMake sometimes cannot find the location where it stands. For instance on Linux the Oracle Java JDK package might be installed in a path not known by the CMake lookup functions causing error message such as:
```
CMake Error at /usr/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
Could NOT find Java (missing: Java_JAR_EXECUTABLE Java_JAVAC_EXECUTABLE
Java_JAVAH_EXECUTABLE Java_JAVADOC_EXECUTABLE)
```
When this happen, provide a Java prefix as a hint on where the package was loaded. For instance on Ubuntu I was obliged to enter:
```
export JAVA_HOME=/usr/lib/jvm/java-8-oracle
```
After that, the compilation of the CONNECT JDBC type was completed successfully.
### Compiling the Java source files
They are the source of the java wrapper classes used to access JDBC drivers. In the source distribution, they are located in the CONNECT source directory.
The default wrapper, JdbcInterface, is the only one distributed with binary distribution. It uses the standard way to get a connection to the drivers via the DriverManager.getConnection method. Other wrappers, only available with source distribution, enable connection to a Data Source, eventually implementing pooling. However, they must be compiled and installed manually.
The available wrappers are:
| Wrapper | Description |
| --- | --- |
| JdbcInterface | Used to make the connection with available drivers the standard way. |
| ApacheInterface | Based on the Apache common-dbcp2 package this interface enables making connections to DBCP data sources with any JDBC drivers. |
| MariadbInterface | Makes connection to a MariaDB data source. |
| MysqlInterface | Makes connection to a Mysql data source. Must be used with a MySQL driver that implements data sources. |
| OracleInterface | Makes connection to an Oracle data source. |
| PostgresqlInterface | Makes connection to a Postgresql data source. |
The wrapper used by default is specified by the [connect\_java\_wrapper](../connect-system-variables/index#connect_java_wrapper) session variable and is initially set to `wrappers/JdbcInterface`. The wrapper to use for a table can also be specified in the option list as a wrapper option of the “create table” statements.
Note: Conforming java naming usage, class names are preceded by the java package name with a slash separator. However, this is not mandatory for CONNECT which adds the package name if it is missing.
The JdbcInterface wrapper is always usable when Java is present on your machine. Binary distributions have this wrapper already compiled as a JdbcInterface.jar file installed in the plugin directory whose path is automatically included in the class path of the JVM. Recent versions also add a JavaWrappers.jar that contains all these wrappers. Therefore there is no need to worry about its path.
Compiling the ApacheInterface wrapper requires that the Apache common-DBCP2 package be installed. Other wrappers are to be used only with the matching JDBC drivers that must be available when compiling them.
Installing the jar file in the plugin directory is the best place because it is part of the class path. Depending on what is installed on your system, the source files can be reduced accordingly. To compile only the JdbcInterface.java file the CMAKE\_JAVA\_INCLUDE\_PATH is not required. Here the paths are the ones existing on my Windows 7 machine and should be localized.
Setting the Required Information
--------------------------------
Before any operation with a JDBC driver can be made, CONNECT must initialize the environment that will make working with Java possible. This will consist of:
1. Loading dynamically the JVM library module.
2. Creating the Java Virtual Machine.
3. Establishing contact with the java wrapper class.
4. Connecting to the used JDBC driver.
Indeed, the JVM library module is not statically linked to the CONNECT plugin. This is to make it possible to use a CONNECT plugin that has been compiled with the JDBC table type on a machine where the Java SDK is not installed. Otherwise, users not interested in the JDBC table type would be obliged to install the Java SDK on their machine to be able to load the CONNECT storage engine.
### JVM Library Location
If the JVM library (jvm.dll on Windows, libjvm.so on Linux) was not placed in the standard library load path, CONNECT cannot find it and must be told where to search for it. This happens in particular on Linux when the Oracle Javapackage was installed in a private location.
If the JAVA\_HOME variable was exported as explained above, CONNECT can sometimes find it using this information. Otherwise, its search path can be added to the LD\_LIBRARY\_PATH environment variable. But all this is complicated because making environment variables permanent on Linux is painful (many different methods must be used depending on the Linux version and the used shell).
This is why CONNECT introduced a new global variable connect\_jvm\_path to store this information. It can be set when starting the server as a command line option or even afterwards before the first use of the JDBC table type. For example:
```
set global connect_jvm_path="/usr/lib/jvm/java-8-oracle/jre/lib/i386/client"
```
or
```
set global connect_jvm_path="/usr/lib/jvm/java-8-oracle/jre/lib/i386/server"
```
The client library is smaller and faster for connection. The server library is more optimized and can be used in case of heavy load usage.
Note that this may not be required on Windows because the path to the JVM library can sometimes be found in the registry.
Once this library is loaded, CONNECT can create the required Java Virtual Machine.
### Java Class Path
This is the list of paths Java searches when loading classes. With CONNECT, the classes to load will be the java wrapper classes used to communicate with the drivers , and the used JDBC driver classes that are grouped inside jar files. If the ApacheInterface wrapper must be used, the class path must also include all three jars used by the Apache package.
Caution: This class path is passed as a parameter to the Java Virtual Machine (JVM) when creating it and cannot be modified as it is a read only property. In addition, because MariaDB is a multi-threading application, this JVM cannot be destroyed and will be used throughout the entire life of the MariaDB server. Therefore, be sure it is correctly set before you use the JDBC table type for the first time. Otherwise, there will be practically no alternative than to shut down the server and restart it.
The path to the wrapper classes must point to the directory containing the wrappers sub-directory. If a JdbcInterface.jar file was made, its path is the directory where it is located followed by the jar file name. It is unclear where because this will depend on the installation process. If you start from a source distribution, it can be in the storage/connect directory where the CONNECT source files are or where you moved them or compiled the JdbcInterface.jar file.
For binary distributions, there is nothing to do because the jar file has been installed in the mysql share directory whose path is always automatically included in the class path available to the JVM.
Remaining are the paths of all the installed JDBC drivers that you intend to use. Remember that their path must include the jar file itself. Some applications use an environment variable CLASSPATH to contain them. Paths are separated by ‘:’ on Linux and by ‘;’ on Windows.
If the CLASSPATH variable actually exists and if it is available inside MariaDB, so far so good. You can check this using an UDF function provided by CONNECT that returns environment variable values:
```
create function envar returns string soname 'ha_connect.so';
select envar('CLASSPATH');
```
Most of the time, this will return null or some required files are missing. This is why CONNECT introduced a global variable to store this information. The paths specified in this variable will be added and have precedence to the ones, if any, of the CLASSPATH environment variable. As for the jvm path, this variable connect\_class\_path should be specified when starting the server but can also be set before using the JDBC table type for the first time.
The current directory (sql/data) is also placed by CONNECT at the beginning of the class path.
As an example, here is how I start MariaDB when doing tests on Linux:
```
olivier@olivier-Aspire-8920:~$ sudo /usr/local/mysql/bin/mysqld -u root --console --default-storage-engine=myisam --skip-innodb --connect_jvm_path="/usr/lib/jvm/java-8-oracle/jre/lib/i386/server" --connect_class_path="/home/olivier/mariadb/10.1/storage/connect:/media/olivier/SOURCE/mysql-connector-java-6.0.2/mysql-connector-java-6.0.2-bin.jar"
```
CONNECT JDBC Tables
-------------------
These tables are given the type JDBC. For instance, supposing you want to access the boys table located on and external local or remote database management system providing a JDBC connector:
```
create table boys (
name char(12),
city char(12),
birth date,
hired date);
```
To access this table via JDBC you can create a table such as:
```
create table jboys engine=connect table_type=JDBC tabname=boys
connection='jdbc:mysql://localhost/dbname?user=root';
```
The CONNECTION option is the URL used to establish the connection with the remote server. Its syntax depends on the external DBMS and in this example is the one used to connect as root to a MySQL or MariaDB local database using the MySQL JDBC connector.
As for ODBC, the columns definition can be omitted and will be retrieved by the discovery process. The restrictions concerning column definitions are the same as for ODBC.
Note: The dbname indicated in the URL corresponds for many DBMS to the catalog information. For MySQL and MariaDB it is the schema (often called database) of the connection.
### Using a Federated Server
Alternatively, a JDBC table can specify its connection options via a Federated server. For instance, supposing you have a table accessing an external Postgresql table defined as:
```
create table juuid engine=connect table_type=JDBC tabname=testuuid
connection='jdbc:postgresql:test?user=postgres&password=pwd';
```
You can create a Federated server:
```
create server 'post1' foreign data wrapper 'postgresql' options (
HOST 'localhost',
DATABASE 'test',
USER 'postgres',
PASSWORD 'pwd',
PORT 0,
SOCKET '',
OWNER 'postgres');
```
Now the JDBC table can be created by:
```
create table juuid engine=connect table_type=JDBC connection='post1' tabname=testuuid;
```
or by:
```
create table juuid engine=connect table_type=JDBC connection='post1/testuuid';
```
In any case, the location of the remote table can be changed in the Federated server without having to alter all the tables using this server.
JDBC needs a URL to establish a connection. CONNECT was able to construct that URL from the information contained in such Federated server definition when the URL syntax is similar to the one of MySQL, MariaDB or Postgresql. However, other DBMSs such as Oracle use a different URL syntax. In this case, simply replace the HOST information by the required URL in the Federated server definition. For instance:
```
create server 'oracle' foreign data wrapper 'oracle' options (
HOST 'jdbc:oracle:thin:@localhost:1521:xe',
DATABASE 'SYSTEM',
USER 'system',
PASSWORD 'manager',
PORT 0,
SOCKET '',
OWNER 'SYSTEM');
```
Now you can create an Oracle table with something like this:
```
create table empor engine=connect table_type=JDBC connection='oracle/HR.EMPLOYEES';
```
Note: Oracle, as Postgresql, does not seem to understand the DATABASE setting as the table schema that must be specified in the Create Table statement.
Connecting to a JDBC driver
---------------------------
When the connection to the driver is established by the JdbcInterface wrapper class, it uses the options that are provided when creating the CONNECT JDBC tables. Inside the default Java wrapper, the driver’s main class is loaded by the DriverManager.getConnection function that takes three arguments:
| | |
| --- | --- |
| URL | That is the URL that you specified in the CONNECTION option. |
| User | As specified in the OPTION\_LIST or NULL if not specified. |
| Password | As specified in the OPTION\_LIST or NULL if not specified. |
The URL varies depending on the connected DBMS. Refer to the documentation of the specific JDBC driver for a description of the syntax to use. User and password can also be specified in the option list.
Beware that the database name in the URL can be interpreted differently depending on the DBMS. For MySQL this is the schema in which the tables are found. However, for Postgresql, this is the catalog and the schema must be specified using the CONNECT dbname option.
For instance a table accessing a Postgresql table via JDBC can be created with a create statement such as:
```
create table jt1 engine=connect table_type=JDBC
connection='jdbc:postgresql://localhost/mtr' dbname=public tabname=t1
option_list='User=mtr,Password=mtr';
```
Note: In previous versions of JDBC, to obtain a connection, java first had to initialize the JDBC driver by calling the method Class.forName. In this case, see the documentation of your DBMS driver to obtain the name of the class that implements the interface java.sql.Driver. This name can be specified as an option DRIVER to be put in the option list. However, most modern JDBC drivers since version 4 are self-loading and do not require this option to be specified.
The wrapper class also creates some required items and, in particular, a statement class. Some characteristics of this statement will depend on the options specified when creating the table:
| | |
| --- | --- |
| Scrollable | To be specified in the option list. Determines the cursor type: no= forward\_only or yes=scroll\_insensitive. |
| Block\_size | Will be used to set the statement fetch size. |
### Fetch Size
The fetch size determines the number of rows that are internally retrieved by the driver on each interaction with the DBMS. Its default value depends on the JDBC driver. It is equal to 10 for some drivers but not for the MySQL or MariaDB connectors.
The MySQL/MariaDB connectors retrieve all the rows returned by one query and keep them in a memory cache. This is generally fine in most cases, but not when retrieving a large result set that can make the query fail with a memory exhausted exception.
To avoid this, when accessing a big table and expecting large result sets, you should specify the BLOCK\_SIZE option to 1 (the only acceptable value). However a problem remains:
Suppose you execute a query such as:
```
select id, name, phone from jbig limit 10;
```
Not knowing the limit clause, CONNECT sends to the remote DBMS the query:
```
SELECT id, name, phone FROM big;
```
In this query big can be a huge table having million rows. Having correctly specified the block size as 1 when creating the table, the wrapper just reads the 10 first rows and stops. However, when closing the statement, these MySQL/MariaDB drivers must still retrieve all the rows returned by the query. This is why, the wrapper class when closing the statement also cancels the query to stop that extra reading.
The bad news is that if it works all right for some previous versions of the MySQL driver, it does not work for new versions as well as for the MariaDB driver that apparently ignores the cancel command. The good news is that you can use an old MySQL driver to access MariaDB databases. It is also possible that this bug will be fixed in future versions of the drivers.
### Connection to a Data Source
This is the java preferred way to establish a connection because a data source can keep a pool of connections that can be re-used when necessary. This makes establishing connections much faster once it was done for the first time.
CONNECT provide additional wrappers whose files are located in the CONNECT source directory. The wrapper to use can be specified in the global variable connect\_java\_wrapper, which defaults to “JdbcInterface”.
It can also be specified for a table in the option list by setting the option wrapper to its name. For instance:
```
create table jboys
engine=CONNECT table_type=JDBC tabname='boys'
connection='jdbc:mariadb://localhost/connect?user=root&useSSL=false'
option_list='Wrapper=MariadbInterface,Scrollable=1';
```
They can be used instead of the standard JdbcInterface and are using created data sources.
The Apache one uses data sources implemented by the Apache-commons-dbcp2 package and can be used with all drivers including those not implementing data sources. However, the Apache package must be installed and its three required jar files accessible via the class path.
1. commons-dbcp2-2.1.1.jar
2. commons-pool2-2.4.2.jar
3. commons-logging-1.2.jar
Note: the versions numbers can be different on your installation.
The other ones use data sources provided by the matching JDBC driver. There are currently four wrappers to be used with mysql-6.0.2, mariadb, oracle and postgresql.
Unlike the class path, the used wrapper can be changed even after the JVM machine was created.
Random Access to JDBC Tables
----------------------------
The same methods described for ODBC tables can be used with JDBC tables.
Note that in the case of the MySQL or MariaDB connectors, because they internally read the whole result set in memory, using the MEMORY option would be a waste of memory. It is much better to specify the use of a scrollable cursor when needed.
Other Operations with JDBC Tables
---------------------------------
Except for the way the connection string is specified and the table type set to JDBC, all operations with ODBC tables are done for JDBC tables the same way. Refer to the ODBC chapter to know about:
* Accessing specified views (SRCDEF)
* Data modifying operations.
* Sending commands to a data source.
* JDBC catalog information.
Note: Some JDBC drivers fail when the global time\_zone variable is ambiguous, which sometimes happens when it is set to SYSTEM. If so, reset it to a not ambiguous value, for instance:
```
set global time_zone = '+2:00';
```
JDBC Specific Restrictions
--------------------------
Connecting via data sources created externally (for instance using Tomcat) is not supported yet.
Other restrictions are the same as for the ODBC table type.
Handling the UUID Data Type
---------------------------
PostgreSQL has a native UUID data type, internally stored as BIN(16). This is neither an SQL nor a MariaDB data type. The best we can do is to handle it by its character representation.
UUID will be translated to CHAR(36) when column definitions are set using discovery. Locally a PostgreSQL UUID column will be handled like a CHAR or VARCHAR column. Example:
Using the PostgreSQL table testuuid in the text database:
```
Table « public.testuuid »
Column | Type | Default
--------+------+--------------------
id | uuid | uuid_generate_v4()
msg | text |
```
Its column definitions can be queried by:
```
create or replace table juuidcol engine=connect table_type=JDBC tabname=testuuid catfunc=columns
connection='jdbc:postgresql:test?user=postgres&password=pwd';
```
```
select table_name "Table", column_name "Column", data_type "Type",
type_name "Name", column_size "Size"
from juuidcol;
```
This query returns:
| Table | Column | Type | Name | Size |
| --- | --- | --- | --- | --- |
| testuuid | id | 1111 | uuid | 2147483647 |
| testuuid | msg | 12 | text | 2147483647 |
Note: PostgreSQL, when a column size is undefined, returns 2147483647, which is not acceptable for MariaDB. CONNECT change it to the value of the connect\_conv\_size session variable. Also, for TEXT columns the data type returned is 12 (SQL\_VARCHAR) instead of -1 the SQL\_TEXT value.
Accessing this table via JDBC by:
```
CREATE TABLE juuid ENGINE=connect TABLE_TYPE=JDBC TABNAME=testuuid
CONNECTION='jdbc:postgresql:test?user=postgres&password=pwd';
```
it will be created by discovery as:
```
CREATE TABLE `juuid` (
`id` char(36) DEFAULT NULL,
`msg` varchar(8192) DEFAULT NULL
) ENGINE=CONNECT DEFAULT CHARSET=latin1 CONNECTION='jdbc:postgresql:test?user=postgres&password=pwd' `TABLE_TYPE`='JDBC' `TABNAME`='testuuid';
```
Note: 8192 being here the \_connect\_conv\_size\_ value.
Let's populate it:
```
insert into juuid(msg) values('First');
insert into juuid(msg) values('Second');
select * from juuid;
```
Result:
| id | msg |
| --- | --- |
| 4b173ee1-1488-4355-a7ed-62ba59c2b3e7 | First |
| 6859f850-94a7-4903-8d3c-fc3c874fc274 | Second |
Here the id column values come from the DEFAULT of the PostgreSQL column that was specified as uuid\_generate\_v4().
It can be set from MariaDB. For instance:
```
insert into juuid
values('2f835fb8-73b0-42f3-a1d3-8a532b38feca','inserted');
insert into juuid values(NULL,'null');
insert into juuid values('','random');
select * from juuid;
```
Result:
| id | msg |
| --- | --- |
| 4b173ee1-1488-4355-a7ed-62ba59c2b3e7 | First |
| 6859f850-94a7-4903-8d3c-fc3c874fc274 | Second |
| 2f835fb8-73b0-42f3-a1d3-8a532b38feca | inserted |
| <null> | null |
| 8fc0a30e-dc66-4b95-ba57-497a161f4180 | random |
The first insert specifies a valid UUID character representation. The second one set it to NULL. The third one (a void string) generates a Java random UUID. UPDATE commands obey the same specification.
These commands both work:
```
select * from juuid where id = '2f835fb8-73b0-42f3-a1d3-8a532b38feca';
delete from juuid where id = '2f835fb8-73b0-42f3-a1d3-8a532b38feca';
```
However, this one fails:
```
select * from juuid where id like '%42f3%';
```
Returning:
1296: Got error 174 'ExecuteQuery: org.postgresql.util.PSQLException: ERROR: operator does not exist: uuid ~ unknown hint: no operator corresponds to the data name and to the argument types.
because CONNECT cond\_push feature added the WHERE clause to the query sent to PostgreSQL:
```
SELECT id, msg FROM testuuid WHERE id LIKE '%42f3%'
```
and the LIKE operator does not apply to UUID in PostgreSQL.
To handle this, a new session variable was added to CONNECT: connect\_cond\_push. It permits to specify if cond\_push is enabled or not for CONNECT and defaults to 1 (enabled). In this case, you can execute:
```
set connect_cond_push=0;
```
Doing so, the where clause will be executed by MariaDB only and the query will not fail anymore.
Executing the JDBC tests
------------------------
Four tests exist but they are disabled because requiring some work to localized them according to the operating system and available java package and JDBC drivers and DBMS.
Two of them, jdbc.test and jdbc\_new.test, are accessing MariaDB via JDBC drivers that are contained in a fat jar file that is part of the test. They should be executable without anything to do on Windows; simply adding the option –enable-disabled when running the tests.
However, on Linux these tests can fail to locate the JVM library. Before executing them, you should export the JAVA\_HOME environment variable set to the prefix of the java installation or export the LD\_LIBRARY\_PATH containing the path to the JVM lib.
Fixing Problem With mysqldump
-----------------------------
In some case or some platform, when CONNECT is set up for use with JDBC table types, this causes [mysqldump](../mysqldump/index) with the option --all-databases to fail.
This was reported by Robert Dyas who found the cause - see the discussion at [MDEV-11238](https://jira.mariadb.org/browse/MDEV-11238).
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb Authentication Plugin - mysql_old_password Authentication Plugin - mysql\_old\_password
============================================
The `mysql_old_password` authentication plugin is the default authentication plugin that will be used for an account created when no authentication plugin is explicitly mentioned and `[old\_passwords=1](../server-system-variables/index#old_passwords)` is set. It uses the pre-MySQL 4.1 password hashing algorithm, which is also used by the `[OLD\_PASSWORD()](../old_password/index)` function and by the `[PASSWORD()](../password/index)` function when `[old\_passwords=1](../server-system-variables/index#old_passwords)` is set.
It is not recommended to use the `mysql_old_password` authentication plugin for new installations. The password hashing algorithm is no longer as secure as it used to be, and the plugin is primarily provided for backward-compatibility. The `[ed25519](../authentication-plugin-ed25519/index)` authentication plugin is a more modern authentication plugin that provides simple password authentication.
Installing the Plugin
---------------------
The `mysql_old_password` authentication plugin is statically linked into the server, so no installation is necessary.
Creating Users
--------------
The easiest way to create a user account with the `mysql_old_password` authentication plugin is to make sure that `[old\_passwords=1](../server-system-variables/index#old_passwords)` is set, and then create a user account via `[CREATE USER](../create-user/index)` that does not specify an authentication plugin, but does specify a password via the `[IDENTIFIED BY](../create-user/index#identified-by-password)` clause. For example:
```
SET old_passwords=1;
CREATE USER username@hostname IDENTIFIED BY 'mariadb';
```
If `[SQL\_MODE](../sql-mode/index)` does not have `NO_AUTO_CREATE_USER` set, then you can also create the user via `[GRANT](../grant/index)`. For example:
```
SET old_passwords=1;
GRANT SELECT ON db.* TO username@hostname IDENTIFIED BY 'mariadb';
```
You can also create the user account by providing a password hash via the `[IDENTIFIED BY PASSWORD](../create-user/index#identified-by-password-password_hash)` clause, and MariaDB will validate whether the password hash is one that is compatible with `mysql_old_password`. For example:
```
SET old_passwords=1;
Query OK, 0 rows affected (0.000 sec)
SELECT PASSWORD('mariadb');
+---------------------+
| PASSWORD('mariadb') |
+---------------------+
| 021bec665bf663f1 |
+---------------------+
1 row in set (0.000 sec)
CREATE USER username@hostname IDENTIFIED BY PASSWORD '021bec665bf663f1';
Query OK, 0 rows affected (0.000 sec)
```
Similar to all other [authentication plugins](../authentication-plugins/index), you could also specify the name of the plugin in the `[IDENTIFIED VIA](../create-user/index#identified-viawith-authentication_plugin)` clause while providing the password hash as the `USING` clause. For example:
```
CREATE USER username@hostname IDENTIFIED VIA mysql_old_password USING '021bec665bf663f1';
Query OK, 0 rows affected (0.000 sec)
```
Changing User Passwords
-----------------------
You can change a user account's password with the `[SET PASSWORD](../set-password/index)` statement while providing the plain-text password as an argument to the `[PASSWORD()](../password/index)` function. For example:
```
SET PASSWORD = PASSWORD('new_secret')
```
You can also change the user account's password with the `[ALTER USER](../alter-user/index)` statement. You would have to make sure that `[old\_passwords=1](../server-system-variables/index#old_passwords)` is set, and then you would have to specify a password via the `[IDENTIFIED BY](../alter-user/index#identified-by-password)` clause. For example:
```
SET old_passwords=1;
ALTER USER username@hostname IDENTIFIED BY 'new_secret';
```
Client Authentication Plugins
-----------------------------
For clients that use the `libmysqlclient` or [MariaDB Connector/C](../mariadb-connector-c/index) libraries, MariaDB provides one client authentication plugin that is compatible with the `mysql_old_password` authentication plugin:
* `mysql_old_password`
When connecting with a [client or utility](../clients-utilities/index) to a server as a user account that authenticates with the `mysql_old_password` authentication plugin, you may need to tell the client where to find the relevant client authentication plugin by specifying the `--plugin-dir` option. For example:
```
mysql --plugin-dir=/usr/local/mysql/lib64/mysql/plugin --user=alice
```
However, the `mysql_old_password` client authentication plugin is generally statically linked into client libraries like `libmysqlclient` or [MariaDB Connector/C](../mariadb-connector-c/index), so this is not usually necessary.
### `mysql_old_password`
The `mysql_old_password` client authentication plugin hashes the password before sending it to the server.
Support in Client Libraries
---------------------------
The `mysql_old_password` authentication plugin is one of the conventional authentication plugins, so all client libraries should support it.
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mariadb Querious Querious
========
Querious is a database administration tool for macOS.
It can be purchased/downloaded at <http://www.araelium.com/querious>
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb dbdeployer dbdeployer
==========
dbdeployer is a tool for installing multiple versions of MariaDB and/or MySQL in isolation from each other. It is primarily used for easily testing different server versions. It is written in Go, and is a replacement for [MySQL Sandbox](../mysql-sandbox/index).
Visit <https://www.dbdeployer.com> for details on how to install and use it.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb SHOW CREATE EVENT SHOW CREATE EVENT
=================
Syntax
------
```
SHOW CREATE EVENT event_name
```
Description
-----------
This statement displays the `[CREATE EVENT](../create-event/index)` statement needed to re-create a given [event](../events/index), as well as the `[SQL\_MODE](../sql-mode/index)` that was used when the trigger has been created and the character set used by the connection. To find out which events are present, use `[SHOW EVENTS](../show-events/index)`.
The output of this statement is unreliably affected by the `[sql\_quote\_show\_create](../server-system-variables/index#sql_quote_show_create)` server system variable - see <http://bugs.mysql.com/bug.php?id=12719>
The `[information\_schema.EVENTS](../information-schema-events-table/index)` table provides similar, but more complete, information.
Examples
--------
```
SHOW CREATE EVENT test.e_daily\G
*************************** 1. row ***************************
Event: e_daily
sql_mode:
time_zone: SYSTEM
Create Event: CREATE EVENT `e_daily`
ON SCHEDULE EVERY 1 DAY
STARTS CURRENT_TIMESTAMP + INTERVAL 6 HOUR
ON COMPLETION NOT PRESERVE
ENABLE
COMMENT 'Saves total number of sessions then
clears the table each day'
DO BEGIN
INSERT INTO site_activity.totals (time, total)
SELECT CURRENT_TIMESTAMP, COUNT(*)
FROM site_activity.sessions;
DELETE FROM site_activity.sessions;
END
character_set_client: latin1
collation_connection: latin1_swedish_ci
Database Collation: latin1_swedish_ci
```
See also
--------
* [Events Overview](../events-overview/index)
* `[CREATE EVENT](../create-event/index)`
* `[ALTER EVENT](../alter-event/index)`
* `[DROP EVENT](../drop-event/index)`
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Merging with a Merge Tree Merging with a Merge Tree
=========================
If you have a [merge tree](../creating-a-new-merge-tree/index), you merge into MariaDB as follows:
1. MariaDB merge trees are in the [mergetrees](https://github.com/MariaDB/mergetrees) repository. Add it as a new remote:
```
git remote add merge https://github.com/MariaDB/mergetrees
```
2. Check out the branch you want to update and merge, for example:
```
git checkout merge-innodb-5.6
```
3. delete everything in the branch
4. download the latest released source tarball, unpack it, copy files into the repository:
* for **InnoDB-5.6**: use the content of the `storage/innobase/` of the latest MySQL 5.6 source release tarball.
* for **performance schema 5.6**: use `storage/perfschema`, `include/mysql/psi`, `mysql-test/suite/perfschema`, and `mysql-test/suite/perfschema_stress` from the latest MySQL 5.6 source release tarball.
* for **SphinxSE**: use `mysqlse/` subdirectory from the latest Sphinx source release tarball.
* for **XtraDB**: use the content of the `storage/innobase/` of the latest Percona-Server source release tarball (5.5 or 5.6 as appropriate).
* for **pcre**: simply unpack the latest pcre release source tarball into the repository, rename `pcre-X-XX/` to `pcre`.
5. Now `git add .`, `git commit` (use the tarball version as a comment), `git push`
6. merge this branch into MariaDB
7. Sometimes after a merge, some changes may be needed:
* for **performance schema 5.6**: update `storage/perfschema/ha_perfschema.cc`, plugin version under `maria_declare_plugin`.
* for **InnoDB-5.6**: update `storage/innobase/include/univ.i`, setting `INNODB_VERSION_MAJOR`, `INNODB_VERSION_MINOR`, `INNODB_VERSION_BUGFIX` to whatever MySQL version you were merging from.
* for **XtraDB-5.5**: update `storage/xtradb/include/univ.i`, setting `PERCONA_INNODB_VERSION`, `INNODB_VERSION_STR` to whatever Percona-Server version you were merging from.
* for **XtraDB-5.6**: update `storage/xtradb/include/univ.i`, setting `PERCONA_INNODB_VERSION`, `INNODB_VERSION_MAJOR`, `INNODB_VERSION_MINOR`, `INNODB_VERSION_BUGFIX` to whatever Percona-Server version you were merging from.
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mariadb MultiPolygonFromText MultiPolygonFromText
====================
A synonym for [MPolyFromText](../mpolyfromtext/index).
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mariadb MyISAM Clients and Utilities MyISAM Clients and Utilities
=============================
Clients and utilities for working with the MyISAM storage engine
| Title | Description |
| --- | --- |
| [myisamchk](../myisamchk/index) | Utility for checking, repairing and optimizing MyISAM tables. |
| [Memory and Disk Use With myisamchk](../memory-and-disk-use-with-myisamchk/index) | myisamchk's performance can be dramatically enhanced for larger tables |
| [myisamchk Table Information](../myisamchk-table-information/index) | myisamchk can be used to obtain information about MyISAM tables |
| [myisamlog](../myisamlog/index) | Process the MyISAM log |
| [myisampack](../myisampack/index) | Tool for compressing MyISAM tables |
| [myisam\_ftdump](../myisam_ftdump/index) | A tool for displaying information on MyISAM FULLTEXT indexes. |
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mariadb RESET REPLICA/SLAVE RESET REPLICA/SLAVE
===================
The terms *master* and *slave* have historically been used in replication, but the terms terms *primary* and *replica* are now preferred. The old terms are used still used in parts of the documentation, and in MariaDB commands, although [MariaDB 10.5](../what-is-mariadb-105/index) has begun the process of renaming. The documentation process is ongoing. See [MDEV-18777](https://jira.mariadb.org/browse/MDEV-18777) to follow progress on this effort.
Syntax
------
```
RESET REPLICA ["connection_name"] [ALL] [FOR CHANNEL "connection_name"] -- from MariaDB 10.5.1
RESET SLAVE ["connection_name"] [ALL] [FOR CHANNEL "connection_name"]
```
Description
-----------
RESET REPLICA/SLAVE makes the replica forget its [replication](../replication/index) position in the master's [binary log](../binary-log/index). This statement is meant to be used for a clean start. It deletes the master.info and relay-log.info files, all the [relay log](../relay-log/index) files, and starts a new relay log file. To use RESET REPLICA/SLAVE, the replica threads must be stopped (use [STOP REPLICA/SLAVE](../stop-replica/index) if necessary).
Note: All relay log files are deleted, even if they have not been completely executed by the slave SQL thread. (This is a condition likely to exist on a replication slave if you have issued a STOP REPLICA/SLAVE statement or if the slave is highly loaded.)
Note: `RESET REPLICA` does not reset the global `gtid_slave_pos` variable. This means that a replica server configured with `CHANGE MASTER TO MASTER_USE_GTID=slave_pos` will not receive events with GTIDs occurring before the state saved in `gtid_slave_pos`. If the intent is to reprocess these events, `gtid_slave_pos` must be manually reset, e.g. by executing `set global gtid_slave_pos=""`.
Connection information stored in the master.info file is immediately reset using any values specified in the corresponding startup options. This information includes values such as master host, master port, master user, and master password. If the replica SQL thread was in the middle of replicating temporary tables when it was stopped, and RESET REPLICA/SLAVE is issued, these replicated temporary tables are deleted on the slave.
The `ALL` also resets the `PORT`, `HOST`, `USER` and `PASSWORD` parameters for the slave. If you are using a connection name, it will permanently delete it and it will not show up anymore in [SHOW ALL REPLICAS/SLAVE STATUS](../show-replica-status/index).
#### connection\_name
The `connection_name` option is used for [multi-source replication](../multi-source-replication/index).
If there is only one nameless primary, or the default primary (as specified by the [default\_master\_connection](../replication-and-binary-log-server-system-variables/index#default_master_connection) system variable) is intended, `connection_name` can be omitted. If provided, the `RESET REPLICA/SLAVE` statement will apply to the specified primary. `connection_name` is case-insensitive.
**MariaDB starting with [10.7.0](https://mariadb.com/kb/en/mariadb-1070-release-notes/)**The `FOR CHANNEL` keyword was added for MySQL compatibility. This is identical as using the channel\_name directly after `RESET REPLICA`.
#### RESET REPLICA
**MariaDB starting with [10.5.1](https://mariadb.com/kb/en/mariadb-1051-release-notes/)**`RESET REPLICA` is an alias for `RESET SLAVE` from [MariaDB 10.5.1](https://mariadb.com/kb/en/mariadb-1051-release-notes/).
See Also
--------
* [STOP REPLICA/SLAVE](../stop-replica/index) stops the replica, but it can be restarted with [START REPLICA/SLAVE](../start-replica/index) or after next MariaDB server restart.
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mariadb IsClosed IsClosed
========
A synonym for [ST\_IsClosed](../st_isclosed/index).
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mariadb JSON_NORMALIZE JSON\_NORMALIZE
===============
**MariaDB starting with [10.7.0](https://mariadb.com/kb/en/mariadb-1070-release-notes/)**JSON\_NORMALIZE was added in [MariaDB 10.7.0](https://mariadb.com/kb/en/mariadb-1070-release-notes/).
Syntax
------
```
JSON_NORMALIZE(json)
```
Description
-----------
Recursively sorts keys and removes spaces, allowing comparison of json documents for equality.
Examples
--------
We may wish our application to use the database to enforce a unique constraint on the JSON contents, and we can do so using the JSON\_NORMALIZE function in combination with a unique key.
For example, if we have a table with a JSON column:
```
CREATE TABLE t1 (
id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
val JSON,
/* other columns here */
PRIMARY KEY (id)
);
```
Add a unique constraint using JSON\_NORMALIZE like this:
```
ALTER TABLE t1
ADD COLUMN jnorm JSON AS (JSON_NORMALIZE(val)) VIRTUAL,
ADD UNIQUE KEY (jnorm);
```
We can test this by first inserting a row as normal:
```
INSERT INTO t1 (val) VALUES ('{"name":"alice","color":"blue"}');
```
And then seeing what happens with a different string which would produce the same JSON object:
```
INSERT INTO t1 (val) VALUES ('{ "color": "blue", "name": "alice" }');
ERROR 1062 (23000): Duplicate entry '{"color":"blue","name":"alice"}' for key 'jnorm'
```
See Also
--------
* [JSON\_EQUALS](../json_equals/index)
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mariadb ELT ELT
===
Syntax
------
```
ELT(N, str1[, str2, str3,...])
```
Description
-----------
Takes a numeric argument and a series of string arguments. Returns the string that corresponds to the given numeric position. For instance, it returns `str1` if `N` is 1, `str2` if `N` is 2, and so on. If the numeric argument is a `[FLOAT](../float/index)`, MariaDB rounds it to the nearest `[INTEGER](../int/index)`. If the numeric argument is less than 1, greater than the total number of arguments, or not a number, `ELT()` returns `NULL`. It must have at least two arguments.
It is complementary to the `[FIELD()](../field/index)` function.
Examples
--------
```
SELECT ELT(1, 'ej', 'Heja', 'hej', 'foo');
+------------------------------------+
| ELT(1, 'ej', 'Heja', 'hej', 'foo') |
+------------------------------------+
| ej |
+------------------------------------+
SELECT ELT(4, 'ej', 'Heja', 'hej', 'foo');
+------------------------------------+
| ELT(4, 'ej', 'Heja', 'hej', 'foo') |
+------------------------------------+
| foo |
+------------------------------------+
```
See also
--------
* [FIND\_IN\_SET()](../find_in_set/index) function. Returns the position of a string in a set of strings.
* [FIELD()](../field/index) function. Returns the index position of a string in a list.
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| programming_docs |
mariadb Window Functions Window Functions
=================
**MariaDB starting with [10.2](../what-is-mariadb-102/index)**Window functions were first introduced in [MariaDB 10.2.0](https://mariadb.com/kb/en/mariadb-1020-release-notes/).
Window functions perform calculations across a set of rows related to the current row
| Title | Description |
| --- | --- |
| [Window Functions Overview](../window-functions-overview/index) | Window functions perform calculations across a set of rows related to the current row. |
| [AVG](../avg/index) | Returns the average value. |
| [BIT\_AND](../bit_and/index) | Bitwise AND. |
| [BIT\_OR](../bit_or/index) | Bitwise OR. |
| [BIT\_XOR](../bit_xor/index) | Bitwise XOR. |
| [COUNT](../count/index) | Returns count of non-null values. |
| [CUME\_DIST](../cume_dist/index) | Window function that returns the cumulative distribution of a given row. |
| [DENSE\_RANK](../dense_rank/index) | Rank of a given row with identical values receiving the same result, no skipping. |
| [FIRST\_VALUE](../first_value/index) | Returns the first result from an ordered set. |
| [JSON\_ARRAYAGG](../json_arrayagg/index) | Returns a JSON array containing an element for each value in a given set of JSON or SQL values. |
| [JSON\_OBJECTAGG](../json_objectagg/index) | Returns a JSON object containing key-value pairs. |
| [LAG](../lag/index) | Accesses data from a previous row in the same result set without the need for a self-join. |
| [LAST\_VALUE](../last_value/index) | Returns the last value in a list or set of values. |
| [LEAD](../lead/index) | Accesses data from a following row in the same result set without the need for a self-join. |
| [MAX](../max/index) | Returns the maximum value. |
| [MEDIAN](../median/index) | Window function that returns the median value of a range of values. |
| [MIN](../min/index) | Returns the minimum value. |
| [NTH\_VALUE](../nth_value/index) | Returns the value evaluated at the specified row number of the window frame. |
| [NTILE](../ntile/index) | Returns an integer indicating which group a given row falls into. |
| [PERCENT\_RANK](../percent_rank/index) | Window function that returns the relative percent rank of a given row. |
| [PERCENTILE\_CONT](../percentile_cont/index) | Continuous percentile. |
| [PERCENTILE\_DISC](../percentile_disc/index) | Discrete percentile. |
| [RANK](../rank/index) | Rank of a given row with identical values receiving the same result. |
| [ROW\_NUMBER](../row_number/index) | Row number of a given row with identical values receiving a different result. |
| [STD](../std/index) | Population standard deviation. |
| [STDDEV](../stddev/index) | Population standard deviation. |
| [STDDEV\_POP](../stddev_pop/index) | Returns the population standard deviation. |
| [STDDEV\_SAMP](../stddev_samp/index) | Standard deviation. |
| [SUM](../sum/index) | Sum total. |
| [VAR\_POP](../var_pop/index) | Population standard variance. |
| [VAR\_SAMP](../var_samp/index) | Returns the sample variance. |
| [VARIANCE](../variance/index) | Population standard variance. |
| [Aggregate Functions as Window Functions](../aggregate-functions-as-window-functions/index) | It is possible to use aggregate functions as window functions. |
| [ColumnStore Window Functions](../window-functions-columnstore-window-functions/index) | Summary of window function use with the ColumnStore engine |
| [Window Frames](../window-frames/index) | Some window functions operate on window frames. |
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mariadb General Thread States General Thread States
=====================
This article documents the major general thread states. More specific lists related to [delayed inserts](../insert-delayed/index), [replication](../replication/index), the [query cache](../query-cache/index) and the [event scheduler](../events/index) are listed in:
* [Event Scheduler Thread States](../event-scheduler-thread-states/index)
* [Query Cache Thread States](../query-cache-thread-states/index)
* [Master Thread States](../master-thread-states/index)
* [Slave Connection Thread States](../slave-connection-thread-states/index)
* [Slave I/O Thread States](../slave-io-thread-states/index)
* [Slave SQL Thread States](../slave-sql-thread-states/index)
These correspond to the `STATE` values listed by the [SHOW PROCESSLIST](../show-processlist/index) statement or in the [Information Schema PROCESSLIST Table](../information-schema-processlist-table/index) as well as the `PROCESSLIST_STATE` value listed in the [Performance Schema threads Table](../performance-schema-threads-table/index)
| Value | Description |
| --- | --- |
| After create | The function that created (or tried to create) a table (temporary or non-temporary) has just ended. |
| Analyzing | Calculating table key distributions, such as when running an [ANALYZE TABLE](../analyze-table/index) statement. |
| checking permissions | Checking to see whether the permissions are adequate to perform the statement. |
| Checking table | [Checking](../sql-commands-check-table/index) the table. |
| cleaning up | Preparing to reset state variables and free memory after executing a command. |
| closing tables | Flushing the changes to disk and closing the table. This state will only persist if the disk is full or under extremely high load. |
| converting HEAP to Aria | Converting an internal [MEMORY](../memory-storage-engine/index) temporary table into an on-disk [Aria](../aria/index) temporary table. |
| converting HEAP to MyISAM | Converting an internal [MEMORY](../memory-storage-engine/index) temporary table into an on-disk [MyISAM](../myisam/index) temporary table. |
| copy to tmp table | A new table has been created as part of an [ALTER TABLE](../alter-table/index) statement, and rows are about to be copied into it. |
| Copying to group table | Sorting the rows by group and copying to a temporary table, which occurs when a statement has different [GROUP BY](../select/index#group-by) and [ORDER BY](../select/index#order-by) criteria. |
| Copying to tmp table | Copying to a temporary table in memory. |
| Copying to tmp table on disk | Copying to a temporary table on disk, as the resultset is too large to fit into memory. |
| Creating index | Processing an [ALTER TABLE ... ENABLE KEYS](../alter-table/index) for an [Aria](../aria/index) or [MyISAM](../myisam/index) table. |
| Creating sort index | Processing a [SELECT](../select/index) statement resolved using an internal temporary table. |
| creating table | Creating a table (temporary or non-temporary). |
| Creating tmp table | Creating a temporary table (in memory or on-disk). |
| deleting from main table | Deleting from the first table in a multi-table [delete](../delete/index), saving columns and offsets for use in deleting from the other tables. |
| deleting from reference tables | Deleting matched rows from secondary reference tables as part of a multi-table [delete](../delete/index). |
| discard\_or\_import\_tablespace | Processing an [ALTER TABLE ... IMPORT TABLESPACE](../alter-table/index) or [ALTER TABLE ... DISCARD TABLESPACE](../alter-table/index) statement. |
| end | State before the final cleanup of an [ALTER TABLE](../alter-table/index), [CREATE VIEW](../create-view/index), [DELETE](../delete/index), [INSERT](../insert/index), [SELECT](../select/index), or [UPDATE](../update/index) statement. |
| executing | Executing a statement. |
| Execution of init\_command | Executing statements specified by the `--init_command` [mysql client](../mysql-command-line-client/index) option. |
| filling schema table | A table in the `[information\_schema](../information-schema/index)` database is being built. |
| freeing items | Freeing items from the [query cache](../query-cache/index) after executing a command. Usually followed by the `cleaning up` state. |
| Flushing tables | Executing a [FLUSH TABLES](../flush/index) statement and waiting for other threads to close their tables. |
| FULLTEXT initialization | Preparing to run a [full-text](../full-text-indexes/index) search |
| init | About to initialize an [ALTER TABLE](../alter-table/index), [DELETE](../delete/index), [INSERT](../insert/index), [SELECT](../select/index), or [UPDATE](../update/index) statement. Could be performaing [query cache](../query-cache/index) cleanup, or flushing the [binary log](../binary-log/index) or InnoDB log. |
| Killed | Thread will abort next time it checks the kill flag. Requires waiting for any locks to be released. |
| Locked | Query has been locked by another query. |
| logging slow query | Writing statement to the [slow query log](../slow-query-log/index). |
| NULL | State used for [SHOW PROCESSLIST](../show-processlist/index). |
| login | Connection thread has not yet been authenticated. |
| manage keys | Enabling or disabling a table index. |
| Opening table[s] | Trying to open a table. Usually very quick unless the limit set by [table\_open\_cache](../server-system-variables/index#table_open_cache) has been reached, or an [ALTER TABLE](../alter-table/index) or [LOCK TABLE](../lock-tables-and-unlock-tables/index) is in progress. |
| optimizing | Server is performing initial optimizations in for a query. |
| preparing | State occurring during query optimization. |
| Purging old relay logs | Relay logs that are no longer needed are being removed. |
| query end | Query has finished being processed, but items have not yet been freed (the `freeing items` state. |
| Reading file | Server is reading the file (for example during [LOAD DATA INFILE](../load-data-infile/index)). |
| Reading from net | Server is reading a network packet. |
| Removing duplicates | Duplicated rows being removed before sending to the client. This happens when `SELECT DISTINCT` is used in a way that the distinct operation could not be optimized at an earlier point. |
| removing tmp table | Removing an internal temporary table after processing a [SELECT](../select/index) statement. |
| rename | Renaming a table. |
| rename result table | Renaming a table that results from an [ALTER TABLE](../alter-table/index) statement having created a new table. |
| Reopen tables | Table is being re-opened after thread obtained a lock but the underlying table structure had changed, so the lock was released. |
| Repair by sorting | Indexes are being created with the use of a sort. Much faster than the related `Repair with keycache`. |
| Repair done | Multi-threaded repair has been completed. |
| Repair with keycache | Indexes are being created through the key cache, one-by-one. Much slower than the related `Repair by sorting`. |
| Rolling back | A transaction is being rolled back. |
| Saving state | New table state is being saved. For example, after, analyzing a [MyISAM](../myisam/index) table, the key distributions, rowcount etc. are saved to the .MYI file. |
| Searching rows for update | Finding matching rows before performing an [UPDATE](../update/index), which is needed when the UPDATE would change the index used for the UPDATE |
| Sending data | Sending data to the client as part of processing a [SELECT](../select/index) statement. Often the longest-occurring state due to the relatively slow disk accesses that may be required. |
| setup | Setting up an [ALTER TABLE](../alter-table/index) operation. |
| Sorting for group | Sorting as part of a [GROUP BY](../select/index#group-by) |
| Sorting for order | Sorting as part of an [ORDER BY](../select/index#order-by) |
| Sorting index | Sorting index pages as part of a table optimization operation. |
| Sorting result | Processing a [SELECT](../select/index) statement using a non-temporary table. |
| statistics | Calculating statistics as part of deciding on a query execution plan. Usually a brief state unless the server is disk-bound. |
| System lock | Requesting or waiting for an *external* lock for a specific table. The [storage engine](../storage-engines/index) determines what kind of *external* lock to use. For example, the [MyISAM](../myisam-storage-engine/index) storage engine uses file-based locks. However, MyISAM's *external* locks are disabled by default, due to the default value of the `[skip\_external\_locking](../server-system-variables/index#skip_external_locking)` system variable. Transactional storage engines such as [InnoDB](../innodb/index) also register the transaction or statement with MariaDB's [transaction coordinator](../transaction-coordinator-log/index) while in this thread state. See [MDEV-19391](https://jira.mariadb.org/browse/MDEV-19391) for more information about that. |
| Table lock | About to request a table's *internal* lock after acquiring the table's *external* lock. This thread state occurs after the *System lock* thread state. |
| update | About to start updating table. |
| Updating | Searching for and updating rows in a table. |
| updating main table | Updating the first table in a multi-table update, and saving columns and offsets for use in the other tables. |
| updating reference tables | Updating the secondary (reference) tables in a multi-table update |
| updating status | This state occurs after a query's execution is complete. If the query's execution time exceeds `[long\_query\_time](../server-system-variables/index#long_query_time)`, then `[Slow\_queries](../server-status-variables/index#slow_queries)` is incremented, and if the [slow query log](../slow-query-log/index) is enabled, then the query is logged. If the `[SERVER\_AUDIT](../mariadb-audit-plugin/index)` plugin is enabled, then the query is also logged into the audit log at this stage. If the `[userstats](../user-statistics/index)` plugin is enabled, then CPU statistics are also updated at this stage. |
| User lock | About to request or waiting for an advisory lock from a [GET LOCK()](../get_lock/index) call. For [SHOW PROFILE](../show-profile/index), means requesting a lock only. |
| User sleep | A [SLEEP()](../sleep/index) call has been invoked. |
| Waiting for commit lock | [FLUSH TABLES WITH READ LOCK](../flush/index) is waiting for a commit lock, or a statement resulting in an explicit or implicit commit is waiting for a read lock to be released. This state was called `Waiting for all running commits to finish` in earlier versions. |
| Waiting for global read lock | Waiting for a global read lock. |
| Waiting for table level lock | External lock acquired,and internal lock about to be requested. Occurs after the `System lock` state. In earlier versions, this was called `Table lock`. |
| Waiting for *xx* lock | Waiting to obtain a lock of type `xx`. |
| Waiting on cond | Waiting for an unspecified condition to occur. |
| Writing to net | Writing a packet to the network. |
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mariadb Partitioning Tables Partitioning Tables
====================
A huge table can be split into smaller subsets. Both data and indexes are partitioned.
| Title | Description |
| --- | --- |
| [Partitioning Overview](../partitioning-overview/index) | A table partitioning overview |
| [Partitioning Types](../partitioning-types/index) | A partitioning type determines how a table rows are distributed across partitions. |
| [Partition Pruning and Selection](../partition-pruning-and-selection/index) | Partition pruning is when the optimizer knows which partitions are relevant for the query. |
| [Partition Maintenance](../partition-maintenance/index) | For time series (includes list of PARTITION uses) |
| [Partitioning Limitations](../partitioning-limitations/index) | Limitations applying to partitioning in MariaDB. |
| [Partitions Files](../partitions-files/index) | A partitioned table is stored in multiple files |
| [Partitions Metadata](../partitions-metadata/index) | How to obtain information about partitions definition |
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mariadb BUFFER BUFFER
======
A synonym for [ST\_BUFFER](../st_buffer/index).
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mariadb Cassandra System Variables Cassandra System Variables
==========================
CassandraSE is no longer actively being developed and has been removed in [MariaDB 10.6](../what-is-mariadb-106/index). See [MDEV-23024](https://jira.mariadb.org/browse/MDEV-23024).
This page documents system variables related to the [Cassandra storage engine](../cassandra/index). See [Server System Variables](../server-system-variables/index) for a complete list of system variables and instructions on setting them.
#### `cassandra_default_thrift_host`
* **Description:** Host to connect to, if not specified on per-table basis.
* **Scope:** Global
* **Dynamic:** Yes
* **Data Type:** `string`
---
#### `cassandra_failure_retries`
* **Description:** Number of times to retry on timeout/unavailable failures.
* **Scope:** Global, Session
* **Dynamic:** Yes
* **Data Type:** `numeric`
* **Default Value:** `3`
* **Valid Values:** `1` to `1073741824`
---
#### `cassandra_insert_batch_size`
* **Description:** INSERT batch size.
* **Scope:** Global, Session
* **Dynamic:** Yes
* **Data Type:** `numeric`
* **Default Value:** `100`
* **Valid Values:** `1` to `1073741824`
---
#### `cassandra_multiget_batch_size`
* **Description:** Batched Key Access batch size.
* **Scope:** Global, Session
* **Dynamic:** Yes
* **Data Type:** `numeric`
* **Default Value:** `100`
* **Valid Values:** `1` to `1073741824`
---
#### `cassandra_read_consistency`
* **Description:** Consistency to use for reading. See [Datastax's documentation](http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dml_config_consistency_c.html) for details.
* **Scope:** Global, Session
* **Default Value:** `ONE`
* **Valid Values:** `ONE`, `TWO`, `THREE`, `ANY`, `ALL`, `QUORUM`, `EACH_QUORUM`, `LOCAL_QUORUM`,
---
#### `cassandra_rnd_batch_size`
* **Description:** Full table scan batch size.
* **Scope:** Global, Session
* **Default Value:** `10000`
* **Valid Values:** `1` to `1073741824`
---
#### `cassandra_write_consistency`
* **Description:** Consistency to use for writing. See [Datastax's documentation](http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dml_config_consistency_c.html) for details.
* **Scope:** Global, Session
* **Default Value:** `ONE`
* **Valid Values:** `ONE`, `TWO`, `THREE`, `ANY`, `ALL`, `QUORUM`, `EACH_QUORUM`, `LOCAL_QUORUM`,
---
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mariadb About the MariaDB RPM Files About the MariaDB RPM Files
===========================
Available RPM Packages
----------------------
The available RPM packages depend on the specific MariaDB release series.
### Available RPM Packages in [MariaDB 10.4](../what-is-mariadb-104/index)
**MariaDB starting with [10.4](../what-is-mariadb-104/index)**In [MariaDB 10.4](../what-is-mariadb-104/index), the following RPMs are available:
| Package Name | Description |
| --- | --- |
| `galera-4` | The WSREP provider for [Galera](../galera/index) 4. |
| `MariaDB-backup` | [Mariabackup](../mariabackup/index) |
| `MariaDB-backup-debuginfo` | Debuginfo for [Mariabackup](../mariabackup/index) |
| `MariaDB-client` | Client tools like `mysql` CLI, `mysqldump`, and others. |
| `MariaDB-client-debuginfo` | Debuginfo for client tools like `mysql` CLI, `mysqldump`, and others. |
| `MariaDB-common` | Character set files and `/etc/my.cnf` |
| `MariaDB-common-debuginfo` | Debuginfo for character set files and `/etc/my.cnf` |
| `MariaDB-compat` | Old shared client libraries, may be needed by old MariaDB or MySQL clients |
| `MariaDB-connect-engine` | The `[CONNECT](../connect/index)` storage engine. |
| `MariaDB-connect-engine-debuginfo` | Debuginfo for the `[CONNECT](../connect/index)` storage engine. |
| `MariaDB-cracklib-password-check` | The `[cracklib\_password\_check](../cracklib-password-check-plugin/index)` password validation plugin. |
| `MariaDB-cracklib-password-check` | Debuginfo for the `[cracklib\_password\_check](../cracklib-password-check-plugin/index)` password validation plugin. |
| `MariaDB-devel` | Development headers and static libraries. |
| `MariaDB-devel-debuginfo` | Debuginfo for development headers and static libraries. |
| `MariaDB-gssapi-server` | The `[gssapi](../authentication-plugin-gssapi/index)` authentication plugin. |
| `MariaDB-gssapi-server-debuginfo` | Debuginfo for the `[gssapi](../authentication-plugin-gssapi/index)` authentication plugin. |
| `MariaDB-rocksdb-engine` | The [MyRocks](../myrocks/index) storage engine. |
| `MariaDB-rocksdb-engine-debuginfo` | Debuginfo for the [MyRocks](../myrocks/index) storage engine. |
| `MariaDB-server` | The server and server tools, like [myisamchk](../myisamchk/index) and [mysqlhotcopy](../mysqlhotcopy/index) are here. |
| `MariaDB-server-debuginfo` | Debuginfo for the server and server tools, like [myisamchk](../myisamchk/index) and [mysqlhotcopy](../mysqlhotcopy/index) are here. |
| `MariaDB-shared` | Dynamic client libraries. |
| `MariaDB-shared-debuginfo` | Debuginfo for dynamic client libraries. |
| `MariaDB-test` | `mysql-client-test` executable, and **mysql-test** framework with the tests. |
| `MariaDB-test-debuginfo` | Debuginfo for `mysql-client-test` executable, and **mysql-test** framework with the tests. |
| `MariaDB-tokudb-engine` | The [TokuDB](../tokudb/index) storage engine. |
| `MariaDB-tokudb-engine-debuginfo` | Debuginfo for the [TokuDB](../tokudb/index) storage engine. |
### Available RPM Packages in [MariaDB 10.2](../what-is-mariadb-102/index) and [MariaDB 10.3](../what-is-mariadb-103/index)
**MariaDB starting with [10.2](../what-is-mariadb-102/index)**In [MariaDB 10.2](../what-is-mariadb-102/index) and [MariaDB 10.3](../what-is-mariadb-103/index), the following RPMs are available:
| Package Name | Description |
| --- | --- |
| `galera` | The WSREP provider for [Galera](../galera/index) 3. |
| `MariaDB-backup` | [Mariabackup](../mariabackup/index) |
| `MariaDB-backup-debuginfo` | Debuginfo for [Mariabackup](../mariabackup/index) |
| `MariaDB-client` | Client tools like `mysql` CLI, `mysqldump`, and others. |
| `MariaDB-client-debuginfo` | Debuginfo for client tools like `mysql` CLI, `mysqldump`, and others. |
| `MariaDB-common` | Character set files and `/etc/my.cnf` |
| `MariaDB-common-debuginfo` | Debuginfo for character set files and `/etc/my.cnf` |
| `MariaDB-compat` | Old shared client libraries, may be needed by old MariaDB or MySQL clients |
| `MariaDB-connect-engine` | The `[CONNECT](../connect/index)` storage engine. |
| `MariaDB-connect-engine-debuginfo` | Debuginfo for the `[CONNECT](../connect/index)` storage engine. |
| `MariaDB-cracklib-password-check` | The `[cracklib\_password\_check](../cracklib-password-check-plugin/index)` password validation plugin. |
| `MariaDB-cracklib-password-check` | Debuginfo for the `[cracklib\_password\_check](../cracklib-password-check-plugin/index)` password validation plugin. |
| `MariaDB-devel` | Development headers and static libraries. |
| `MariaDB-devel-debuginfo` | Debuginfo for development headers and static libraries. |
| `MariaDB-gssapi-server` | The `[gssapi](../authentication-plugin-gssapi/index)` authentication plugin. |
| `MariaDB-gssapi-server-debuginfo` | Debuginfo for the `[gssapi](../authentication-plugin-gssapi/index)` authentication plugin. |
| `MariaDB-rocksdb-engine` | The [MyRocks](../myrocks/index) storage engine. |
| `MariaDB-rocksdb-engine-debuginfo` | Debuginfo for the [MyRocks](../myrocks/index) storage engine. |
| `MariaDB-server` | The server and server tools, like [myisamchk](../myisamchk/index) and [mysqlhotcopy](../mysqlhotcopy/index) are here. |
| `MariaDB-server-debuginfo` | Debuginfo for the server and server tools, like [myisamchk](../myisamchk/index) and [mysqlhotcopy](../mysqlhotcopy/index) are here. |
| `MariaDB-shared` | Dynamic client libraries. |
| `MariaDB-shared-debuginfo` | Debuginfo for dynamic client libraries. |
| `MariaDB-test` | `mysql-client-test` executable, and **mysql-test** framework with the tests. |
| `MariaDB-test-debuginfo` | Debuginfo for `mysql-client-test` executable, and **mysql-test** framework with the tests. |
| `MariaDB-tokudb-engine` | The [TokuDB](../tokudb/index) storage engine. |
| `MariaDB-tokudb-engine-debuginfo` | Debuginfo for the [TokuDB](../tokudb/index) storage engine. |
### Available RPM Packages in [MariaDB 10.1](../what-is-mariadb-101/index)
**MariaDB starting with [10.1](../what-is-mariadb-101/index)**In [MariaDB 10.1](../what-is-mariadb-101/index), the following RPMs are available:
| Package Name | Description |
| --- | --- |
| `galera` | The WSREP provider for [Galera](../galera/index) 3. |
| `MariaDB-backup` | [Mariabackup](../mariabackup/index) |
| `MariaDB-backup-debuginfo` | Debuginfo for [Mariabackup](../mariabackup/index) |
| `MariaDB-client` | Client tools like `mysql` CLI, `mysqldump`, and others. |
| `MariaDB-client-debuginfo` | Debuginfo for client tools like `mysql` CLI, `mysqldump`, and others. |
| `MariaDB-common` | Character set files and `/etc/my.cnf` |
| `MariaDB-common-debuginfo` | Debuginfo for character set files and `/etc/my.cnf` |
| `MariaDB-compat` | Old shared client libraries, may be needed by old MariaDB or MySQL clients |
| `MariaDB-connect-engine` | The `[CONNECT](../connect/index)` storage engine. |
| `MariaDB-connect-engine-debuginfo` | Debuginfo for the `[CONNECT](../connect/index)` storage engine. |
| `MariaDB-cracklib-password-check` | The `[cracklib\_password\_check](../cracklib-password-check-plugin/index)` password validation plugin. |
| `MariaDB-cracklib-password-check` | Debuginfo for the `[cracklib\_password\_check](../cracklib-password-check-plugin/index)` password validation plugin. |
| `MariaDB-devel` | Development headers and static libraries. |
| `MariaDB-devel-debuginfo` | Debuginfo for development headers and static libraries. |
| `MariaDB-gssapi-server` | The `[gssapi](../authentication-plugin-gssapi/index)` authentication plugin. |
| `MariaDB-gssapi-server-debuginfo` | Debuginfo for the `[gssapi](../authentication-plugin-gssapi/index)` authentication plugin. |
| `MariaDB-server` | The server and server tools, like [myisamchk](../myisamchk/index) and [mysqlhotcopy](../mysqlhotcopy/index) are here. |
| `MariaDB-server-debuginfo` | Debuginfo for the server and server tools, like [myisamchk](../myisamchk/index) and [mysqlhotcopy](../mysqlhotcopy/index) are here. |
| `MariaDB-shared` | Dynamic client libraries. |
| `MariaDB-shared-debuginfo` | Debuginfo for dynamic client libraries. |
| `MariaDB-test` | `mysql-client-test` executable, and **mysql-test** framework with the tests. |
| `MariaDB-test-debuginfo` | Debuginfo for `mysql-client-test` executable, and **mysql-test** framework with the tests. |
| `MariaDB-tokudb-engine` | The [TokuDB](../tokudb/index) storage engine. |
| `MariaDB-tokudb-engine-debuginfo` | Debuginfo for the [TokuDB](../tokudb/index) storage engine. |
Installing RPM Packages
-----------------------
Preferably, you should install MariaDB RPM packages using the package manager of your Linux distribution, for example **`yum`** or **`zypper`**. But you can also use the lower-level **`rpm`** tool.
Actions Performed by RPM Packages
---------------------------------
### Users and Groups Created
When the `MariaDB-server` RPM package is installed, it will create a user and group named `mysql`, if it does not already exist.
See Also
--------
* [Installing MariaDB with yum](../yum/index)
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb mysqlslap mysqlslap
=========
**MariaDB starting with [10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/)**From [MariaDB 10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/), `mariadb-slap` is a symlink to `mysqlslap`.
**MariaDB starting with [10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/)**From [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/), `mysqlslap` is the symlink, and `mariadb-slap` the binary name.
`mysqlslap` is a tool for load-testing MariaDB. It allows you to emulate multiple concurrent connections, and run a set of queries multiple times.
It returns a benchmark including the following information:
* Average number of seconds to run all queries
* Minimum number of seconds to run all queries
* Maximum number of seconds to run all queries
* Number of clients running queries
* Average number of queries per client
Using mysqlslap
---------------
The command to use `mysqlslap` and the general syntax is:
```
mysqlslap [options]
```
### Options
`mysqlslap` supports the following options:
| Option | Description |
| --- | --- |
| `-a`, `--auto-generate-sql` | Generate SQL statements automatically when they are not supplied in files or via command options. |
| `--auto-generate-sql-add-autoincrement` | Add an [AUTO\_INCREMENT](../auto_increment/index) column to auto-generated tables. |
| `--auto-generate-sql-execute-number=num` | Specify how many queries to generate automatically. |
| `--auto-generate-sql-guid-primary` | Add GUID based primary keys to auto-generated tables. |
| `--auto-generate-sql-load-type=name` | Specify the test load type. The allowable values are `read` (scan tables), `write` (insert into tables), `key` (read primary keys), `update` (update primary keys), or `mixed` (half inserts, half scanning selects). The default is mixed. |
| `--auto-generate-sql-secondary-indexes=num` | Number of secondary indexes to add to auto-generated tables. By default, none are added. |
| `--auto-generate-sql-unique-query-number=num` | Number of unique queries to generate for automatic tests. For example, if you run a key test that performs 1000 selects, you can use this option with a value of 1000 to run 1000 unique queries, or with a value of 50 to perform 50 different selects. The default is 10. |
| `--auto-generate-sql-unique-write-number=num` | Number of unique queries to generate for `auto-generate-sql-write-number`. |
| `--auto-generate-sql-write-number=num` | Number of row inserts to perform for each thread. The default is 100. |
| `--commit=num` | Number of statements to execute before committing. The default is 0. |
| `-C`, `--compress` | Use compression in server/client protocol if both support it. |
| `-c name`, `--concurrency=name` | Number of clients to simulate for query to run. |
| `--create=name` | File or string containing the statement to use for creating the table. |
| `--create-schema=name` | Schema to run tests in. |
| `--csv[=name]` | Generate comma-delimited output to named file or to standard output if no file is named. |
| `-#` , `--debug[=options]` | For debug builds, write a debugging log. A typical debug\_options string is `d:t:o,file_name`. The default is `d:t:o,/tmp/mysqlslap.trace`. |
| `--debug-check` | Check memory and open file usage at exit. |
| `-T, --debug-info` | Print some debug info at exit. |
| `--default-auth=name` | Default authentication client-side plugin to use. |
| `--defaults-extra-file=name` | Read this file after the global files are read. Must be given as the first option. |
| `--defaults-file=name` | Only read default options from the given file *name* Must be given as the first option. |
| `-F name`, `--delimiter=name` | Delimiter to use in SQL statements supplied in file or command line. |
| `--detach=num` | Detach (close and reopen) connections after the specified number of requests. The default is 0 (connections are not detached). |
| `-e name`, `--engine=name` | Comma separated list of storage engines to use for creating the table. The test is run for each engine. You can also specify an option for an engine after a #:#, for example `memory:max_row=2300`. |
| `-?`, `--help` | Display help and exit. |
| `-h name`, `--host=name` | Connect to the MariaDB server on the given host. |
| `--init-command=name` | SQL Command to execute when connecting to the MariaDB server. Will automatically be re-executed when reconnecting. Added in [MariaDB 5.5.34](https://mariadb.com/kb/en/mariadb-5534-release-notes/). |
| `-i num`, `--iterations=num` | Number of times to run the tests. |
| `--no-defaults` | Don't read default options from any option file. Must be given as the first option. |
| `--no-drop` | Do not drop any schema created during the test after the test is complete. |
| `-x name`, `--number-char-cols=name` | Number of [VARCHAR](../varchar/index) columns to create in table if specifying `--auto-generate-sql`. |
| `-y name`, `--number-int-cols=name` | Number of [INT](../int/index) columns to create in table if specifying `--auto-generate-sql`. |
| `--number-of-queries=num` | Limit each client to approximately this number of queries. Query counting takes into account the statement delimiter. For example, if you invoke as follows, `mysqlslap --delimiter=";" --number-of-queries=10` `--query="use test;insert into t values(null)"`, the #;# delimiter is recognized so that each instance of the query string counts as two queries. As a result, 5 rows (not 10) are inserted. |
| `--only-print` | Do not connect to the databases, but instead print out what would have been done. |
| `-p[password]`, `--password[=password]` | Password to use when connecting to server. If password is not given it's asked from the command line. Specifying a password on the command line should be considered insecure. You can use an option file to avoid giving the password on the command line. |
| `-W`, `--pipe` | On Windows, connect to the server via a named pipe. This option applies only if the server supports named-pipe connections. |
| `--plugin-dir=name` | Directory for client-side plugins. |
| `-P num`, `--port=num` | Port number to use for connection. |
| `--post-query=name` | Query to run or file containing query to execute after tests have completed. This execution is not counted for timing purposes. |
| `--post-system=name` | system() string to execute after tests have completed. This execution is not counted for timing purposes. |
| `--pre-query=name` | Query to run or file containing query to execute before running tests. This execution is not counted for timing purposes. |
| `--pre-system=name` | system() string to execute before running tests. This execution is not counted for timing purposes. |
| `--print-defaults` | Print the program argument list and exit. Must be given as the first option. |
| `--protocol=name` | The protocol to use for connection (tcp, socket, pipe, memory). |
| `-q name`, `--query=name` | Query to run or file containing query to run. |
| `--shared-memory-base-name` | Shared-memory name to use for Windows connections using shared memory to a local server (started with the `--shared-memory` option). Case-sensitive. |
| `-s`, `--silent` | Run program in silent mode - no output. |
| `-S`, `--socket=name` | For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use. |
| `--ssl` | Enables [TLS](../data-in-transit-encryption/index). TLS is also enabled even without setting this option when certain other TLS options are set. Starting with [MariaDB 10.2](../what-is-mariadb-102/index), the `--ssl` option will not enable [verifying the server certificate](../secure-connections-overview/index#server-certificate-verification) by default. In order to verify the server certificate, the user must specify the `--ssl-verify-server-cert` option. |
| `--ssl-ca=name` | Defines a path to a PEM file that should contain one or more X509 certificates for trusted Certificate Authorities (CAs) to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. See [Secure Connections Overview: Certificate Authorities (CAs)](../secure-connections-overview/index#certificate-authorities-cas) for more information. This option implies the `--ssl` option. |
| `--ssl-capath=name` | Defines a path to a directory that contains one or more PEM files that should each contain one X509 certificate for a trusted Certificate Authority (CA) to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. The directory specified by this option needs to be run through the `[openssl rehash](https://www.openssl.org/docs/man1.1.1/man1/rehash.html)` command. See [Secure Connections Overview: Certificate Authorities (CAs)](../secure-connections-overview/index#certificate-authorities-cas) for more information. This option is only supported if the client was built with OpenSSL or yaSSL. If the client was built with GnuTLS or Schannel, then this option is not supported. See [TLS and Cryptography Libraries Used by MariaDB](../tls-and-cryptography-libraries-used-by-mariadb/index) for more information about which libraries are used on which platforms. This option implies the `--ssl` option. |
| `--ssl-cert=name` | Defines a path to the X509 certificate file to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. This option implies the `--ssl` option. |
| `--ssl-cipher=name` | List of permitted ciphers or cipher suites to use for [TLS](../data-in-transit-encryption/index). This option implies the `--ssl` option. |
| `--ssl-crl=name` | Defines a path to a PEM file that should contain one or more revoked X509 certificates to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. See [Secure Connections Overview: Certificate Revocation Lists (CRLs)](../secure-connections-overview/index#certificate-revocation-lists-crls) for more information. This option is only supported if the client was built with OpenSSL or Schannel. If the client was built with yaSSL or GnuTLS, then this option is not supported. See [TLS and Cryptography Libraries Used by MariaDB](../tls-and-cryptography-libraries-used-by-mariadb/index) for more information about which libraries are used on which platforms. |
| `--ssl-crlpath=name` | Defines a path to a directory that contains one or more PEM files that should each contain one revoked X509 certificate to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. The directory specified by this option needs to be run through the `[openssl rehash](https://www.openssl.org/docs/man1.1.1/man1/rehash.html)` command. See [Secure Connections Overview: Certificate Revocation Lists (CRLs)](../secure-connections-overview/index#certificate-revocation-lists-crls) for more information. This option is only supported if the client was built with OpenSSL. If the client was built with yaSSL, GnuTLS, or Schannel, then this option is not supported. See [TLS and Cryptography Libraries Used by MariaDB](../tls-and-cryptography-libraries-used-by-mariadb/index) for more information about which libraries are used on which platforms. |
| `--ssl-key=name` | Defines a path to a private key file to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. This option implies the `--ssl` option. |
| `--ssl-verify-server-cert` | Enables [server certificate verification](../secure-connections-overview/index#server-certificate-verification). This option is disabled by default. |
| `-u`, `--user=name` | User for login if not current user. |
| `-v`, `--verbose` | More verbose output; you can use this multiple times to get even more verbose output. |
| `-V`, `--version` | Output version information and exit. |
### Option Files
In addition to reading options from the command-line, `mysqlslap` can also read options from [option files](../configuring-mariadb-with-option-files/index). If an unknown option is provided to `mysqlslap` in an option file, then it is ignored.
The following options relate to how MariaDB command-line tools handles option files. They must be given as the first argument on the command-line:
| Option | Description |
| --- | --- |
| `--print-defaults` | Print the program argument list and exit. |
| `--no-defaults` | Don't read default options from any option file. |
| `--defaults-file=#` | Only read default options from the given file #. |
| `--defaults-extra-file=#` | Read this file after the global files are read. |
| `--defaults-group-suffix=#` | In addition to the default option groups, also read option groups with this suffix. |
In [MariaDB 10.2](../what-is-mariadb-102/index) and later, `mysqlslap` is linked with [MariaDB Connector/C](../about-mariadb-connector-c/index). However, MariaDB Connector/C does not yet handle the parsing of option files for this client. That is still performed by the server option file parsing code. See [MDEV-19035](https://jira.mariadb.org/browse/MDEV-19035) for more information.
#### Option Groups
`mysqlslap` reads options from the following [option groups](../configuring-mariadb-with-option-files/index#option-groups) from [option files](../configuring-mariadb-with-option-files/index):
| Group | Description |
| --- | --- |
| `[mysqlslap]` | Options read by `mysqlslap`, which includes both MariaDB Server and MySQL Server. |
| `[mariadb-slap]` | Options read by `mysqlslap`. Available starting with [MariaDB 10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/). |
| `[client]` | Options read by all MariaDB and MySQL [client programs](../clients-utilities/index), which includes both MariaDB and MySQL clients. For example, `mysqldump`. |
| `[client-server]` | Options read by all MariaDB [client programs](../clients-utilities/index) and the MariaDB Server. This is useful for options like socket and port, which is common between the server and the clients. |
| `[client-mariadb]` | Options read by all MariaDB [client programs](../clients-utilities/index). |
Examples
--------
Create a table with data, and then query it with 40 simultaneous connections 100 times each.
```
mysqlslap
--delimiter=";"
--create="CREATE TABLE t (a int);INSERT INTO t VALUES (5)"
--query="SELECT * FROM t"
--concurrency=40
--iterations=100
Benchmark
Average number of seconds to run all queries: 0.010 seconds
Minimum number of seconds to run all queries: 0.009 seconds
Maximum number of seconds to run all queries: 0.020 seconds
Number of clients running queries: 40
Average number of queries per client: 1
```
Using files to store the create and query SQL. Each file can contain multiple statements separated by the specified delimiter.
```
mysqlslap
--create=define.sql
--query=query.sql
--concurrency=10
--iterations=20
--delimiter=";"
Benchmark
Average number of seconds to run all queries: 0.002 seconds
Minimum number of seconds to run all queries: 0.002 seconds
Maximum number of seconds to run all queries: 0.004 seconds
Number of clients running queries: 10
Average number of queries per client: 1
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Delayed Insert Handler Thread States Delayed Insert Handler Thread States
====================================
This article documents thread states that are related to the handler thread that inserts the results of [INSERT DELAYED](../insert-delayed/index) statements.
These correspond to the `STATE` values listed by the [SHOW PROCESSLIST](../show-processlist/index) statement or in the [Information Schema PROCESSLIST Table](../information-schema-processlist-table/index) as well as the `PROCESSLIST_STATE` value listed in the [Performance Schema threads Table](../performance-schema-threads-table/index).
| Value | Description |
| --- | --- |
| insert | About to insert rows into the table. |
| reschedule | Sleeping in order to let other threads function, after inserting a number of rows into the table. |
| upgrading lock | Attempting to get lock on the table in order to insert rows. |
| Waiting for INSERT | Waiting for the delayed-insert connection thread to add rows to the queue. |
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb User and Group Mapping with PAM User and Group Mapping with PAM
===============================
Even when using the `[pam](../authentication-plugin-pam/index)` authentication plugin, the authenticating PAM user account still needs to exist in MariaDB, and the account needs to have privileges in the database. Creating these MariaDB accounts and making sure the privileges are correct can be a lot of work. To decrease the amount of work involved, some users would like to be able to map a PAM user to a different MariaDB user. For example, let’s say that `alice` and `bob` are both DBAs. It would be nice if each of them could log into MariaDB with their own PAM username and password, while MariaDB sees both of them as the same `dba` user. That way, there is only one MariaDB account to keep track of.
Although most PAM modules usually do not do things like this, PAM supports the ability to change the user name in the process of authentication.The MariaDB `pam` authentication plugin fully supports this feature of PAM.
The pam\_user\_map PAM Module
-----------------------------
Rather than building user and group mapping into the `pam` authentication plugin, MariaDB thought that it would cover the most use cases and offer the most flexibility to offload this functionality to an external PAM module. The `pam_user_map` PAM module was implemented by MariaDB to facilitate this. This PAM module can be [configured in the PAM service](../authentication-plugin-pam/index#configuring-the-pam-service) used by the `pam` authentication plugin, just like other PAM modules.
### Lack of Support for MySQL/Percona Group Mapping Syntax
Unlike MariaDB, MySQL and Percona implemented group mapping in their PAM authentication plugins. If you've read through [MySQL's PAM authentication documentation on group mapping](https://dev.mysql.com/doc/refman/8.0/en/pam-pluggable-authentication.html#pam-authentication-unix-with-proxy) or [Percona's PAM authentication documentation on group mapping](https://www.percona.com/doc/percona-server/8.0/management/pam_plugin.html#supplementary-groups-support), you've probably seen syntax where the group mappings are provided in the `[CREATE USER](../create-user/index)` statement like this:
```
CREATE USER ''@''
IDENTIFIED WITH authentication_pam
AS 'mysql, root=developer, users=data_entry';
```
Since MariaDB's user and group mapping is performed by an external PAM module, MariaDB's `pam` authentication plugin does not support this syntax. Instead, the user and group mappings for the `pam_user_map` PAM module are configured in an external configuration file. This is discussed in a later section.
Installing the pam\_user\_map PAM Module
----------------------------------------
The `pam_user_map` PAM module gets installed as part of all our MariaDB server packages since [MariaDB 10.5](../what-is-mariadb-105/index), and was added since 10.2.31, 10.3.22, and 10.4.12 in previous MariaDB major releases where it was not present from the beginning.
Some Linux distributions have not picked up this change in their own packages yet, so when e.g. installing MariaDB server from stock Ubuntu packages on Ubuntu 20.04LTS you still won't have the `pam_user_map` module installed even though the MariaDB server installed is more recent than [MariaDB 10.3.22](https://mariadb.com/kb/en/mariadb-10322-release-notes/).
When using such an installation, and not being able to switch to our own MariaDB package repositories, it may be necessary to compile the PAM module from source as described in the next section, or to manually extract it from one of our server packages and copy it to the target system.
### Installing the pam\_user\_map PAM Module from Source
#### Installing Compilation Dependencies
Before the module can be compiled from source, you may need to install some dependencies.
On RHEL, CentOS, and other similar Linux distributions that use [RPM packages](../rpm/index), you need to install `gcc`, `pam-devel` and `MariaDB-devel`. For example:
```
sudo yum install gcc pam-devel MariaDB-devel
```
On Debian, Ubuntu, and other similar Linux distributions that use [DEB packages](../installing-mariadb-deb-files/index), you need to install `gcc`, `libpam0g-dev`. For example:
```
sudo apt-get install gcc libpam0g-dev libmariadb-dev
```
#### Compiling and Installing the pam\_user\_map PAM Module
The `pam_user_map` PAM module can be built by downloading `plugin/auth_pam/mapper/pam_user_map.c` file from the MariaDB source tree and compiling it after minor adjustments. Once it is built, it can be installed to the system's PAM module directory, which is typically `/lib64/security/`.
For example: (replace 10.4 in the URL with the actual server versions)
```
wget https://raw.githubusercontent.com/MariaDB/server/10.4/plugin/auth_pam/mapper/pam_user_map.c
sed -ie 's/config_auth_pam/plugin_auth_common/' pam_user_map.c
gcc -I/usr/include/mysql/ pam_user_map.c -shared -lpam -fPIC -o pam_user_map.so
sudo install --mode=0755 pam_user_map.so /lib64/security/
```
You will also need to adjust the major version number in the URL on the first line to match your installed MariaDB version, and the #-I# include path argument on the `gcc` line, as depending on operating system and MariaDB server version the plugin\_auth\_common.h file may be installed in different directories than `/usr/include/mysql/`
Configuring the pam\_user\_map PAM Module
-----------------------------------------
The `pam_user_map` PAM module uses the configuration file at the path `/etc/security/user_map.conf` to determine its user and group mappings. The file's format is described below.
To map a specific PAM user to a specific MariaDB user:
```
orig_pam_user_name: mapped_mariadb_user_name
```
Or to map any PAM user in a specific PAM group to a specific MariaDB user, the group name is prefixed with `@`:
```
@orig_pam_group_name: mapped_mariadb_user_name
```
For example, here is an example `/etc/security/user_map.conf`:
```
=========================================================
#comments and empty lines are ignored
john: jack
bob: admin
top: accounting
@group_ro: readonly
```
Configuring PAM
---------------
With user and group mapping, configuring PAM is done similar to how it is [normally done with the `pam` authentication plugin](../authentication-plugin-pam/index#configuring-pam). However, when configuring the PAM service, you will have to add an `auth` line for the `pam_user_map` PAM module to the service's PAM configuration file. For example:
```
auth required pam_unix.so audit
auth required pam_user_map.so
account required pam_unix.so audit
```
Creating Users
--------------
With user and group mapping, creating users is done similar to how it is [normally done with the `pam` authentication plugin](../authentication-plugin-pam/index#creating-users). However, one major difference is that you will need to `[GRANT](../grant/index)` the `[PROXY](../grant/index#proxy-privileges)` privilege on the mapped user to the original user.
For example, if you have the following configured in `/etc/security/user_map.conf`:
```
foo: bar
@dba:dba
```
Then you could execute the following to grant the relevant privileges:
```
CREATE USER 'bar'@'%' IDENTIFIED BY 'strongpassword';
GRANT ALL PRIVILEGES ON *.* TO 'bar'@'%' ;
CREATE USER 'dba'@'%' IDENTIFIED BY 'strongpassword';
GRANT ALL PRIVILEGES ON *.* TO 'dba'@'%' ;
CREATE USER ''@'%' IDENTIFIED VIA pam USING 'mariadb';
GRANT PROXY ON 'bar'@'%' TO ''@'%';
GRANT PROXY ON 'dba'@'%' TO ''@'%';
```
Note that the `''@'%'` account is a special catch-all [anonymous account](../create-user/index#anonymous-accounts). Any login by a user that has no more specific account match in the system will be matched by this anonymous account.
Also note that you might not be able to create the `''@'%'` anonymous account by default on some systems without doing some extra steps first. See [Fixing a Legacy Default Anonymous Account](../create-user/index#fixing-a-legacy-default-anonymous-account) for more information.
Verifying that Mapping is Occurring
-----------------------------------
In case any user mapping is performed, the original user name is returned by the SQL function `[USER()](../user/index)`, while the authenticated user name is returned by the SQL function `[CURRENT\_USER()](../current_user/index)`. The latter actually defines what privileges are available to a connected user.
For example, if we have the following configured:
```
foo: bar
```
Then the following output would verify that it is working properly:
```
$ mysql -u foo -h 172.30.0.198
[mariadb] Password:
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 22
Server version: 10.3.10-MariaDB MariaDB Server
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> SELECT USER(), CURRENT_USER();
+------------------------------------------------+----------------+
| USER() | CURRENT_USER() |
+------------------------------------------------+----------------+
| [email protected] | bar@% |
+------------------------------------------------+----------------+
1 row in set (0.000 sec)
```
We can verify that our `foo` PAM user was properly mapped to the `bar` MariaDB user by looking at the return value of `[CURRENT\_USER()](../current_user/index)`.
Logging
-------
By default, the `pam_user_map` PAM module does not perform any logging. However, if you want to enable debug logging, then you can add the `debug` module argument to the service's PAM configuration file. For example:
```
auth required pam_unix.so audit
auth required pam_user_map.so debug
account required pam_unix.so audit
```
When debug logging is enabled, the `pam_user_map` PAM module will write log entries to the [same syslog location](../authentication-plugin-pam/index#logging) as other PAM modules, which is typically `/var/log/secure` on many systems.
For example, this debug log output can look like the following:
```
Jan 9 05:42:13 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Opening file '/etc/security/user_map.conf'.
Jan 9 05:42:13 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Incoming username 'alice'.
Jan 9 05:42:13 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): User belongs to 2 groups [alice,dba].
Jan 9 05:42:13 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Check if user is in group 'dba': YES
Jan 9 05:42:13 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): User mapped as 'dba'
Jan 9 05:43:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Opening file '/etc/security/user_map.conf'.
Jan 9 05:43:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Incoming username 'bob'.
Jan 9 05:43:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): User belongs to 2 groups [bob,dba].
Jan 9 05:43:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Check if user is in group 'dba': YES
Jan 9 05:43:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): User mapped as 'dba'
Jan 9 06:08:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Opening file '/etc/security/user_map.conf'.
Jan 9 06:08:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Incoming username 'foo'.
Jan 9 06:08:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): User belongs to 1 group [foo].
Jan 9 06:08:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Check if user is in group 'dba': NO
Jan 9 06:08:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): Check if username 'foo': YES
Jan 9 06:08:36 ip-172-30-0-198 mysqld: pam_user_map(mariadb:auth): User mapped as 'bar'
```
Known Issues
------------
### PAM User with Same Name as Mapped MariaDB User Must Exist
With user and group mapping, any PAM user or any PAM user in a given PAM group can be mapped to a specific MariaDB user account. However, due to the way PAM works, a PAM user with the same name as the mapped MariaDB user account must exist.
For example, if the configuration file for the PAM service file contained the following:
```
auth required pam_sss.so
auth required pam_user_map.so debug
account sufficient pam_unix.so
account sufficient pam_sss.so
```
And if `/etc/security/user_map.conf` contained the following:
```
@dba: dba
```
Then any PAM user in the PAM group `dba` would be mapped to the MariaDB user account `dba`. But if a PAM user with the name `dba` did not also exist, then the `pam_user_map` PAM module's debug logging would write errors to the syslog like the following:
```
Sep 27 17:17:05 dbserver1 mysqld: pam_user_map(mysql:auth): Opening file '/etc/security/user_map.conf'.
Sep 27 17:17:05 dbserver1 mysqld: pam_user_map(mysql:auth): Incoming username 'alice'.
Sep 27 17:17:05 dbserver1 mysqld: pam_user_map(mysql:auth): User belongs to 4 groups [dba,mongod,mongodba,mysql].
Sep 27 17:17:05 dbserver1 mysqld: pam_user_map(mysql:auth): Check if user is in group 'mysql': YES
Sep 27 17:17:05 dbserver1 mysqld: pam_user_map(mysql:auth): User mapped as 'dba'
Sep 27 17:17:05 dbserver1 mysqld: pam_unix(mysql:account): could not identify user (from getpwnam(dba))
Sep 27 17:17:05 dbserver1 mysqld: pam_sss(mysql:account): Access denied for user dba: 10 (User not known to the underlying authentication module)
Sep 27 17:17:05 dbserver1 mysqld: 2018-09-27 17:17:05 72 [Warning] Access denied for user 'alice'@'localhost' (using password: NO)
```
In the above log snippet, notice that both the `pam_unix` and the `pam_sss` PAM modules are complaining that the `dba` PAM user does not appear to exist, and that these complaints cause the PAM authentication process to fail, which causes the MariaDB authentication process to fail as well.
This can be fixed by creating a PAM user with the same name as the mapped MariaDB user account, which is `dba` in this case.
You may also be able to work around this problem by essentially disabling PAM's account verification for the service with the `[pam\_permit](https://linux.die.net/man/8/pam_permit)` PAM module. For example, in the above case, that would be:
```
auth required pam_sss.so
auth required pam_user_map.so debug
account required pam_permit.so
```
See [MDEV-17315](https://jira.mariadb.org/browse/MDEV-17315) for more information.
Tutorials
---------
You may find the following PAM and user mapping-related tutorials helpful:
* [Configuring PAM Authentication and User Mapping with Unix Authentication](../configuring-pam-authentication-and-user-mapping-with-unix-authentication/index)
* [Configuring PAM Authentication and User Mapping with LDAP Authentication](../configuring-pam-authentication-and-user-mapping-with-ldap-authentication/index)
See Also
--------
* [Configuring PAM Authentication and User Mapping with MariaDB](https://mariadb.com/resources/blog/configuring-pam-authentication-and-user-mapping-with-mariadb/)
* [Configuring PAM Group Mapping with MariaDB](https://mariadb.com/resources/blog/configuring-pam-group-mapping-with-mariadb/)
* [Configuring LDAP Authentication and Group Mapping With MariaDB](http://www.geoffmontee.com/configuring-ldap-authentication-and-group-mapping-with-mariadb/)
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb PREPARE Statement PREPARE Statement
=================
Syntax
------
```
PREPARE stmt_name FROM preparable_stmt
```
Description
-----------
The `PREPARE` statement prepares a statement and assigns it a name, `stmt_name`, by which to refer to the statement later. Statement names are not case sensitive. `preparable_stmt` is either a string literal or a [user variable](../user-defined-variables/index) (not a [local variable](../declare-variable/index), an SQL expression or a subquery) that contains the text of the statement. The text must represent a single SQL statement, not multiple statements. Within the statement, "?" characters can be used as parameter markers to indicate where data values are to be bound to the query later when you execute it. The "?" characters should not be enclosed within quotes, even if you intend to bind them to string values. Parameter markers can be used only where expressions should appear, not for SQL keywords, identifiers, and so forth.
The scope of a prepared statement is the session within which it is created. Other sessions cannot see it.
If a prepared statement with the given name already exists, it is deallocated implicitly before the new statement is prepared. This means that if the new statement contains an error and cannot be prepared, an error is returned and no statement with the given name exists.
Prepared statements can be PREPAREd and EXECUTEd in a stored procedure, but not in a stored function or trigger. Also, even if the statement is PREPAREd in a procedure, it will not be deallocated when the procedure execution ends.
A prepared statement can access [user-defined variables](../user-defined-variables/index), but not [local variables](../declare-variable/index) or procedure's parameters.
If the prepared statement contains a syntax error, PREPARE will fail. As a side effect, stored procedures can use it to check if a statement is valid. For example:
```
CREATE PROCEDURE `test_stmt`(IN sql_text TEXT)
BEGIN
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
SELECT CONCAT(sql_text, ' is not valid');
END;
SET @SQL := sql_text;
PREPARE stmt FROM @SQL;
DEALLOCATE PREPARE stmt;
END;
```
The [FOUND\_ROWS()](../found_rows/index) and [ROW\_COUNT()](../information-functions-row_count/index) functions, if called immediatly after EXECUTE, return the number of rows read or affected by the prepared statements; however, if they are called after DEALLOCATE PREPARE, they provide information about this statement. If the prepared statement produces errors or warnings, [GET DIAGNOSTICS](../get-diagnostics/index) return information about them. DEALLOCATE PREPARE shouldn't clear the [diagnostics area](../diagnostics-area/index), unless it produces an error.
A prepared statement is executed with `[EXECUTE](../execute-statement/index)` and released with `[DEALLOCATE PREPARE](../deallocate-drop-prepared-statement/index)`.
The [max\_prepared\_stmt\_count](../server-system-variables/index#max_prepared_stmt_count) server system variable determines the number of allowed prepared statements that can be prepared on the server. If it is set to 0, prepared statements are not allowed. If the limit is reached, an error similar to the following will be produced:
```
ERROR 1461 (42000): Can't create more than max_prepared_stmt_count statements
(current value: 0)
```
### Oracle Mode
**MariaDB starting with [10.3](../what-is-mariadb-103/index)**In [Oracle mode from MariaDB 10.3](../sql_modeoracle-from-mariadb-103/index#prepared-statements), `PREPARE stmt FROM 'SELECT :1, :2'` is used, instead of `?`.
Permitted Statements
--------------------
Not all statements can be prepared. Only the following SQL commands are permitted:
* [ALTER TABLE](../alter-table/index)
* [ANALYZE TABLE](../analyze-table/index)
* [BINLOG](../binlog/index)
* [CACHE INDEX](../cache-index/index)
* [CALL](../call/index)
* [CHANGE MASTER](../change-master-to/index)
* [CHECKSUM {TABLE | TABLES}](../checksum-table/index)
* [COMMIT](../commit/index)
* {[CREATE](../create-database/index) | [DROP](../drop-database/index)} DATABASE
* {[CREATE](../create-index/index) | [DROP](../drop-index/index)} INDEX
* {[CREATE](../create-table/index) | [RENAME](../rename-table/index) | [DROP](../drop-table/index)} TABLE
* {[CREATE](../create-user/index) | [RENAME](../rename-user/index) | [DROP](../drop-user/index)} USER
* {[CREATE](../create-view/index) | [DROP](../drop-view/index)} VIEW
* [DELETE](../delete/index)
* [DESCRIBE](../describe/index)
* [DO](../do/index)
* [EXPLAIN](../explain/index)
* [FLUSH](../flush/index) {TABLE | TABLES | TABLES WITH READ LOCK | HOSTS | PRIVILEGES | LOGS | STATUS | MASTER | SLAVE | DES\_KEY\_FILE | USER\_RESOURCES | [QUERY CACHE](../flush-query-cache/index) | TABLE\_STATISTICS | INDEX\_STATISTICS | USER\_STATISTICS | CLIENT\_STATISTICS}
* [GRANT](../grant/index)
* [INSERT](../insert/index)
* INSTALL {[PLUGIN](../install-plugin/index) | [SONAME](../install-soname/index)}
* [HANDLER READ](../handler-commands/index)
* [KILL](../kill/index)
* [LOAD INDEX INTO CACHE](../load-index/index)
* [OPTIMIZE TABLE](../optimize-table/index)
* [REPAIR TABLE](../repair-table/index)
* [REPLACE](../replace/index)
* [RESET](../reset/index) {[MASTER](../reset-master/index) | [SLAVE](../reset-slave-connection_name/index) | [QUERY CACHE](../reset/index)}
* [REVOKE](../revoke/index)
* [ROLLBACK](../rollback/index)
* [SELECT](../select/index)
* [SET](../set/index)
* [SET GLOBAL SQL\_SLAVE\_SKIP\_COUNTER](../set-global-sql_slave_skip_counter/index)
* [SET ROLE](../set-role/index)
* [SET SQL\_LOG\_BIN](../set-sql_log_bin/index)
* [SET TRANSACTION ISOLATION LEVEL](../set-transaction/index)
* [SHOW EXPLAIN](../show-explain/index)
* SHOW {[DATABASES](../show-databases/index) | [TABLES](../show-tables/index) | [OPEN TABLES](../show-open-tables/index) | [TABLE STATUS](../show-table-status/index) | [COLUMNS](../show-columns/index) | [INDEX](../show-index/index) | [TRIGGERS](../show-triggers/index) | [EVENTS](../show-events/index) | [GRANTS](../show-grants/index) | [CHARACTER SET](../show-character-set/index) | [COLLATION](../show-collation/index) | [ENGINES](../show-events/index) | [PLUGINS [SONAME](../show-plugins/index)] | [PRIVILEGES](../show-privileges/index) | [PROCESSLIST](../show-processlist/index) | [PROFILE](../show-profile/index) | [PROFILES](../show-profiles/index) | [VARIABLES](../show-variables/index) | [STATUS](../show-status/index) | [WARNINGS](../show-warnings/index) | [ERRORS](../show-errors/index) | [TABLE\_STATISTICS](../show-table-statistics/index) | [INDEX\_STATISTICS](../show-index-statistics/index) | [USER\_STATISTICS](../show-user-statistics/index) | [CLIENT\_STATISTICS](../show-client-statistics/index) | [AUTHORS](../show-authors/index) | [CONTRIBUTORS](../show-contributors/index)}
* SHOW CREATE {[DATABASE](../show-create-database/index) | [TABLE](../show-create-table/index) | [VIEW](../show-create-view/index) | [PROCEDURE](../show-create-procedure/index) | [FUNCTION](../show-create-function/index) | [TRIGGER](../show-create-trigger/index) | [EVENT](../show-create-event/index)}
* SHOW {[FUNCTION](../show-function-code/index) | [PROCEDURE](../show-procedure-code/index)} CODE
* [SHOW BINLOG EVENTS](../show-binlog-events/index)
* [SHOW SLAVE HOSTS](../show-replica-hosts/index)
* SHOW {MASTER | BINARY} LOGS
* SHOW {MASTER | SLAVE | TABLES | INNODB | FUNCTION | PROCEDURE} STATUS
* SLAVE {[START](../start-slave/index) | [STOP](../stop-slave/index)}
* [TRUNCATE TABLE](../truncate-table/index)
* [SHUTDOWN](../shutdown/index)
* UNINSTALL {PLUGIN | SONAME}
* [UPDATE](../update/index)
Synonyms are not listed here, but can be used. For example, DESC can be used instead of DESCRIBE.
**MariaDB starting with [10.1.1](https://mariadb.com/kb/en/mariadb-1011-release-notes/)**[Compound statements](../using-compound-statements-outside-of-stored-programs/index) can be prepared too.
Note that if a statement can be run in a stored routine, it will work even if it is called by a prepared statement. For example, [SIGNAL](../signal/index) can't be directly prepared. However, it is allowed in [stored routines](../stored-routines/index). If the x() procedure contains SIGNAL, you can still prepare and execute the 'CALL x();' prepared statement.
**MariaDB starting with [10.2.3](https://mariadb.com/kb/en/mariadb-1023-release-notes/)**PREPARE now supports most kinds of expressions as well, for example:
```
PREPARE stmt FROM CONCAT('SELECT * FROM ', table_name);
```
**MariaDB starting with [10.6.2](https://mariadb.com/kb/en/mariadb-1062-release-notes/)**All statements can be prepared, except [PREPARE](index), [EXECUTE](../execute-statement/index), and [DEALLOCATE / DROP PREPARE](../deallocate-drop-prepare/index).
When PREPARE is used with a statement which is not supported, the following error is produced:
```
ERROR 1295 (HY000): This command is not supported in the prepared statement protocol yet
```
Example
-------
```
create table t1 (a int,b char(10));
insert into t1 values (1,"one"),(2, "two"),(3,"three");
prepare test from "select * from t1 where a=?";
set @param=2;
execute test using @param;
+------+------+
| a | b |
+------+------+
| 2 | two |
+------+------+
set @param=3;
execute test using @param;
+------+-------+
| a | b |
+------+-------+
| 3 | three |
+------+-------+
deallocate prepare test;
```
Since identifiers are not permitted as prepared statements parameters, sometimes it is necessary to dynamically compose an SQL statement. This technique is called *dynamic SQL*). The following example shows how to use dynamic SQL:
```
CREATE PROCEDURE test.stmt_test(IN tab_name VARCHAR(64))
BEGIN
SET @sql = CONCAT('SELECT COUNT(*) FROM ', tab_name);
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END;
CALL test.stmt_test('mysql.user');
+----------+
| COUNT(*) |
+----------+
| 4 |
+----------+
```
Use of variables in prepared statements:
```
PREPARE stmt FROM 'SELECT @x;';
SET @x = 1;
EXECUTE stmt;
+------+
| @x |
+------+
| 1 |
+------+
SET @x = 0;
EXECUTE stmt;
+------+
| @x |
+------+
| 0 |
+------+
DEALLOCATE PREPARE stmt;
```
See Also
--------
* [Out parameters in PREPARE](../out-parameters-in-prepare/index)
* [EXECUTE Statement](../execute-statement/index)
* [DEALLOCATE / DROP Prepared Statement](../deallocate-drop-prepared-statement/index)
* [EXECUTE IMMEDIATE](../execute-immediate/index)
* [Oracle mode from MariaDB 10.3](../sql_modeoracle-from-mariadb-103/index#prepared-statements)
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb sysbench v0.5 - Single Five Minute Runs on T500 Laptop sysbench v0.5 - Single Five Minute Runs on T500 Laptop
======================================================
MariDB/MySQL sysbench benchmark comparison in %
```
Number of threads
1 4 8 16 32 64 128
sysbench test
delete 92.42 82.60 88.05 89.85 94.68 98.75 97.77
insert 100.70 99.90 103.21 89.51 85.16 105.39 108.51
oltp_complex_ro 101.09 101.83 100.32 103.78 102.10 101.29 102.92
oltp_complex_rw 95.04 90.22 91.84 88.78 100.98 101.96 101.60
oltp_simple 100.29 99.90 101.69 102.22 102.61 102.18 101.49
select 101.57 101.73 100.26 102.15 101.99 102.39 102.09
update_index 96.01 103.06 105.89 108.35 108.13 104.36 101.61
update_non_index 99.85 102.05 110.76 119.51 119.69 118.25 122.77
(MariaDB q/s / MySQL q/s * 100)
```
Run on Lenovo ThinkPad T500 with dual core 2.80GHz and 4GB RAM
MariaDB and MySQL were compiled with
```
BUILD/compile-amd64-max
```
MariaDB revision was:
```
revno: 2818 timestamp: Wed 2010-02-17 21:10:02 +0100
```
MySQL revision was:
```
revno: 3360 [merge] timestamp: Wed 2010-02-17 18:48:40 +0100
```
sysbench was run with these parameters:
```
--oltp-table-size=2000000 \
--max-time=300 \
--max-requests=0 \
--mysql-table-engine=InnoDB \
--mysql-user=root \
--mysql-engine-trx=yes
```
and this variable part of parameters
```
--num-threads=$THREADS --test=${TEST_DIR}/${SYSBENCH_TEST}
```
Configuration used for MariDB and MySQL:
```
--no-defaults \
--skip-grant-tables \
--language=./sql/share/english \
--datadir=$DATA_DIR \
--tmpdir=$TEMP_DIR \
--socket=$MY_SOCKET \
--table_open_cache=512 \
--thread_cache=512 \
--query_cache_size=0 \
--query_cache_type=0 \
--innodb_data_home_dir=$DATA_DIR \
--innodb_data_file_path=ibdata1:128M:autoextend \
--innodb_log_group_home_dir=$DATA_DIR \
--innodb_buffer_pool_size=1024M \
--innodb_additional_mem_pool_size=32M \
--innodb_log_file_size=256M \
--innodb_log_buffer_size=16M \
--innodb_flush_log_at_trx_commit=1 \
--innodb_lock_wait_timeout=50 \
--innodb_doublewrite=0 \
--innodb_flush_method=O_DIRECT \
--innodb_thread_concurrency=0 \
--innodb_max_dirty_pages_pct=80"
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Debugging Memory Usage Debugging Memory Usage
======================
Debugging memory usage on CentOS 7.
This page describes how to debug MariaDB's memory usage. It uses CentOS 7 but can be applied to other systems as well.
The idea is to employ Google PerfTools: <https://gperftools.github.io/gperftools/heapprofile.html>
On CentOS :
```
sudo yum install gperftools
service mariadb stop
systemctl edit mariadb
```
This will open an editor.
Add this content and close the file:
```
[Service]
Environment="HEAPPROFILE=/tmp/heap-prof-1"
Environment="HEAP_PROFILE_ALLOCATION_INTERVAL=10737418240"
Environment="HEAP_PROFILE_INUSE_INTERVAL=1073741824"
Environment="LD_PRELOAD=/usr/lib64/libtcmalloc.so.4"
```
Then run
```
service mariadb start
```
Then, run the workload. When memory consumption becomes large enough, ruh
```
ls -la /tmp/heap-prof-*
```
This should show several files.
Copy away the last one of them:
```
cp /tmp/heap-prof-1.0007.heap .
```
Then, run
```
pprof --dot /usr/sbin/mysqld heap-prof-1.0007.heap > 7.dot
```
(Note: this produces a lot of statements like `/bin/addr2line: Dwarf Error: ...` . Is this because it cannot find locations from the plugin .so files in mariadbd? Anyhow, this is not a showstopper at the moment)
Then, please send us the 7.dot file.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Copying Tables Between Different MariaDB Databases and MariaDB Servers Copying Tables Between Different MariaDB Databases and MariaDB Servers
======================================================================
With MariaDB it's very easy to copy tables between different MariaDB databases and different MariaDB servers. This works for tables created with the [Archive](../archive/index), [Aria](../aria/index), [CSV](../csv/index), [InnoDB](../innodb/index), [MyISAM](../myisam/index), [MERGE](../merge/index), and [XtraDB](../innodb/index) engines.
The normal procedures to copy a table is:
```
FLUSH TABLES db_name.table_name FOR EXPORT
# Copy the relevant files associated with the table
UNLOCK TABLES;
```
The table files can be found in [datadir](../server-system-variables/index#datadir)/databasename (you can execute `SELECT @@datadir` to find the correct directory). When copying the files, you should copy all files with the same table\_name + various extensions. For example, for an Aria table of name foo, you will have files foo.frm, foo.MAI, foo.MAD and possibly foo.TRG if you have [triggers](../triggers/index).
If one wants to distribute a table to a user that doesn't need write access to the table and one wants to minimize the storage size of the table, the recommended engine to use is Aria or MyISAM as one can pack the table with [aria\_pack](../aria_pack/index) or [myisampack](../myisampack/index) respectively to make it notablly smaller. MyISAM is the most portable format as it's not dependent on whether the server settings are different. Aria and InnoDB require the same block size on both servers.
Copying Tables When the MariaDB Server is Down
----------------------------------------------
The following storage engines support export without `FLUSH TABLES ... FOR EXPORT`, assuming the source server is down and the receiving server is not accessing the files during the copy.
| Engine | Comment |
| --- | --- |
| [Archive](../archive/index) | |
| [Aria](../aria/index) | Requires clean shutdown. Table will automatically be fixed on the receiving server if `aria_chk --zerofill` was not run. If `aria_chk --zerofill` is run, then the table is immediately usable without any delays |
| [CSV](../csv/index) | |
| [MyISAM](../myisam/index) | |
| [MERGE](../merge/index) | .MRG files can be copied even while server is running as the file only contains a list of tables that are part of merge. |
Copying Tables Live From a Running MariaDB Server
-------------------------------------------------
For all of the above storage engines (Archive, Aria, CSV, MyISAM and MERGE), one can copy tables even from a live server under the following circumstances:
* You have done a `FLUSH TABLES` or `FLUSH TABLE table_name` for the specific table.
* The server is not accessing the tables during the copy process.
The advantage of [FLUSH TABLES table\_name FOR EXPORT](../flush-tables-for-export/index) is that the table is read locked until [UNLOCK TABLES](https://mariadb.com/lock-tables-and-unlock-tables) is executed.
**Warning**: If you do the above live copy, you are doing this on **your own risk** as if you do something wrong, the copied table is very likely to be corrupted. The original table will of course be fine.
An Efficient Way to Give Someone Else Access to a Read Only Table
-----------------------------------------------------------------
If you want to give a user access to some data in a table for the user to use in their MariaDB server, you can do the following:
First let's create the table we want to export. To speed up things, we create this without any indexes. We use `TRANSACTIONAL=0
ROW_FORMAT=DYNAMIC` for Aria to use the smallest possible row format.
```
CREATE TABLE new_table ... ENGINE=ARIA TRANSACTIONAL=0;
ALTER TABLE new_table DISABLE_KEYS;
# Fill the table with data:
INSERT INTO new_table SELECT * ...
FLUSH TABLE new_table WITH READ LOCK;
# Copy table data to some external location, like /tmp with something
# like cp /my/data/test/new_table.* /tmp/
UNLOCK TABLES;
```
Then we pack it and generate the indexes. We use a big sort buffer to speed up generating the index.
```
> ls -l /tmp/new_table.*
-rw-rw---- 1 mysql my 42396148 Sep 21 17:58 /tmp/new_table.MAD
-rw-rw---- 1 mysql my 8192 Sep 21 17:58 /tmp/new_table.MAI
-rw-rw---- 1 mysql my 1039 Sep 21 17:58 /tmp/new_table.frm
> aria_pack /tmp/new_table
Compressing /tmp/new_table.MAD: (922666 records)
- Calculating statistics
- Compressing file
46.07%
> aria_chk -rq --ignore-control-file --sort_buffer_size=1G /tmp/new_table
Recreating table '/tmp/new_table'
- check record delete-chain
- recovering (with sort) Aria-table '/tmp/new_table'
Data records: 922666
- Fixing index 1
State updated
> ls -l /tmp/new_table.*
-rw-rw---- 1 mysql my 26271608 Sep 21 17:58 /tmp/new_table.MAD
-rw-rw---- 1 mysql my 10207232 Sep 21 17:58 /tmp/new_table.MAI
-rw-rw---- 1 mysql my 1039 Sep 21 17:58 /tmp/new_table.frm
```
The procedure for MyISAM tables is identical, except that [myisamchk](../myisamchk/index) doesn't have the `--ignore-control-file` option.
Copying InnoDB's Transportable Tablespaces
------------------------------------------
InnoDB's file-per-table tablespaces are transportable, which means that you can copy a file-per-table tablespace from one MariaDB Server to another server. See [Copying Transportable Tablespaces](../innodb-file-per-table-tablespaces/index#copying-transportable-tablespaces) for more information.
Importing Tables
----------------
Tables that use most storage engines are immediately usable when their files are copied to the new `[datadir](../server-system-variables/index#datadir)`.
However, this is not true for tables that use [InnoDB](../innodb/index). InnoDB tables have to be imported with `[ALTER TABLE ... IMPORT TABLESPACE](../alter-table/index#import-tablespace)`. See [Copying Transportable Tablespaces](../innodb-file-per-table-tablespaces/index#copying-transportable-tablespaces) for more information.
See Also
--------
* [FLUSH TABLES FOR EXPORT](../flush-tables-for-export/index)
* [FLUSH TABLES](../flush/index)
* [myisampack](../myisampack/index) - Compressing the MyISAM data file for easier distribution.
* [aria\_pack](../aria_pack/index) - Compressing the Aria data file for easier distribution
* [mysqldump](../mysqldump/index) - Copying tables to other SQL servers. You can use the `--tab` to create a CSV file of your table content.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb Optimizing MEMORY Tables Optimizing MEMORY Tables
========================
[MEMORY tables](../memory-storage-engine/index) are a good choice for data that needs to be accessed often, and is rarely updated. Being in memory, it's not suitable for critical data or for storage, but if data can be moved to memory for reading without needing to be regenerated often, if at all, it can provide a significant performance boost.
The [MEMORY Storage Engine](../memory-storage-engine/index) has a key feature in that it permits its indexes to be either B-tree or Hash. Choosing the best index type can lead to better performance. See [Storage Engine index types](../storage-engine-index-types/index) for more on the characteristics of each index type.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb TokuDB Status Variables TokuDB Status Variables
=======================
TokuDB has been deprecated by its upstream maintainer. It is disabled from [MariaDB 10.5](../what-is-mariadb-105/index) and has been been removed in [MariaDB 10.6](../what-is-mariadb-106/index) - [MDEV-19780](https://jira.mariadb.org/browse/MDEV-19780). We recommend [MyRocks](../myrocks/index) as a long-term migration path.
This page documents status variables related to the [TokuDB storage engine](../tokudb/index). See [Server Status Variables](../server-status-variables/index) for a complete list of status variables that can be viewed with [SHOW STATUS](../show-status/index).
See also the [Full list of MariaDB options, system and status variables](../full-list-of-mariadb-options-system-and-status-variables/index).
#### `Tokudb_basement_deserialization_fixed_key`
* **Description:** Number of deserialized basement nodes where all keys were the same size. This leaves the basement in an optimal format for in-memory workloads.
---
#### `Tokudb_basement_deserialization_variable_key`
* **Description:** Number of deserialized basement nodes where all keys had different size keys, which are not eligible for in-memory optimization.
---
#### `Tokudb_basements_decompressed_for_write`
* **Description:** Number of basement nodes decompressed for write operations.
---
#### `Tokudb_basements_decompressed_prefetch`
* **Description:** Number of basement nodes decompressed by a prefetch thread. See [tokudb\_disable\_prefetching](../tokudb-system-variables/index#tokudb_disable_prefetching).
---
#### `Tokudb_basements_decompressed_prelocked_range`
* **Description:** Number of basement nodes aggressively decompressed by queries.
---
#### `Tokudb_basements_decompressed_target_query`
* **Description:** Number of basement nodes decompressed for queries
---
#### `Tokudb_basements_fetched_for_write`
* **Description:** Number of basement nodes fetched for writes off the disk.
---
#### `Tokudb_basements_fetched_for_write_bytes`
* **Description:** Total basement node bytes fetched for writes off the disk.
---
#### `Tokudb_basements_fetched_for_write_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching basement nodes from disk for writes.
---
#### `Tokudb_basements_fetched_prefetch`
* **Description:** Number of basement nodes fetched off the disk by a prefetch thread.
---
#### `Tokudb_basements_fetched_prefetch_bytes`
* **Description:** Total basement node bytes fetched off the disk by a prefetch thread..
---
#### `Tokudb_basements_fetched_prefetch_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching off the disk by a prefetch thread.
---
#### `Tokudb_basements_fetched_prelocked_range`
* **Description:** Number of basement nodes aggressively fetched from disk.
---
#### `Tokudb_basements_fetched_prelocked_range_bytes`
* **Description:** Total basement node bytes aggressively fetched off the disk.
---
#### `Tokudb_basements_fetched_prelocked_range_seconds`
* **Description:** Time in seconds spent waiting for IO while aggressively fetching basement nodes from disk.
---
#### `Tokudb_basements_fetched_target_query`
* **Description:** Number of basement nodes fetched for queries off the disk.
---
#### `Tokudb_basements_fetched_target_query_bytes`
* **Description:** Total basement node bytes fetched for queries off the disk.
---
#### `Tokudb_basements_fetched_target_query_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching basement nodes from disk for queries.
---
#### `Tokudb_broadcase_messages_injected_at_root`
* **Description:** Number of broadcast messages injected at root.
---
#### `Tokudb_buffers_decompressed_for_write`
* **Description:** Number of buffers decompressed for writes.
---
#### `Tokudb_buffers_decompressed_prefetch`
* **Description:** Number of buffers decompressed by a prefetch thread.
---
#### `Tokudb_buffers_decompressed_prelocked_range`
* **Description:** Number of buffers decompressed for queries.
---
#### `Tokudb_buffers_decompressed_target_query`
* **Description:** Number of buffers aggressively decompressed by queries.
---
#### `Tokudb_buffers_fetched_for_write`
* **Description:** Number of buffers fetched for write off the disk.
---
#### `Tokudb_buffers_fetched_for_write_bytes`
* **Description:** Total buffer bytes fetched for writes off the disk.
---
#### `Tokudb_buffers_fetched_for_write_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching buffers from disk for writes.
---
#### `Tokudb_buffers_fetched_prefetch`
* **Description:** Number of buffers fetched for queries off the disk by a prefetch thread.
---
#### `Tokudb_buffers_fetched_prefetch_bytes`
* **Description:** Total buffer bytes fetched for queries off the disk by a prefetch thread.
---
#### `Tokudb_buffers_fetched_prefetch_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching buffers from disk for queries by a prefetch thread.
---
#### `Tokudb_buffers_fetched_prelocked_range`
* **Description:** Number of buffers aggressively fetched for queries off the disk.
---
#### `Tokudb_buffers_fetched_prelocked_range_bytes`
* **Description:** Total buffer bytes aggressively fetched for queries off the disk.
---
#### `Tokudb_buffers_fetched_prelocked_range_seconds`
* **Description:** Time in seconds spent waiting for IO while aggressively fetching buffers from disk for queries.
---
#### `Tokudb_buffers_fetched_target_query`
* **Description:** Number of buffers fetched for queries off the disk.
---
#### `Tokudb_buffers_fetched_target_query_bytes`
* **Description:** Total buffer bytes fetched for queries off the disk.
---
#### `Tokudb_buffers_fetched_target_query_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching buffers from disk for queries.
---
#### `Tokudb_cachetable_cleaner_executions`
* **Description:** Number of times the cleaner thread loop has executed.
---
#### `Tokudb_cachetable_cleaner_iterations`
* **Description:** Number of cleaner operations performed each cleaner period.
---
#### `Tokudb_cachetable_cleaner_period`
* **Description:** Time in seconds between the end of a group of cleaner operations and the beginning of the next. The TokuDB cleaner thread runs in the background, optimizing indexes and performing work not needing to be done by the client thread.
---
#### `Tokudb_cachetable_evictions`
* **Description:** Number of blocks evicted from the cache.
---
#### `Tokudb_cachetable_long_wait_pressure_count`
* **Description:** Number of times a thread was stalled for more than one second due to cache pressure.
---
#### `Tokudb_cachetable_long_wait_pressure_time`
* **Description:** Time in microseconds spent waiting for more than one second for cache pressure to ease.
---
#### `Tokudb_cachetable_miss`
* **Description:** Number of times the system failed to access data in the internal cache.
---
#### `Tokudb_cachetable_miss_time`
* **Description:** Total time in microseconds spent waiting for disk reads (when the cache could not supply the data) to finish.
---
#### `Tokudb_cachetable_prefetches`
* **Description:** Total number of times that a block of memory was prefetched into the database cache. This happens when it's determined that a block of memory is likely to be accessed by the application.
---
#### `Tokudb_cachetable_size_cachepressure`
* **Description:** Size in bytes of data causing cache pressure, or the sum of the buffers and workdone counters.
---
#### `Tokudb_cachetable_size_cloned`
* **Description:** Memory in bytes currently used for cloned nodes. Dirty nodes are cloned before serialization/compression during checkpoint operations, after which they are written to disk and the memory freed for re-use.
---
#### `Tokudb_cachetable_size_current`
* **Description:** Size in bytes of the uncompressed data in the cache.
---
#### `Tokudb_cachetable_size_leaf`
* **Description:** Size in bytes of the leaf nodes in the cache.
---
#### `Tokudb_cachetable_size_limit`
* **Description:** Size in bytes of the uncompressed data that could fit in the cache.
---
#### `Tokudb_cachetable_size_nonleaf`
* **Description:** Size in bytes of the nonleaf nodes in the cache.
---
#### `Tokudb_cachetable_size_rollback`
* **Description:** Size in bytes of the rollback nodes in the cache.
---
#### `Tokudb_cachetable_size_writing`
* **Description:** Size in bytes currently queued to be written to disk.
---
#### `Tokudb_cachetable_wait_pressure_count`
* **Description:** Number of times a thread was stalled due to cache pressure.
---
#### `Tokudb_cachetable_wait_pressure_time`
* **Description:** Time in microseconds spent waiting for cache pressure to ease.
---
#### `Tokudb_checkpoint_begin_time`
* **Description:** Cumulative time in microseconds needed to mark all dirty nodes as pending a checkpoint.
---
#### `Tokudb_checkpoint_duration`
* **Description:** Time in seconds needed to complete all checkpoints.
---
#### `Tokudb_checkpoint_duration_last`
* **Description:** Time in seconds needed to complete the last checkpoint.
---
#### `Tokudb_checkpoint_failed`
* **Description:** Total number of checkpoints failed.
---
#### `Tokudb_checkpoint_last_began`
* **Description:** Date and time the most recent checkpoint began, for example `Wed May 14 11:26:42 2014` Will be `Dec 31, 1969` on Linux if no checkpoint has ever begun.
---
#### `Tokudb_checkpoint_last_complete_began`
* **Description:** Date and time the last complete checkpoint started.
---
#### `Tokudb_checkpoint_last_complete_ended`
* **Description:** Date and time the last complete checkpoint ended.
---
#### `Tokudb_checkpoint_long_begin_count`
* **Description:** Number of long checkpoint begins (checkpoint begins taking more than 1 second).
---
#### `Tokudb_checkpoint_long_begin_time`
* **Description:** Total time in microseconds of long checkpoint begins (checkpoint begins taking more than 1 second).
---
#### `Tokudb_checkpoint_period`
* **Description:** Time in seconds between the end of one automatic checkpoint and the beginning of the next.
---
#### `Tokudb_checkpoint_taken`
* **Description:** Total number of checkpoints taken.
---
#### `Tokudb_cursor_skip_deleted_leaf_entry`
* **Description:** Deleted leaf entries skipped during a range scan.
* **Introduced:** TokuDB 7.5.4
---
#### `Tokudb_db_closes`
* **Description:** Number of db\_close operations.
---
#### `Tokudb_db_open_current`
* **Description:** Number of databases currently open.
---
#### `Tokudb_db_open_max`
* **Description:** Maximum of number of databases open at the same time.
---
#### `Tokudb_db_opens`
* **Description:** Number of db\_open operations.
---
#### `Tokudb_descriptor_set`
* **Description:** Number of times a descriptor was updated when the entire dictionary was updated.
---
#### `Tokudb_dictionary_broadcast_updates`
* **Description:** Number of successful broadcast updates (an update that affects all rows in a dictionary).
---
#### `Tokudb_dictionary_updates`
* **Description:** Total number of rows updated in all primary and secondary indexes that have been done with a separate recovery log entry per index.
---
#### `Tokudb_filesystem_fsync_num`
* **Description:** Total number of times the database has flushed the operating system’s file buffers to disk.
---
#### `Tokudb_filesystem_fsync_time`
* **Description:** Total time in microseconds used to fsync to disk.
---
#### `Tokudb_filesystem_long_fsync_num`
* **Description:** Total number of times the database has flushed the operating system’s file buffers to disk when the operation took more than one second.
---
#### `Tokudb_filesystem_long_fsync_time`
* **Description:** Total time in microseconds used to fsync to disk when the operation took more than one second.
---
#### `Tokudb_filesystem_threads_blocked_by_full_disk`
* **Description:** Number of threads currently blocked due to attempting to write to a full disk. A warning appears in the `disk free space` field if not zero.
---
#### `Tokudb_leaf_compression_to_memory_seconds`
* **Description:** Time in seconds spent on compressing leaf nodes.
---
#### `Tokudb_leaf_decompression_to_memory_seconds`
* **Description:** Time in seconds spent on decompressing leaf nodes.
---
#### `Tokudb_leaf_deserialization_to_memory_seconds`
* **Description:** Time in seconds spent on deserializing leaf nodes.
---
#### `Tokudb_leaf_node_compression_ratio`
* **Description:** Ratio of uncompressed bytes in-memory to compressed bytes on-disk for leaf nodes.
---
#### `Tokudb_leaf_node_full_evictions`
* **Description:** Number of times a full leaf node was evicted from the cache.
---
#### `Tokudb_leaf_node_full_evictions_bytes`
* **Description:** Total bytes freed when a full leaf node was evicted from the cache.
---
#### `Tokudb_leaf_node_partial_evictions`
* **Description:** Number of times part of a leaf node (a partition) was evicted from the cache.
---
#### `Tokudb_leaf_node_partial_evictions_bytes`
* **Description:** Total bytes freed when part of a leaf node (a partition) was evicted from the cache.
---
#### `Tokudb_leaf_nodes_created`
* **Description:** Total number of leaf nodes created.
---
#### `Tokudb_leaf_nodes_destroyed`
* **Description:** Total number of leaf nodes destroyed.
---
#### `Tokudb_leaf_nodes_flushed_checkpoint`
* **Description:** Number of leaf nodes flushed to disk as part of a checkpoint.
---
#### `Tokudb_leaf_nodes_flushed_checkpoint_bytes`
* **Description:** Size in bytes of leaf nodes flushed to disk as part of a checkpoint.
---
#### `Tokudb_leaf_nodes_flushed_checkpoint_seconds`
* **Description:** Time in seconds spent waiting for IO while writing leaf nodes flushed to disk as part of a checkpoint.
---
#### `Tokudb_leaf_nodes_flushed_checkpoint_uncompressed_bytes`
* **Description:** Size in uncompressed bytes of leaf nodes flushed to disk as part of a checkpoint.
---
#### `Tokudb_leaf_nodes_flushed_not_checkpoint`
* **Description:** Number of leaf nodes flushed to disk not as part of a checkpoint.
---
#### `Tokudb_leaf_nodes_flushed_not_checkpoint_bytes`
* **Description:** Size in bytes of leaf nodes flushed to disk not as part of a checkpoint.
---
#### `Tokudb_leaf_nodes_flushed_not_checkpoint_seconds`
* **Description:** Time in seconds spent waiting for IO while writing leaf nodes flushed to disk not as part of a checkpoint.
---
#### `Tokudb_leaf_nodes_flushed_not_checkpoint_uncompressed_bytes`
* **Description:** Size in uncompressed bytes of leaf nodes flushed to disk not as part of a checkpoint.
---
#### `Tokudb_leaf_serialization_to_memory_seconds`
* **Description:** Time in seconds spent on serializing leaf nodes.
---
#### `Tokudb_loader_num_created`
* **Description:** Number of times a loader has been created.
---
#### `Tokudb_loader_num_current`
* **Description:** Number of currently existing loaders.
---
#### `Tokudb_loader_num_max`
* **Description:** Maximum number of loaders that existed at one time.
---
#### `Tokudb_locktree_escalation_num`
* **Description:** Number of times the locktree needed reduce its memory footprint by running lock escalation.
---
#### `Tokudb_locktree_escalation_seconds`
* **Description:** Time in seconds spent performing locktree escalation.
---
#### `Tokudb_locktree_latest_post_escalation_memory_size`
* **Description:** Memory size in bytes of the locktree after most recent locktree escalation.
---
#### `Tokudb_locktree_long_wait_count`
* **Description:** Number of times of more than one second duration that a lock could not be acquired as a result of a conflict with another transaction.
---
#### `Tokudb_locktree_long_wait_escalation_count`
* **Description:** Number of times a client thread waited for more than one second for lock escalation to free up memory.
---
#### `Tokudb_locktree_long_wait_escalation_time`
* **Description:** Time in microseconds of long waits (more than one second) for lock escalation to free up memory.
---
#### `Tokudb_locktree_long_wait_time`
* **Description:**Total time in microseconds spent by clients waiting for more than one second for a lock conflict to be resolved.
---
#### `Tokudb_locktree_memory_size`
* **Description:** Memory in bytes currently being used by the locktree.
---
#### `Tokudb_locktree_memory_size_limit`
* **Description:** Maximum memory in bytes the locktree can use.
---
#### `Tokudb_locktree_open_current`
* **Description:** Number of currently open locktrees.
---
#### `Tokudb_locktree_pending_lock_requests`
* **Description:** Number of requests waiting for a lock to be granted.
---
#### `Tokudb_locktree_sto_eligible_num`
* **Description:** Number of locktrees eligible for single transaction optimizations.
---
#### `Tokudb_locktree_sto_ended_num`
* **Description:** Total number of times a single transaction optimization completed early as a result of another transaction beginning.
---
#### `Tokudb_locktree_sto_ended_seconds`
* **Description:** Time in seconds spent ending single transaction optimizations.
---
#### `Tokudb_locktree_timeout_count`
* **Description:** Number of times a lock request timed out.
---
#### `Tokudb_locktree_wait_count`
* **Description:** Number of times a lock could not be acquired as a result of a conflict with another transaction.
---
#### `Tokudb_locktree_wait_escalation_count`
* **Description:** Number of times a client thread has waited on lock escalation. Lock escalation is run on a background thread when the sum of the acquired lock sizes reaches the lock tree limit.
---
#### `Tokudb_locktree_wait_escalation_time`
* **Description:** Time in microseconds that a client thread spent waiting for lock escalation.
---
#### `Tokudb_locktree_wait_time`
* **Description:** Total time in microseconds spent by clients waiting for a lock conflict to be resolved.
---
#### `Tokudb_logger_wait_long`
* **Description:**
---
#### `Tokudb_logger_writes`
* **Description:** Number of times the logger has written to disk.
---
#### `Tokudb_logger_writes_bytes`
* **Description:** Total bytes the logger has written to disk.
---
#### `Tokudb_logger_writes_seconds`
* **Description:** Time in seconds spent waiting for IO while writing logs to disk.
---
#### `Tokudb_logger_writes_uncompressed_bytes`
* **Description:** Total uncompressed bytes the logger has written to disk.
---
#### `Tokudb_mem_estimated_maximum_memory_footprint`
* **Description:**
---
#### `Tokudb_messages_flushed_from_h1_to_leaves_bytes`
* **Description:** Total bytes of the messages flushed from h1 nodes to leaves.
---
#### `Tokudb_messages_ignored_by_leaf_due_to_msn`
* **Description:** Number of messages ignored by a leaf because it had already been applied.
---
#### `Tokudb_messages_in_trees_estimate_bytes`
* **Description:** Estimate of the total bytes of messages currently in trees.
---
#### `Tokudb_messages_injected_at_root`
* **Description:** Number of messages injected at root.
---
#### `Tokudb_messages_injected_at_root_bytes`
* **Description:** Total bytes of messages injected at root for all trees.
---
#### `Tokudb_nonleaf_compression_to_memory_seconds`
* **Description:** Time in seconds spent on compressing non-leaf nodes.
---
#### `Tokudb_nonleaf_decompression_to_memory_seconds`
* **Description:** Time in seconds spent on decompressing non-leaf nodes.
---
#### `Tokudb_nonleaf_deserialization_to_memory_seconds`
* **Description:** Time in seconds spent on deserializing non-leaf nodes.
---
#### `Tokudb_nonleaf_node_compression_ratio`
* **Description:** Ratio of uncompressed bytes in-memory to compressed bytes on-disk for nonleaf nodes.
---
#### `Tokudb_nonleaf_node_full_evictions`
* **Description:** Number of times a full non-leaf node was evicted from the cache.
---
#### `Tokudb_nonleaf_node_full_evictions_bytes`
* **Description:** Total bytes freed when a full non-leaf node was evicted from the cache.
---
#### `Tokudb_nonleaf_node_partial_evictions`
* **Description:** Number of times part of a non-leaf node (a partition) was evicted from the cache.
---
#### `Tokudb_nonleaf_node_partial_evictions_bytes`
* **Description:** Total bytes freed when part of a non-leaf node (a partition) was evicted from the cache.
---
#### `Tokudb_nonleaf_nodes_created`
* **Description:** Total number of non-leaf nodes created.
---
#### `Tokudb_nonleaf_nodes_destroyed`
* **Description:** Total number of non-leaf nodes destroyed.
---
#### `Tokudb_nonleaf_nodes_flushed_to_disk_checkpoint`
* **Description:** Number of non-leaf nodes flushed to disk as part of a checkpoint.
---
#### `Tokudb_nonleaf_nodes_flushed_to_disk_checkpoint_bytes`
* **Description:** Size in bytes of non-leaf nodes flushed to disk as part of a checkpoint.
---
#### `Tokudb_nonleaf_nodes_flushed_to_disk_checkpoint_seconds`
* **Description:** Time in seconds spent waiting for IO while writing non-leaf nodes flushed to disk as part of a checkpoint.
---
#### `Tokudb_nonleaf_nodes_flushed_to_disk_checkpoint_uncompressed_bytes`
* **Description:** Size in uncompressed bytes of non-leaf nodes flushed to disk as part of a checkpoint.
---
#### `Tokudb_nonleaf_nodes_flushed_to_disk_not_checkpoint`
* **Description:** Number of non-leaf nodes flushed to disk not as part of a checkpoint.
---
#### `Tokudb_nonleaf_nodes_flushed_to_disk_not_checkpoint_bytes`
* **Description:** Size in bytes of non-leaf nodes flushed to disk not as part of a checkpoint.
---
#### `Tokudb_nonleaf_nodes_flushed_to_disk_not_checkpoint_seconds`
* **Description:** Time in seconds spent waiting for IO while writing non-leaf nodes flushed to disk not as part of a checkpoint.
---
#### `Tokudb_nonleaf_nodes_flushed_to_disk_not_checkpoint_uncompressed_bytes`
* **Description:** Size in uncompressed bytes of non-leaf nodes flushed to disk not as part of a checkpoint.
---
#### `Tokudb_nonleaf_serialization_to_memory_seconds`
* **Description:** Time in seconds spent on serializing nonleaf nodes.
---
#### `Tokudb_overall_node_compression_ratio`
* **Description:** Ratio of uncompressed bytes in-memory to compressed bytes on-disk for all nodes.
---
#### `Tokudb_pivots_fetched_for_query`
* **Description:** Total number of pivot nodes fetched for queries.
---
#### `Tokudb_pivots_fetched_for_query_bytes`
* **Description:** Number of bytes of pivot nodes fetched for queries.
---
#### `Tokudb_pivots_fetched_for_query_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching pivot nodes for queries.
---
#### `Tokudb_pivots_fetched_for_prefetch`
* **Description:** Total number of pivot nodes fetched by a prefetch thread.
---
#### `Tokudb_pivots_fetched_for_prefetch_bytes`
* **Description:** Number of bytes of pivot nodes fetched by a prefetch thread.
---
#### `Tokudb_pivots_fetched_for_prefetch_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching pivot nodes by a prefetch thread.
---
#### `Tokudb_pivots_fetched_for_write`
* **Description:** Total number of pivot nodes fetched for writes.
---
#### `Tokudb_pivots_fetched_for_write_bytes`
* **Description:** Number of bytes of pivot nodes fetched for writes.
---
#### `Tokudb_pivots_fetched_for_write_seconds`
* **Description:** Time in seconds spent waiting for IO while fetching pivot nodes for writes.
---
#### `Tokudb_promotion_h1_roots_injected_into`
* **Description:** Number of times a message stopped at a root with a height of 1.
---
#### `Tokudb_promotion_injections_at_depth_0`
* **Description:** Number of times a message stopped at a depth of zero.
---
#### `Tokudb_promotion_injections_at_depth_1`
* **Description:** Number of times a message stopped at a depth of one.
---
#### `Tokudb_promotion_injections_at_depth_2`
* **Description:** Number of times a message stopped at a depth of two.
---
#### `Tokudb_promotion_injections_at_depth_3`
* **Description:** Number of times a message stopped at a depth of three.
---
#### `Tokudb_promotion_injections_lower_than_depth_3`
* **Description:** Number of times a message stopped at a depth of greater than three.
---
#### `Tokudb_promotion_leaf_roots_injected_into`
* **Description:** Number of times a message stopped at a root with a height of 0.
---
#### `Tokudb_promotion_roots_split`
* **Description:** Number of times the root split during promotion.
---
#### `Tokudb_promotion_stopped_after_locking_child`
* **Description:** Number of times a message stopped before a locked child.
---
#### `Tokudb_promotion_stopped_at_height_1`
* **Description:** Number of times a message stopped due to reaching a height of one.
---
#### `Tokudb_promotion_stopped_child_locked_or_not_in_memory`
* **Description:** Number of times a message stopped due to being unable to cheaply access (locked or not stored in memory) a child.
---
#### `Tokudb_promotion_stopped_child_not_fully_in_memory`
* **Description:** Number of times a message stopped due to being unable to cheaply access (not fully stored in memory) a child.
---
#### `Tokudb_promotion_stopped_nonempty_buffer`
* **Description:** Number of times a message stopped due to reaching a buffer that wasn't empty.
---
#### `Tokudb_txn_aborts`
* **Description:** Number of transactions that have been aborted.
---
#### `Tokudb_txn_begin`
* **Description:** Number of transactions that have been started.
---
#### `Tokudb_txn_begin_read_only`
* **Description:** Number of read-only transactions that have been started.
---
#### `Tokudb_txn_commits`
* **Description:** Number of transactions that have been committed.
---
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| programming_docs |
mariadb Database Normalization: 3rd Normal Form Database Normalization: 3rd Normal Form
=======================================
This article follows on from [Database Normalization: 2nd Normal Form](../database-normalization-2nd-normal-form/index).
After converting to second normal form, the following table structure was achieved:
| Plant location table |
| --- |
| *Plant code* |
| *Location code* |
| Plant table |
| --- |
| *Plant code* |
| Plant name |
| Soil category |
| Soil description |
| Location table |
| --- |
| *Location code* |
| Location name |
Are these tables in 3rd normal form?
A table is in 3rd normal form if:
* it is in 2nd normal form
* it contains no transitive dependencies (where a non-key attribute is dependent on the primary key through another non-key attribute)
If a table only contains one non-key attribute, it is obviously impossible for a non-key attribute to be dependent on another non-key attribute. Any tables where this is the case that are in 2nd normal form are then therefore also in 3rd normal form.
As only the plant table has more than one non-key attribute, you can ignore the others because they are in 3rd normal form already. All fields are dependent on the primary key in some way, since the tables are in second normal form. But is this dependency on another non-key field? *Plant name* is not dependent on either *soil category* or *soil description*. Nor is *soil category* dependent on either *soil description* or *plant name*.
However, *soil description* is dependent on *soil category*. You use the same procedure as before, removing it, and placing it in its own table with the attribute that it was dependent on as the key. You are left with the tables below:
### Plant location table remains unchanged
| Plant location table |
| --- |
| *Plant code* |
| *Location code* |
### Plant table with soil description removed
| Plant table |
| --- |
| *Plant code* |
| Plant name |
| Soil category |
### The new soil table
| Soil table |
| --- |
| *Soil category* |
| Soil description |
### Location table remains unchanged
| Location table |
| --- |
| *Location code* |
| Location name |
All of these tables are now in 3rd normal form. 3rd normal form is usually sufficient for most tables because it avoids the most common kind of data anomalies. It's suggested getting most tables you work with to 3rd normal form before you implement them, as this will achieve the aims of normalization listed in [Database Normalization Overview](../database-normalization-overview/index) in the vast majority of cases.
The normal forms beyond this, such as Boyce-Codd normal form and 4th normal form, are rarely useful for business applications. In most cases, tables in 3rd normal form are already in these normal forms anyway. But any skilful database practitioner should know the exceptions, and be able to normalize to the higher levels when required.
The next article covers Boyce-Codd normal form.
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mariadb Building Cassandra Storage Engine for Packaging Building Cassandra Storage Engine for Packaging
===============================================
THIS PAGE IS OBSOLETE, it describes how to build a branch of MariaDB-5.5 with Cassandra SE. Cassandra SE is a part of [MariaDB 10.0](../what-is-mariadb-100/index), which uses different approach to building.
These are instructions on how exactly we build Cassandra SE packages.
Getting into build environment
------------------------------
See How\_to\_access\_buildbot\_VMs page on the internal wiki. The build VM to use is
```
ezvm precise-amd64-build
```
Get into the VM and continue to next section.
Set up Thrift
-------------
```
mkdir build
cd build
wget https://dist.apache.org/repos/dist/release/thrift/0.8.0/thrift-0.8.0.tar.gz
sudo apt-get install bzr
sudo apt-get install flex
tar zxvf thrift-0.8.0.tar.gz
cd thrift-0.8.0/
./configure --prefix=/home/buildbot/build/thrift-inst --without-qt4 --without-c_glib --without-csharp --without-java --without-erlang --without-python --without-perl --without-php --without-php_extension --without-ruby --without-haskell --without-go --without-d
make
make install
# free some space
make clean
cd ..
```
Get the bzr checkout
--------------------
* Create another SSH connection to terrier, run the script suggested by motd.
* Press (C-a C-c) to create another window
* Copy the base bazaar repository into the VM:
```
scp /home/psergey/5.5-cassandra-base.tgz runvm:
```
Then, get back to the window with VM, and run in VM:
```
tar zxvf ../5.5-cassandra-base.tgz
rm -rf ../5.5-cassandra-base.tgz
cd 5.5-cassandra/
bzr pull lp:~maria-captains/maria/5.5-cassandra
```
Compile
-------
```
export LIBS="-lthrift"
export LDFLAGS=-L/home/buildbot/build/thrift-inst/lib
mkdir mkdist
cd mkdist
cmake ..
make dist
```
```
basename mariadb-*.tar.gz .tar.gz > ../distdirname.txt
cp mariadb-5.5.25.tar.gz ../
cd ..
tar zxf "mariadb-5.5.25.tar.gz"
mv "mariadb-5.5.25" build
cd build
mkdir mkbin
cd mkbin
cmake -DBUILD_CONFIG=mysql_release ..
make -j4 package
```
This should end with:
```
CPack: - package: /home/buildbot/build/5.5-cassandra/build/mkbin/mariadb-5.5.25-linux-x86_64.tar.gz generated.
```
Free up some disk space:
```
rm -fr ../../mkdist/
```
```
mv mariadb-5.5.25-linux-x86_64.tar.gz ../..
cd ../..
rm -rf build
```
Patch the tarball to include Thrift
-----------------------------------
```
mkdir fix-package
cd fix-package
tar zxvf ../mariadb-5.5.25-linux-x86_64.tar.gz
```
Verify that mysqld was built with Cassandra SE:
```
ldd mariadb-5.5.25-linux-x86_64/bin/mysqld
```
This should point to libthrift-0.8.0.so.
```
cp /home/buildbot/build/thrift-inst/lib/libthrift* mariadb-5.5.25-linux-x86_64/lib/
tar czf mariadb-5.5.25-linux-x86_64.tar.gz mariadb-5.5.25-linux-x86_64/
cp mariadb-5.5.25-linux-x86_64.tar.gz ..
```
Copy the data out of VM
-----------------------
In the second window (the one that's on terrier, but not in VM), run:
```
mkdir build-cassandra
cd build-cassandra
scp runvm:/home/buildbot/build/5.5-cassandra/mariadb-5.5.25.tar.gz .
scp runvm:/home/buildbot/build/5.5-cassandra/mariadb-5.5.25-linux-x86_64.tar.gz .
```
References
----------
1. <http://buildbot.askmonty.org/buildbot/builders/kvm-tarbake-jaunty-x86/builds/2578>
2. <http://buildbot.askmonty.org/buildbot/builders/kvm-bintar-hardy-amd64/builds/1907>
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mariadb SET CHARACTER SET SET CHARACTER SET
=================
Syntax
------
```
SET {CHARACTER SET | CHARSET}
{charset_name | DEFAULT}
```
Description
-----------
Sets the [character\_set\_client](../server-system-variables/index#character_set_client) and [character\_set\_results](../server-system-variables/index#character_set_results) session system variables to the specified character set and [collation\_connection](../server-system-variables/index#collation_connection) to the value of [collation\_database](../server-system-variables/index#collation_database), which implicitly sets [character\_set\_connection](../server-system-variables/index#character_set_connection) to the value of [character\_set\_database](../server-system-variables/index#character_set_database).
This maps all strings sent between the current client and the server with the given mapping.
Example
-------
```
SHOW VARIABLES LIKE 'character_set\_%';
+--------------------------+--------+
| Variable_name | Value |
+--------------------------+--------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | latin1 |
| character_set_system | utf8 |
+--------------------------+--------+
SHOW VARIABLES LIKE 'collation%';
+----------------------+-------------------+
| Variable_name | Value |
+----------------------+-------------------+
| collation_connection | utf8_general_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
+----------------------+-------------------+
SET CHARACTER SET utf8mb4;
SHOW VARIABLES LIKE 'character_set\_%';
+--------------------------+---------+
| Variable_name | Value |
+--------------------------+---------+
| character_set_client | utf8mb4 |
| character_set_connection | latin1 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | utf8mb4 |
| character_set_server | latin1 |
| character_set_system | utf8 |
+--------------------------+---------+
SHOW VARIABLES LIKE 'collation%';
+----------------------+-------------------+
| Variable_name | Value |
+----------------------+-------------------+
| collation_connection | latin1_swedish_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
+----------------------+-------------------+
```
See Also
--------
* [SET NAMES](../set-names/index)
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mariadb ColumnStore Conditions ColumnStore Conditions
======================
A condition is a combination of expressions and operators that return TRUE, FALSE or NULL.The following syntax shows the conditions that can be used to return a TRUE, FALSE,or NULL condition.
filter
------
```
filter:
column| literal| function [=|!=|<>|<|<=|>=|>] column| literal| function | select_statement
column| function [NOT] IN (select_statement | literal, literal,...)
column| function [NOT] BETWEEN (select_statement | literal, literal,...)
column| function IS [NOT] NULL
string_column|string_function [NOT] LIKE pattern
EXISTS (select_statement)
NOT (filter)
(filter|function) [AND|OR] (filter|function)
```
Note: A ‘literal’ may be a constant (e.g. 3) or an expression that evaluates to a constant [e.g. 100 - (27 \* 3)]. For date columns, you may use the SQL ‘interval’ syntax to perform date arithmetic, as long as all the components of the expression are constants (e.g. ‘1998-12-01’ - interval ‘1’ year)
### String comparisons
ColumnStore, unlike the MyISAM engine, is case sensitive for string comparisons used in filters. For the most accurate results, and to avoid confusing results, make sure string filter constants are no longer than the column width itself.
### Pattern matching
Pattern matching as described with the LIKE condition allows you to use “\_” to match any single character and “%” to match an arbitrary number of characters (including zero characters). To test for literal instances of a wildcard character, (“%” or “\_”),precede it by the “\” character.
### OR processing
OR Processing has the following restrictions:
* Only column comparisons against a literal are allowed in conjunction with an OR. The following query would be allowed since all comparisons are against literals. `SELECT count(*) from lineitem WHERE l_partkey < 100 OR l_linestatus =‘F‘;`
* ColumnStore binds AND’s more tightly than OR’s, just like any other SQLparser. Therefore you must enclose OR-relations in parentheses, just like in any other SQL parser.
```
SELECT count(*) FROM orders, lineitem
WHERE (lineitem.l_orderkey < 100 OR lineitem.l_linenumber > 10)
AND lineitem.l_orderkey =orders.o_orderkey;
```
table filter
------------
The following syntax show the conditions you can use when executing a condition against two columns. Note that the columns must be from the same table.
```
col_name_1 [=|!=|<>|<|<=|>=|>] col_name_2
```
join
----
The following syntax show the conditions you can use when executing a join on two tables.
```
join_condition [AND join_condition]
join_condition:
[col_name_1|function_name_1] = [col_name_2|function_name_2]
```
Notes:
* ColumnStore tables can only be joined with non-ColumnStore tables in table mode only. See Operating Mode for information.
* ColumnStore will require a join in the WHERE clause for each set of tables in the FROM clause. No cartesian product queries will be allowed.
* ColumnStore requires that joins must be on the same datatype. In addition, numeric datatypes (INT variations, NUMERIC, DECIMAL) may be mixed in the join if they have the same scale.
* Circular joins are not supported in ColumnStore. See the Troubleshooting section
* When the join memory limit is exceeded, a disk-based join will be used for processing if this option has been enabled.
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mariadb HANDLER Commands HANDLER Commands
================
Syntax
------
```
HANDLER tbl_name OPEN [ [AS] alias]
HANDLER tbl_name READ index_name { = | >= | <= | < } (value1,value2,...)
[ WHERE where_condition ] [LIMIT ... ]
HANDLER tbl_name READ index_name { FIRST | NEXT | PREV | LAST }
[ WHERE where_condition ] [LIMIT ... ]
HANDLER tbl_name READ { FIRST | NEXT }
[ WHERE where_condition ] [LIMIT ... ]
HANDLER tbl_name CLOSE
```
Description
-----------
The `HANDLER` statement provides direct access to table storage engine interfaces for key lookups and key or table scans. It is available for at least [Aria](../aria-formerly-known-as-maria/index), [Memory](../memory-storage-engine/index), [MyISAM](../myisam-storage-engine/index) and [InnoDB](../xtradb-and-innodb/index) tables (and should work with most 'normal' storage engines, but not with system tables, [MERGE](../merge/index) or [views](../views/index)).
`HANDLER ... OPEN` opens a table, allowing it to be accessible to subsequent `HANDLER ... READ` statements. The table can either be opened using an alias (which must then be used by `HANDLER ... READ`, or a table name.
The table object is only closed when `HANDLER ... CLOSE` is called by the session, and is not shared by other sessions.
[Prepared statements](../prepared-statements/index) work with `HANDLER READ`, which gives a much higher performance (50% speedup) as there is no parsing and all data is transformed in binary (without conversions to text, as with the normal protocol).
The HANDLER command does not work with [partitioned tables](../managing-mariadb-partitioning/index).
Key Lookup
----------
A key lookup is started with:
```
HANDLER tbl_name READ index_name { = | >= | <= | < } (value,value) [LIMIT...]
```
The values stands for the value of each of the key columns. For most key types (except for HASH keys in MEMORY storage engine) you can use a prefix subset of it's columns.
If you are using LIMIT, then in case of >= or > then there is an implicit NEXT implied, while if you are using <= or < then there is an implicit PREV implied.
After the initial read, you can use
```
HANDLER tbl_name READ index_name NEXT [ LIMIT ... ]
or
HANDLER tbl_name READ index_name PREV [ LIMIT ... ]
```
to scan the rows in key order.
Note that the row order is not defined for keys with duplicated values and will vary from engine to engine.
Key Scans
---------
You can scan a table in key order by doing:
```
HANDLER tbl_name READ index_name FIRST [ LIMIT ... ]
HANDLER tbl_name READ index_name NEXT [ LIMIT ... ]
```
or, if the handler supports backwards key scans (most do):
```
HANDLER tbl_name READ index_name LAST [ LIMIT ... ]
HANDLER tbl_name READ index_name PREV [ LIMIT ... ]
```
Table Scans
-----------
You can scan a table in row order by doing:
```
HANDLER tbl_name READ FIRST [ LIMIT ... ]
HANDLER tbl_name READ NEXT [ LIMIT ... ]
```
Limitations
-----------
As this is a direct interface to the storage engine, some limitations may apply for what you can do and what happens if the table changes. Here follows some of the common limitations:
### Finding 'Old Rows'
HANDLER READ is not transaction safe, consistent or atomic. It's ok for the storage engine to returns rows that existed when you started the scan but that were later deleted. This can happen as the storage engine may cache rows as part of the scan from a previous read.
You may also find rows committed since the scan originally started.
### Invisible Columns
`HANDLER ... READ` also reads the data of [invisible-columns](../invisible-columns/index).
### System-Versioned Tables
`HANDLER ... READ` reads everything from [system-versioned tables](../system-versioned-tables/index), and so includes `row_start` and `row_end` fields, as well as all rows that have since been deleted or changed, including when history partitions are used.
### Other Limitations
* If you do an [ALTER TABLE](../alter-table/index), all your HANDLERs for that table are automatically closed.
* If you do an ALTER TABLE for a table that is used by some other connection with HANDLER, the ALTER TABLE will wait for the HANDLER to be closed.
* For HASH keys, you must use all key parts when searching for a row.
* For HASH keys, you can't do a key scan of all values. You can only find all rows with the same key value.
* While each HANDLER READ command is atomic, if you do a scan in many steps, then some engines may give you error 1020 if the table changed between the commands. Please refer to the [specific engine handler page](../handler-handler/index) if this happens.
Error Codes
-----------
* Error 1031 (ER\_ILLEGAL\_HA) Table storage engine for 't1' doesn't have this option
+ If you get this for HANDLER OPEN it means the storage engine doesn't support HANDLER calls.
+ If you get this for HANDLER READ it means you are trying to use an incomplete HASH key.
* Error 1020 (ER\_CHECKREAD) Record has changed since last read in table '...'
+ This means that the table changed between two reads and the handler can't handle this case for the given scan.
See Also
--------
* [What is MariaDB 5.3](../what-is-mariadb-53/index)
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mariadb CREATE DATABASE CREATE DATABASE
===============
Syntax
------
```
CREATE [OR REPLACE] {DATABASE | SCHEMA} [IF NOT EXISTS] db_name
[create_specification] ...
create_specification:
[DEFAULT] CHARACTER SET [=] charset_name
| [DEFAULT] COLLATE [=] collation_name
| COMMENT [=] 'comment'
```
Description
-----------
`CREATE DATABASE` creates a database with the given name. To use this statement, you need the [CREATE privilege](../grant/index) for the database. `CREATE SCHEMA` is a synonym for `CREATE DATABASE`.
For valid identifiers to use as database names, see [Identifier Names](../identifier-names/index).
#### OR REPLACE
**MariaDB starting with [10.1.3](https://mariadb.com/kb/en/mariadb-1013-release-notes/)**The `OR REPLACE` clause was added in [MariaDB 10.1.3](https://mariadb.com/kb/en/mariadb-1013-release-notes/)
If the optional `OR REPLACE` clause is used, it acts as a shortcut for:
```
DROP DATABASE IF EXISTS db_name;
CREATE DATABASE db_name ...;
```
#### IF NOT EXISTS
When the `IF NOT EXISTS` clause is used, MariaDB will return a warning instead of an error if the specified database already exists.
#### COMMENT
**MariaDB starting with [10.5.0](https://mariadb.com/kb/en/mariadb-1050-release-notes/)**From [MariaDB 10.5.0](https://mariadb.com/kb/en/mariadb-1050-release-notes/), it is possible to add a comment of a maximum of 1024 bytes. If the comment length exceeds this length, a error/warning code 4144 is thrown. The database comment is also added to the db.opt file, as well as to the [information\_schema.schemata table](../information-schema-schemata-table/index).
Examples
--------
```
CREATE DATABASE db1;
Query OK, 1 row affected (0.18 sec)
CREATE DATABASE db1;
ERROR 1007 (HY000): Can't create database 'db1'; database exists
CREATE OR REPLACE DATABASE db1;
Query OK, 2 rows affected (0.00 sec)
CREATE DATABASE IF NOT EXISTS db1;
Query OK, 1 row affected, 1 warning (0.01 sec)
SHOW WARNINGS;
+-------+------+----------------------------------------------+
| Level | Code | Message |
+-------+------+----------------------------------------------+
| Note | 1007 | Can't create database 'db1'; database exists |
+-------+------+----------------------------------------------+
```
Setting the [character sets and collation](../data-types-character-sets-and-collations/index). See [Setting Character Sets and Collations](../setting-character-sets-and-collations/index) for more details.
```
CREATE DATABASE czech_slovak_names
CHARACTER SET = 'keybcs2'
COLLATE = 'keybcs2_bin';
```
Comments, from [MariaDB 10.5.0](https://mariadb.com/kb/en/mariadb-1050-release-notes/):
```
CREATE DATABASE presentations COMMENT 'Presentations for conferences';
```
See Also
--------
* [Identifier Names](../identifier-names/index)
* [DROP DATABASE](../drop-database/index)
* [SHOW CREATE DATABASE](../show-create-database/index)
* [ALTER DATABASE](../alter-database/index)
* [SHOW DATABASES](../show-databases/index)
* [Character Sets and Collations](../character-sets-and-collations/index)
* [Information Schema SCHEMATA Table](../information-schema-schemata-table/index)
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb MariaDB ColumnStore software upgrade 1.1.6 GA to 1.2.0 Alpha MariaDB ColumnStore software upgrade 1.1.6 GA to 1.2.0 Alpha
============================================================
MariaDB ColumnStore software upgrade 1.1.6 GA to 1.2.0 Alpha
------------------------------------------------------------
One change that was made for 1.2.0 is to have the default install type by postConfigure to be Non-Distributed from Distributed in the 1.1.X releases. But this doesnt effect upgrades. It will perform the upgraded based on how to previous 1.1.x package was installed. If it was install as Distributed, then the upgrade will also be done as Distributed. Same goes for Non-Distributed.
Note: Columnstore.xml modifications you manually made are not automatically carried forward on an upgrade. These modifications will need to be incorporated back into .XML once the upgrade has occurred.
The previous configuration file will be saved as /usr/local/mariadb/columnstore/etc/Columnstore.xml.rpmsave.
If you have specified a root database password (which is good practice), then you must configure a .my.cnf file with user credentials for the upgrade process to use. Create a .my.cnf file in the user home directory with 600 file permissions with the following content (updating PASSWORD as appropriate):
```
[mysqladmin]
user = root
password = PASSWORD
```
### MariaDB Server Password setup
If there is a root user password in the MariaDB server Database, remember to setup the Password Configuration file on each User Module and Performance Module that has User Modules functionality.
[https://mariadb.com/kb/en/library/mariadb-columnstore-system-usage/#logging-into-mariadb-columnstore-mariadb-console](../library/mariadb-columnstore-system-usage/index#logging-into-mariadb-columnstore-mariadb-console)
Also make sure that the file .my.cnf doesn't exist if no password is setup.
### Choosing the type of upgrade
As noted on the Preparing guide, you can installing MariaDB ColumnStore with the use of soft-links. If you have the softlinks be setup at the Data Directory Levels, like mariadb/columnstore/data and mariadb/columnstore/dataX, then your upgrade will happen without any issues. In the case where you have a softlink at the top directory, like /usr/local/mariadb, you will need to upgrade using the binary package. If you updating using the rpm package and tool, this softlink will be deleted when you perform the upgrade process and the upgrade will fail.
#### Root User Installs
#### Upgrading MariaDB ColumnStore using RPMs tar package
Upgrade MariaDB ColumnStore as user root on the server designated as PM1:
**Download the package mariadb-columnstore-1.2.0-1-centos#.x86\_64.rpm.tar.gz to the PM1 server where you are installing MariaDB ColumnStore.** Shutdown the MariaDB ColumnStore system:
```
# mcsadmin shutdownsystem y
```
* Unpack the tarball, which will generate a set of RPMs that will reside in the /root/ directory.
```
# tar -zxf mariadb-columnstore-1.2.0-1-centos#.x86_64.rpm.tar.gz
```
* Upgrade the RPMs. The MariaDB ColumnStore software will be installed in /usr/local/.
```
# rpm -e --nodeps $(rpm -qa | grep '^mariadb-columnstore')
# rpm -ivh mariadb-columnstore-*1.2.0*rpm
```
* Run postConfigure using the upgrade option, which will utilize the configuration from the Columnstore.xml.rpmsave
```
# /usr/local/mariadb/columnstore/bin/postConfigure -u
```
For RPM Upgrade, the previous configuration file will be saved as:
/usr/local/mariadb/columnstore/etc/Columnstore.xml.rpmsave
#### Upgrading MariaDB ColumnStore using RPM Package Repositories
The system can be upgrade when it was previously installed from the Package Repositories. This will need to be run on each module in the system
Additional information can be found in this document on how to setup and install using the 'yum' package repo command:
[https://mariadb.com/kb/en/library/installing-mariadb-ax-from-the-package-repositories](../library/installing-mariadb-ax-from-the-package-repositories)
Upgrade MariaDB ColumnStore as user root on the server designated as PM1:
**Shutdown the MariaDB ColumnStore system:**
```
# mcsadmin shutdownsystem y
```
* Uninstall MariaDB ColumnStore Packages
```
# yum remove mariadb-columnstore*
```
* Install MariaDB ColumnStore Packages
```
# yum --enablerepo=mariadb-columnstore clean metadata
# yum install mariadb-columnstore*
```
NOTE: On the non-pm1 module, start the columnstore service
```
# /usr/local/mariadb/columnstore/bin/columnstore start
```
* Run postConfigure using the upgrade and non-distributed options, which will utilize the configuration from the Columnstore.xml.rpmsave
```
# /usr/local/mariadb/columnstore/bin/postConfigure -u -n
```
For RPM Upgrade, the previous configuration file will be saved as:
/usr/local/mariadb/columnstore/etc/Columnstore.xml.rpmsave
### Initial download/install of MariaDB ColumnStore binary package
Upgrade MariaDB ColumnStore as user root on the server designated as PM1:
* Download the package into the /usr/local directory -mariadb-columnstore-1.2.0-1.x86\_64.bin.tar.gz (Binary 64-BIT)to the server where you are installing MariaDB ColumnStore.
* Shutdown the MariaDB ColumnStore system:
```
# mcsadmin shutdownsystem y
```
* Run pre-uninstall script
```
# /usr/local/mariadb/columnstore/bin/pre-uninstall
```
* Unpack the tarball, in the /usr/local/ directory.
```
# tar -zxvf mariadb-columnstore-1.2.0-1.x86_64.bin.tar.gz
```
* Run post-install scripts
```
# /usr/local/mariadb/columnstore/bin/post-install
```
* Run postConfigure using the upgrade option, which will utilize the configuration from the Columnstore.xml,rpmsave
```
# /usr/local/mariadb/columnstore/bin/postConfigure -u
```
### Upgrading MariaDB ColumnStore using the DEB package
A DEB upgrade would be done on a system that supports DEBs like Debian or Ubuntu systems.
Upgrade MariaDB ColumnStore as user root on the server designated as PM1:
* Download the package into the /root directory
mariadb-columnstore-1.2.0-1.amd64.deb.tar.gz
(DEB 64-BIT) to the server where you are installing MariaDB ColumnStore.
* Shutdown the MariaDB ColumnStore system:
```
# mcsadmin shutdownsystem y
```
* Unpack the tarball, which will generate DEBs.
```
# tar -zxf mariadb-columnstore-1.2.0-1.amd64.deb.tar.gz
```
* Remove and install all MariaDB ColumnStore debs
```
# cd /root/
# dpkg -r $(dpkg --list | grep 'mariadb-columnstore' | awk '{print $2}')
# dpkg --install mariadb-columnstore-*1.2.0-1*deb
```
* Run postConfigure using the upgrade option, which will utilize the configuration from the Columnstore.xml,rpmsave
```
# /usr/local/mariadb/columnstore/bin/postConfigure -u
```
#### Upgrading MariaDB ColumnStore using DEB Package Repositories
The system can be upgrade when it was previously installed from the Package Repositories. This will need to be run on each module in the system
Additional information can be found in this document on how to setup and install using the 'apt-get' package repo command:
[https://mariadb.com/kb/en/library/installing-mariadb-ax-from-the-package-repositories](../library/installing-mariadb-ax-from-the-package-repositories)
Upgrade MariaDB ColumnStore as user root on the server designated as PM1:
**Shutdown the MariaDB ColumnStore system:**
```
# mcsadmin shutdownsystem y
```
* Uninstall MariaDB ColumnStore Packages
```
# apt-get remove mariadb-columnstore*
```
* Install MariaDB ColumnStore Packages
```
# apt-get update
# sudo apt-get install mariadb-columnstore*
```
NOTE: On the non-pm1 module, start the columnstore service
```
# /usr/local/mariadb/columnstore/bin/columnstore start
```
* Run postConfigure using the upgrade and non-distributed options, which will utilize the configuration from the Columnstore.xml.rpmsave
```
# /usr/local/mariadb/columnstore/bin/postConfigure -u -n
```
For RPM Upgrade, the previous configuration file will be saved as:
/usr/local/mariadb/columnstore/etc/Columnstore.xml.rpmsave
#### Non-Root User Installs
### Initial download/install of MariaDB ColumnStore binary package
Upgrade MariaDB ColumnStore as user root on the server designated as PM1:
* Download the package into the /home/'non-root-user" directory
mariadb-columnstore-1.2.0-1.x86\_64.bin.tar.gz (Binary 64-BIT)to the server where you are installing MariaDB ColumnStore.
* Shutdown the MariaDB ColumnStore system:
```
# mcsadmin shutdownsystem y
```
* Run pre-uninstall script
```
# $HOME/mariadb/columnstore/bin/pre-uninstall --installdir=/home/guest/mariadb/columnstore
```
* Unpack the tarball, which will generate the $HOME/ directory.
```
# tar -zxvf mariadb-columnstore-1.2.0-1.x86_64.bin.tar.gz
```
* Run post-install scripts
```
# $HOME/mariadb/columnstore/bin/post-install --installdir=/home/guest/mariadb/columnstore
```
* Run postConfigure using the upgrade option, which will utilize the configuration from the Columnstore.xml,rpmsave
```
# $HOME/mariadb/columnstore/bin/postConfigure -u -i /home/guest/mariadb/columnstore
```
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mariadb Changing & Deleting Data Changing & Deleting Data
=========================
| Title | Description |
| --- | --- |
| [DELETE](../delete/index) | Delete rows from one or more tables. |
| [HIGH\_PRIORITY and LOW\_PRIORITY](../high_priority-and-low_priority/index) | Modifying statement priority in storage engines supporting table-level locks. |
| [IGNORE](../ignore/index) | Suppress errors while trying to violate a UNIQUE constraint. |
| [REPLACE](../replace/index) | Equivalent to DELETE + INSERT, or just an INSERT if no rows are returned. |
| [REPLACE...RETURNING](../replacereturning/index) | Returns a resultset of the replaced rows. |
| [TRUNCATE TABLE](../truncate-table/index) | DROP and re-CREATE a table. |
| [UPDATE](../update/index) | Modify rows in one or more tables. |
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mariadb TOAD Edge TOAD Edge
=========
#### Characteristics
Toad Edge™ is a database management application that allows you to perform database administration tasks with ease.
Toad Edge™ allows you to:
* Connect to your MySQL database, view, explore and edit database structure, database objects and properties.
* Manage database objects, easily add, edit or drop objects in Object Explorer.
* Manage data stored in your database, add, edit or remove records.
* Write complex SQL code comfortably in Worksheet.
* Compare and synchronize databases using powerful Schema Compare.
* Obtain detailed information about your databases.
In TOAD Edge 1.2, support for [MariaDB 10.1](../what-is-mariadb-101/index) has been added.
#### Product Information
<https://www.toadworld.com/products/toad-edge>
<https://www.toadworld.com/p/downloads>
#### Download: Freeware
<https://www.toadworld.com/m/freeware/1657>
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mariadb CONNECT - Adding the REST Feature as a Library Called by an OEM Table CONNECT - Adding the REST Feature as a Library Called by an OEM Table
=====================================================================
If you are using a version of MariaDB that does not support REST, this is how the REST feature can be added as a library called by an OEM table.
Before making the REST OEM module, the Microsoft Casablanca package must be installed as for compiling MariaDB from source.
Even if this module is to be used with a binary distribution, you need some CONNECT source files in order to successfully make it. It is made with four files existing in the version 1.06.0010 of CONNECT: tabrest.cpp, restget.cpp, tabrest.h and mini-global.h. It also needs the CONNECT header files that are included in tabrest.cpp and the ones they can include. This can be obtained by going to a recent download site of a version of MariaDB that includes the REST feature, downloading the MariaDB source file tar.gz and extracting from it the CONNECT sources files in a directory that will be added to the additional source directories if it is not the directory containing the above files.
On Windows, use a recent version of Visual Studio. Make a new empty DLL project and add the source files tabrest.cpp and restget.cpp. Visual studio should automatically generate all necessary connections to the cpprest SDK. Just edit the properties of the project to add the additional include directory (the one where the CONNECT source was downloaded) et the link to the ha\_connect.lib of the binary version of MariaDB (in the same directory than ha\_connect.dll in your binary distribution). Add the preprocessor definition XML\_SUPPORT. Also set in the linker input page of the project property the Module definition File to the rest.def file (with its full path) also existing in the CONNECT source files. If you are making a debug configuration, make sure that in the C/C++ Code generation page the Runtime library line specifies Multi-threaded Debug DLL (/MDd) or your server will crash when using the feature.
This is not really simple but it is nothing compared with Linux! Someone having made an OEM module for its own application have written:
For whatever reason, g++ / ld on Linux are both extremely picky about what they will and won't consider a \*"library"\* for linking purposes. In order to get them to recognize and therefore find `ha\_connect.so` as a "valid" linkable library, `ha\_connect.so` must exist in a directory whose path is in `/etc/ld.so.conf` or `/etc/ld.so.conf.d/ha\_connect.conf` \*AND\* its filename must begin with "lib".
On Fedora, you can make a link to ha\_connect.so by:
```
$ sudo ln -s /..path to../ha_connect.so /usr/lib64/libconnect.so
```
This provides a library whose name begins with “lib”. It was made in /usr/lib64/ because it was the directory of the libcpprest.so Casablanca library. This solved the need of a file in /etc/ld.so.conf.d as this was already done for the cpprest library. Note that the -s parameter is a must, without it all sort of nasty errors are met when using the feature.
Then compile and install the OEM module with:
```
$ makdir oem
$ cd oem
$ makedir Release
$ make -f oemrest.mak
$ sudo cp rest.so /usr/local/mysql/lib/plugin
```
The oemrest.mak file:
```
#LINUX
CPP = g++
LD = g++
OD = ./Release/
SD = /home/olivier/MariaDB/server/storage/connect/
CD =/usr/lib64
# flags to compile object files that can be used in a dynamic library
CFLAGS= -Wall -c -O3 -std=c++11 -fPIC -fno-rtti -I$(SD) -DXML_SUPPORT
# Replace -03 by -g for debug
LDFLAGS = -L$(CD) -lcpprest -lconnect
# Flags to create a dynamic library.
DYNLINKFLAGS = -shared
# on some platforms, use '-G' instead.
# REST library's archive file
OEMREST = rest.so
SRCS_CPP = $(SD)tabrest.cpp $(SD)restget.cpp
OBJS_CPP = $(OD)tabrest.o $(OD)restget.o
# top-level rule
all: $(OEMREST)
$(OEMREST): $(OBJS_CPP)
$(LD) $(OBJS_CPP) $(LDFLAGS) $(DYNLINKFLAGS) -o $@
#CPP Source files
$(OD)tabrest.o: $(SD)tabrest.cpp $(SD)mini-global.h $(SD)global.h $(SD)plgdbsem.h $(SD)xtable.h $(SD)filamtxt.h $(SD)plgxml.h $(SD)tabdos.h $(SD)tabfmt.h $(SD)tabjson.h $(SD)tabrest.h $(SD)tabxml.h
$(CPP) $(CFLAGS) -o $@ $(SD)$(*F).cpp
$(OD)restget.o: $(SD)restget.cpp $(SD)mini-global.h $(SD)global.h
$(CPP) $(CFLAGS) -o $@ $(SD)$(*F).cpp
# clean everything
clean:
$(RM) $(OBJS_CPP) $(OEMREST)
```
The SD and CD variables are the directories of the CONNECT source files and the one containing the libcpprest.so lib. They can be edited to match those on your machine OD is the directory that was made to contain the object files.
A very important flag is -fno-rtti. Without it you would be in big trouble.
The resulting module, for instance rest.so or rest.dll, must be placed in the plugin directory of the MariaDB server. Then, you will be able to use NoSQL tables simply replacing in the CREATE TABLE statement the TABLE\_TYPE option =JSON or XML by TABLE\_TYPE=OEM SUBTYPE=REST MODULE=’rest.(so|dll)’. Actually, the module name, here supposedly ‘rest’, can be anything you like.
The file type is JSON by default. If not, it must be specified like this:
```
OPTION_LIST=’Ftype=XML’
```
To be added to the create table statement. For instance:
```
CREATE TABLE webw
ENGINE=CONNECT TABLE_TYPE=OEM MODULE='Rest.dll' SUBTYPE=REST
FILE_NAME='weatherdata.xml'
HTTP='https://samples.openweathermap.org/data/2.5/forecast?q=London,us&mode=xml&appid=b6907d289e10d714a6e88b30761fae22'
OPTION_LIST='Ftype=XML,Depth=3,Rownode=weatherdata';
```
Note: this last example returns an XML file whose format was not recognized by old CONNECT versions. It is here the reason of the option ‘Rownode=weatherdata’.
If you have trouble making the module, you can post an issue on [JIRA](../jira/index).
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mariadb mysql.spider_xa Table mysql.spider\_xa Table
======================
The `mysql.spider_xa` table is installed by the [Spider storage engine](../spider/index).
**MariaDB starting with [10.4](../what-is-mariadb-104/index)**In [MariaDB 10.4](../what-is-mariadb-104/index) and later, this table uses the [Aria](../aria/index) storage engine.
**MariaDB until [10.3](../what-is-mariadb-103/index)**In [MariaDB 10.3](../what-is-mariadb-103/index) and before, this table uses the [MyISAM](../myisam-storage-engine/index) storage engine.
It contains the following fields:
| Field | Type | Null | Key | Default | Description |
| --- | --- | --- | --- | --- | --- |
| format\_id | int(11) | NO | PRI | 0 | |
| gtrid\_length | int(11) | NO | PRI | 0 | |
| bqual\_length | int(11) | NO | | 0 | |
| data | binary(128) | NO | PRI | | |
| status | char(8) | NO | MUL | | |
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mariadb SEQUENCE Functions SEQUENCE Functions
===================
**MariaDB starting with [10.3](../what-is-mariadb-103/index)**SEQUENCEs were introduced in [MariaDB 10.3](../what-is-mariadb-103/index).
Functions that can be used on SEQUENCEs
| Title | Description |
| --- | --- |
| [LASTVAL](../lastval/index) | Synonym for PREVIOUS VALUE for sequence\_name. |
| [NEXT VALUE for sequence\_name](../next-value-for-sequence_name/index) | Generate next value for a SEQUENCE. Same as NEXTVAL(). |
| [NEXTVAL](../nextval/index) | Synonym for NEXT VALUE for sequence\_name. |
| [PREVIOUS VALUE FOR sequence\_name](../previous-value-for-sequence_name/index) | Get last value generated from a SEQUENCE. Same as LASTVAL(). |
| [SETVAL](../setval/index) | Set the next value to be returned from a SEQUENCE. |
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| programming_docs |
mariadb Variables and Modes Variables and Modes
====================
The different variables and modes to use to affect how MariaDB works.
| Title | Description |
| --- | --- |
| [Full List of MariaDB Options, System and Status Variables](../full-list-of-mariadb-options-system-and-status-variables/index) | Complete alphabetical list of all MariaDB options as well as system and status variables. |
| [Server Status Variables](../server-status-variables/index) | List and description of the Server Status Variables. |
| [Server System Variables](../server-system-variables/index) | List of system variables. |
| [OLD\_MODE](../old-mode/index) | Used to emulate behavior from older MariaDB and MySQL versions. |
| [SQL\_MODE](../sql-mode/index) | Used to emulate behavior from other SQL servers. |
| [SQL\_MODE=MSSQL](../sql_modemssql/index) | Microsoft SQL Server compatibility mode. |
| [SQL\_MODE=ORACLE](../sql_modeoracle/index) | MariaDB understands a subset of Oracle's PL/SQL language. |
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mariadb SHOW CREATE VIEW SHOW CREATE VIEW
================
Syntax
------
```
SHOW CREATE VIEW view_name
```
Description
-----------
This statement shows a [CREATE VIEW](../create-view/index) statement that creates the given [view](../views/index), as well as the character set used by the connection when the view was created. This statement also works with views.
`SHOW CREATE VIEW` quotes table, column and stored function names according to the value of the [sql\_quote\_show\_create](../server-system-variables/index#sql_quote_show_create) server system variable.
Examples
--------
```
SHOW CREATE VIEW example\G
*************************** 1. row ***************************
View: example
Create View: CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL
SECURITY DEFINER VIEW `example` AS (select `t`.`id` AS `id`,`t`.`s` AS `s` from
`t`)
character_set_client: cp850
collation_connection: cp850_general_ci
```
With `[sql\_quote\_show\_create](../server-system-variables/index#sql_quote_show_create)` off:
```
SHOW CREATE VIEW example\G
*************************** 1. row ***************************
View: example
Create View: CREATE ALGORITHM=UNDEFINED DEFINER=root@localhost SQL SECU
RITY DEFINER VIEW example AS (select t.id AS id,t.s AS s from t)
character_set_client: cp850
collation_connection: cp850_general_ci
```
Grants
------
To be able to see a view, you need to have the [SHOW VIEW](../grant/index#table-privileges) and the [SELECT](../grant/index#table-privileges) privilege on the view:
```
GRANT SHOW VIEW,SELECT ON test_database.test_view TO 'test'@'localhost';
```
See Also
--------
* [Grant privileges to tables, views etc](../grant/index)
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mariadb InnoDB Encryption Overview InnoDB Encryption Overview
==========================
MariaDB supports data-at-rest encryption for tables using the [InnoDB](../innodb/index) storage engines. When enabled, the server encrypts data when it writes it to and decrypts data when it reads it from the file system. You can [configure InnoDB encryption](../innodb-enabling-encryption/index) to automatically have all new InnoDB tables automatically encrypted, or specify encrypt per table.
For encrypting data with the Aria storage engine, see [Encrypting Data for Aria](../encrypting-data-for-aria/index).
Basic Configuration
-------------------
Using data-at-rest encryption requires that you first configure an [Encryption Key Management](../encryption-key-management/index) plugin, such as the `[file\_key\_management](../file-key-management-encryption-plugin/index)` or `[aws\_key\_management](../aws-key-management-encryption-plugin/index)` plugins. MariaDB uses this plugin to store, retrieve and manage the various keys it uses when encrypting data to and decrypting data from the file system.
Once you have the plugin configured, you need to set a few additional system variables to enable encryption on InnoDB and XtraDB tables, including `[innodb\_encrypt\_tables](../innodb-system-variables/index#innodb_encrypt_tables)`, `[innodb\_encrypt\_logs](../innodb-system-variables/index#innodb_encrypt_logs)`, `[innodb\_encryption\_threads](../innodb-system-variables/index#innodb_encryption_threads)`, and `[innodb\_encryption\_rotate\_key\_age](../innodb-system-variables/index#innodb_encryption_rotate_key_age)`.
```
[mariadb]
...
# File Key Management
plugin_load_add = file_key_management
file_key_management_filename = /etc/mysql/encryption/keyfile.enc
file_key_management_filekey = FILE:/etc/mysql/encryption/keyfile.key
file_key_management_encryption_algorithm = AES_CTR
# InnoDB/XtraDB Encryption
innodb_encrypt_tables = ON
innodb_encrypt_temporary_tables = ON
innodb_encrypt_log = ON
innodb_encryption_threads = 4
innodb_encryption_rotate_key_age = 1
```
For more information on system variables for encryption and other features, see the InnoDB [system variables](../innodb-system-variables/index) page.
Finding Encrypted Tables
------------------------
When using data-at-rest encryption with the InnoDB or XtraDB storage engines, it is not necessary that you encrypt every table in your database. You can check which tables are encrypted and which are not by querying the `[INNODB\_TABLESPACES\_ENCRYPTION](../information-schema-innodb_tablespaces_encryption-table/index)` table in the [Information Schema](../information-schema/index). This table provides information on which tablespaces are encrypted, which encryption key each tablespace is encrypted with, and whether the background encryption threads are currently working on the tablespace. Since the [system tablespace](../innodb-system-tablespaces/index) can also contain tables, it can be helpful to join the `[INNODB\_TABLESPACES\_ENCRYPTION](../information-schema-innodb_tablespaces_encryption-table/index)` table with the `[INNODB\_SYS\_TABLES](../information-schema-innodb_sys_tables-table/index)` table to find out the encryption status of each specific table, rather than each tablespace. For example:
```
SELECT st.SPACE, st.NAME, te.ENCRYPTION_SCHEME, te.ROTATING_OR_FLUSHING
FROM information_schema.INNODB_TABLESPACES_ENCRYPTION te
JOIN information_schema.INNODB_SYS_TABLES st
ON te.SPACE = st.SPACE \G
*************************** 1. row ***************************
SPACE: 0
NAME: SYS_DATAFILES
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 2. row ***************************
SPACE: 0
NAME: SYS_FOREIGN
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 3. row ***************************
SPACE: 0
NAME: SYS_FOREIGN_COLS
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 4. row ***************************
SPACE: 0
NAME: SYS_TABLESPACES
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 5. row ***************************
SPACE: 0
NAME: SYS_VIRTUAL
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 6. row ***************************
SPACE: 0
NAME: db1/default_encrypted_tab1
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 7. row ***************************
SPACE: 416
NAME: db1/default_encrypted_tab2
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 8. row ***************************
SPACE: 402
NAME: db1/tab
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 9. row ***************************
SPACE: 185
NAME: db1/tab1
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 10. row ***************************
SPACE: 184
NAME: db1/tab2
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 11. row ***************************
SPACE: 414
NAME: db1/testgb2
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 12. row ***************************
SPACE: 4
NAME: mysql/gtid_slave_pos
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 13. row ***************************
SPACE: 2
NAME: mysql/innodb_index_stats
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 14. row ***************************
SPACE: 1
NAME: mysql/innodb_table_stats
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
*************************** 15. row ***************************
SPACE: 3
NAME: mysql/transaction_registry
ENCRYPTION_SCHEME: 1
ROTATING_OR_FLUSHING: 0
15 rows in set (0.000 sec)
```
Redo Logs
---------
Using data-at-rest encryption with InnoDB, the `[innodb\_encrypt\_tables](../innodb-system-variables/index#innodb_encrypt_tables)` system variable only encrypts the InnoDB tablespaces. In order to also encrypt the InnoDB Redo Logs, you also need to set the `[innodb\_encrypt\_logs](innodb-server-system-variables#innodb_encrypt_logs)` system variable.
Beginning in [MariaDB 10.4](../what-is-mariadb-104/index), where the encryption key management plugin supports key rotation the InnoDB Redo Log can also rotate encryption keys. In previous releases, the Redo Log can only use the first encryption key.
See Also
--------
* [Data at Rest Encryption](../data-at-rest-encryption/index)
* [Why Encrypt MariaDB Data?](../why-encrypt-mariadb-data/index)
* [Encryption Key Management](../encryption-key-management/index)
* [Information Schema INNODB\_TABLESPACES\_ENCRYPTION table](../information-schema-innodb_tablespaces_encryption-table/index)
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mariadb Information Schema ENGINES Table Information Schema ENGINES Table
================================
The [Information Schema](../information_schema/index) `ENGINES` table displays status information about the server's [storage engines](../mariadb-storage-engines/index).
It contains the following columns:
| Column | Description |
| --- | --- |
| `ENGINE` | Name of the storage engine. |
| `SUPPORT` | Whether the engine is the default, or is supported or not. |
| `COMMENT` | Storage engine comments. |
| `TRANSACTIONS` | Whether or not the engine supports [transactions](../transactions/index). |
| `XA` | Whether or not the engine supports [XA transactions](../xa-transactions/index). |
| `SAVEPOINTS` | Whether or not [savepoints](../savepoint/index) are supported. |
It provides identical information to the `[SHOW ENGINES](../show-engines/index)` statement. Since storage engines are plugins, different information about them is also shown in the `[information\_schema.PLUGINS](../information_schemaplugins-table/index)` table and by the `[SHOW PLUGINS](../show-plugins/index)` statement.
The table is not a standard Information Schema table, and is a MySQL and MariaDB extension.
Note that both MySQL's InnoDB and Percona's XtraDB replacement are labeled as `InnoDB`. However, if XtraDB is in use, it will be specified in the `COMMENT` field. See [XtraDB and InnoDB](../xtradb-and-innodb/index). The same applies to [FederatedX](../federatedx/index).
Example
-------
```
SELECT * FROM information_schema.ENGINES\G;
*************************** 1. row ***************************
ENGINE: InnoDB
SUPPORT: DEFAULT
COMMENT: Supports transactions, row-level locking, and foreign keys
TRANSACTIONS: YES
XA: YES
SAVEPOINTS: YES
*************************** 2. row ***************************
ENGINE: CSV
SUPPORT: YES
COMMENT: CSV storage engine
TRANSACTIONS: NO
XA: NO
SAVEPOINTS: NO
*************************** 3. row ***************************
ENGINE: MyISAM
SUPPORT: YES
COMMENT: MyISAM storage engine
TRANSACTIONS: NO
XA: NO
SAVEPOINTS: NO
*************************** 4. row ***************************
ENGINE: BLACKHOLE
SUPPORT: YES
COMMENT: /dev/null storage engine (anything you write to it disappears)
TRANSACTIONS: NO
XA: NO
SAVEPOINTS: NO
*************************** 5. row ***************************
ENGINE: FEDERATED
SUPPORT: YES
COMMENT: FederatedX pluggable storage engine
TRANSACTIONS: YES
XA: NO
SAVEPOINTS: YES
*************************** 6. row ***************************
ENGINE: MRG_MyISAM
SUPPORT: YES
COMMENT: Collection of identical MyISAM tables
TRANSACTIONS: NO
XA: NO
SAVEPOINTS: NO
*************************** 7. row ***************************
ENGINE: ARCHIVE
SUPPORT: YES
COMMENT: Archive storage engine
TRANSACTIONS: NO
XA: NO
SAVEPOINTS: NO
*************************** 8. row ***************************
ENGINE: MEMORY
SUPPORT: YES
COMMENT: Hash based, stored in memory, useful for temporary tables
TRANSACTIONS: NO
XA: NO
SAVEPOINTS: NO
*************************** 9. row ***************************
ENGINE: PERFORMANCE_SCHEMA
SUPPORT: YES
COMMENT: Performance Schema
TRANSACTIONS: NO
XA: NO
SAVEPOINTS: NO
*************************** 10. row ***************************
ENGINE: Aria
SUPPORT: YES
COMMENT: Crash-safe tables with MyISAM heritage
TRANSACTIONS: NO
XA: NO
SAVEPOINTS: NO
10 rows in set (0.00 sec)
```
Check if a given storage engine is available:
```
SELECT SUPPORT FROM information_schema.ENGINES WHERE ENGINE LIKE 'tokudb';
Empty set
```
Check which storage engine supports XA transactions:
```
SELECT ENGINE FROM information_schema.ENGINES WHERE XA = 'YES';
+--------+
| ENGINE |
+--------+
| InnoDB |
+--------+
```
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mariadb mysql Command-line Client mysql Command-line Client
=========================
About the mysql Command-Line Client
-----------------------------------
**mysql** (from [MariaDB 10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/), [also called mariadb](../mariadb-command-line-client/index)) is a simple SQL shell (with GNU readline capabilities). It supports interactive and non-interactive use. When used interactively, query results are presented in an ASCII-table format. When used non-interactively (for example, as a filter), the result is presented in tab-separated format. The output format can be changed using command options.
If you have problems due to insufficient memory for large result sets, use the `--quick` option. This forces mysql to retrieve results from the server a row at a time rather than retrieving the entire result set and buffering it in memory before displaying it. This is done by returning the result set using the `mysql_use_result()` C API function in the client/server library rather than `mysql_store_result()`.
Using mysql is very easy. Invoke it from the prompt of your command interpreter as follows:
```
mysql db_name
```
Or:
```
mysql --user=user_name --password=your_password db_name
```
Then type an SQL statement, end it with “;”, \g, or \G and press Enter.
Typing Control-C causes mysql to attempt to kill the current statement. If this cannot be done, or Control-C is typed again before the statement is killed, mysql exits.
You can execute SQL statements in a script file (batch file) like this:
```
mysql db_name < script.sql > output.tab
```
From [MariaDB 10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/), `mariadb` is available as a symlink to `mysql`.
From [MariaDB 10.5.2](https://mariadb.com/kb/en/mariadb-1052-release-notes/), `mysql` is the symlink, and `mariadb` the binary name.
Using mysql
-----------
The command to use `mysql` and the general syntax is:
```
mysql <options>
```
### Options
`mysql` supports the following options:
| Option | Description |
| --- | --- |
| `-?`, `--help` | Display this help and exit. |
| `-I`, `--help` | Synonym for `-?` |
| `--abort-source-on-error` | Abort 'source filename' operations in case of errors. |
| `--auto-rehash` | Enable automatic rehashing. This option is on by default, which enables database, table, and column name completion. Use `--disable-auto-rehash`, `--no-auto-rehash` or `skip-auto-rehash` to disable rehashing. That causes mysql to start faster, but you must issue the rehash command if you want to use name completion. To complete a name, enter the first part and press Tab. If the name is unambiguous, mysql completes it. Otherwise, you can press Tab again to see the possible names that begin with what you have typed so far. Completion does not occur if there is no default database. |
| `-A`, `--no-auto-rehash` | No automatic rehashing. One has to use 'rehash' to get table and field completion. This gives a quicker start of mysql and disables rehashing on reconnect. |
| `--auto-vertical-output` | Automatically switch to vertical output mode if the result is wider than the terminal width. |
| `-B`, `--batch` | Print results using tab as the column separator, with each row on a new line. With this option, mysql does not use the history file. Batch mode results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the `--raw` option. (Enables `--silent`.) |
| `--binary-mode` | By default, ASCII '\0' is disallowed and '\r\n' is translated to '\n'. This switch turns off both features, and also turns off parsing of all client commands except \C and DELIMITER, in non-interactive mode (for input piped to mysql or loaded using the 'source' command). This is necessary when processing output from [mysqlbinlog](../mysqlbinlog/index) that may contain blobs. |
| `--character-sets-dir=name` | Directory for [character set](../data-types-character-sets-and-collations/index) files. |
| `--column-names` | Write column names in results. (Defaults to on; use `--skip-column-names` to disable.) |
| `--column-type-info` | Display column type information. |
| `-c`, `--comments` | Preserve comments. Send comments to the server. The default is `--skip-comments` (discard comments), enable with `--comments`. |
| `-C`, `--compress` | Compress all information sent between the client and the server if both support compression. |
| `--connect-expired-password` | Notify the server that this client is prepared to handle [expired password sandbox mode](../user-password-expiry/index) even if `--batch` was specified. From [MariaDB 10.4.3](https://mariadb.com/kb/en/mariadb-1043-release-notes/). |
| `--connect-timeout=num` | Number of seconds before connection timeout. Defaults to zero. |
| `-D`, `--database=name` | Database to use. |
| `-# [options]`, `--debug[=options]` | On debugging builds, write a debugging log. A typical debug\_options string is `d:t:o,file_name`. The default is `d:t:o,/tmp/mysql.trace`. |
| `--debug-check` | Check memory and open file usage at exit. |
| `-T`, `--debug-info` | Print some debug info at exit. |
| `--default-auth=plugin` | Default authentication client-side plugin to use. |
| `--default-character-set=name` | Set the default [character set](../data-types-character-sets-and-collations/index). A common issue that can occur when the operating system uses utf8 or another multibyte character set is that output from the mysql client is formatted incorrectly, due to the fact that the MariaDB client uses the latin1 character set by default. You can usually fix such issues by using this option to force the client to use the system character set instead. If set to `auto` the character set is taken from the client environment (`LC_CTYPE` on Unix). |
| `--defaults-extra-file=file` | Read this file after the global files are read. Must be given as the first option. |
| `--defaults-file=file` | Only read default options from the given *file*. Must be given as the first option. |
| `--defaults-group-suffix=suffix` | In addition to the given groups, also read groups with this suffix. |
| `--delimiter=name` | Delimiter to be used. The default is the semicolon character (“;”). |
| `--enable-cleartext-plugin` | Obsolete option. Exists only for MySQL compatibility. From [MariaDB 10.3.36](https://mariadb.com/kb/en/mariadb-10336-release-notes/). |
| `-e`, `--execute=name` | Execute statement and quit. Disables `--force` and history file. The default output format is like that produced with `--batch`. |
| `-f`, `--force` | Continue even if we get an SQL error. Sets `--abort-source-on-error` to 0. |
| `-h`, `--host=name` | Connect to host. |
| `-H`, `--html` | Produce HTML output. |
| `-U`, `--i-am-a-dummy` | Synonym for option `--safe-updates`, `-U`. |
| `-i`, `--ignore-spaces` | Ignore space after function names. Allows one to have spaces (including tab characters and new line characters) between function name and '('. The drawback is that this causes built in functions to become reserved words. |
| `--init-command=str` | SQL Command to execute when connecting to the MariaDB server. Will automatically be re-executed when reconnecting. |
| `--line-numbers` | Write line numbers for errors. (Defaults to on; use `--skip-line-numbers` to disable.) |
| `--local-infile` | Enable or disable LOCAL capability for [LOAD DATA INFILE](../load-data-infile/index). With no value, the option enables LOCAL. The option may be given as`--local-infile=0` or `--local-infile=1` to explicitly disable or enable LOCAL. Enabling LOCAL has no effect if the server does not also support it. |
| `--max-allowed-packet=num` | The maximum packet length to send to or receive from server. The default is 16MB, the maximum 1GB. |
| `--max-join-size=num` | Automatic limit for rows in a join when using `--safe-updates`. Default is 1000000. |
| `-G`, `--named-commands` | Enable named commands. Named commands mean mysql's internal commands (see below) . When enabled, the named commands can be used from any line of the query, otherwise only from the first line, before an enter. Long-format commands are allowed, not just short-format commands. For example, `quit` and `\q` are both recognized. Disable with `--disable-named-commands`. This option is disabled by default. |
| `--net-buffer-length=num` | The buffer size for TCP/IP and socket communication. Default is 16KB. |
| `-b`, `--no-beep` | Turn off beep on error. |
| `--no-defaults` | Don't read default options from any option file. Must be given as the first option. |
| `-o`, `--one-database` | Ignore statements except those those that occur while the default database is the one named on the command line. This filtering is limited, and based only on [USE](../use/index) statements. This is useful for skipping updates to other databases in the binary log. |
| `--pager[=name]` | Pager to use to display results (Unix only). If you don't supply an option, the default pager is taken from your ENV variable PAGER. Valid pagers are *less*, *more*, *cat [> filename]*, etc. See interactive help (\h) also. This option does not work in batch mode. Disable with `--disable-pager`. This option is disabled by default. |
| `-p`, `--password[=name]` | Password to use when connecting to server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the `--password` or `-p` option on the command line, mysql prompts for one. Specifying a password on the command line should be considered insecure. You can use an option file to avoid giving the password on the command line. |
| `--plugin-dir=name` | Directory for client-side plugins. |
| `-P`, `--port=num` | Port number to use for connection or 0 for default to, in order of preference, my.cnf, $MYSQL\_TCP\_PORT, /etc/services, built-in default (3306). |
| `--print-defaults` | Print the program argument list and exit. Must be given as the first option. |
| `--progress-reports` | Get [progress reports](../progress-reporting/index) for long running commands (such as [ALTER TABLE](../alter-table/index)). (Defaults to on; use `--skip-progress-reports` to disable.) |
| `--prompt=name` | Set the mysql prompt to this value. See [prompt command](#prompt-command) for options. |
| `--protocol=name` | The protocol to use for connection (tcp, socket, pipe, memory). |
| `-q`, `--quick` | Don't cache result, print it row by row. This may slow down the server if the output is suspended. Doesn't use history file. |
| `-r`, `--raw` | For tabular output, the “boxing” around columns enables one column value to be distinguished from another. For nontabular output (such as is produced in batch mode or when the `--batch` or `--silent` option is given), special characters are escaped in the output so they can be identified easily. Newline, tab, NUL, and backslash are written as `\n`, `\t`, `\0`, and . The `--raw` option disables this character escaping. |
| `--reconnect` | Reconnect if the connection is lost. This option is enabled by default. Disable with `--disable-reconnect` or `skip-reconnect`. |
| `-U`, `--safe-updates` | Allow only those [UPDATE](../update/index) and [DELETE](../delete/index) statements that specify which rows to modify by using key values. If you have set this option in an option file, you can override it by using `--safe-updates` on the command line. See [using the --safe-updates option](#using-the-safe-updates-option) for more. |
| `--secure-auth` | Refuse client connecting to server if it uses old (pre-MySQL4.1.1) protocol. Defaults to false (unlike MySQL since 5,6, which defaults to true). |
| `--select-limit=num` | Automatic limit for SELECT when using --safe-updates. Default 1000. |
| `--server-arg=name` | Send embedded server this as a parameter. |
| `--shared-memory-base-name=name` | Shared-memory name to use for Windows connections using shared memory to a local server (started with the --shared-memory option). Case-sensitive. |
| `--show-warnings` | Show warnings after every statement. Applies to interactive and batch mode. |
| `--sigint-ignore` | Ignore SIGINT signals (usually CTRL-C). |
| `-s`, `--silent` | Be more silent. This option can be given multiple times to produce less and less output. This option results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the `--raw` option. |
| `-L`, `--skip-auto-rehash` | Disable automatic rehashing. See `--auto-rehash`. |
| `-N`, `--skip-column-names` | Don't write column names in results. See `--column-names`. |
| `-L`, `--skip-comments` | Discard comments. Set by default, see `--comments` to enable. |
| `-L`, `--skip-line-numbers` | Don't write line number for errors. See `--line-numbers`. |
| `-L`, `--skip-progress-reports` | Disables getting [progress reports](../progress-reporting/index) for long running commands. See `--progress-reports`. |
| `-L`, `--skip-reconnect` | Don't reconnect if the connection is lost. See `--reconnect`. |
| `-S`, `--socket=name` | For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use. |
| `--ssl` | Enables [TLS](../data-in-transit-encryption/index). TLS is also enabled even without setting this option when certain other TLS options are set. Starting with [MariaDB 10.2](../what-is-mariadb-102/index), the `--ssl` option will not enable [verifying the server certificate](../secure-connections-overview/index#server-certificate-verification) by default. In order to verify the server certificate, the user must specify the `--ssl-verify-server-cert` option. Set by default from [MariaDB 10.10](../what-is-mariadb-1010/index). |
| `--ssl-ca=name` | Defines a path to a PEM file that should contain one or more X509 certificates for trusted Certificate Authorities (CAs) to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. See [Secure Connections Overview: Certificate Authorities (CAs)](../secure-connections-overview/index#certificate-authorities-cas) for more information. This option implies the `--ssl` option. |
| `--ssl-capath=name` | Defines a path to a directory that contains one or more PEM files that should each contain one X509 certificate for a trusted Certificate Authority (CA) to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. The directory specified by this option needs to be run through the `[openssl rehash](https://www.openssl.org/docs/man1.1.1/man1/rehash.html)` command. See [Secure Connections Overview: Certificate Authorities (CAs)](../secure-connections-overview/index#certificate-authorities-cas) for more information. This option is only supported if the client was built with OpenSSL or yaSSL. If the client was built with GnuTLS or Schannel, then this option is not supported. See [TLS and Cryptography Libraries Used by MariaDB](../tls-and-cryptography-libraries-used-by-mariadb/index) for more information about which libraries are used on which platforms. This option implies the `--ssl` option. |
| `--ssl-cert=name` | Defines a path to the X509 certificate file to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. This option implies the `--ssl` option. |
| `--ssl-cipher=name` | List of permitted ciphers or cipher suites to use for [TLS](../data-in-transit-encryption/index). This option implies the `--ssl` option. |
| `--ssl-crl=name` | Defines a path to a PEM file that should contain one or more revoked X509 certificates to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. See [Secure Connections Overview: Certificate Revocation Lists (CRLs)](../secure-connections-overview/index#certificate-revocation-lists-crls) for more information. This option is only supported if the client was built with OpenSSL or Schannel. If the client was built with yaSSL or GnuTLS, then this option is not supported. See [TLS and Cryptography Libraries Used by MariaDB](../tls-and-cryptography-libraries-used-by-mariadb/index) for more information about which libraries are used on which platforms. |
| `--ssl-crlpath=name` | Defines a path to a directory that contains one or more PEM files that should each contain one revoked X509 certificate to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. The directory specified by this option needs to be run through the `[openssl rehash](https://www.openssl.org/docs/man1.1.1/man1/rehash.html)` command. See [Secure Connections Overview: Certificate Revocation Lists (CRLs)](../secure-connections-overview/index#certificate-revocation-lists-crls) for more information. This option is only supported if the client was built with OpenSSL. If the client was built with yaSSL, GnuTLS, or Schannel, then this option is not supported. See [TLS and Cryptography Libraries Used by MariaDB](../tls-and-cryptography-libraries-used-by-mariadb/index) for more information about which libraries are used on which platforms. |
| `--ssl-key=name` | Defines a path to a private key file to use for [TLS](../data-in-transit-encryption/index). This option requires that you use the absolute path, not a relative path. This option implies the `--ssl` option. |
| `--ssl-verify-server-cert` | Enables [server certificate verification](../secure-connections-overview/index#server-certificate-verification). This option is disabled by default. |
| `-t`, `--table` | Display output in table format. This is the default for interactive use, but can be used to produce table output in batch mode. |
| `--tee=name` | Append everything into outfile. See interactive help (\h) also. Does not work in batch mode. Disable with `--disable-tee`. This option is disabled by default. |
| `--tls-version=name` | This option accepts a comma-separated list of TLS protocol versions. A TLS protocol version will only be enabled if it is present in this list. All other TLS protocol versions will not be permitted. See [Secure Connections Overview: TLS Protocol Versions](../secure-connections-overview/index#tls-protocol-versions) for more information. This option was added in [MariaDB 10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/). |
| `-n`, `--unbuffered` | Flush buffer after each query. |
| `-u`, `--user=name` | User for login if not current user. |
| `-v`, `--verbose` | Write more. (-v -v -v gives the table output format). |
| `-V`, `--version` | Output version information and exit. |
| `-E`, `--vertical` | Print the output of a query (rows) vertically. Use the `\G` delimiter to apply to a particular statement if this option is not enabled. |
| `-w`, `--wait` | If the connection cannot be established, wait and retry instead of aborting. |
| `-X`, `--xml` | Produce XML output. See the [mysqldump --xml option](../mysqldump/index#null-null-and-empty-values-in-xml) for more. |
### Option Files
In addition to reading options from the command-line, `mysql` can also read options from [option files](../configuring-mariadb-with-option-files/index). If an unknown option is provided to `mysql` in an option file, then it is ignored.
The following options relate to how MariaDB command-line tools handles option files. They must be given as the first argument on the command-line:
| Option | Description |
| --- | --- |
| `--print-defaults` | Print the program argument list and exit. |
| `--no-defaults` | Don't read default options from any option file. |
| `--defaults-file=#` | Only read default options from the given file #. |
| `--defaults-extra-file=#` | Read this file after the global files are read. |
| `--defaults-group-suffix=#` | In addition to the default option groups, also read option groups with this suffix. |
In [MariaDB 10.2](../what-is-mariadb-102/index) and later, `mysql` is linked with [MariaDB Connector/C](../about-mariadb-connector-c/index). However, MariaDB Connector/C does not yet handle the parsing of option files for this client. That is still performed by the server option file parsing code. See [MDEV-19035](https://jira.mariadb.org/browse/MDEV-19035) for more information.
#### Option Groups
`mysql` reads options from the following [option groups](../configuring-mariadb-with-option-files/index#option-groups) from [option files](../configuring-mariadb-with-option-files/index):
| Group | Description |
| --- | --- |
| `[mysql]` | Options read by `mysql`, which includes both MariaDB Server and MySQL Server. |
| `[mariadb-client]` | Options read by `mysql`. Available starting with [MariaDB 10.4.6](https://mariadb.com/kb/en/mariadb-1046-release-notes/). |
| `[client]` | Options read by all MariaDB and MySQL [client programs](../clients-utilities/index), which includes both MariaDB and MySQL clients. For example, `mysqldump`. |
| `[client-server]` | Options read by all MariaDB [client programs](../clients-utilities/index) and the MariaDB Server. This is useful for options like socket and port, which is common between the server and the clients. |
| `[client-mariadb]` | Options read by all MariaDB [client programs](../clients-utilities/index). |
How to Specify Which Protocol to Use When Connecting to the mysqld Server
-------------------------------------------------------------------------
You can force which protocol to be used to connect to the `mysqld` server by giving the `protocol` option one of the following values: `tcp`, `socket`, `pipe` or `memory`.
If `protocol` is not specified, before [MariaDB 10.6.1](https://mariadb.com/kb/en/mariadb-1061-release-notes/), command line connection properties that do not force protocol are ignored.
From [MariaDB 10.6.1](https://mariadb.com/kb/en/mariadb-1061-release-notes/), a connection property specified via the command line (e.g. `--port=3306`) will force its type. The protocol that matches the respective connection property is used, e.g. a TCP/IP connection is created when `--port` is specified.
If multiple or no connection properties are specified via the command-line, then the following happens:
### Linux/Unix
* If `hostname` is not specified or `hostname` is `localhost`, then Unix sockets are used.
* In other cases (`hostname` is given and it's not `localhost`) then a TCP/IP connection through the `port` option is used.
Note that `localhost` is a special value. Using 127.0.0.1 is not the same thing. The latter will connect to the mysqld server through TCP/IP.
### Windows
* If `shared-memory-base-name` is specified and `hostname` is not specified or `hostname` is `localhost`, then the connection will happen through shared memory.
* If `shared-memory-base-name` is not specified and `hostname` is not specified or `hostname` is `localhost`, then the connection will happen through windows named pipes.
* Named pipes will also be used if the `libmysql` / `libmariadb` client library detects that the client doesn't support TCP/IP.
* In other cases then a TCP/IP connection through the `port` option is used.
How to Test Which Protocol is Used
----------------------------------
The `status` command shows you information about which protocol is used:
```
shell> mysql test
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 10
Server version: 10.2.2-MariaDB-valgrind-max-debug Source distribution
Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [test]> status;
--------------
mysql Ver 15.1 Distrib 10.0.25-MariaDB, for Linux (x86_64) using readline 5.2
Connection id: 10
Current database: test
Current user: monty@localhost
...
Connection: Localhost via UNIX socket
...
UNIX socket: /tmp/mysql-dbug.sock
```
mysql Commands
--------------
There are also a number of commands that can be run inside the client. Note that all text commands must be first on line and end with ';'
| Command | Description |
| --- | --- |
| `?`, `\?` | Synonym for `help'. |
| `clear`, `\c` | Clear the current input statement. |
| `connect`, `\r` | Reconnect to the server. Optional arguments are db and host. |
| `delimiter`, `\d` | Set statement delimiter. |
| `edit`, `\e` | Edit command with $EDITOR. |
| `ego`, `\G` | Send command to mysql server, display result vertically. |
| `exit`, `\q` | Exit mysql. Same as quit. |
| `go`, `\g` | Send command to mysql server. |
| `help`, `\h` | Display this help. |
| `nopager`, `\n` | Disable pager, print to stdout. |
| `notee`, `\t` | Don't write into outfile. |
| `pager`, `\P` | Set PAGER [to\_pager]. Print the query results via PAGER. |
| `print`, `\p` | Print current command. |
| `prompt`, `\R` | Change your mysql prompt. See [prompt command](#prompt-command) for options. |
| `quit`, `\q` | Quit mysql. |
| `rehash`, `\#` | Rebuild completion hash. |
| `source`, `\.` | Execute an SQL script file. Takes a file name as an argument. |
| `status`, `\s` | Get status information from the server. |
| `system`, `\!` | Execute a system shell command. Only works in Unix-like systems. |
| `tee`, `\T` | Set outfile [to\_outfile]. Append everything into given outfile. |
| `use`, `\u` | Use another database. Takes database name as argument. |
| `charset`, `\C` | Switch to another charset. Might be needed for processing binlog with multi-byte charsets. |
| `warnings`, `\W` | Show warnings after every statement. |
| `nowarning`, `\w` | Don't show warnings after every statement. |
The mysql\_history File
-----------------------
On Unix, the mysql client writes a record of executed statements to a history file. By default, this file is named `.mysql_history` and is created in your home directory. To specify a different file, set the value of the MYSQL\_HISTFILE environment variable.
The .mysql\_history file should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords.
If you do not want to maintain a history file, first remove .mysql\_history if it exists, and then use either of the following techniques:
* Set the MYSQL\_HISTFILE variable to /dev/null. To cause this setting to take effect each time you log in, put the setting in one of your shell's startup files.
* Create .mysql\_history as a symbolic link to /dev/null:
```
shell> ln -s /dev/null $HOME/.mysql_history
```
You need do this only once.
prompt Command
--------------
The prompt command reconfigures the default prompt `\N [\d]>`. The string for defining the prompt can contain the following special sequences.
| Option | Description |
| --- | --- |
| `\c` | A counter that increments for each statement you issue. |
| `\D` | The full current date. |
| `\d` | The default database. |
| `\h` | The server host. |
| `\l` | The current delimiter. |
| `\m` | Minutes of the current time. |
| `\n` | A newline character. |
| `\O` | The current month in three-letter format (Jan, Feb, ...). |
| `\o` | The current month in numeric format. |
| `\P` | am/pm. |
| `\p` | The current TCP/IP port or socket file. |
| `\R` | The current time, in 24-hour military time (0–23). |
| `\r` | The current time, standard 12-hour time (1–12). |
| `\S` | Semicolon. |
| `\s` | Seconds of the current time. |
| `\t` | A tab character. |
| `\U` | Your full user\_name@host\_name account name. |
| `\u` | Your user name. |
| `\v` | The server version. |
| `\w` | The current day of the week in three-letter format (Mon, Tue, ...). |
| `\Y` | The current year, four digits. |
| `\y` | The current year, two digits. |
| `\_` | A space. |
| `\` | A space (a space follows the backslash). |
| `\'` | Single quote. |
| `\"` | Double quote. |
| `\ \` | A literal “\” backslash character. |
| `\x` | x, for any “x” not listed above. |
mysql Tips
----------
This section describes some techniques that can help you use `**mysql**` more effectively.
### Displaying Query Results Vertically
Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output:
```
mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G
*************************** 1. row ***************************
msg_nro: 3068
date: 2000-03-01 23:29:50
time_zone: +0200
mail_from: Monty
reply: [email protected]
mail_to: "Thimble Smith" <[email protected]>
sbj: UTF-8
txt: >>>>> "Thimble" == Thimble Smith writes:
Thimble> Hi. I think this is a good idea. Is anyone familiar
Thimble> with UTF-8 or Unicode? Otherwise, I´ll put this on my
Thimble> TODO list and see what happens.
Yes, please do that.
Regards,
Monty
file: inbox-jani-1
hash: 190402944
1 row in set (0.09 sec)
```
### Using the --safe-updates Option
For beginners, a useful startup option is `--safe-updates` (or `--i-am-a-dummy`, which has the same effect). It is helpful for cases when you might have issued a `DELETE FROM tbl_name` statement but forgotten the `WHERE` clause. Normally, such a statement deletes all rows from the table. With `--safe-updates`, you can delete rows only by specifying the key values that identify them. This helps prevent accidents.
When you use the `--safe-updates` option, mysql issues the following statement when it connects to the MariaDB server:
```
SET sql_safe_updates=1, sql_select_limit=1000, sql_max_join_size=1000000;
```
The [SET](../set/index) statement has the following effects:
* You are not allowed to execute an [UPDATE](../update/index) or [DELETE](../delete/index) statement unless you specify a key constraint in the WHERE clause or provide a LIMIT clause (or both). For example:
```
UPDATE tbl_name SET not_key_column=val WHERE key_column=val;
UPDATE tbl_name SET not_key_column=val LIMIT 1;
```
* The server limits all large`SELECT` results to 1,000 rows unless the statement includes a `LIMIT` clause.
* The server aborts multiple-table `SELECT` statements that probably need to examine more than 1,000,000 row combinations.
To specify limits different from 1,000 and 1,000,000, you can override the defaults by using the `--select_limit` and `--max_join_size` options:
```
mysql --safe-updates --select_limit=500 --max_join_size=10000
```
### Disabling mysql Auto-Reconnect
If the mysql client loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even if mysql succeeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it:
```
mysql> SET @a=1;
Query OK, 0 rows affected (0.05 sec)
mysql> INSERT INTO t VALUES(@a);
ERROR 2006: MySQL server has gone away
No connection. Trying to reconnect...
Connection id: 1
Current database: test
Query OK, 1 row affected (1.30 sec)
mysql> SELECT * FROM t;
+------+
| a |
+------+
| NULL |
+------+
```
The @a user variable has been lost with the connection, and after the reconnection it is undefined. If it is important to have mysql terminate with an error if the connection has been lost, you can start the mysql client with the `--skip-reconnect` option.
See Also
--------
* [Troubleshooting Connection Issues](../troubleshooting-connection-issues/index)
* [Readline commands and configuration](https://docs.freebsd.org/info/readline/readline.pdf)
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb MBRWithin MBRWithin
=========
Syntax
------
```
MBRWithin(g1,g2)
```
Description
-----------
Returns 1 or 0 to indicate whether the Minimum Bounding Rectangle of g1 is within the Minimum Bounding Rectangle of g2. This tests the opposite relationship as [MBRContains()](../mbrcontains/index).
Examples
--------
```
SET @g1 = GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))');
SET @g2 = GeomFromText('Polygon((0 0,0 5,5 5,5 0,0 0))');
SELECT MBRWithin(@g1,@g2), MBRWithin(@g2,@g1);
+--------------------+--------------------+
| MBRWithin(@g1,@g2) | MBRWithin(@g2,@g1) |
+--------------------+--------------------+
| 1 | 0 |
+--------------------+--------------------+
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb Installing MariaDB ColumnStore from the MariaDB Download Installing MariaDB ColumnStore from the MariaDB Download
========================================================
Introduction
============
MariaDB ColumnStore packages can be downloaded from the [MariaDB Downloads](https://mariadb.com/downloads/#mariadb-platform-mariadb_columnstore)
MariaDB ColumnStore packages:
* MariaDB ColumnStore Platform
* MariaDB ColumnStore API (Bulk Write SDK)
* MariaDB ColumnStore Data-Adapters
+ MaxScale kafka
+ Kafka Avro
+ Kettle bulk exporter plugin
+ Maxscale CDC
* MariaDB ColumnStore Tools
* MariaDB Maxscale
* MariaDB Connectors
+ MariaDB Maxscale CDC Connector
+ MariaDB ODBC Connector
+ MariaDB Java-client Connector jar file
NOTE: Centos 6 and Suse 12 doesn't contain all of the above packages. Some features arent supported for those 2 OSs.
You can install MariaDB ColumnStore packages for Single-Server installs and for Multi-Server installs. For Multi-Server systems, the Downloaded package will need to be installed on all servers in the ColumnStore deployment.
Before install, make sure you go through the preparation guide to complete the system setup before installs the packages
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/](../library/preparing-for-columnstore-installation-11x/index)
NOTE: the Release is shown as x.x.x-x. replace that will the matching version that is downloaded. Example 1.1.3-1.
Centos 6
========
Centos 6 RPM package
--------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-centos6.x86_64.rpm.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore/
+ mariadb-columnstore-1.1.3-1-centos6.x86\_64.rpm.tar.gz
* MariaDB-ColumnStore-Tools/
+ mariadb-columnstore-tools-1.1.3-1.rpm
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-rhel6-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.centos.6.x86\_64.rpm
+ maxscale-cdc-connector-2.2.2-1.centos.6.x86\_64.rpm
Centos 6 RPM package installation
---------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore RPMs
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Centos 6 Binary Package
-----------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-centos6.x86_64.bin.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore/
+ mariadb-columnstore-1.1.3-1-centos6.x86\_64.bin.tar.gz
* MariaDB-ColumnStore-Tools/
+ mariadb-columnstore-tools-1.1.3-1.bin.tar.gz
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-rhel6-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.centos.6.tar.gz
+ maxscale-cdc-connector-2.2.2-1.centos.6.x86\_64.rpm
Centos 6 Binary Package installation
------------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore binary package
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Centos 7
========
Centos 7 RPM package
--------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-centos7.x86_64.rpm.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore/
+ mariadb-columnstore-1.1.3-1-centos7.x86\_64.rpm.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64-centos7.rpm
* MariaDB-ColumnStore-Tools/
+ mariadb-columnstore-tools-1.1.3-1.rpm
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-rhel7-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters/
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-centos7.rpm
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-centos7.rpm
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.centos.7.x86\_64.rpm
+ maxscale-cdc-connector-2.2.2-1.centos.7.x86\_64.rpm
Centos 7 RPM package installation
---------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore RPMs
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API RPM
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Centos 7 Binary Package
-----------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-centos7.x86_64.bin.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore/
+ mariadb-columnstore-1.1.3-1-centos7.x86\_64.bin.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64-centos7.rpm
* MariaDB-ColumnStore-Tools/
+ mariadb-columnstore-tools-1.1.3-1.bin.tar.gz
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-rhel7-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters/
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-centos7.rpm
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-centos7.rpm
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.centos.7.tar.gz
+ maxscale-cdc-connector-2.2.2-1.centos.7.x86\_64.rpm
Centos 7 Binary Package installation
------------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore binary package
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API RPM
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Suse 12
=======
Suse 12 RPM package
-------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-sles12.x86_64.rpm.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore/
+ mariadb-columnstore-1.1.3-1-sles12.x86\_64.rpm.tar.gz
* MariaDB-ColumnStore-Tools/
+ mariadb-columnstore-tools-1.1.3-1.rpm
* MariaDB-Connectors/
+ mariadb-java-client-2.2.2.jar
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.sles/12.x86\_64.rpm
+ maxscale-cdc-connector-2.2.2-1.sles.12.x86\_64.rpm
Suse 12 RPM package installation
--------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore RPMs
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Suse 12 Binary Package
----------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-sles12.x86_64.bin.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-sles12.x86\_64.bin.tar.gz
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.bin.tar.gz
* MariaDB-Connectors/
+ mariadb-java-client-2.2.2.jar
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.sles.12.tar.gz
+ maxscale-cdc-connector-2.2.2-1.sles.12.x86\_64.rpm
Suse 12 Binary Package installation
-----------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore binary package
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Debian 8 (jessie)
=================
Debian 8 DEB package
--------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-1.1.3-1-jessie.amd64.deb.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-jessie.amd64.rpm.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64.jessie.deb
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.amd64.deb
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-debian-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters/
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-jessie.deb
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-jessie.deb
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.debian.jessie.x86\_64.deb
+ maxscale-cdc-connector-2.2.2-1.debian.jessie.x86\_64.deb
Debian 8 DEB package installation
---------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore DEBs
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API DEB
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Debian 8 Binary Package
-----------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-jessie.x86_64.bin.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-jessie.amd64.bin.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64-jessie.deb
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.tar.gz
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-debian-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters/
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-jessie.deb
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-jessie.deb
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.debian.jessie.tar.gz
+ maxscale-cdc-connector-2.2.2-1.debian.jessie.x86\_64.deb
Debian 8 Binary Package installation
------------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore binary package
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API RPM
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Debian 9 (stretch)
==================
Debian 9 DEB package
--------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-1.1.3-1-stretch.amd64.deb.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-stretch.amd64.rpm.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64.stretch.deb
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.amd64.deb
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-debian-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters/
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-stretch.deb
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-stretch.deb
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.debian.stretch.x86\_64.deb
+ maxscale-cdc-connector-2.2.2-1.debian.stretch.x86\_64.deb
Debian 9 DEB package installation
---------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore DEBs
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API DEB
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Debian 9 Binary Package
-----------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-stretch.x86_64.bin.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-stretch.amd64.bin.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64-stretch.deb
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.tar.gz
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-debian-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters/
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-stretch.deb
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-stretch.deb
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.debian.stretch.tar.gz
+ maxscale-cdc-connector-2.2.2-1.debian.stretch.x86\_64.deb
Debian 9 Binary Package installation
------------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore binary package
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API RPM
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Ubuntu 16 (xenial)
==================
Ubuntu 16 DEB package
---------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-1.1.3-1-xenial.amd64.deb.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-xenial.amd64.rpm.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64.xenial.deb
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.amd64.deb
* MariaDB-Connectors/
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-debian-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters/
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-xenial.deb
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-xenial.deb
* MariaDB-MaxScale/
+ maxscale-2.2.2-1.debian.xenial.x86\_64.deb
+ maxscale-cdc-connector-2.2.2-1.debian.xenial.x86\_64.deb
Ubuntu 16 DEB package installation
----------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore DEBs
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API DEB
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Ubuntu 16 Binary Package
------------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-xenial.adm64.bin.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-xenial.amd64.bin.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64-xenial.deb
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.tar.gz
* MariaDB-Connectors
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-debian-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-xenial.deb
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-xenial.deb
* MariaDB-MaxScale
+ maxscale-2.2.2-1.debian.xenial.tar.gz
+ maxscale-cdc-connector-2.2.2-1.debian.xenial.x86\_64.deb
Ubuntu 16 Binary Package installation
-------------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore binary package
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API RPM
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Ubuntu 18 (bionic)
==================
Ubuntu 18 DEB package
---------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-1.1.3-1-bionic.amd64.deb.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-bionic.amd64.rpm.tar.gz
* MariaDB-ColumnStore-API
+ mariadb-columnstore-api-1.1.3-1-x86\_64.bionic.deb
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.amd64.deb
* MariaDB-Connectors
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-debian-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-bionic.deb
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-bionic.deb
* MariaDB-MaxScale
+ maxscale-2.2.2-1.debian.bionic.x86\_64.deb
+ maxscale-cdc-connector-2.2.2-1.debian.bionic.x86\_64.deb
Ubuntu 18 DEB package installation
----------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore DEBs
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API DEB
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Ubuntu 18 Binary Package
------------------------
Once the package is downloaded, it can be untarred with the following command:
```
tar zxvf mariadb-columnstore-x.x.x-x-bionic.adm64.bin.tar.gz
```
This is the contents of the installed package:
* MariaDB-ColumnStore
+ mariadb-columnstore-1.1.3-1-bionic.amd64.bin.tar.gz
* MariaDB-ColumnStore-API/
+ mariadb-columnstore-api-1.1.3-1-x86\_64-bionic.deb
* MariaDB-ColumnStore-Tools
+ mariadb-columnstore-tools-1.1.3-1.tar.gz
* MariaDB-Connectors
+ mariadb-connector-[ODBC-3](https://jira.mariadb.org/browse/ODBC-3).0.2-ga-debian-i686.tar.gz
+ mariadb-java-client-2.2.2.jar
* MariaDB-Data-Adapters
+ mariadb-columnstore-kafka-adapters-1.1.3-1-x86\_64-bionic.deb
+ mariadb-columnstore-maxscale-cdc-adapters-1.1.3-1-x86\_64-bionic.deb
* MariaDB-MaxScale
+ maxscale-2.2.2-1.debian.bionic.tar.gz
+ maxscale-cdc-connector-2.2.2-1.debian.bionic.x86\_64.deb
Ubuntu 18 Binary Package installation
-------------------------------------
### MariaDB ColumnStore
Follow the instructions for installing MariaDB Columnstore binary package
[https://mariadb.com/kb/en/library/preparing-for-columnstore-installation-11x/#choosing-the-type-of-initial-downloadinstall](../library/preparing-for-columnstore-installation-11x/index#choosing-the-type-of-initial-downloadinstall)
### MariaDB ColumnStore API (Bulk Write SDK)
Follow the instructions for installing MariaDB Columnstore API RPM
[https://mariadb.com/kb/en/library/columnstore-bulk-write-sdk/](../library/columnstore-bulk-write-sdk/index)
### MariaDB ColumnStore Tools
Follow the instructions for installing MariaDB Columnstore Tools
[https://mariadb.com/kb/en/library/backup-and-restore-for-mariadb-columnstore-110-onwards/](../library/backup-and-restore-for-mariadb-columnstore-110-onwards/index)
### MariaDB ColumnStore Connectors
#### ODBC Connector
How to Install the ODBC Connector:
[https://mariadb.com/kb/en/library/about-mariadb-connector-odbc/](../library/about-mariadb-connector-odbc/index)
Additional Information on the ODBC connector:
[https://mariadb.com/kb/en/library/mariadb-connector-odbc/](../library/mariadb-connector-odbc/index)
#### Java Connector
How to Install the Java Connector:
[https://mariadb.com/kb/en/library/getting-started-with-the-java-connector/](../library/getting-started-with-the-java-connector/index)
Additional information on the Java Connector:
[https://mariadb.com/kb/en/library/mariadb-connector-j/](../library/mariadb-connector-j/index)
### MariaDB ColumnStore Data Adapters
How to Install on the Data Adapters:
[https://mariadb.com/kb/en/library/columnstore-streaming-data-adapters/](../library/columnstore-streaming-data-adapters/index)
### MariaDB MaxScale
How to Install on the MariaDB MaxScale:
[https://mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/](../mariadb-enterprise/mariadb-maxscale-22-installing-mariadb-maxscale-using-a-tarball/index)
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
| programming_docs |
mariadb LevelDB Storage Engine MS2 LevelDB Storage Engine MS2
==========================
Remove the need for a second database
-------------------------------------
MS1 code needs to use two databases, because
* `leveldb` database uses type-aware key comparison. This means, one must have knowledge about types of values in indexes before the database can be opened.
* `leveldb-ddl` stores information about
+ datatypes used by various indexes.
+ Mapping from `dbname.tablename.index_no` to `index_number`.
The database itself uses default key comparison function, so one can open it without any knowledge.
It is possible to switch to having one database, if the keys can use the default key comparison function, memcmp(). The database will store
* table/index data
* Mapping from `dbname.tablename.index_no` to `index_number`.
It seems, it is possible to convert MySQL field values into values comparable with memcmp() by using Field::make\_sort\_key() function.
### Index-only scans
Index-only scans require that it is possible to restore key value from its memcmp()'able form.
In general, it is not possible. For some particular datatypes, it is possible. We want to target the following types:
* `INT`, `BIGINT`, `TINYINT`, and their `UNSIGNED` variants (i.e., all INT-based types)
* `CHAR(n) COLLATE latin1_bin`, `VARCHAR(n) COLLATE latin1_bin`, possibly support `utf8_bin`.
#### INT-based types
For INT-based types, mem-comparable form is the integer stored in most-significant-bytes-first order. For SIGNED types, one needs to make negative values precede positive ones (memcmp() assumes all bytes are unsigned). This can be achieved by adding MAX\_VALUE/2 to the number.
It is apparent that one can restore integer values back from their mem-comparable form.
#### String-based types
For string-based types, getting the value back from its mem-comparable form is harder.
##### Problem#1: case-insensitivity
For case-insensitive collations, conversion to mem-comparable form is, roughly speaking, conversion of all characters to upper case (it's actually more complex, but that's the idea)
For example, for column='foo' and column='FOO' the mem-comparable form is 'FOO', and there is no way to get the original case back.
##### Problem#2: VARCHAR and end-spaces
Consider a [VAR]CHAR(n) type. The mem-comparable form must have the same length for all values. If some values have different length, we won't be able to support multi-part keys.
In MySQL charset functions, mem-comparable form does have a fixed length. Fixed length is achieved by end-padding the value with spaces (more precisely, with mem-comparable images of spaces). This raises a question of, how do we get rid of these spaces when we're decoding the value back?
For `CHAR(n)` fields, the problem doesn't exist, because MySQL strips all trailing spaces:
```
create table t10 (a char(10) primary key);
insert into t10 values ('abc ');
select a, length(a) from t10;
+-----+-----------+
| a | length(a) |
+-----+-----------+
| abc | 3 |
+-----+-----------+
```
(@@sql\_mode has a PAD\_CHAR\_TO\_FULL\_LENGTH flag which will make MySQL to pad strings with as many spaces as possible instead of stripping. But either way, we don't have to care about how many end-spaces are in a CHAR(n) value).
For VARCHAR fields, end-spaces are not removed:
```
create table t11 (a varchar(10) primary key);
insert into t11 values ('abc ');
select a, length(a) from t11;
+--------+-----------+
| a | length(a) |
+--------+-----------+
| abc | 6 |
+--------+-----------+
```
When we try to decode a string from its mem-comparable form, we will not know how many end-spaces were in the original value. We need to store the length somewhere.
##### Solution for case-insensitivity
We will avoid the problem of upper-casing by supporting index-only reads when used collations do not map two different characters to the same mem-comparable value. The following collations are ok:
* `BINARY` - characters are not transformed
* `latin1_bin` - characters are not transformed
* `utf8_bin` - characters are transformed into 2-byte images with `my_utf8_uni()` and can be restored with `my_uni_utf8()`. The functions are stored in `cs->cset->mb_wc` and `cs->cset->wc_mb`.
* `utf8mb4_bin` - characters are transformed into 3-byte images with `my_mb_wc_utf8mb4()` and can be restored with `my_wc_mb_utf8mb4()`
##### Solution for end-spaces
We need to store the original length of the value somewhere. There is no way we could put it into a mem-comparable form. If we put it there, we would have
```
memcmp(mem_comparable('abc'), mem_comparable('abc '), len) != 0
```
which would make equal values be compared as non equal.
The solution is: don't store length in leveldb key.
* For PRIMARY KEY, length is stored in leveldb's Value (we have entire table->record[0] there, with special encoding for blobs).
* For secondary indexes, we will store length in the leveldb's Value (which is currently empty).
Fix CANT-SEE-OWN-CHANGES
------------------------
The property is described at [leveldb-storage-engine-ms1](../leveldb-storage-engine-ms1/index) page. A solution is also described there:
After MS1, LevelDB SE will make sure that CANT-SEE-OWN changes is not observed. It will use the following approach:
* keep track of what records have been modified by this transaction in a buffer $R.
* If SQL layer makes a request to read a row, then
+ Consult $R if the record was INSERTed. If yes, return what was inserted.
+ Consult $R if the record was modified. if yes, return what was recorded as the result of modification
+ Consult $R if the record was deleted. If yes, return "record not found".
+ Finally, try reading the row from the LevelDB.
Note: this allows us to keep only the last update if the transaction has made multiple updates in the same row. (as long as we didn't use to store both transaction and statement's changes together. In that case, we need to keep both transaction's and statement's changes)
More test coverage
------------------
Adopt a storage-engine-independent testsuite to be used together with leveldb.
Statement rollback inside a transaction
---------------------------------------
A truly transactional MySQL engine needs to support two kinds of rollback
1. Rollback a statement
2. Rollback a transaction
If a statement fails inside a transaction, the engine will need to rollback the statement, but not the transaction. Currently, leveldb SE is unable to do so, because transaction's changes and statement's changes are stored in a single `leveldb::WriteBatch` object.
The solution will be to keep transaction's changes and statement's changes separate, and put statement's changes into transaction's changes on statement end.
Another way: when we maintain a hashtable of changes, remember query\_id of every change. If we need to roll back a statement, go through the changes and remove those that have query\_id equal to the last query (TODO: is statement the same as query here, or not?)
Fix the build process
---------------------
[MDEV-4154](https://jira.mariadb.org/browse/MDEV-4154): Currently, leveldb SE hardcodes paths to leveldb library. Lift this limitation.
@@leveldb\_max\_row\_locks
--------------------------
Transaction locks are held in memory. Hence, there is an idea: prevent transactions from getting too big - have a variable that explicitly limits how many locks a transaction can take. (there was a similar variable in BDB storage engine). If a transaction attempts to take more locks than allowed, an error will be returned.
Tasks
-----
### Remove the need for a second database
* Store mem-comparable values as keys (no index-only support)
* Switch rowlock table to use the same hash value?
### Index-only scans
* Analyze index definition and set HA\_KEYREAD\_ONLY only when appropriate
* Unpack functions for integer columns
* Unpack function for CHAR(n)
* Storage an unpack for VARCHAR(n)
### Fix CANT-SEE-OWN-CHANGES
* Maintain a hash table of changes made by the transaction
* Have read functions consult the hashtable before reading actual data
### Statement rollback inside a transaction
* Maintain transaction's changes and last statement's changes separately.
+ Roll back the right set of changes on statement/transaction abort.
### More test coverage
* Adopt the engine-independent testsuite to be used with leveldb
Misc
----
* (from skype discussion)\_Currently max. auto\_increment value is loaded every time a TABLE is opened. Make it to be loaded only when TABLE\_SHARE is opened.
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb MariaDB Developer Meeting - Athens MariaDB Developer Meeting - Athens
===================================
11-13 Nov 2011 - Notes and Plans from the Athens Developer meeting.
| Title | Description |
| --- | --- |
| [MariaDB Developer Meeting - Athens - Friday, 11 Nov 2011](../mariadb-developer-meeting-athens-friday-11-nov-2011/index) | Agenda and notes from day 1 of the MariaDB Developer Meeting in Athens, Gre... |
| [MariaDB Developer Meeting - Athens - Saturday, 12 Nov 2011](../mariadb-developer-meeting-athens-saturday-12-nov-2011/index) | Agenda and notes from day 2 of the MariaDB Developer Meeting in Athens, Gre... |
| [MariaDB Developer Meeting - Athens - Sunday, 13 Nov 2011](../mariadb-developer-meeting-athens-sunday-13-nov-2011/index) | Agenda and notes from day 3 of the MariaDB Developer Meeting in Athens, Gre... |
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
mariadb MAKETIME MAKETIME
========
Syntax
------
```
MAKETIME(hour,minute,second)
```
Description
-----------
Returns a time value calculated from the `hour`, `minute`, and `second` arguments.
If `minute` or `second` are out of the range 0 to 60, NULL is returned. The `hour` can be in the range -838 to 838, outside of which the value is truncated with a warning.
Examples
--------
```
SELECT MAKETIME(13,57,33);
+--------------------+
| MAKETIME(13,57,33) |
+--------------------+
| 13:57:33 |
+--------------------+
SELECT MAKETIME(-13,57,33);
+---------------------+
| MAKETIME(-13,57,33) |
+---------------------+
| -13:57:33 |
+---------------------+
SELECT MAKETIME(13,67,33);
+--------------------+
| MAKETIME(13,67,33) |
+--------------------+
| NULL |
+--------------------+
SELECT MAKETIME(-1000,57,33);
+-----------------------+
| MAKETIME(-1000,57,33) |
+-----------------------+
| -838:59:59 |
+-----------------------+
1 row in set, 1 warning (0.00 sec)
SHOW WARNINGS;
+---------+------+-----------------------------------------------+
| Level | Code | Message |
+---------+------+-----------------------------------------------+
| Warning | 1292 | Truncated incorrect time value: '-1000:57:33' |
+---------+------+-----------------------------------------------+
```
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.
esbuild esbuild esbuild
=======
> An extremely fast bundler for the web
Above: the time to do a production bundle of 10 copies of the [three.js](https://github.com/mrdoob/three.js) library from scratch using default settings, including minification and source maps. More info [here](faq/index#benchmark-details).Our current build tools for the web are 10-100x slower than they could be. The main goal of the esbuild bundler project is to bring about a new era of build tool performance, and create an easy-to-use modern bundler along the way.
Major features:
* Extreme speed without needing a cache
* [JavaScript](content-types/index#javascript), [CSS](content-types/index#css), [TypeScript](content-types/index#typescript), and [JSX](content-types/index#jsx) built-in
* A straightforward [API](api/index) for CLI, JS, and Go
* Bundles ESM and CommonJS modules
* Tree shaking, [minification](api/index#minify), and [source maps](api/index#sourcemap)
* [Local server](api/index#serve), [watch mode](api/index#watch), and [plugins](plugins/index)
Check out the [getting started](getting-started/index) instructions if you want to give esbuild a try.
esbuild Plugins Plugins
=======
The plugin API allows you to inject code into various parts of the build process. Unlike the rest of the API, it's not available from the command line. You must write either JavaScript or Go code to use the plugin API. Plugins can also only be used with the [build](../api/index#build) API, not with the [transform](../api/index#transform) API.
Finding plugins
---------------
If you're looking for an existing esbuild plugin, you should check out the [list of existing esbuild plugins](https://github.com/esbuild/community-plugins). Plugins on this list have been deliberately added by the author and are intended to be used by others in the esbuild community.
If you want to share your esbuild plugin, you should:
1. [Publish it to npm](https://docs.npmjs.com/creating-and-publishing-unscoped-public-packages) so others can install it.
2. Add it to the [list of existing esbuild plugins](https://github.com/esbuild/community-plugins) so others can find it.
Using plugins
-------------
An esbuild plugin is an object with a `name` and a `setup` function. They are passed in an array to the [build](../api/index#build) API call. The `setup` function is run once for each build API call.
Here's a simple plugin example that allows you to import the current environment variables at build time:
```
import * as esbuild from 'esbuild'
let envPlugin = {
name: 'env',
setup(build) {
// Intercept import paths called "env" so esbuild doesn't attempt
// to map them to a file system location. Tag them with the "env-ns"
// namespace to reserve them for this plugin.
build.onResolve({ filter: /^env$/ }, args => ({
path: args.path,
namespace: 'env-ns',
}))
// Load paths tagged with the "env-ns" namespace and behave as if
// they point to a JSON file containing the environment variables.
build.onLoad({ filter: /.*/, namespace: 'env-ns' }, () => ({
contents: JSON.stringify(process.env),
loader: 'json',
}))
},
}
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
plugins: [envPlugin],
})
```
```
package main
import "encoding/json"
import "os"
import "strings"
import "github.com/evanw/esbuild/pkg/api"
var envPlugin = api.Plugin{
Name: "env",
Setup: func(build api.PluginBuild) {
// Intercept import paths called "env" so esbuild doesn't attempt
// to map them to a file system location. Tag them with the "env-ns"
// namespace to reserve them for this plugin.
build.OnResolve(api.OnResolveOptions{Filter: `^env$`},
func(args api.OnResolveArgs) (api.OnResolveResult, error) {
return api.OnResolveResult{
Path: args.Path,
Namespace: "env-ns",
}, nil
})
// Load paths tagged with the "env-ns" namespace and behave as if
// they point to a JSON file containing the environment variables.
build.OnLoad(api.OnLoadOptions{Filter: `.*`, Namespace: "env-ns"},
func(args api.OnLoadArgs) (api.OnLoadResult, error) {
mappings := make(map[string]string)
for _, item := range os.Environ() {
if equals := strings.IndexByte(item, '='); equals != -1 {
mappings[item[:equals]] = item[equals+1:]
}
}
bytes, err := json.Marshal(mappings)
if err != nil {
return api.OnLoadResult{}, err
}
contents := string(bytes)
return api.OnLoadResult{
Contents: &contents,
Loader: api.LoaderJSON,
}, nil
})
},
}
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outfile: "out.js",
Plugins: []api.Plugin{envPlugin},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
You would use it like this:
```
import { PATH } from 'env'
console.log(`PATH is ${PATH}`)
```
Concepts
--------
Writing a plugin for esbuild works a little differently than writing a plugin for other bundlers. The concepts below are important to understand before developing your plugin:
### Namespaces
Every module has an associated namespace. By default esbuild operates in the `file` namespace, which corresponds to files on the file system. But esbuild can also handle "virtual" modules that don't have a corresponding location on the file system. One case when this happens is when a module is provided using [stdin](../api/index#stdin).
Plugins can be used to create virtual modules. Virtual modules usually use a namespace other than `file` to distinguish them from file system modules. Usually the namespace is specific to the plugin that created them. For example, the sample [HTTP plugin](#http-plugin) below uses the `http-url` namespace for downloaded files.
### Filters
Every callback must provide a regular expression as a filter. This is used by esbuild to skip calling the callback when the path doesn't match its filter, which is done for performance. Calling from esbuild's highly-parallel internals into single-threaded JavaScript code is expensive and should be avoided whenever possible for maximum speed.
You should try to use the filter regular expression instead of using JavaScript code for filtering whenever you can. This is faster because the regular expression is evaluated inside of esbuild without calling out to JavaScript at all. For example, the sample [HTTP plugin](#http-plugin) below uses a filter of `^https?://` to ensure that the performance overhead of running the plugin is only incurred for paths that start with `http://` or `https://`.
The allowed regular expression syntax is the syntax supported by Go's [regular expression engine](https://pkg.go.dev/regexp/). This is slightly different than JavaScript. Specifically, look-ahead, look-behind, and backreferences are not supported. Go's regular expression engine is designed to avoid the catastrophic exponential-time worst case performance issues that can affect JavaScript regular expressions.
Note that namespaces can also be used for filtering. Callbacks must provide a filter regular expression but can optionally also provide a namespace to further restrict what paths are matched. This can be useful for "remembering" where a virtual module came from. Keep in mind that namespaces are matched using an exact string equality test instead of a regular expression, so unlike module paths they are not intended for storing arbitrary data.
On-resolve callbacks
--------------------
A callback added using `onResolve` will be run on each import path in each module that esbuild builds. The callback can customize how esbuild does path resolution. For example, it can intercept import paths and redirect them somewhere else. It can also mark paths as external. Here is an example:
```
import * as esbuild from 'esbuild'
import path from 'node:path'
let exampleOnResolvePlugin = {
name: 'example',
setup(build) {
// Redirect all paths starting with "images/" to "./public/images/"
build.onResolve({ filter: /^images\// }, args => {
return { path: path.join(args.resolveDir, 'public', args.path) }
})
// Mark all paths starting with "http://" or "https://" as external
build.onResolve({ filter: /^https?:\/\// }, args => {
return { path: args.path, external: true }
})
},
}
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
plugins: [exampleOnResolvePlugin],
loader: { '.png': 'binary' },
})
```
```
package main
import "os"
import "path/filepath"
import "github.com/evanw/esbuild/pkg/api"
var exampleOnResolvePlugin = api.Plugin{
Name: "example",
Setup: func(build api.PluginBuild) {
// Redirect all paths starting with "images/" to "./public/images/"
build.OnResolve(api.OnResolveOptions{Filter: `^images/`},
func(args api.OnResolveArgs) (api.OnResolveResult, error) {
return api.OnResolveResult{
Path: filepath.Join(args.ResolveDir, "public", args.Path),
}, nil
})
// Mark all paths starting with "http://" or "https://" as external
build.OnResolve(api.OnResolveOptions{Filter: `^https?://`},
func(args api.OnResolveArgs) (api.OnResolveResult, error) {
return api.OnResolveResult{
Path: args.Path,
External: true,
}, nil
})
},
}
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outfile: "out.js",
Plugins: []api.Plugin{exampleOnResolvePlugin},
Write: true,
Loader: map[string]api.Loader{
".png": api.LoaderBinary,
},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
The callback can return without providing a path to pass on responsibility for path resolution to the next callback. For a given import path, all `onResolve` callbacks from all plugins will be run in the order they were registered until one takes responsibility for path resolution. If no callback returns a path, esbuild will run its default path resolution logic.
Keep in mind that many callbacks may be running concurrently. In JavaScript, if your callback does expensive work that can run on another thread such as `fs.existsSync()`, you should make the callback `async` and use `await` (in this case with `fs.promises.exists()`) to allow other code to run in the meantime. In Go, each callback may be run on a separate goroutine. Make sure you have appropriate synchronization in place if your plugin uses any shared data structures.
### On-resolve options
The `onResolve` API is meant to be called within the `setup` function and registers a callback to be triggered in certain situations. It takes a few options:
```
interface OnResolveOptions {
filter: RegExp;
namespace?: string;
}
```
```
type OnResolveOptions struct {
Filter string
Namespace string
}
```
* `filter` Every callback must provide a filter, which is a regular expression. The registered callback will be skipped when the path doesn't match this filter. You can read more about filters [here](#filters).
* `namespace` This is optional. If provided, the callback is only run on paths within modules in the provided namespace. You can read more about namespaces [here](#namespaces).
### On-resolve arguments
When esbuild calls the callback registered by `onResolve`, it will provide these arguments with information about the imported path:
```
interface OnResolveArgs {
path: string;
importer: string;
namespace: string;
resolveDir: string;
kind: ResolveKind;
pluginData: any;
}
type ResolveKind =
| 'entry-point'
| 'import-statement'
| 'require-call'
| 'dynamic-import'
| 'require-resolve'
| 'import-rule'
| 'url-token'
```
```
type OnResolveArgs struct {
Path string
Importer string
Namespace string
ResolveDir string
Kind ResolveKind
PluginData interface{}
}
const (
ResolveEntryPoint ResolveKind
ResolveJSImportStatement ResolveKind
ResolveJSRequireCall ResolveKind
ResolveJSDynamicImport ResolveKind
ResolveJSRequireResolve ResolveKind
ResolveCSSImportRule ResolveKind
ResolveCSSURLToken ResolveKind
)
```
* `path` This is the verbatim unresolved path from the underlying module's source code. It can take any form. While esbuild's default behavior is to interpret import paths as either a relative path or a package name, plugins can be used to introduce new path forms. For example, the sample [HTTP plugin](#http-plugin) below gives special meaning to paths starting with `http://`.
* `importer` This is the path of the module containing this import to be resolved. Note that this path is only guaranteed to be a file system path if the namespace is `file`. If you want to resolve a path relative to the directory containing the importer module, you should use `resolveDir` instead since that also works for virtual modules.
* `namespace` This is the namespace of the module containing this import to be resolved, as set by the [on-load callback](#on-load) that loaded this file. This defaults to the `file` namespace for modules loaded with esbuild's default behavior. You can read more about namespaces [here](#namespaces).
* `resolveDir` This is the file system directory to use when resolving an import path to a real path on the file system. For modules in the `file` namespace, this value defaults to the directory part of the module path. For virtual modules this value defaults to empty but [on-load callbacks](#on-load) can optionally give virtual modules a resolve directory too. If that happens, it will be provided to resolve callbacks for unresolved paths in that file.
* `kind` This says how the path to be resolved is being imported. For example, `'entry-point'` means the path was provided to the API as an entry point path, `'import-statement'` means the path is from a JavaScript `import` or `export` statement, and `'import-rule'` means the path is from a CSS `@import` rule.
* `pluginData` This property is passed from the previous plugin, as set by the [on-load callback](#on-load) that loaded this file.
### On-resolve results
This is the object that can be returned by a callback added using `onResolve` to provide a custom path resolution. If you would like to return from the callback without providing a path, just return the default value (so `undefined` in JavaScript and `OnResolveResult{}` in Go). Here are the optional properties that can be returned:
```
interface OnResolveResult {
errors?: Message[];
external?: boolean;
namespace?: string;
path?: string;
pluginData?: any;
pluginName?: string;
sideEffects?: boolean;
suffix?: string;
warnings?: Message[];
watchDirs?: string[];
watchFiles?: string[];
}
interface Message {
text: string;
location: Location | null;
detail: any; // The original error from a JavaScript plugin, if applicable
}
interface Location {
file: string;
namespace: string;
line: number; // 1-based
column: number; // 0-based, in bytes
length: number; // in bytes
lineText: string;
}
```
```
type OnResolveResult struct {
Errors []Message
External bool
Namespace string
Path string
PluginData interface{}
PluginName string
SideEffects SideEffects
Suffix string
Warnings []Message
WatchDirs []string
WatchFiles []string
}
type Message struct {
Text string
Location *Location
Detail interface{} // The original error from a Go plugin, if applicable
}
type Location struct {
File string
Namespace string
Line int // 1-based
Column int // 0-based, in bytes
Length int // in bytes
LineText string
}
```
* `path` Set this to a non-empty string to resolve the import to a specific path. If this is set, no more on-resolve callbacks will be run for this import path in this module. If this is not set, esbuild will continue to run on-resolve callbacks that were registered after the current one. Then, if the path still isn't resolved, esbuild will default to resolving the path relative to the resolve directory of the current module.
* `external` Set this to `true` to mark the module as [external](../api/index#external), which means it will not be included in the bundle and will instead be imported at run-time.
* `namespace` This is the namespace associated with the resolved path. If left empty, it will default to the `file` namespace for non-external paths. Paths in the file namespace must be an absolute path for the current file system (so starting with a forward slash on Unix and with a drive letter on Windows).
If you want to resolve to a path that isn't a file system path, you should set the namespace to something other than `file` or an empty string. This tells esbuild to not treat the path as pointing to something on the file system.
* `errors` and `warnings` These properties let you pass any log messages generated during path resolution to esbuild where they will be displayed in the terminal according to the current [log level](../api/index#log-level) and end up in the final build result. For example, if you are calling a library and that library can return errors and/or warnings, you will want to forward them using these properties.
If you only have a single error to return, you don't have to pass it via `errors`. You can simply throw the error in JavaScript or return the `error` object as the second return value in Go.
* `watchFiles` and `watchDirs` These properties let you return additional file system paths for esbuild's [watch mode](../api/index#watch) to scan. By default esbuild will only scan the path provided to `onLoad` plugins, and only if the namespace is `file`. If your plugin needs to react to additional changes in the file system, it needs to use one of these properties.
A rebuild will be triggered if any file in the `watchFiles` array has been changed since the last build. Change detection is somewhat complicated and may check the file contents and/or the file's metadata.
A rebuild will also be triggered if the list of directory entries for any directory in the `watchDirs` array has been changed since the last build. Note that this does not check anything about the contents of any file in these directories, and it also does not check any subdirectories. Think of this as checking the output of the Unix `ls` command.
For robustness, you should include all file system paths that were used during the evaluation of the plugin. For example, if your plugin does something equivalent to `require.resolve()`, you'll need to include the paths of all "does this file exist" checks, not just the final path. Otherwise a new file could be created that causes the build to become outdated, but esbuild doesn't detect it because that path wasn't listed.
* `pluginName` This property lets you replace this plugin's name with another name for this path resolution operation. It's useful for proxying another plugin through this plugin. For example, it lets you have a single plugin that forwards to a child process containing multiple plugins. You probably won't need to use this.
* `pluginData` This property will be passed to the next plugin that runs in the plugin chain. If you return it from an `onLoad` plugin, it will be passed to the `onResolve` plugins for any imports in that file, and if you return it from an `onResolve` plugin, an arbitrary one will be passed to the `onLoad` plugin when it loads the file (it's arbitrary since the relationship is many-to-one). This is useful to pass data between different plugins without them having to coordinate directly.
* `sideEffects` Setting this property to false tells esbuild that imports of this module can be removed if the imported names are unused. This behaves as if `"sideEffects": false` was specified the corresponding `package.json` file. For example, `import { x } from "y"` may be completely removed if `x` is unused and `y` has been marked as `sideEffects: false`. You can read more about what `sideEffects` means in [Webpack's documentation about the feature](https://webpack.js.org/guides/tree-shaking/#mark-the-file-as-side-effect-free).
* `suffix` Returning a value here lets you pass along an optional URL query or hash to append to the path that is not included in the path itself. Storing this separately is beneficial in cases when the path is processed by something that is not aware of the suffix, either by esbuild itself or by another plugin.
For example, an on-resolve plugin might return a suffix of `?#iefix` for a `.eot` file in a build with a different on-load plugin for paths ending in `.eot`. Keeping the suffix separate means the suffix is still associated with the path but the `.eot` plugin will still match the file without needing to know anything about suffixes.
If you do set a suffix, it must begin with either `?` or `#` because it's intended to be a URL query or hash. This feature has certain obscure uses such as hacking around bugs in IE8's CSS parser and may not be that useful otherwise. If you do use it, keep in mind that each unique namespace, path, and suffix combination is considered by esbuild to be a unique module identifier so by returning a different suffix for the same path, you are telling esbuild to create another copy of the module.
On-load callbacks
-----------------
A callback added using `onLoad` will be run for each unique path/namespace pair that has not been marked as external. Its job is to return the contents of the module and to tell esbuild how to interpret it. Here's an example plugin that converts `.txt` files into an array of words:
```
import * as esbuild from 'esbuild'
import fs from 'node:fs'
let exampleOnLoadPlugin = {
name: 'example',
setup(build) {
// Load ".txt" files and return an array of words
build.onLoad({ filter: /\.txt$/ }, async (args) => {
let text = await fs.promises.readFile(args.path, 'utf8')
return {
contents: JSON.stringify(text.split(/\s+/)),
loader: 'json',
}
})
},
}
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
plugins: [exampleOnLoadPlugin],
})
```
```
package main
import "encoding/json"
import "io/ioutil"
import "os"
import "strings"
import "github.com/evanw/esbuild/pkg/api"
var exampleOnLoadPlugin = api.Plugin{
Name: "example",
Setup: func(build api.PluginBuild) {
// Load ".txt" files and return an array of words
build.OnLoad(api.OnLoadOptions{Filter: `\.txt$`},
func(args api.OnLoadArgs) (api.OnLoadResult, error) {
text, err := ioutil.ReadFile(args.Path)
if err != nil {
return api.OnLoadResult{}, err
}
bytes, err := json.Marshal(strings.Fields(string(text)))
if err != nil {
return api.OnLoadResult{}, err
}
contents := string(bytes)
return api.OnLoadResult{
Contents: &contents,
Loader: api.LoaderJSON,
}, nil
})
},
}
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outfile: "out.js",
Plugins: []api.Plugin{exampleOnLoadPlugin},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
The callback can return without providing the contents of the module. In that case the responsibility for loading the module is passed to the next registered callback. For a given module, all `onLoad` callbacks from all plugins will be run in the order they were registered until one takes responsibility for loading the module. If no callback returns contents for the module, esbuild will run its default module loading logic.
Keep in mind that many callbacks may be running concurrently. In JavaScript, if your callback does expensive work that can run on another thread such as `fs.readFileSync()`, you should make the callback `async` and use `await` (in this case with `fs.promises.readFile()`) to allow other code to run in the meantime. In Go, each callback may be run on a separate goroutine. Make sure you have appropriate synchronization in place if your plugin uses any shared data structures.
### On-load options
The `onLoad` API is meant to be called within the `setup` function and registers a callback to be triggered in certain situations. It takes a few options:
```
interface OnLoadOptions {
filter: RegExp;
namespace?: string;
}
```
```
type OnLoadOptions struct {
Filter string
Namespace string
}
```
* `filter` Every callback must provide a filter, which is a regular expression. The registered callback will be skipped when the path doesn't match this filter. You can read more about filters [here](#filters).
* `namespace` This is optional. If provided, the callback is only run on paths within modules in the provided namespace. You can read more about namespaces [here](#namespaces).
### On-load arguments
When esbuild calls the callback registered by `onLoad`, it will provide these arguments with information about the module to load:
```
interface OnLoadArgs {
path: string;
namespace: string;
suffix: string;
pluginData: any;
}
```
```
type OnLoadArgs struct {
Path string
Namespace string
Suffix string
PluginData interface{}
}
```
* `path` This is the fully-resolved path to the module. It should be considered a file system path if the namespace is `file`, but otherwise the path can take any form. For example, the sample [HTTP plugin](#http-plugin) below gives special meaning to paths starting with `http://`.
* `namespace` This is the namespace that the module path is in, as set by the [on-resolve callback](#on-resolve) that resolved this file. It defaults to the `file` namespace for modules loaded with esbuild's default behavior. You can read more about namespaces [here](#namespaces).
* `suffix` This is the URL query and/or hash at the end of the file path, if there is one. It's either filled in by esbuild's native path resolution behavior or returned by the [on-resolve callback](#on-resolve) that resolved this file. This is stored separately from the path so that most plugins can just deal with the path and ignore the suffix. The on-load behavior that's built into esbuild just ignores the suffix and loads the file from its path alone.
For context, IE8's CSS parser has a bug where it considers certain URLs to extend to the last `)` instead of the first `)`. So the CSS code `url('Foo.eot') format('eot')` is incorrectly considered to have a URL of `Foo.eot') format('eot`. To avoid this, people typically add something like `?#iefix` so that IE8 sees the URL as `Foo.eot?#iefix') format('eot`. Then the path part of the URL is `Foo.eot` and the query part is `?#iefix') format('eot`, which means IE8 can find the file `Foo.eot` by discarding the query.
The suffix feature was added to esbuild to handle CSS files containing these hacks. A URL of `Foo.eot?#iefix` should be considered [external](../api/index#external) if all files matching `*.eot` have been marked as external, but the `?#iefix` suffix should still be present in the final output file.
* `pluginData` This property is passed from the previous plugin, as set by the [on-resolve callback](#on-resolve) that runs in the plugin chain.
### On-load results
This is the object that can be returned by a callback added using `onLoad` to provide the contents of a module. If you would like to return from the callback without providing any contents, just return the default value (so `undefined` in JavaScript and `OnLoadResult{}` in Go). Here are the optional properties that can be returned:
```
interface OnLoadResult {
contents?: string | Uint8Array;
errors?: Message[];
loader?: Loader;
pluginData?: any;
pluginName?: string;
resolveDir?: string;
warnings?: Message[];
watchDirs?: string[];
watchFiles?: string[];
}
interface Message {
text: string;
location: Location | null;
detail: any; // The original error from a JavaScript plugin, if applicable
}
interface Location {
file: string;
namespace: string;
line: number; // 1-based
column: number; // 0-based, in bytes
length: number; // in bytes
lineText: string;
}
```
```
type OnLoadResult struct {
Contents *string
Errors []Message
Loader Loader
PluginData interface{}
PluginName string
ResolveDir string
Warnings []Message
WatchDirs []string
WatchFiles []string
}
type Message struct {
Text string
Location *Location
Detail interface{} // The original error from a Go plugin, if applicable
}
type Location struct {
File string
Namespace string
Line int // 1-based
Column int // 0-based, in bytes
Length int // in bytes
LineText string
}
```
* `contents` Set this to a string to specify the contents of the module. If this is set, no more on-load callbacks will be run for this resolved path. If this is not set, esbuild will continue to run on-load callbacks that were registered after the current one. Then, if the contents are still not set, esbuild will default to loading the contents from the file system if the resolved path is in the `file` namespace.
* `loader` This tells esbuild how to interpret the contents. For example, the [`js`](../content-types/index#javascript) loader interprets the contents as JavaScript and the [`css`](../content-types/index#css) loader interprets the contents as CSS. The loader defaults to `js` if it's not specified. See the [content types](../content-types/index) page for a complete list of all built-in loaders.
* `resolveDir` This is the file system directory to use when resolving an import path in this module to a real path on the file system. For modules in the `file` namespace, this value defaults to the directory part of the module path. Otherwise this value defaults to empty unless the plugin provides one. If the plugin doesn't provide one, esbuild's default behavior won't resolve any imports in this module. This directory will be passed to any [on-resolve callbacks](#on-resolve) that run on unresolved import paths in this module.
* `errors` and `warnings` These properties let you pass any log messages generated during path resolution to esbuild where they will be displayed in the terminal according to the current [log level](../api/index#log-level) and end up in the final build result. For example, if you are calling a library and that library can return errors and/or warnings, you will want to forward them using these properties.
If you only have a single error to return, you don't have to pass it via `errors`. You can simply throw the error in JavaScript or return the `error` object as the second return value in Go.
* `watchFiles` and `watchDirs` These properties let you return additional file system paths for esbuild's [watch mode](../api/index#watch) to scan. By default esbuild will only scan the path provided to `onLoad` plugins, and only if the namespace is `file`. If your plugin needs to react to additional changes in the file system, it needs to use one of these properties.
A rebuild will be triggered if any file in the `watchFiles` array has been changed since the last build. Change detection is somewhat complicated and may check the file contents and/or the file's metadata.
A rebuild will also be triggered if the list of directory entries for any directory in the `watchDirs` array has been changed since the last build. Note that this does not check anything about the contents of any file in these directories, and it also does not check any subdirectories. Think of this as checking the output of the Unix `ls` command.
For robustness, you should include all file system paths that were used during the evaluation of the plugin. For example, if your plugin does something equivalent to `require.resolve()`, you'll need to include the paths of all "does this file exist" checks, not just the final path. Otherwise a new file could be created that causes the build to become outdated, but esbuild doesn't detect it because that path wasn't listed.
* `pluginName` This property lets you replace this plugin's name with another name for this module load operation. It's useful for proxying another plugin through this plugin. For example, it lets you have a single plugin that forwards to a child process containing multiple plugins. You probably won't need to use this.
* `pluginData` This property will be passed to the next plugin that runs in the plugin chain. If you return it from an `onLoad` plugin, it will be passed to the `onResolve` plugins for any imports in that file, and if you return it from an `onResolve` plugin, an arbitrary one will be passed to the `onLoad` plugin when it loads the file (it's arbitrary since the relationship is many-to-one). This is useful to pass data between different plugins without them having to coordinate directly.
### Caching your plugin
Since esbuild is so fast, it's often the case that plugin evaluation is the main bottleneck when building with esbuild. Caching of plugin evaluation is left up to each plugin instead of being a part of esbuild itself because cache invalidation is plugin-specific. If you are writing a slow plugin that needs a cache to be fast, you will have to write the cache logic yourself.
A cache is essentially a map that memoizes the transform function that represents your plugin. The keys of the map usually contain the inputs to your transform function and the values of the map usually contain the outputs of your transform function. In addition, the map usually has some form of least-recently-used cache eviction policy to avoid continually growing larger in size over time.
The cache can either be stored in memory (beneficial for use with esbuild's [rebuild](../api/index#rebuild) API), on disk (beneficial for caching across separate build script invocations), or even on a server (beneficial for really slow transforms that can be shared between different developer machines). Where to store the cache is case-specific and depends on your plugin.
Here is a simple caching example. Say we want to cache the function `slowTransform()` that takes as input the contents of a file in the `*.example` format and transforms it to JavaScript. An in-memory cache that avoids redundant calls to this function when used with esbuild's [rebuild](../api/index#rebuild) API) might look something like this:
```
import fs from 'node:fs'
let examplePlugin = {
name: 'example',
setup(build) {
let cache = new Map
build.onLoad({ filter: /\.example$/ }, async (args) => {
let input = await fs.promises.readFile(args.path, 'utf8')
let key = args.path
let value = cache.get(key)
if (!value || value.input !== input) {
let contents = slowTransform(input)
value = { input, output: { contents } }
cache.set(key, value)
}
return value.output
})
}
}
```
Some important caveats about the caching code above:
* There is no cache eviction policy present in the code above. Memory usage will continue to grow if more and more keys are added to the cache map.
To combat this limitation somewhat, the `input` value is stored in the cache `value` instead of in the cache `key`. This means that changing the contents of a file will not leak memory because the key only includes the file path, not the file contents. Changing the file contents only overwrites the previous cache entry. This is probably fine for common usage where someone repeatedly edits the same file in between incremental rebuilds and only occasionally adds or renames files. But the cache will continue to grow in size if each build contains new unique path names (e.g. perhaps an auto-generated temporary file path containing the current time). A more advanced version might use a least-recently-used eviction policy.
* Cache invalidation only works if `slowTransform()` is a [pure function](https://en.wikipedia.org/wiki/Pure_function) (meaning that the output of the function *only* depends on the inputs to the function) and if all of the inputs to the function are somehow captured in the lookup to the cache map. For example if the transform function automatically reads the contents of some other files and the output depends on the contents of those files too, then the cache would fail to be invalidated when those files are changed because they are not included in the cache key.
This part is easy to mess up so it's worth going through a specific example. Consider a plugin that implements a compile-to-CSS language. If that plugin implements `@import` rules itself by parsing imported files and either bundles them or makes any exported variable declarations available to the importing code, your plugin will not be correct if it only checks that the importing file's contents haven't changed because a change to the imported file could also invalidate the cache.
You may be thinking that you could just add the contents of the imported file to the cache key to fix this problem. However, even that may be incorrect. Say for example this plugin uses [`require.resolve()`](https://nodejs.org/api/modules.html#modules_require_resolve_request_options) to resolve the import path to an absolute file path. This is a common approach because it uses node's built-in path resolution that can resolve to a path inside a package. This function usually does many checks for files in different locations before returning the resolved path. For example, importing the path `pkg/file` from the file `src/entry.css` might check the following locations (yes, node's package resolution algorithm is very inefficient):
```
src/node_modules/pkg/file
src/node_modules/pkg/file.css
src/node_modules/pkg/file/package.json
src/node_modules/pkg/file/main
src/node_modules/pkg/file/main.css
src/node_modules/pkg/file/main/index.css
src/node_modules/pkg/file/index.css
node_modules/pkg/file
node_modules/pkg/file.css
node_modules/pkg/file/package.json
node_modules/pkg/file/main
node_modules/pkg/file/main.css
node_modules/pkg/file/main/index.css
node_modules/pkg/file/index.css
```
Say the import `pkg/file` was ultimately resolved to the absolute path `node_modules/pkg/file/index.css`. Even if you cache the contents of both the importing file and the imported file and verify that the contents of both files are still the same before reusing the cache entry, the cache entry could still be stale if one of the other files that `require.resolve()` checks for has either been created or deleted since the cache entry was added. Caching this correctly essentially involves always re-running all such path resolutions even when none of the input files have been changed and verifying that none of the path resolutions have changed either.
* These cache keys are only correct for an in-memory cache. It would be incorrect to implement a file system cache using the same cache keys. While an in-memory cache is guaranteed to always run the same code for every build because the code is also stored in memory, a file system cache could potentially be accessed by two separate builds that each contain different code. Specifically the code for the `slowTransform()` function may have been changed in between builds.
This can happen in various cases. The package containing the function `slowTransform()` may have been updated, or one of its transitive dependencies may have been updated even if you have pinned the package's version due to how npm handles semver, or someone may have [mutated the package contents](https://www.npmjs.com/package/patch-package) on the file system in the meantime, or the transform function may be calling a node API and different builds could be running on different node versions.
If you want to store your cache on the file system, you should guard against changes to the code for the transform function by storing some representation of the code for the transform function in the cache key. This is usually some form of [hash](https://nodejs.org/api/crypto.html#crypto_class_hash) that contains the contents of all relevant files in all relevant packages as well as potentially other details such as which node version you are currently running on. Getting all of this to be correct is non-trivial.
On-start callbacks
------------------
Register an on-start callback to be notified when a new build starts. This triggers for all builds, not just the initial build, so it's especially useful for [rebuilds](../api/index#rebuild), [watch mode](../api/index#watch), and [serve mode](../api/index#serve). Here's how to add an on-start callback:
```
let examplePlugin = {
name: 'example',
setup(build) {
build.onStart(() => {
console.log('build started')
})
},
}
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
import "os"
var examplePlugin = api.Plugin{
Name: "example",
Setup: func(build api.PluginBuild) {
build.OnStart(func() (api.OnStartResult, error) {
fmt.Fprintf(os.Stderr, "build started\n")
return api.OnStartResult{}, nil
})
},
}
func main() {
}
```
You should not use an on-start callback for initialization since it can be run multiple times. If you want to initialize something, just put your plugin initialization code directly inside the `setup` function instead.
The on-start callback can be `async` and can return a promise. All on-start callbacks from all plugins are run concurrently, and then the build waits for all on-start callbacks to finish before proceeding. On-start callbacks can optionally return errors and/or warnings to be included with the build.
Note that on-start callbacks do not have the ability to mutate the [build options](#build-options). The initial build options can only be modified within the `setup` function and are consumed once `setup` returns. All builds after the first one reuse the same initial options so the initial options are never re-consumed, and modifications to `build.initialOptions` that are done within the start callback are ignored.
On-end callbacks
----------------
Register an on-end callback to be notified when a new build ends. This triggers for all builds, not just the initial build, so it's especially useful for [rebuilds](../api/index#rebuild), [watch mode](../api/index#watch), and [serve mode](../api/index#serve). Here's how to add an on-end callback:
```
let examplePlugin = {
name: 'example',
setup(build) {
build.onEnd(result => {
console.log(`build ended with ${result.errors.length} errors`)
})
},
}
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
import "os"
var examplePlugin = api.Plugin{
Name: "example",
Setup: func(build api.PluginBuild) {
build.OnEnd(func(result *api.BuildResult) (api.OnEndResult, error) {
fmt.Fprintf(os.Stderr, "build ended with %d errors\n", len(result.Errors))
return api.OnEndResult{}, nil
})
},
}
func main() {
}
```
All on-end callbacks are run in serial and each callback is given access to the final build result. It can modify the build result before returning and can delay the end of the build by returning a promise. If you want to be able to inspect the build graph, you should enable the [metafile](../api/index#metafile) setting on the [initial options](#build-options) and the build graph will be returned as the `metafile` property on the build result object.
On-dispose callbacks
--------------------
Register an on-dispose callback to perform cleanup when the plugin is no longer used. It will be called after every `build()` call regardless of whether the build failed or not, as well as after the first `dispose()` call on a given build context. Here's how to add an on-dispose callback:
```
let examplePlugin = {
name: 'example',
setup(build) {
build.onDispose(() => {
console.log('This plugin is no longer used')
})
},
}
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
var examplePlugin = api.Plugin{
Name: "example",
Setup: func(build api.PluginBuild) {
build.OnDispose(func() {
fmt.Println("This plugin is no longer used")
})
},
}
func main() {
}
```
Accessing build options
-----------------------
Plugins can access the initial build options from within the `setup` method. This lets you inspect how the build is configured as well as modify the build options before the build starts. Here is an example:
```
let examplePlugin = {
name: 'auto-node-env',
setup(build) {
const options = build.initialOptions
options.define = options.define || {}
options.define['process.env.NODE_ENV'] =
options.minify ? '"production"' : '"development"'
},
}
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
var examplePlugin = api.Plugin{
Name: "auto-node-env",
Setup: func(build api.PluginBuild) {
options := build.InitialOptions
if options.Define == nil {
options.Define = map[string]string{}
}
if options.MinifyWhitespace && options.MinifyIdentifiers && options.MinifySyntax {
options.Define[`process.env.NODE_ENV`] = `"production"`
} else {
options.Define[`process.env.NODE_ENV`] = `"development"`
}
},
}
func main() {
}
```
Note that modifications to the build options after the build starts do not affect the build. In particular, [rebuilds](../api/index#rebuild), [watch mode](../api/index#watch), and [serve mode](../api/index#serve) do not update their build options if plugins mutate the build options object after the first build has started.
Resolving paths
---------------
When a plugin returns a result from an [on-resolve callback](#on-resolve), the result completely replaces esbuild's built-in path resolution. This gives the plugin complete control over how path resolution works, but it means that the plugin may have to reimplement some of the behavior that esbuild already has built-in if it wants to have similar behavior. For example, a plugin may want to search for a package in the user's `node_modules` directory, which is something esbuild already implements.
Instead of reimplementing esbuild's built-in behavior, plugins have the option of running esbuild's path resolution manually and inspecting the result. This lets you adjust the inputs and/or the outputs of esbuild's path resolution. Here's an example:
```
import * as esbuild from 'esbuild'
let examplePlugin = {
name: 'example',
setup(build) {
build.onResolve({ filter: /^example$/ }, async () => {
const result = await build.resolve('./foo', {
kind: 'import-statement',
resolveDir: './bar',
})
if (result.errors.length > 0) {
return { errors: result.errors }
}
return { path: result.path, external: true }
})
},
}
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
plugins: [examplePlugin],
})
```
```
package main
import "os"
import "github.com/evanw/esbuild/pkg/api"
var examplePlugin = api.Plugin{
Name: "example",
Setup: func(build api.PluginBuild) {
build.OnResolve(api.OnResolveOptions{Filter: `^example$`},
func(api.OnResolveArgs) (api.OnResolveResult, error) {
result := build.Resolve("./foo", api.ResolveOptions{
Kind: api.ResolveJSImportStatement,
ResolveDir: "./bar",
})
if len(result.Errors) > 0 {
return api.OnResolveResult{Errors: result.Errors}, nil
}
return api.OnResolveResult{Path: result.Path, External: true}, nil
})
},
}
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outfile: "out.js",
Plugins: []api.Plugin{examplePlugin},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
This plugin intercepts imports to the path `example`, tells esbuild to resolve the import `./foo` in the directory `./bar`, forces whatever path esbuild returns to be considered external, and maps the import for `example` to that external path.
Here are some additional things to know about this API:
* If you don't pass the optional `resolveDir` parameter, esbuild will still run `onResolve` plugin callbacks but will not attempt any path resolution itself. All of esbuild's path resolution logic depends on the `resolveDir` parameter including looking for packages in `node_modules` directories (since it needs to know where those `node_modules` directories might be).
* If you want to resolve a file name in a specific directory, make sure the input path starts with `./`. Otherwise the input path will be treated as a package path instead of a relative path. This behavior is identical to esbuild's normal path resolution logic.
* If path resolution fails, the `errors` property on the returned object will be a non-empty array containing the error information. This function does not always throw an error when it fails. You need to check for errors after calling it.
* The behavior of this function depends on the build configuration. That's why it's a property of the `build` object instead of being a top-level API call. This also means you can't call it until all plugin `setup` functions have finished since these give plugins the opportunity to adjust the build configuration before it's frozen at the start of the build. So the `resolve` function is going to be most useful inside your `onResolve` and/or `onLoad` callbacks.
* There is currently no attempt made to detect infinite path resolution loops. Calling `resolve` from within `onResolve` with the same parameters is almost certainly a bad idea.
### Resolve options
The `resolve` function takes the path to resolve as the first argument and an object with optional properties as the second argument. This options object is very similar to the [arguments that are passed to `onResolve`](#on-resolve-arguments). Here are the available options:
```
interface ResolveOptions {
kind: ResolveKind;
importer?: string;
namespace?: string;
resolveDir?: string;
pluginData?: any;
}
type ResolveKind =
| 'entry-point'
| 'import-statement'
| 'require-call'
| 'dynamic-import'
| 'require-resolve'
| 'import-rule'
| 'url-token'
```
```
type ResolveOptions struct {
Kind ResolveKind
Importer string
Namespace string
ResolveDir string
PluginData interface{}
}
const (
ResolveEntryPoint ResolveKind
ResolveJSImportStatement ResolveKind
ResolveJSRequireCall ResolveKind
ResolveJSDynamicImport ResolveKind
ResolveJSRequireResolve ResolveKind
ResolveCSSImportRule ResolveKind
ResolveCSSURLToken ResolveKind
)
```
* `kind` This tells esbuild how the path was imported, which can affect path resolution. For example, [node's path resolution rules](https://nodejs.org/api/packages.html#conditional-exports) say that paths imported using `'require-call'` should respect [conditional package imports](../api/index#conditions) in the `"require"` section in `package.json` while paths imported using `'import-statement'` should respect conditional package imports in the `"import"` section instead.
* `importer` If set, this is interpreted as the path of the module containing this import to be resolved. This affects plugins with `onResolve` callbacks that check the `importer` value.
* `namespace` If set, this is interpreted as the namespace of the module containing this import to be resolved. This affects plugins with `onResolve` callbacks that check the `namespace` value. You can read more about namespaces [here](#namespaces).
* `resolveDir` This is the file system directory to use when resolving an import path to a real path on the file system. This must be set for esbuild's built-in path resolution to be able to find a given file, even for non-relative package paths (since esbuild needs to know where the `node_modules` directory is).
* `pluginData` This property can be used to pass custom data to whatever [on-resolve callbacks](#on-resolve) match this import path. The meaning of this data is left entirely up to you.
### Resolve results
The `resolve` function returns an object that's very similar to what plugins can [return from an `onResolve` callback](#on-resolve-results). It has the following properties:
```
export interface ResolveResult {
errors: Message[];
external: boolean;
namespace: string;
path: string;
pluginData: any;
sideEffects: boolean;
suffix: string;
warnings: Message[];
}
interface Message {
text: string;
location: Location | null;
detail: any; // The original error from a JavaScript plugin, if applicable
}
interface Location {
file: string;
namespace: string;
line: number; // 1-based
column: number; // 0-based, in bytes
length: number; // in bytes
lineText: string;
}
```
```
type ResolveResult struct {
Errors []Message
External bool
Namespace string
Path string
PluginData interface{}
SideEffects bool
Suffix string
Warnings []Message
}
type Message struct {
Text string
Location *Location
Detail interface{} // The original error from a Go plugin, if applicable
}
type Location struct {
File string
Namespace string
Line int // 1-based
Column int // 0-based, in bytes
Length int // in bytes
LineText string
}
```
* `path` This is the result of path resolution, or an empty string if path resolution failed.
* `external` This will be `true` if the path was marked as [external](../api/index#external), which means it will not be included in the bundle and will instead be imported at run-time.
* `namespace` This is the namespace associated with the resolved path. You can read more about namespaces [here](#namespaces).
* `errors` and `warnings` These properties hold any log messages generated during path resolution, either by any plugins that responded to this path resolution operation or by esbuild itself. These log messages are not automatically included in the log, so they will be completely invisible if you discard them. If you want them to be included in the log, you'll need to return them from either `onResolve` or `onLoad`.
* `pluginData` If a plugin responded to this path resolution operation and returned `pluginData` from its `onResolve` callback, that data will end up here. This is useful to pass data between different plugins without them having to coordinate directly.
* `sideEffects` This property will be `true` unless the module is somehow annotated as having no side effects, in which case it will be `false`. This will be `false` for packages that have `"sideEffects": false` in the corresponding `package.json` file, and also if a plugin responds to this path resolution operation and returns `sideEffects: false`. You can read more about what `sideEffects` means in [Webpack's documentation about the feature](https://webpack.js.org/guides/tree-shaking/#mark-the-file-as-side-effect-free).
* `suffix` This can contain an optional URL query or hash if there was one at the end of the path to be resolved and if removing it was required for the path to resolve successfully.
Example plugins
---------------
The example plugins below are meant to give you an idea of the different types of things you can do with the plugin API.
### HTTP plugin
*This example demonstrates: using a path format other than file system paths, namespace-specific path resolution, using resolve and load callbacks together.*
This plugin allows you to import HTTP URLs into JavaScript code. The code will automatically be downloaded at build time. It enables the following workflow:
```
import { zip } from 'https://unpkg.com/[email protected]/lodash.js'
console.log(zip([1, 2], ['a', 'b']))
```
This can be accomplished with the following plugin. Note that for real usage the downloads should be cached, but caching has been omitted from this example for brevity:
```
import * as esbuild from 'esbuild'
import https from 'node:https'
import http from 'node:http'
let httpPlugin = {
name: 'http',
setup(build) {
// Intercept import paths starting with "http:" and "https:" so
// esbuild doesn't attempt to map them to a file system location.
// Tag them with the "http-url" namespace to associate them with
// this plugin.
build.onResolve({ filter: /^https?:\/\// }, args => ({
path: args.path,
namespace: 'http-url',
}))
// We also want to intercept all import paths inside downloaded
// files and resolve them against the original URL. All of these
// files will be in the "http-url" namespace. Make sure to keep
// the newly resolved URL in the "http-url" namespace so imports
// inside it will also be resolved as URLs recursively.
build.onResolve({ filter: /.*/, namespace: 'http-url' }, args => ({
path: new URL(args.path, args.importer).toString(),
namespace: 'http-url',
}))
// When a URL is loaded, we want to actually download the content
// from the internet. This has just enough logic to be able to
// handle the example import from unpkg.com but in reality this
// would probably need to be more complex.
build.onLoad({ filter: /.*/, namespace: 'http-url' }, async (args) => {
let contents = await new Promise((resolve, reject) => {
function fetch(url) {
console.log(`Downloading: ${url}`)
let lib = url.startsWith('https') ? https : http
let req = lib.get(url, res => {
if ([301, 302, 307].includes(res.statusCode)) {
fetch(new URL(res.headers.location, url).toString())
req.abort()
} else if (res.statusCode === 200) {
let chunks = []
res.on('data', chunk => chunks.push(chunk))
res.on('end', () => resolve(Buffer.concat(chunks)))
} else {
reject(new Error(`GET ${url} failed: status ${res.statusCode}`))
}
}).on('error', reject)
}
fetch(args.path)
})
return { contents }
})
},
}
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
plugins: [httpPlugin],
})
```
```
package main
import "io/ioutil"
import "net/http"
import "net/url"
import "os"
import "github.com/evanw/esbuild/pkg/api"
var httpPlugin = api.Plugin{
Name: "http",
Setup: func(build api.PluginBuild) {
// Intercept import paths starting with "http:" and "https:" so
// esbuild doesn't attempt to map them to a file system location.
// Tag them with the "http-url" namespace to associate them with
// this plugin.
build.OnResolve(api.OnResolveOptions{Filter: `^https?://`},
func(args api.OnResolveArgs) (api.OnResolveResult, error) {
return api.OnResolveResult{
Path: args.Path,
Namespace: "http-url",
}, nil
})
// We also want to intercept all import paths inside downloaded
// files and resolve them against the original URL. All of these
// files will be in the "http-url" namespace. Make sure to keep
// the newly resolved URL in the "http-url" namespace so imports
// inside it will also be resolved as URLs recursively.
build.OnResolve(api.OnResolveOptions{Filter: ".*", Namespace: "http-url"},
func(args api.OnResolveArgs) (api.OnResolveResult, error) {
base, err := url.Parse(args.Importer)
if err != nil {
return api.OnResolveResult{}, err
}
relative, err := url.Parse(args.Path)
if err != nil {
return api.OnResolveResult{}, err
}
return api.OnResolveResult{
Path: base.ResolveReference(relative).String(),
Namespace: "http-url",
}, nil
})
// When a URL is loaded, we want to actually download the content
// from the internet. This has just enough logic to be able to
// handle the example import from unpkg.com but in reality this
// would probably need to be more complex.
build.OnLoad(api.OnLoadOptions{Filter: ".*", Namespace: "http-url"},
func(args api.OnLoadArgs) (api.OnLoadResult, error) {
res, err := http.Get(args.Path)
if err != nil {
return api.OnLoadResult{}, err
}
defer res.Body.Close()
bytes, err := ioutil.ReadAll(res.Body)
if err != nil {
return api.OnLoadResult{}, err
}
contents := string(bytes)
return api.OnLoadResult{Contents: &contents}, nil
})
},
}
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outfile: "out.js",
Plugins: []api.Plugin{httpPlugin},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
The plugin first uses a resolver to move `http://` and `https://` URLs to the `http-url` namespace. Setting the namespace tells esbuild to not treat these paths as file system paths. Then, a loader for the `http-url` namespace downloads the module and returns the contents to esbuild. From there, another resolver for import paths inside modules in the `http-url` namespace picks up relative paths and translates them into full URLs by resolving them against the importing module's URL. That then feeds back into the loader allowing downloaded modules to download additional modules recursively.
### WebAssembly plugin
*This example demonstrates: working with binary data, creating virtual modules using import statements, re-using the same path with different namespaces.*
This plugin allows you to import `.wasm` files into JavaScript code. It does not generate the WebAssembly files themselves; that can either be done by another tool or by modifying this example plugin to suit your needs. It enables the following workflow:
```
import load from './example.wasm'
load(imports).then(exports => { ... })
```
When you import a `.wasm` file, this plugin generates a virtual JavaScript module in the `wasm-stub` namespace with a single function that loads the WebAssembly module exported as the default export. That stub module looks something like this:
```
import wasm from '/path/to/example.wasm'
export default (imports) =>
WebAssembly.instantiate(wasm, imports).then(
result => result.instance.exports)
```
Then that stub module imports the WebAssembly file itself as another module in the `wasm-binary` namespace using esbuild's built-in [binary](../content-types/index#binary) loader. This means importing a `.wasm` file actually generates two virtual modules. Here's the code for the plugin:
```
import * as esbuild from 'esbuild'
import path from 'node:path'
import fs from 'node:fs'
let wasmPlugin = {
name: 'wasm',
setup(build) {
// Resolve ".wasm" files to a path with a namespace
build.onResolve({ filter: /\.wasm$/ }, args => {
// If this is the import inside the stub module, import the
// binary itself. Put the path in the "wasm-binary" namespace
// to tell our binary load callback to load the binary file.
if (args.namespace === 'wasm-stub') {
return {
path: args.path,
namespace: 'wasm-binary',
}
}
// Otherwise, generate the JavaScript stub module for this
// ".wasm" file. Put it in the "wasm-stub" namespace to tell
// our stub load callback to fill it with JavaScript.
//
// Resolve relative paths to absolute paths here since this
// resolve callback is given "resolveDir", the directory to
// resolve imports against.
if (args.resolveDir === '') {
return // Ignore unresolvable paths
}
return {
path: path.isAbsolute(args.path) ? args.path : path.join(args.resolveDir, args.path),
namespace: 'wasm-stub',
}
})
// Virtual modules in the "wasm-stub" namespace are filled with
// the JavaScript code for compiling the WebAssembly binary. The
// binary itself is imported from a second virtual module.
build.onLoad({ filter: /.*/, namespace: 'wasm-stub' }, async (args) => ({
contents: `import wasm from ${JSON.stringify(args.path)}
export default (imports) =>
WebAssembly.instantiate(wasm, imports).then(
result => result.instance.exports)`,
}))
// Virtual modules in the "wasm-binary" namespace contain the
// actual bytes of the WebAssembly file. This uses esbuild's
// built-in "binary" loader instead of manually embedding the
// binary data inside JavaScript code ourselves.
build.onLoad({ filter: /.*/, namespace: 'wasm-binary' }, async (args) => ({
contents: await fs.promises.readFile(args.path),
loader: 'binary',
}))
},
}
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
plugins: [wasmPlugin],
})
```
```
package main
import "encoding/json"
import "io/ioutil"
import "os"
import "path/filepath"
import "github.com/evanw/esbuild/pkg/api"
var wasmPlugin = api.Plugin{
Name: "wasm",
Setup: func(build api.PluginBuild) {
// Resolve ".wasm" files to a path with a namespace
build.OnResolve(api.OnResolveOptions{Filter: `\.wasm$`},
func(args api.OnResolveArgs) (api.OnResolveResult, error) {
// If this is the import inside the stub module, import the
// binary itself. Put the path in the "wasm-binary" namespace
// to tell our binary load callback to load the binary file.
if args.Namespace == "wasm-stub" {
return api.OnResolveResult{
Path: args.Path,
Namespace: "wasm-binary",
}, nil
}
// Otherwise, generate the JavaScript stub module for this
// ".wasm" file. Put it in the "wasm-stub" namespace to tell
// our stub load callback to fill it with JavaScript.
//
// Resolve relative paths to absolute paths here since this
// resolve callback is given "resolveDir", the directory to
// resolve imports against.
if args.ResolveDir == "" {
return api.OnResolveResult{}, nil // Ignore unresolvable paths
}
if !filepath.IsAbs(args.Path) {
args.Path = filepath.Join(args.ResolveDir, args.Path)
}
return api.OnResolveResult{
Path: args.Path,
Namespace: "wasm-stub",
}, nil
})
// Virtual modules in the "wasm-stub" namespace are filled with
// the JavaScript code for compiling the WebAssembly binary. The
// binary itself is imported from a second virtual module.
build.OnLoad(api.OnLoadOptions{Filter: `.*`, Namespace: "wasm-stub"},
func(args api.OnLoadArgs) (api.OnLoadResult, error) {
bytes, err := json.Marshal(args.Path)
if err != nil {
return api.OnLoadResult{}, err
}
contents := `import wasm from ` + string(bytes) + `
export default (imports) =>
WebAssembly.instantiate(wasm, imports).then(
result => result.instance.exports)`
return api.OnLoadResult{Contents: &contents}, nil
})
// Virtual modules in the "wasm-binary" namespace contain the
// actual bytes of the WebAssembly file. This uses esbuild's
// built-in "binary" loader instead of manually embedding the
// binary data inside JavaScript code ourselves.
build.OnLoad(api.OnLoadOptions{Filter: `.*`, Namespace: "wasm-binary"},
func(args api.OnLoadArgs) (api.OnLoadResult, error) {
bytes, err := ioutil.ReadFile(args.Path)
if err != nil {
return api.OnLoadResult{}, err
}
contents := string(bytes)
return api.OnLoadResult{
Contents: &contents,
Loader: api.LoaderBinary,
}, nil
})
},
}
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outfile: "out.js",
Plugins: []api.Plugin{wasmPlugin},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
The plugin works in multiple steps. First, a resolve callback captures `.wasm` paths in normal modules and moves them to the `wasm-stub` namespace. Then load callback for the `wasm-stub` namespace generates a JavaScript stub module that exports the loader function and imports the `.wasm` path. This invokes the resolve callback again which this time moves the path to the `wasm-binary` namespace. Then the second load callback for the `wasm-binary` namespace causes the WebAssembly file to be loaded using the `binary` loader, which tells esbuild to embed the file itself in the bundle.
### Svelte plugin
*This example demonstrates: supporting a compile-to-JavaScript language, reporting warnings and errors, integrating source maps.*
This plugin allows you to bundle `.svelte` files, which are from the [Svelte](https://svelte.dev/) framework. You write code in an HTML-like syntax that is then converted to JavaScript by the Svelte compiler. Svelte code looks something like this:
```
<script>
let a = 1;
let b = 2;
</script>
<input type="number" bind:value={a}>
<input type="number" bind:value={b}>
<p>{a} + {b} = {a + b}</p>
```
Compiling this code with the Svelte compiler generates a JavaScript module that depends on the `svelte/internal` package and that exports the component as a a single class using the `default` export. This means `.svelte` files can be compiled independently, which makes Svelte a good fit for an esbuild plugin. This plugin is triggered by importing a `.svelte` file like this:
```
import Button from './button.svelte'
```
Here's the code for the plugin (there is no Go version of this plugin because the Svelte compiler is written in JavaScript):
```
import * as esbuild from 'esbuild'
import * as svelte from 'svelte/compiler.mjs'
import path from 'node:path'
import fs from 'node:fs'
let sveltePlugin = {
name: 'svelte',
setup(build) {
build.onLoad({ filter: /\.svelte$/ }, async (args) => {
// This converts a message in Svelte's format to esbuild's format
let convertMessage = ({ message, start, end }) => {
let location
if (start && end) {
let lineText = source.split(/\r\n|\r|\n/g)[start.line - 1]
let lineEnd = start.line === end.line ? end.column : lineText.length
location = {
file: filename,
line: start.line,
column: start.column,
length: lineEnd - start.column,
lineText,
}
}
return { text: message, location }
}
// Load the file from the file system
let source = await fs.promises.readFile(args.path, 'utf8')
let filename = path.relative(process.cwd(), args.path)
// Convert Svelte syntax to JavaScript
try {
let { js, warnings } = svelte.compile(source, { filename })
let contents = js.code + `//# sourceMappingURL=` + js.map.toUrl()
return { contents, warnings: warnings.map(convertMessage) }
} catch (e) {
return { errors: [convertMessage(e)] }
}
})
}
}
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
plugins: [sveltePlugin],
})
```
This plugin only needs a load callback, not a resolve callback, because it's simple enough that it just needs to transform the loaded code into JavaScript without worrying about where the code comes from.
It appends a `//# sourceMappingURL=` comment to the generated JavaScript to tell esbuild how to map the generated JavaScript back to the original source code. If source maps are enabled during the build, esbuild will use this to ensure that the generated positions in the final source map are mapped all the way back to the original Svelte file instead of to the intermediate JavaScript code.
Plugin API limitations
----------------------
This API does not intend to cover all use cases. It's not possible to hook into every part of the bundling process. For example, it's not currently possible to modify the AST directly. This restriction exists to preserve the excellent performance characteristics of esbuild as well as to avoid exposing too much API surface which would be a maintenance burden and would prevent improvements that involve changing the AST.
One way to think about esbuild is as a "linker" for the web. Just like a linker for native code, esbuild's job is to take a set of files, resolve and bind references between them, and generate a single file containing all of the code linked together. A plugin's job is to generate the individual files that end up being linked.
Plugins in esbuild work best when they are relatively scoped and only customize a small aspect of the build. For example, a plugin for a special configuration file in a custom format (e.g. YAML) is very appropriate. The more plugins you use, the slower your build will get, especially if your plugin is written in JavaScript. If a plugin applies to every file in your build, then your build will likely be very slow. If caching is applicable, it must be done by the plugin itself.
| programming_docs |
esbuild FAQ FAQ
===
This is a collection of common questions about esbuild. You can also ask questions on the [GitHub issue tracker](https://github.com/evanw/esbuild/issues).
* [Why is esbuild fast?](#why-is-esbuild-fast)
* [Benchmark details](#benchmark-details)
* [Upcoming roadmap](#upcoming-roadmap)
* [Production readiness](#production-readiness)
* [Anti-virus software](#anti-virus-software)
Why is esbuild fast?
--------------------
Several reasons:
* It's written in [Go](https://go.dev/) and compiles to native code.
Most other bundlers are written in JavaScript, but a command-line application is a worst-case performance situation for a JIT-compiled language. Every time you run your bundler, the JavaScript VM is seeing your bundler's code for the first time without any optimization hints. While esbuild is busy parsing your JavaScript, node is busy parsing your bundler's JavaScript. By the time node has finished parsing your bundler's code, esbuild might have already exited and your bundler hasn't even started bundling yet.
In addition, Go is designed from the core for parallelism while JavaScript is not. Go has shared memory between threads while JavaScript has to serialize data between threads. Both Go and JavaScript have parallel garbage collectors, but Go's heap is shared between all threads while JavaScript has a separate heap per JavaScript thread. This seems to cut the amount of parallelism that's possible with JavaScript worker threads in half [according to my testing](https://github.com/evanw/esbuild/issues/111#issuecomment-719910381), presumably since half of your CPU cores are busy collecting garbage for the other half.
* Parallelism is used heavily.
The algorithms inside esbuild are carefully designed to fully saturate all available CPU cores when possible. There are roughly three phases: parsing, linking, and code generation. Parsing and code generation are most of the work and are fully parallelizable (linking is an inherently serial task for the most part). Since all threads share memory, work can easily be shared when bundling different entry points that import the same JavaScript libraries. Most modern computers have many cores so parallelism is a big win.
* Everything in esbuild is written from scratch.
There are a lot of performance benefits with writing everything yourself instead of using 3rd-party libraries. You can have performance in mind from the beginning, you can make sure everything uses consistent data structures to avoid expensive conversions, and you can make wide architectural changes whenever necessary. The drawback is of course that it's a lot of work.
For example, many bundlers use the official TypeScript compiler as a parser. But it was built to serve the goals of the TypeScript compiler team and they do not have performance as a top priority. Their code makes pretty heavy use of [megamorphic object shapes](https://mrale.ph/blog/2015/01/11/whats-up-with-monomorphism.html) and unnecessary [dynamic property accesses](https://github.com/microsoft/TypeScript/issues/39247) (both well-known JavaScript speed bumps). And the TypeScript parser appears to still run the type checker even when type checking is disabled. None of these are an issue with esbuild's custom TypeScript parser.
* Memory is used efficiently.
Compilers are ideally mostly O(n) complexity in the length of the input. So if you are processing a lot of data, memory access speed is likely going to heavily affect performance. The fewer passes you have to make over your data (and also the fewer different representations you need to transform your data into), the faster your compiler will go.
For example, esbuild only touches the whole JavaScript AST three times:
1. A pass for lexing, parsing, scope setup, and declaring symbols
2. A pass for binding symbols, minifying syntax, JSX/TS to JS, and ESNext-to-ES2015
3. A pass for minifying identifiers, minifying whitespace, generating code, and generating source maps This maximizes reuse of AST data while it's still hot in the CPU cache. Other bundlers do these steps in separate passes instead of interleaving them. They may also convert between data representations to glue multiple libraries together (e.g. string→TS→JS→string, then string→JS→older JS→string, then string→JS→minified JS→string) which uses more memory and slows things down.
Another benefit of Go is that it can store things compactly in memory, which enables it to use less memory and fit more in the CPU cache. All object fields have types and fields are packed tightly together so e.g. several boolean flags only take one byte each. Go also has value semantics and can embed one object directly in another so it comes "for free" without another allocation. JavaScript doesn't have these features and also has other drawbacks such as JIT overhead (e.g. hidden class slots) and inefficient representations (e.g. non-integer numbers are heap-allocated with pointers).
Each one of these factors is only a somewhat significant speedup, but together they can result in a bundler that is multiple orders of magnitude faster than other bundlers commonly in use today.
Benchmark details
-----------------
Here are the details about each benchmark:
JavaScript benchmarkThis benchmark approximates a large JavaScript codebase by duplicating the [three.js](https://github.com/mrdoob/three.js) library 10 times and building a single bundle from scratch, without any caches. The benchmark can be run with `make bench-three` in the [esbuild repo](https://github.com/evanw/esbuild).
| Bundler | Time | Relative slowdown | Absolute speed | Output size |
| --- | --- | --- | --- | --- |
| esbuild | 0.37s | 1x | 1479.6 kloc/s | 5.80mb |
| parcel 2 | 30.50s | 80x | 17.9 kloc/s | 5.87mb |
| rollup + terser | 32.07s | 84x | 17.1 kloc/s | 5.81mb |
| webpack 5 | 39.70s | 104x | 13.8 kloc/s | 5.84mb |
Each time reported is the best of three runs. I'm running esbuild with `--bundle --minify --sourcemap`. I used the [`@rollup/plugin-terser`](https://github.com/rollup/plugins/tree/master/packages/terser) plugin because Rollup itself doesn't support minification. Webpack 5 uses `--mode=production --devtool=sourcemap`. Parcel 2 uses the default options. Absolute speed is based on the total line count including comments and blank lines, which is currently 547,441. The tests were done on a 6-core 2019 MacBook Pro with 16gb of RAM and with [macOS Spotlight](https://en.wikipedia.org/wiki/Spotlight_(software)) disabled.
TypeScript benchmarkThis benchmark uses the old [Rome](https://github.com/rome/tools) code base (prior to their Rust rewrite) to approximate a large TypeScript codebase. All code must be combined into a single minified bundle with source maps and the resulting bundle must work correctly. The benchmark can be run with `make bench-rome` in the [esbuild repo](https://github.com/evanw/esbuild).
| Bundler | Time | Relative slowdown | Absolute speed | Output size |
| --- | --- | --- | --- | --- |
| esbuild | 0.10s | 1x | 1318.4 kloc/s | 0.97mb |
| parcel 2 | 8.18s | 82x | 16.1 kloc/s | 0.97mb |
| webpack 5 | 15.96s | 160x | 8.3 kloc/s | 1.27mb |
Each time reported is the best of three runs. I'm running esbuild with `--bundle --minify --sourcemap --platform=node`. Webpack 5 uses [`ts-loader`](https://github.com/TypeStrong/ts-loader) with `transpileOnly: true` and `--mode=production --devtool=sourcemap`. Parcel 2 uses `"engines": "node"` in `package.json`. Absolute speed is based on the total line count including comments and blank lines, which is currently 131,836. The tests were done on a 6-core 2019 MacBook Pro with 16gb of RAM and with [macOS Spotlight](https://en.wikipedia.org/wiki/Spotlight_(software)) disabled.
The results don't include Rollup because I couldn't get it to work for reasons relating to TypeScript compilation. I tried [`@rollup/plugin-typescript`](https://github.com/rollup/plugins/tree/master/packages/typescript) but you can't disable type checking, and I tried [`@rollup/plugin-sucrase`](https://github.com/rollup/plugins/tree/master/packages/sucrase) but there's no way to provide a `tsconfig.json` file (which is required for correct path resolution).
Upcoming roadmap
----------------
These features are already in progress and are first priority:
* Code splitting ([#16](https://github.com/evanw/esbuild/issues/16), [docs](../api/index#splitting))
* CSS content type ([#20](https://github.com/evanw/esbuild/issues/20), [docs](../content-types/index#css))
* Plugin API ([#111](https://github.com/evanw/esbuild/issues/111))
These are potential future features but may not happen or may happen to a more limited extent:
* HTML content type ([#31](https://github.com/evanw/esbuild/issues/31))
* Lowering to ES5 ([#297](https://github.com/evanw/esbuild/issues/297))
* Bundling top-level await ([#253](https://github.com/evanw/esbuild/issues/253))
After that point, I will consider esbuild to be relatively complete. I'm planning for esbuild to reach a mostly stable state and then stop accumulating more features. This will involve saying "no" to requests for adding major features to esbuild itself. I don't think esbuild should become an all-in-one solution for all frontend needs. In particular, I want to avoid the pain and problems of the "webpack config" model where the underlying tool is too flexible and usability suffers.
For example, I am *not* planning to include these features in esbuild's core itself:
* Support for other frontend languages (e.g. [Elm](https://elm-lang.org/), [Svelte](https://svelte.dev/), [Vue](https://vuejs.org/), [Angular](https://angular.io/))
* TypeScript type checking (just run `tsc` separately)
* An API for custom AST manipulation
* Hot-module reloading
* Module federation
I hope that the extensibility points I'm adding to esbuild ([plugins](../plugins/index) and the [API](../api/index)) will make esbuild useful to include as part of more customized build workflows, but I'm not intending or expecting these extensibility points to cover all use cases. If you have very custom requirements then you should be using other tools. I also hope esbuild inspires other build tools to dramatically improve performance by overhauling their implementations so that everyone can benefit, not just those that use esbuild.
I am planning to continue to maintain everything in esbuild's existing scope even after esbuild reaches stability. This means implementing support for newly-released JavaScript and TypeScript syntax features, for example.
Production readiness
--------------------
This project has not yet hit version 1.0.0 and is still in active development. That said, it is far beyond the alpha stage and is pretty stable. I think of it as a late-stage beta. For some early-adopters that means it's good enough to use for real things. Some other people think this means esbuild isn't ready yet. This section doesn't try to convince you either way. It just tries to give you enough information so you can decide for yourself whether you want to use esbuild as your bundler.
Some data points:
* **Used by other projects** The API is already being used as a library within many other developer tools. For example, [Vite](https://vitejs.dev/) and [Snowpack](https://www.snowpack.dev/) are using esbuild to transform TypeScript into JavaScript and [Amazon CDK](https://aws.amazon.com/cdk/) (Cloud Development Kit) and [Phoenix](https://www.phoenixframework.org/) are using esbuild to bundle code.
* **API stability** Even though esbuild's version is not yet 1.0.0, effort is still made to keep the API stable. Patch versions are intended for backwards-compatible changes and minor versions are intended for backwards-incompatible changes. If you plan to use esbuild for something real, you should either pin the exact version (maximum safety) or pin the major and minor versions (only accept backwards-compatible upgrades).
* **Only one main developer** This tool is primarily built by [me](https://github.com/evanw). For some people this is fine, but for others this means esbuild is not a suitable tool for their organization. That's ok with me. I'm building esbuild because I find it fun to build and because it's the tool I'd want to use. I'm sharing it with the world because there are others that want to use it too, because the feedback makes the tool itself better, and because I think it will inspire the ecosystem to make better tools.
* **Not always open to scope expansion** I'm not planning on including major features that I'm not interested in building and/or maintaining. I also want to limit the project's scope so it doesn't get too complex and unwieldy, both from an architectural perspective, a testing and correctness perspective, and from a usability perspective. Think of esbuild as a "linker" for the web. It knows how to transform and bundle JavaScript and CSS. But the details of how your source code ends up as plain JavaScript or CSS may need to be 3rd-party code.
I'm hoping that [plugins](../plugins/index) will allow the community to add major features (e.g. WebAssembly import) without needing to contribute to esbuild itself. However, not everything is exposed in the plugin API and it may be the case that it's not possible to add a particular feature to esbuild that you may want to add. This is intentional; esbuild is not meant to be an all-in-one solution for all frontend needs.
Anti-virus software
-------------------
Since esbuild is written in native code, anti-virus software can sometimes incorrectly flag it as a virus. *This does not mean esbuild is a virus.* I do not publish malicious code and I take supply chain security very seriously.
Virtually all of esbuild's code is first-party code except for [one dependency](https://github.com/evanw/esbuild/blob/main/go.mod) on Google's set of supplemental Go packages. My development work is done on different machine that is isolated from the one I use to publish builds. I have done additional work to ensure that esbuild's published builds are completely reproducible and after every release, published builds are [automatically compared](https://github.com/evanw/esbuild/blob/main/.github/workflows/validate.yml) to ones locally-built in an unrelated environment to ensure that they are bitwise identical (i.e. that the Go compiler itself has not been compromised). You can also build esbuild from source yourself and compare your build artifacts to the published ones to independently verify this.
Having to deal with false-positives is an unfortunate reality of using anti-virus software. Here are some possible workarounds if your anti-virus won't let you use esbuild:
* Ignore your anti-virus software and remove esbuild from quarantine
* Report the specific esbuild native executable as a false-positive to your anti-virus software vendor
* Use [`esbuild-wasm`](../getting-started/index#wasm) instead of `esbuild` to bypass your anti-virus software (which likely won't flag WebAssembly files the same way it flags native executables)
* Use another build tool instead of esbuild
esbuild Getting Started Getting Started
===============
Install esbuild
---------------
First, download and install the esbuild command locally. A prebuilt native executable can be installed using [npm](https://docs.npmjs.com/cli/v8/commands/npm-install) (which is automatically installed when you install the [node](https://nodejs.org/) JavaScript runtime):
```
npm install --save-exact esbuild
```
This should have installed esbuild in your local `node_modules` folder. You can run the esbuild executable to verify that everything is working correctly:
```
./node_modules/.bin/esbuild --version
```
```
.\node_modules\.bin\esbuild --version
```
The recommended way to install esbuild is to install the native executable using npm. But if you don't want to do that, there are also some [other ways to install](#other-ways-to-install).
Your first bundle
-----------------
This is a quick real-world example of what esbuild is capable of and how to use it. First, install the `react` and `react-dom` packages:
```
npm install react react-dom
```
Then create a file called `app.jsx` containing the following code:
```
import * as React from 'react'
import * as Server from 'react-dom/server'
let Greet = () => <h1>Hello, world!</h1>
console.log(Server.renderToString(<Greet />))
```
Finally, tell esbuild to bundle the file:
```
./node_modules/.bin/esbuild app.jsx --bundle --outfile=out.js
```
```
.\node_modules\.bin\esbuild app.jsx --bundle --outfile=out.js
```
This should have created a file called `out.js` containing your code and the React library bundled together. The code is completely self-contained and no longer depends on your `node_modules` directory. If you run the code using `node out.js`, you should see something like this:
```
<h1 data-reactroot="">Hello, world!</h1>
```
Notice that esbuild also converted JSX syntax to JavaScript without any configuration other than the `.jsx` extension. While esbuild can be configured, it attempts to have reasonable defaults so that many common situations work automatically. If you would like to use JSX syntax in `.js` files instead, you can tell esbuild to allow this using the `--loader:.js=jsx` flag. You can read more about the available configuration options in the [API documentation](../api/index).
Build scripts
-------------
Your build command is something you will be running repeatedly, so you will want to automate it. A natural way of doing this is to add a build script to your `package.json` file like this:
```
{
"scripts": {
"build": "esbuild app.jsx --bundle --outfile=out.js"
}
}
```
Notice that this uses the `esbuild` command directly without a relative path. This works because everything in the `scripts` section is run with the `esbuild` command already in the path (as long as you have [installed the package](#install-esbuild)).
The build script can be invoked like this:
```
npm run build
```
However, using the command-line interface can become unwieldy if you need to pass many options to esbuild. For more sophisticated uses you will likely want to write a build script in JavaScript using esbuild's JavaScript API. That might look something like this (note that this code must be saved in a file with the `.mjs` extension because it uses the `import` keyword):
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.jsx'],
bundle: true,
outfile: 'out.js',
})
```
The `build` function runs the esbuild executable in a child process and returns a promise that resolves when the build is complete. There is also a `buildSync` API that is not asynchronous, but the asynchronous API is better for build scripts because [plugins](../plugins/index) only work with the asynchronous API. You can read more about the configuration options for the build API in the [API documentation](../api/index#build).
Bundling for the browser
------------------------
The bundler outputs code for the browser by default, so no additional configuration is necessary to get started. For development builds you probably want to enable [source maps](../api/index#sourcemap) with `--sourcemap`, and for production builds you probably want to enable [minification](../api/index#minify) with `--minify`. You probably also want to configure the [target](../api/index#target) environment for the browsers you support so that JavaScript syntax which is too new will be transformed into older JavaScript syntax. All of that might looks something like this:
```
esbuild app.jsx --bundle --minify --sourcemap --target=chrome58,firefox57,safari11,edge16
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.jsx'],
bundle: true,
minify: true,
sourcemap: true,
target: ['chrome58', 'firefox57', 'safari11', 'edge16'],
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.jsx"},
Bundle: true,
MinifyWhitespace: true,
MinifyIdentifiers: true,
MinifySyntax: true,
Engines: []api.Engine{
{api.EngineChrome, "58"},
{api.EngineFirefox, "57"},
{api.EngineSafari, "11"},
{api.EngineEdge, "16"},
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Some npm packages you want to use may not be designed to be run in the browser. Sometimes you can use esbuild's configuration options to work around certain issues and successfully bundle the package anyway. Undefined globals can be replaced with either the [define](../api/index#define) feature in simple cases or the [inject](../api/index#inject) feature in more complex cases.
Bundling for node
-----------------
Even though a bundler is not necessary when using node, sometimes it can still be beneficial to process your code with esbuild before running it in node. Bundling can automatically strip TypeScript types, convert ECMAScript module syntax to CommonJS, and transform newer JavaScript syntax into older syntax for a specific version of node. And it may be beneficial to bundle your package before publishing it so that it's a smaller download and so it spends less time reading from the file system when being loaded.
If you are bundling code that will be run in node, you should configure the [platform](../api/index#platform) setting by passing `--platform=node` to esbuild. This simultaneously changes a few different settings to node-friendly default values. For example, all packages that are built-in to node such as `fs` are automatically marked as external so esbuild doesn't try to bundle them. This setting also disables the interpretation of the browser field in `package.json`.
If your code uses newer JavaScript syntax that doesn't work in your version of node, you will want to configure the [target](../api/index#target) version of node:
```
esbuild app.js --bundle --platform=node --target=node10.4
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
platform: 'node',
target: ['node10.4'],
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Platform: api.PlatformNode,
Engines: []api.Engine{
{api.EngineNode, "10.4"},
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
You also may not want to bundle your dependencies with esbuild. There are many node-specific features that esbuild doesn't support while bundling such as `__dirname`, `import.meta.url`, `fs.readFileSync`, and `*.node` native binary modules. You can exclude all of your dependencies from the bundle by setting [packages](../api/index#packages) to external:
```
esbuild app.jsx --bundle --platform=node --packages=external
```
```
require('esbuild').buildSync({
entryPoints: ['app.jsx'],
bundle: true,
platform: 'node',
packages: 'external',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.jsx"},
Bundle: true,
Platform: api.PlatformNode,
Packages: api.PackagesExternal,
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
If you do this, your dependencies must still be present on the file system at run-time since they are no longer included in the bundle.
Simultaneous platforms
----------------------
You cannot install esbuild on one OS, copy the `node_modules` directory to another OS without reinstalling, and then run esbuild on that other OS. This won't work because esbuild is written with native code and needs to install a platform-specific binary executable. Normally this isn't an issue because you typically check your `package.json` file into version control, not your `node_modules` directory, and then everyone runs `npm install` on their local machine after cloning the repository.
However, people sometimes get into this situation by installing esbuild on Windows or macOS and copying their `node_modules` directory into a [Docker](https://www.docker.com/) image that runs Linux, or by copying their `node_modules` directory between Windows and [WSL](https://docs.microsoft.com/en-us/windows/wsl/) environments. The way to get this to work depends on your package manager:
* **npm/pnpm:** If you are installing with npm or pnpm, you can try not copying the `node_modules` directory when you copy the files over, and running `npm ci` or `npm install` on the destination platform after the copy. Or you could consider using [Yarn](https://yarnpkg.com/) instead which has built-in support for installing a package on multiple platforms simultaneously.
* **Yarn:** If you are installing with Yarn, you can try listing both this platform and the other platform in your `.yarnrc.yml` file using [the `supportedArchitectures` feature](https://yarnpkg.com/configuration/yarnrc/#supportedArchitectures). Keep in mind that this means multiple copies of esbuild will be present on the file system.
You can also get into this situation on a macOS computer with an ARM processor if you install esbuild using the ARM version of npm but then try to run esbuild with the x86-64 version of node running inside of [Rosetta](https://en.wikipedia.org/wiki/Rosetta_(software)). In that case, an easy fix is to run your code using the ARM version of node instead, which can be downloaded here: <https://nodejs.org/en/download/>.
Another alternative is to [use the `esbuild-wasm` package instead](#wasm), which works the same way on all platforms. But it comes with a heavy performance cost and can sometimes be 10x slower than the `esbuild` package, so you may also not want to do that.
Using Yarn Plug'n'Play
----------------------
Yarn's [Plug'n'Play](https://yarnpkg.com/features/pnp/) package installation strategy is supported natively by esbuild. To use it, make sure you are running esbuild such that the [current working directory](../api/index#working-directory) contains Yarn's generated package manifest JavaScript file (either `.pnp.cjs` or `.pnp.js`). If a Yarn Plug'n'Play package manifest is detected, esbuild will automatically resolve package imports to paths inside the `.zip` files in Yarn's package cache, and will automatically extract these files on the fly during bundling.
Because esbuild is written in Go, support for Yarn Plug'n'Play has been completely re-implemented in Go instead of relying on Yarn's JavaScript API. This allows Yarn Plug'n'Play package resolution to integrate well with esbuild's fully parallelized bundling pipeline for maximum speed. Note that Yarn's command-line interface adds a lot of unavoidable performance overhead to every command. For maximum esbuild performance, you may want to consider running esbuild without using Yarn's CLI (i.e. not using `yarn esbuild`). This can result in esbuild running 10x faster.
Other ways to install
---------------------
The recommended way to install esbuild is to [install the native executable using npm](#install-esbuild). But you can also install esbuild in these ways:
### Download a build
If you have a Unix system, you can use the following command to download the `esbuild` binary executable for your current platform (it will be downloaded to the current working directory):
```
curl -fsSL https://esbuild.github.io/dl/v0.17.2 | sh
```
You can also use `latest` instead of the version number to download the most recent version of esbuild:
```
curl -fsSL https://esbuild.github.io/dl/latest | sh
```
If you don't want to evaluate a shell script from the internet to download esbuild, you can also manually download the package from npm yourself instead (which is all the above shell script is doing). Although the precompiled native executables are hosted using npm, you don't actually need npm installed to download them. The npm package registry is a normal HTTP server and packages are normal gzipped tar files.
Here is an example of downloading a binary executable directly:
```
curl -O https://registry.npmjs.org/@esbuild/darwin-x64/-/darwin-x64-0.17.2.tgz
tar xzf ./darwin-x64-0.17.2.tgz
./package/bin/esbuild
Usage:
esbuild [options] [entry points]
...
```
The native executable in the `@esbuild/darwin-x64` package is for the macOS operating system and the 64-bit Intel architecture. As of writing, this is the full list of native executable packages for the platforms esbuild supports:
| Package name | OS | Architecture | Download |
| --- | --- | --- | --- |
| [`@esbuild/android-arm`](https://www.npmjs.org/package/@esbuild/android-arm) | `android` | `arm` | |
| [`@esbuild/android-arm64`](https://www.npmjs.org/package/@esbuild/android-arm64) | `android` | `arm64` | |
| [`@esbuild/android-x64`](https://www.npmjs.org/package/@esbuild/android-x64) | `android` | `x64` | |
| [`@esbuild/darwin-arm64`](https://www.npmjs.org/package/@esbuild/darwin-arm64) | `darwin` | `arm64` | |
| [`@esbuild/darwin-x64`](https://www.npmjs.org/package/@esbuild/darwin-x64) | `darwin` | `x64` | |
| [`@esbuild/freebsd-arm64`](https://www.npmjs.org/package/@esbuild/freebsd-arm64) | `freebsd` | `arm64` | |
| [`@esbuild/freebsd-x64`](https://www.npmjs.org/package/@esbuild/freebsd-x64) | `freebsd` | `x64` | |
| [`@esbuild/linux-arm`](https://www.npmjs.org/package/@esbuild/linux-arm) | `linux` | `arm` | |
| [`@esbuild/linux-arm64`](https://www.npmjs.org/package/@esbuild/linux-arm64) | `linux` | `arm64` | |
| [`@esbuild/linux-ia32`](https://www.npmjs.org/package/@esbuild/linux-ia32) | `linux` | `ia32` | |
| [`@esbuild/linux-loong64`](https://www.npmjs.org/package/@esbuild/linux-loong64) | `linux` | `loong64`2 | |
| [`@esbuild/linux-mips64el`](https://www.npmjs.org/package/@esbuild/linux-mips64el) | `linux` | `mips64el`2 | |
| [`@esbuild/linux-ppc64`](https://www.npmjs.org/package/@esbuild/linux-ppc64) | `linux` | `ppc64` | |
| [`@esbuild/linux-riscv64`](https://www.npmjs.org/package/@esbuild/linux-riscv64) | `linux` | `riscv64`2 | |
| [`@esbuild/linux-s390x`](https://www.npmjs.org/package/@esbuild/linux-s390x) | `linux` | `s390x` | |
| [`@esbuild/linux-x64`](https://www.npmjs.org/package/@esbuild/linux-x64) | `linux` | `x64` | |
| [`@esbuild/netbsd-x64`](https://www.npmjs.org/package/@esbuild/netbsd-x64) | `netbsd`1 | `x64` | |
| [`@esbuild/openbsd-x64`](https://www.npmjs.org/package/@esbuild/openbsd-x64) | `openbsd` | `x64` | |
| [`@esbuild/sunos-x64`](https://www.npmjs.org/package/@esbuild/sunos-x64) | `sunos` | `x64` | |
| [`@esbuild/win32-arm64`](https://www.npmjs.org/package/@esbuild/win32-arm64) | `win32` | `arm64` | |
| [`@esbuild/win32-ia32`](https://www.npmjs.org/package/@esbuild/win32-ia32) | `win32` | `ia32` | |
| [`@esbuild/win32-x64`](https://www.npmjs.org/package/@esbuild/win32-x64) | `win32` | `x64` | |
**Why this is not recommended:** This approach only works on Unix systems that can run shell scripts, so it will require [WSL](https://learn.microsoft.com/en-us/windows/wsl/) on Windows. An additional drawback is that you cannot use [plugins](../plugins/index) with the native version of esbuild.
If you choose to write your own code to download esbuild directly from npm, then you are relying on internal implementation details of esbuild's native executable installer. These details may change at some point, in which case this approach will no longer work for new esbuild versions. This is only a minor drawback though since the approach should still work forever for existing esbuild versions (packages published to npm are immutable).
### Install the WASM version
In addition to the `esbuild` npm package, there is also an `esbuild-wasm` package that functions similarly but that uses WebAssembly instead of native code. Installing it will also install an executable called `esbuild`:
```
npm install --save-exact esbuild-wasm
```
**Why this is not recommended:** The WebAssembly version is much, much slower than the native version. In many cases it is an order of magnitude (i.e. 10x) slower. This is for various reasons including a) node re-compiles the WebAssembly code from scratch on every run, b) Go's WebAssembly compilation approach is single-threaded, and c) node has WebAssembly bugs that can delay the exiting of the process by many seconds. The WebAssembly version also excludes some features such as the local file server. You should only use the WebAssembly package like this if there is no other option, such as when you want to use esbuild on an unsupported platform. The WebAssembly package is primarily intended to only be used [in the browser](../api/index#browser).
### Deno instead of node
There is also basic support for the [Deno](https://deno.land) JavaScript environment if you'd like to use esbuild with that instead. The package is hosted at <https://deno.land/x/esbuild> and uses the native esbuild executable. The executable will be downloaded and cached from npm at run-time so your computer will need network access to registry.npmjs.org to make use of this package. Using the package looks like this:
```
import * as esbuild from 'https://deno.land/x/[email protected]/mod.js'
let ts = 'let test: boolean = true'
let result = await esbuild.transform(ts, { loader: 'ts' })
console.log('result:', result)
esbuild.stop()
```
It has basically the same API as esbuild's npm package with one addition: you need to call `stop()` when you're done because unlike node, Deno doesn't provide the necessary APIs to allow Deno to exit while esbuild's internal child process is still running.
If you would like to use esbuild's WebAssembly implementation instead of esbuild's native implementation with Deno, you can do that by importing `wasm.js` instead of `mod.js` like this:
```
import * as esbuild from 'https://deno.land/x/[email protected]/wasm.js'
let ts = 'let test: boolean = true'
let result = await esbuild.transform(ts, { loader: 'ts' })
console.log('result:', result)
esbuild.stop()
```
Using WebAssembly instead of native means you do not need to specify Deno's `--allow-run` permission, and WebAssembly the only option in situations where the file system is unavailable such as with [Deno Deploy](https://deno.com/deploy). However, keep in mind that the WebAssembly version of esbuild is a lot slower than the native version. Another thing to know about WebAssembly is that Deno currently has a bug where process termination is unnecessarily delayed until all loaded WebAssembly modules are fully optimized, which can take many seconds. You may want to manually call `Deno.exit(0)` after your code is done if you are writing a short-lived script that uses esbuild's WebAssembly implementation so that your code exits in a reasonable timeframe.
**Why this is not recommended:** Deno is newer than node, less widely used, and supports fewer platforms than node, so node is recommended as the primary way to run esbuild. Deno also uses the internet as a package system instead of existing JavaScript package ecosystems, and esbuild is designed around and optimized for npm-style package management. You should still be able to use esbuild with Deno, but you will need a plugin if you would like to be able to bundle HTTP URLs.
### Build from source
To build esbuild from source:
1. Install the Go compiler: <https://go.dev/dl/>
2. Download the source code for esbuild:
```
git clone --depth 1 --branch v0.17.2 https://github.com/evanw/esbuild.git
cd esbuild
```
3. Build the `esbuild` executable (it will be `esbuild.exe` on Windows):
```
go build ./cmd/esbuild
```
If you want to build for other platforms, you can just prefix the build command with the platform information. For example, you can build the 32-bit Linux version using this command:
```
GOOS=linux GOARCH=386 go build ./cmd/esbuild
```
**Why this is not recommended:** The native version can only be used via the command-line interface, which can be unergonomic for complex use cases and which does not support [plugins](../plugins/index). You will need to write JavaScript or Go code and use [esbuild's API](../api/index) to use plugins.
| programming_docs |
esbuild API API
===
The API can be accessed in one of three languages: on the command line, in JavaScript, and in Go. The concepts and parameters are largely identical between the three languages so they will be presented together here instead of having separate documentation for each language. You can switch between languages using the `CLI`, `JS`, and `Go` tabs in the top-right corner of each code example. Some specifics for each language:
* **CLI:** If you are using the command-line API, it may be helpful to know that the flags come in one of three forms: `--foo`, `--foo=bar`, or `--foo:bar`. The form `--foo` is used for enabling boolean flags such as [`--minify`](#minify), the form `--foo=bar` is used for flags that have a single value and are only specified once such as [`--platform=`](#platform), and the form `--foo:bar` is used for flags that have multiple values and can be re-specified multiple times such as [`--external:`](#external).
* **JavaScript:** If you are using JavaScript be sure to check out the [JS-specific details](#js-details) and [browser](#browser) sections below. You may also find the [TypeScript type definitions](https://github.com/evanw/esbuild/blob/main/lib/shared/types.ts) for esbuild helpful as a reference.
* **Go:** If you are using Go, you may find the automatically generated Go documentation for esbuild helpful as a reference. There is separate documentation for both of the public Go packages: [`pkg/api`](https://pkg.go.dev/github.com/evanw/esbuild/pkg/api) and [`pkg/cli`](https://pkg.go.dev/github.com/evanw/esbuild/pkg/cli).
Overview
--------
The two most commenly-used esbuild APIs are [build](#build) and [transform](#transform). Each is described below at a high level, followed by documentation for each individual API option.
### Build
This is the primary interface to esbuild. You typically pass one or more [entry point](#entry-points) files to process along with various options, and then esbuild writes the results back out to the file system. Here's a simple example that enables [bundling](#bundle) with an [output directory](#outdir):
```
esbuild app.ts --bundle --outdir=dist
```
```
import * as esbuild from 'esbuild'
let result = await esbuild.build({
entryPoints: ['app.ts'],
bundle: true,
outdir: 'dist',
})
console.log(result)
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Bundle: true,
Outdir: "dist",
})
if len(result.Errors) != 0 {
os.Exit(1)
}
}
```
Advanced use of the build API involves setting up a long-running build context. This context is an explicit object in JS and Go but is implicit with the CLI. All builds done with a given context share the same build options, and subsequent builds are done incrementally (i.e. they reuse some work from previous builds to improve performance). This is useful for development because esbuild can rebuild your app in the background for you while you work.
There are three different incremental build APIs:
* [**Watch mode**](#watch) tells esbuild to watch the file system and automatically rebuild for you whenever you edit and save a file that could invalidate the build. Here's an example:
```
esbuild app.ts --bundle --outdir=dist --watch
[watch] build finished, watching for changes...
```
```
let ctx = await esbuild.context({
entryPoints: ['app.ts'],
bundle: true,
outdir: 'dist',
})
await ctx.watch()
```
```
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Bundle: true,
Outdir: "dist",
})
err2 := ctx.Watch(api.WatchOptions{})
```
* [**Serve mode**](#serve) starts a local development server that serves the results of the latest build. Incoming requests automatically start new builds so your web app is always up to date when you reload the page in the browser. Here's an example:
```
esbuild app.ts --bundle --outdir=dist --serve
> Local: http://127.0.0.1:8000/
> Network: http://192.168.0.1:8000/
127.0.0.1:61302 - "GET /" 200 [1ms]
```
```
let ctx = await esbuild.context({
entryPoints: ['app.ts'],
bundle: true,
outdir: 'dist',
})
let { host, port } = await ctx.serve()
```
```
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Bundle: true,
Outdir: "dist",
})
server, err2 := ctx.Serve(api.ServeOptions{})
```
* [**Rebuild mode**](#rebuild) lets you manually invoke a build. This is useful when integrating esbuild with other tools (e.g. using a custom file watcher or development server instead of esbuild's built-in ones). Here's an example:
```
# The CLI does not have an API for "rebuild"
```
```
let ctx = await esbuild.context({
entryPoints: ['app.ts'],
bundle: true,
outdir: 'dist',
})
for (let i = 0; i < 5; i++) {
let result = await ctx.rebuild()
}
```
```
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Bundle: true,
Outdir: "dist",
})
for i := 0; i < 5; i++ {
result := ctx.Rebuild()
}
```
These three incremental build APIs can be combined. To enable [live reloading](#live-reload) (automatically reloading the page when you edit and save a file) you'll need to enable [watch](#watch) and [serve](#serve) together on the same context.
When you are done with a context object, you can call `dispose()` on the context to wait for existing builds to finish, stop watch and/or serve mode, and free up resources.
The build and context APIs both take the following options:
**General options:*** [Bundle](#bundle)
* [Cancel](#cancel)
* [Live reload](#live-reload)
* [Platform](#platform)
* [Rebuild](#rebuild)
* [Serve](#serve)
* [Tsconfig](#tsconfig)
* [Watch](#watch)
**Input:*** [Entry points](#entry-points)
* [Loader](#loader)
* [Stdin](#stdin)
**Output contents:*** [Banner](#banner)
* [Charset](#charset)
* [Footer](#footer)
* [Format](#format)
* [Global name](#global-name)
* [Legal comments](#legal-comments)
* [Splitting](#splitting)
**Output location:*** [Allow overwrite](#allow-overwrite)
* [Asset names](#asset-names)
* [Chunk names](#chunk-names)
* [Entry names](#entry-names)
* [Out extension](#out-extension)
* [Outbase](#outbase)
* [Outdir](#outdir)
* [Outfile](#outfile)
* [Public path](#public-path)
* [Write](#write)
**Path resolution:*** [Alias](#alias)
* [Conditions](#conditions)
* [External](#external)
* [Main fields](#main-fields)
* [Node paths](#node-paths)
* [Packages](#packages)
* [Preserve symlinks](#preserve-symlinks)
* [Resolve extensions](#resolve-extensions)
* [Working directory](#working-directory)
**Transformation:*** [JSX](#jsx)
* [JSX dev](#jsx-dev)
* [JSX factory](#jsx-factory)
* [JSX fragment](#jsx-fragment)
* [JSX import source](#jsx-import-source)
* [JSX side effects](#jsx-side-effects)
* [Supported](#supported)
* [Target](#target)
**Optimization:*** [Define](#define)
* [Drop](#drop)
* [Ignore annotations](#ignore-annotations)
* [Inject](#inject)
* [Keep names](#keep-names)
* [Mangle props](#mangle-props)
* [Minify](#minify)
* [Pure](#pure)
* [Tree shaking](#tree-shaking)
**Source maps:*** [Source root](#source-root)
* [Sourcefile](#sourcefile)
* [Sourcemap](#sourcemap)
* [Sources content](#sources-content)
**Build metadata:*** [Analyze](#analyze)
* [Metafile](#metafile)
**Logging:*** [Color](#color)
* [Format messages](#format-messages)
* [Log level](#log-level)
* [Log limit](#log-limit)
* [Log override](#log-override)
### Transform
This is a limited special-case of [build](#build) that transforms a string of code representing an in-memory file in an isolated environment that's completely disconnected from any other files. Common uses include minifying code and transforming TypeScript into JavaScript. Here's an example:
```
echo 'let x: number = 1' | esbuild --loader=ts
let x = 1;
```
```
import * as esbuild from 'esbuild'
let ts = 'let x: number = 1'
let result = await esbuild.transform(ts, {
loader: 'ts',
})
console.log(result)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
ts := "let x: number = 1"
result := api.Transform(ts, api.TransformOptions{
Loader: api.LoaderTS,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
Taking a string instead of a file as input is more ergonomic for certain use cases. File system isolation has certain advantages (e.g. works in the browser, not affected by nearby `package.json` files) and certain disadvantages (e.g. can't be used with [bundling](#bundle) or [plugins](../plugins/index)). If your use case doesn't fit the transform API then you should use the more general [build](#build) API instead.
The transform API takes the following options:
**General options:*** [Platform](#platform)
* [Tsconfig raw](#tsconfig-raw)
**Input:*** [Loader](#loader)
**Output contents:*** [Banner](#banner)
* [Charset](#charset)
* [Footer](#footer)
* [Format](#format)
* [Global name](#global-name)
* [Legal comments](#legal-comments)
**Transformation:*** [JSX](#jsx)
* [JSX dev](#jsx-dev)
* [JSX factory](#jsx-factory)
* [JSX fragment](#jsx-fragment)
* [JSX import source](#jsx-import-source)
* [JSX side effects](#jsx-side-effects)
* [Supported](#supported)
* [Target](#target)
**Optimization:*** [Define](#define)
* [Drop](#drop)
* [Ignore annotations](#ignore-annotations)
* [Keep names](#keep-names)
* [Mangle props](#mangle-props)
* [Minify](#minify)
* [Pure](#pure)
* [Tree shaking](#tree-shaking)
**Source maps:*** [Source root](#source-root)
* [Sourcefile](#sourcefile)
* [Sourcemap](#sourcemap)
* [Sources content](#sources-content)
**Logging:*** [Color](#color)
* [Format messages](#format-messages)
* [Log level](#log-level)
* [Log limit](#log-limit)
* [Log override](#log-override)
### JS-specific details
The JS API for esbuild comes in both asynchronous and synchronous flavors. The [asynchronous API](#js-async) is recommended because it works in all environments and it's faster and more powerful. The [synchronous API](#js-sync) only works in node and can only do certain things, but it's sometimes necessary in certain node-specific situations. In detail:
#### Async API
Asynchronous API calls return their results using a promise. Note that you'll likely have to use the `.mjs` file extension in node due to the use of the `import` and top-level `await` keywords:
```
import * as esbuild from 'esbuild'
let result1 = await esbuild.transform(code, options)
let result2 = await esbuild.build(options)
```
Pros:
* You can use [plugins](../plugins/index) with the asynchronous API
* The current thread is not blocked so you can perform other work in the meantime
* You can run many simultaneous esbuild API calls concurrently which are then spread across all available CPUs for maximum performance
Cons:
* Using promises can result in messier code, especially in CommonJS where [top-level await](https://v8.dev/features/top-level-await) is not available
* Doesn't work in situations that must be synchronous such as within [`require.extensions`](https://nodejs.org/api/modules.html#requireextensions)
#### Sync API
Synchronous API calls return their results inline:
```
let esbuild = require('esbuild')
let result1 = esbuild.transformSync(code, options)
let result2 = esbuild.buildSync(options)
```
Pros:
* Avoiding promises can result in cleaner code, especially when [top-level await](https://v8.dev/features/top-level-await) is not available
* Works in situations that must be synchronous such as within [`require.extensions`](https://nodejs.org/api/modules.html#requireextensions)
Cons:
* You can't use [plugins](../plugins/index) with the synchronous API since plugins are asynchronous
* It blocks the current thread so you can't perform other work in the meantime
* Using the synchronous API prevents esbuild from parallelizing esbuild API calls
### In the browser
The esbuild API can also run in the browser using WebAssembly in a Web Worker. To take advantage of this you will need to install the `esbuild-wasm` package instead of the `esbuild` package:
```
npm install esbuild-wasm
```
The API for the browser is similar to the API for node except that you need to call `initialize()` first, and you need to pass the URL of the WebAssembly binary. The synchronous versions of the API are also not available. Assuming you are using a bundler, that would look something like this:
```
import * as esbuild from 'esbuild-wasm'
await esbuild.initialize({
wasmURL: './node_modules/esbuild-wasm/esbuild.wasm',
})
let result1 = await esbuild.transform(code, options)
let result2 = esbuild.build(options)
```
If you're already running this code from a worker and don't want `initialize` to create another worker, you can pass `worker: false` to it. Then it will create a WebAssembly module in the same thread as the thread that calls `initialize`.
You can also use esbuild's API as a script tag in a HTML file without needing to use a bundler by loading the `lib/browser.min.js` file with a `<script>` tag. In this case the API creates a global called `esbuild` that holds the API object:
```
<script src="./node_modules/esbuild-wasm/lib/browser.min.js"></script>
<script>
esbuild.initialize({
wasmURL: './node_modules/esbuild-wasm/esbuild.wasm',
}).then(() => {
...
})
</script>
```
If you want to use this API with ECMAScript modules, you should import the `esm/browser.min.js` file instead:
```
<script type="module">
import * as esbuild from './node_modules/esbuild-wasm/esm/browser.min.js'
await esbuild.initialize({
wasmURL: './node_modules/esbuild-wasm/esbuild.wasm',
})
...
</script>
```
General options
---------------
### Bundle
*Supported by: [Build](#build)*
To bundle a file means to inline any imported dependencies into the file itself. This process is recursive so dependencies of dependencies (and so on) will also be inlined. By default esbuild will *not* bundle the input files. Bundling must be explicitly enabled like this:
```
esbuild in.js --bundle
```
```
import * as esbuild from 'esbuild'
console.log(await esbuild.build({
entryPoints: ['in.js'],
bundle: true,
outfile: 'out.js',
}))
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"in.js"},
Bundle: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Refer to the [getting started guide](../getting-started/index#your-first-bundle) for an example of bundling with real-world code.
Note that bundling is different than file concatenation. Passing esbuild multiple input files with bundling enabled will create multiple separate bundles instead of joining the input files together. To join a set of files together with esbuild, import them all into a single entry point file and bundle just that one file with esbuild.
#### Non-analyzable imports
Bundling with esbuild only works with statically-defined imports (i.e. when the import path is a string literal). Imports that are defined at run-time (i.e. imports that depend on run-time code evaluation) are not bundled, since bundling is a compile-time operation. For example:
```
// Analyzable imports (will be bundled by esbuild)
import 'pkg';
import('pkg');
require('pkg');
// Non-analyzable imports (will not be bundled by esbuild)
import(`pkg/${foo}`);
require(`pkg/${foo}`);
['pkg'].map(require);
```
The way to work around this issue is to mark the package containing this problematic code as [external](#external) so that it's not included in the bundle. You will then need to ensure that a copy of the external package is available to your bundled code at run-time.
Some bundlers such as [Webpack](https://webpack.js.org/) try to support this by including all potentially-reachable files in the bundle and then emulating a file system at run-time. However, run-time file system emulation is out of scope and will not be implemented in esbuild. If you really need to bundle code that does this, you will likely need to use another bundler instead of esbuild.
### Cancel
*Supported by: [Build](#build)*
If you are using [rebuild](#rebuild) to manually invoke incremental builds, you may want to use this cancel API to end the current build early so that you can start a new one. You can do that like this:
```
# The CLI does not have an API for "cancel"
```
```
import * as esbuild from 'esbuild'
import process from 'node:process'
let ctx = await esbuild.context({
entryPoints: ['app.ts'],
bundle: true,
outdir: 'www',
logLevel: 'info',
})
// Whenever we get some data over stdin
process.stdin.on('data', async () => {
try {
// Cancel the already-running build
await ctx.cancel()
// Then start a new build
console.log('build:', await ctx.rebuild())
} catch (err) {
console.error(err)
}
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Bundle: true,
Outdir: "www",
LogLevel: api.LogLevelInfo,
})
if err != nil {
os.Exit(1)
}
// Whenever we get some data over stdin
buf := make([]byte, 100)
for {
if n, err := os.Stdin.Read(buf); err != nil || n == 0 {
break
}
go func() {
// Cancel the already-running build
ctx.Cancel()
// Then start a new build
result := ctx.Rebuild()
fmt.Fprintf(os.Stderr, "build: %v\n", result)
}()
}
}
```
Make sure to wait until the cancel operation is done before starting a new build (i.e. `await` the returned promise when using JavaScript), otherwise the next [rebuild](#rebuild) will give you the just-canceled build that still hasn't ended yet. Note that plugin [on-end callbacks](../plugins/index#on-end) will still be run regardless of whether or not the build was canceled.
### Live reload
*Supported by: [Build](#build)*
Live reload is an approach to development where you have your browser open and visible at the same time as your code editor. When you edit and save your source code, the browser automatically reloads and the reloaded version of the app contains your changes. This means you can iterate faster because you don't have to manually switch to your browser, reload, and then switch back to your code editor after every change. It's very helpful when changing CSS, for example.
There is no esbuild API for live reloading directly. Instead, you can construct live reloading by combining [watch mode](#watch) (to automatically start a build when you edit and save a file) and [serve mode](#serve) (to serve the latest build, but block until it's done) plus a small bit of client-side JavaScript code that you add to your app only during development.
The first step is to enable [watch](#watch) and [serve](#serve) together:
```
esbuild app.ts --bundle --outdir=www --watch --servedir=www
```
```
import * as esbuild from 'esbuild'
let ctx = await esbuild.context({
entryPoints: ['app.ts'],
bundle: true,
outdir: 'www',
})
await ctx.watch()
let { host, port } = await ctx.serve({
servedir: 'www',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Bundle: true,
Outdir: "www",
})
if err != nil {
os.Exit(1)
}
err2 := ctx.Watch(api.WatchOptions{})
if err2 != nil {
os.Exit(1)
}
result, err3 := ctx.Serve(api.ServeOptions{
Servedir: "www",
})
if err3 != nil {
os.Exit(1)
}
}
```
The second step is to add some code to your JavaScript that subscribes to the `/esbuild` [server-sent event](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events) source. When you get the `change` event, you can reload the page to get the latest version of the app. You can do this in a single line of code:
```
new EventSource('/esbuild').addEventListener('change', () => location.reload())
```
That's it! If you load your app in the browser, the page should now automatically reload when you edit and save a file (assuming there are no build errors).
This should only be included during development, and should not be included in production. One way to remove this code in production is to guard it with an if statement such as `if (!window.IS_PRODUCTION)` and then use [define](#define) to set `window.IS_PRODUCTION` to `true` in production.
#### Live reload caveats
Implementing live reloading like this has a few known caveats:
* These events only trigger when esbuild's output changes. They do not trigger when files unrelated to the build being watched are changed. If your HTML file references other files that esbuild doesn't know about and those files are changed, you can either manually reload the page or you can implement your own live reloading infrastructure instead of using esbuild's built-in behavior.
* The `EventSource` API is supposed to automatically reconnect for you. However, there's [a bug in Firefox](https://bugzilla.mozilla.org/show_bug.cgi?id=1809332) that breaks this if the server is ever temporarily unreachable. Workarounds are to use any other browser, to manually reload the page if this happens, or to write more complicated code that manually closes and re-creates the `EventSource` object if there is a connection error.
* Browser vendors have decided to not implement HTTP/2 without TLS. This means that when using the `http://` protocol, each `/esbuild` event source will take up one of your precious 6 simultaneous per-domain HTTP/1.1 connections. So if you open more than six HTTP tabs that use this live-reloading technique, you will be unable to use live reloading in some of those tabs (and other things will likely also break). The workaround is to [enable the `https://` protocol](#https).
#### Hot-reloading for CSS
The `change` event also contains additional information to enable more advanced use cases. It currently contains the `added`, `removed`, and `updated` arrays with the paths of the files that have changed since the previous build, which can be described by the following TypeScript interface:
```
interface ChangeEvent {
added: string[]
removed: string[]
updated: string[]
}
```
The code sample below enables "hot reloading" for CSS, which is when the CSS is automatically updated in place without reloading the page. If an event arrives that isn't CSS-related, then the whole page will be reloaded as a fallback:
```
new EventSource('/esbuild').addEventListener('change', e => {
const { added, removed, updated } = JSON.parse(e.data)
if (!added.length && !removed.length && updated.length === 1) {
for (const link of document.getElementsByTagName("link")) {
const url = new URL(link.href)
if (url.host === location.host && url.pathname === updated[0]) {
const next = link.cloneNode()
next.href = updated[0] + '?' + Math.random().toString(36).slice(2)
next.onload = () => link.remove()
link.parentNode.insertBefore(next, link.nextSibling)
return
}
}
}
location.reload()
})
```
#### Hot-reloading for JavaScript
Hot-reloading for JavaScript is not currently implemented by esbuild. It's possible to transparently implement hot-reloading for CSS because CSS is stateless, but JavaScript is stateful so you cannot transparently implement hot-reloading for JavaScript like you can for CSS.
Some other development servers implement hot-reloading for JavaScript anyway, but it requires additional APIs, sometimes requires framework-specific hacks, and sometimes introduces transient state-related bugs during an editing session. Doing this is outside of esbuild's scope. You are welcome to use other tools instead of esbuild if hot-reloading for JavaScript is one of your requirements.
However, with esbuild's live-reloading you can persist your app's current JavaScript state in [`sessionStorage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/sessionStorage) to more easily restore your app's JavaScript state after a page reload. If your app loads quickly (which it already should for your users' sake), live-reloading with JavaScript can be almost as fast as hot-reloading with JavaScript would be.
### Platform
*Supported by: [Build](#build) and [Transform](#transform)*
By default, esbuild's bundler is configured to generate code intended for the browser. If your bundled code is intended to run in node instead, you should set the platform to `node`:
```
esbuild app.js --bundle --platform=node
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
platform: 'node',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Platform: api.PlatformNode,
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
When the platform is set to `browser` (the default value):
* When [bundling](#bundle) is enabled the default output [format](#format) is set to `iife`, which wraps the generated JavaScript code in an immediately-invoked function expression to prevent variables from leaking into the global scope.
* If a package specifies a map for the [`browser`](https://gist.github.com/defunctzombie/4339901/49493836fb873ddaa4b8a7aa0ef2352119f69211) field in its `package.json` file, esbuild will use that map to replace specific files or modules with their browser-friendly versions. For example, a package might contain a substitution of [`path`](https://nodejs.org/api/path.html) with [`path-browserify`](https://www.npmjs.com/package/path-browserify).
* The [main fields](#main-fields) setting is set to `browser,module,main` but with some additional special behavior: if a package provides `module` and `main` entry points but not a `browser` entry point then `main` is used instead of `module` if that package is ever imported using `require()`. This behavior improves compatibility with CommonJS modules that export a function by assigning it to `module.exports`. If you want to disable this additional special behavior, you can explicitly set the [main fields](#main-fields) setting to `browser,module,main`.
* The [conditions](#conditions) setting automatically includes the `browser` condition. This changes how the `exports` field in `package.json` files is interpreted to prefer browser-specific code.
* If no custom [conditions](#conditions) are configured, the Webpack-specific `module` condition is also included. The `module` condition is used by package authors to provide a tree-shakable ESM alternative to a CommonJS file without creating a [dual package hazard](https://nodejs.org/api/packages.html#dual-package-hazard). You can prevent the `module` condition from being included by explicitly configuring some custom conditions (even an empty list).
* When using the [build](#build) API, all `process.env.NODE_ENV` expressions are automatically [defined](#define) to `"production"` if all [minification](#minify) options are enabled and `"development"` otherwise. This only happens if `process`, `process.env`, and `process.env.NODE_ENV` are not already defined. This substitution is necessary to avoid React-based code crashing instantly (since `process` is a node API, not a web API).
* The character sequence `</script>` will be escaped in JavaScript code and the character sequence `</style>` will be escaped in CSS code. This is done in case you inline esbuild's output directly into an HTML file. This can be disabled with esbuild's [supported](#supported) feature by setting `inline-script` (for JavaScript) and/or `inline-style` (for CSS) to `false`.
When the platform is set to `node`:
* When [bundling](#bundle) is enabled the default output [format](#format) is set to `cjs`, which stands for CommonJS (the module format used by node). ES6-style exports using `export` statements will be converted into getters on the CommonJS `exports` object.
* All [built-in node modules](https://nodejs.org/docs/latest/api/) such as `fs` are automatically marked as [external](#external) so they don't cause errors when the bundler tries to bundle them.
* The [main fields](#main-fields) setting is set to `main,module`. This means tree shaking will likely not happen for packages that provide both `module` and `main` since tree shaking works with ECMAScript modules but not with CommonJS modules.
Unfortunately some packages incorrectly treat `module` as meaning "browser code" instead of "ECMAScript module code" so this default behavior is required for compatibility. You can manually configure the [main fields](#main-fields) setting to `module,main` if you want to enable tree shaking and know it is safe to do so.
* The [conditions](#conditions) setting automatically includes the `node` condition. This changes how the `exports` field in `package.json` files is interpreted to prefer node-specific code.
* If no custom [conditions](#conditions) are configured, the Webpack-specific `module` condition is also included. The `module` condition is used by package authors to provide a tree-shakable ESM alternative to a CommonJS file without creating a [dual package hazard](https://nodejs.org/api/packages.html#dual-package-hazard). You can prevent the `module` condition from being included by explicitly configuring some custom conditions (even an empty list).
* When the [format](#format) is set to `cjs` but the entry point is ESM, esbuild will add special annotations for any named exports to enable importing those named exports using ESM syntax from the resulting CommonJS file. Node's documentation has more information about [node's detection of CommonJS named exports](https://nodejs.org/api/esm.html#commonjs-namespaces).
* The [`binary`](../content-types/index#binary) loader will make use of node's built-in [`Buffer.from`](https://nodejs.org/api/buffer.html#static-method-bufferfromstring-encoding) API to decode the base64 data embedded in the bundle into a `Uint8Array`. This is faster than what esbuild can do otherwise since it's implemented by node in native code.
When the platform is set to `neutral`:
* When [bundling](#bundle) is enabled the default output [format](#format) is set to `esm`, which uses the `export` syntax introduced with ECMAScript 2015 (i.e. ES6). You can change the output format if this default is not appropriate.
* The [main fields](#main-fields) setting is empty by default. If you want to use npm-style packages, you will likely have to configure this to be something else such as `main` for the standard main field used by node.
* The [conditions](#conditions) setting does not automatically include any platform-specific values.
See also [bundling for the browser](../getting-started/index#bundling-for-the-browser) and [bundling for node](../getting-started/index#bundling-for-node).
### Rebuild
*Supported by: [Build](#build)*
You may want to use this API if your use case involves calling esbuild's [build](#build) API repeatedly with the same options. For example, this is useful if you are implementing your own file watcher service. Rebuilding is more efficient than building again because some of the data from the previous build is cached and can be reused if the original files haven't changed since the previous build. There are currently two forms of caching used by the rebuild API:
* Files are stored in memory and are not re-read from the file system if the file metadata hasn't changed since the last build. This optimization only applies to file system paths. It does not apply to virtual modules created by [plugins](../plugins/index).
* Parsed [ASTs](https://en.wikipedia.org/wiki/Abstract_syntax_tree) are stored in memory and re-parsing the AST is avoided if the file contents haven't changed since the last build. This optimization applies to virtual modules created by plugins in addition to file system modules, as long as the virtual module path remains the same.
Here's how to do a rebuild:
```
# The CLI does not have an API for "rebuild"
```
```
import * as esbuild from 'esbuild'
let ctx = await esbuild.context({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
})
// Call "rebuild" as many times as you want
for (let i = 0; i < 5; i++) {
let result = await ctx.rebuild()
}
// Call "dispose" when you're done to free up resources
ctx.dispose()
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outfile: "out.js",
})
if err != nil {
os.Exit(1)
}
// Call "Rebuild" as many times as you want
for i := 0; i < 5; i++ {
result := ctx.Rebuild()
if len(result.Errors) > 0 {
os.Exit(1)
}
}
// Call "Dispose" when you're done to free up resources
ctx.Dispose()
}
```
### Serve
*Supported by: [Build](#build)*
If you want your app to automatically reload as you edit, you should read about [live reloading](#live-reload). It combines serve mode with [watch mode](#watch) to listen for changes to the file system.
Serve mode starts a web server that serves your code to your browser on your device. Here's an example that bundles `src/app.ts` into `www/js/app.js` and then also serves the `www` directory over `http://localhost:8000/`:
```
esbuild src/app.ts --outdir=www/js --bundle --servedir=www
```
```
import * as esbuild from 'esbuild'
let ctx = await esbuild.context({
entryPoints: ['src/app.ts'],
outdir: 'www/js',
bundle: true,
})
let { host, port } = await ctx.serve({
servedir: 'www',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"src/app.ts"},
Outdir: "www/js",
Bundle: true,
})
if err != nil {
os.Exit(1)
}
server, err2 := ctx.Serve(api.ServeOptions{
Servedir: "www",
})
if err2 != nil {
os.Exit(1)
}
// Returning from main() exits immediately in Go.
// Block forever so we keep serving and don't exit.
<-make(chan struct{})
}
```
If you create the file `www/index.html` with the following contents, the code contained in `src/app.ts` will load when you navigate to `http://localhost:8000/`:
```
<script src="js/app.js"></script>
```
One benefit of using esbuild's built-in web server instead of another web server is that whenever you reload, the files that esbuild serves are always up to date. That's not necessarily the case with other development setups. One common setup is to run a local file watcher that rebuilds output files whenever their input files change, and then separately to run a local file server to serve those output files. But that means reloading after an edit may reload the old output files if the rebuild hasn't finished yet. With esbuild's web server, each incoming request starts a rebuild if one is not already in progress, and then waits for the current rebuild to complete before serving the file. This means esbuild never serves stale build results.
Note that this web server is intended to only be used in development. *Do not use this in production.*
#### Arguments
The arguments to the serve API are as follows:
```
# Enable serve mode
--serve
# Set the port
--serve=9000
# Set the host and port (IPv4)
--serve=127.0.0.1:9000
# Set the host and port (IPv6)
--serve=[::1]:9000
# Set the directory to serve
--servedir=www
# Enable HTTPS
--keyfile=your.key --certfile=your.cert
```
```
interface ServeOptions {
port?: number
host?: string
servedir?: string
keyfile?: string
certfile?: string
onRequest?: (args: ServeOnRequestArgs) => void
}
interface ServeOnRequestArgs {
remoteAddress: string
method: string
path: string
status: number
timeInMS: number
}
```
```
type ServeOptions struct {
Port uint16
Host string
Servedir string
Keyfile string
Certfile string
OnRequest func(ServeOnRequestArgs)
}
type ServeOnRequestArgs struct {
RemoteAddress string
Method string
Path string
Status int
TimeInMS int
}
```
* `host` By default, esbuild makes the web server available on all IPv4 network interfaces. This corresponds to a host address of `0.0.0.0`. If you would like to configure a different host (for example, to only serve on the `127.0.0.1` loopback interface without exposing anything to the network), you can specify the host using this argument.
If you need to use IPv6 instead of IPv4, you just need to specify an IPv6 host address. The equivalent to the `127.0.0.1` loopback interface in IPv6 is `::1` and the equivalent to the `0.0.0.0` universal interface in IPv6 is `::`.
* `port` The HTTP port can optionally be configured here. If omitted, it will default to an open port with a preference for ports in the range 8000 to 8009.
* `servedir` This is a directory of extra content for esbuild's HTTP server to serve instead of a 404 when incoming requests don't match any of the generated output file paths. This lets you use esbuild as a general-purpose local web server.
For example, you might want to create an `index.html` file and then set `servedir` to `"."` to serve the current directory (which includes the `index.html` file). If you don't set `servedir` then esbuild will only serve the build results, but not any other files.
* `keyfile` and `certfile` If you pass a private key and certificate to esbuild using `keyfile` and `certfile`, then esbuild's web server will use the `https://` protocol instead of the `http://` protocol. See [enabling HTTPS](#https) for more information.
* `onRequest` This is called once for each incoming request with some information about the request. This callback is used by the CLI to print out a log message for each request. The time field is the time to generate the data for the request, but it does not include the time to stream the request to the client.
Note that this is called after the request has completed. It's not possible to use this callback to modify the request in any way. If you want to do this, you should [put a proxy in front of esbuild](#serve-proxy) instead.
#### Return values
```
# The CLI will print the host and port like this:
> Local: http://127.0.0.1:8000/
```
```
interface ServeResult {
host: string
port: number
}
```
```
type ServeResult struct {
Host string
Port uint16
}
```
* `host` This is the host that ended up being used by the web server. It will be `0.0.0.0` (i.e. serving on all available network interfaces) unless a custom host was configured. If you are using the CLI and the host is `0.0.0.0`, all available network interfaces will be printed as hosts instead.
* `port` This is the port that ended up being used by the web server. You'll want to use this if you don't specify a port since esbuild will end up picking an arbitrary open port, and you need to know which port it picked to be able to connect to it.
#### Enabling HTTPS
By default, esbuild's web server uses the `http://` protocol. However, certain modern web features are unavailable to HTTP websites. If you want to use these features, then you'll need to tell esbuild to use the `https://` protocol instead.
To enable HTTPS with esbuild:
1. Generate a self-signed certificate. There are many ways to do this. Here's one way, assuming you have the `openssl` command installed:
```
openssl req -x509 -newkey rsa:4096 -keyout your.key -out your.cert -days 9999 -nodes -subj /CN=127.0.0.1
```
2. Pass `your.key` and `your.cert` to esbuild using the `keyfile` and `certfile` [serve arguments](#serve-arguments).
3. Click past the scary warning in your browser when you load your page (self-signed certificates aren't secure, but that doesn't matter since we're just doing local development).
If you have more complex needs than this, you can still [put a proxy in front of esbuild](#serve-proxy) and use that for HTTPS instead. Note that if you see the message `Client sent an HTTP request to an HTTPS server` when you load your page, then you are using the incorrect protocol. Replace `http://` with `https://` in your browser's URL bar.
Keep in mind that esbuild's HTTPS support has nothing to do with security. The only reason to enable HTTPS in esbuild is because browsers have made it impossible to do local development with certain modern web features without jumping through these extra hoops. *Please do not use esbuild's development server for anything that needs to be secure.* It's only intended for local development and no considerations have been made for production environments whatsoever.
#### Customizing server behavior
It's not possible to hook into esbuild's local server to customize the behavior of the server itself. Instead, behavior should be customized by putting a proxy in front of esbuild.
Here's a simple example of a proxy server to get you started, using node's built-in [`http`](https://nodejs.org/api/http.html) module. It adds a custom 404 page instead of esbuild's default 404 page:
```
import * as esbuild from 'esbuild'
import http from 'node:http'
// Start esbuild's server on a random local port
let ctx = await esbuild.context({
// ... your build options go here ...
})
// The return value tells us where esbuild's local server is
let { host, port } = await ctx.serve({ servedir: '.' })
// Then start a proxy server on port 3000
http.createServer((req, res) => {
const options = {
hostname: host,
port: port,
path: req.url,
method: req.method,
headers: req.headers,
}
// Forward each incoming request to esbuild
const proxyReq = http.request(options, proxyRes => {
// If esbuild returns "not found", send a custom 404 page
if (proxyRes.statusCode === 404) {
res.writeHead(404, { 'Content-Type': 'text/html' })
res.end('<h1>A custom 404 page</h1>')
return
}
// Otherwise, forward the response from esbuild to the client
res.writeHead(proxyRes.statusCode, proxyRes.headers)
proxyRes.pipe(res, { end: true })
})
// Forward the body of the request to esbuild
req.pipe(proxyReq, { end: true })
}).listen(3000)
```
This code starts esbuild's server on random local port and then starts a proxy server on port 3000. During development you would load <http://localhost:3000> in your browser, which talks to the proxy. This example demonstrates modifying a response after esbuild has handled the request, but you can also modify or replace the request before esbuild has handled it.
You can do many things with a proxy like this including:
* Injecting your own 404 page (the example above)
* Customizing the mapping of routes to files on the file system
* Redirecting some routes to an API server instead of to esbuild
You can also use a real proxy such as [nginx](https://nginx.org/en/docs/beginners_guide.html#proxy) if you have more advanced needs.
### Tsconfig
*Supported by: [Build](#build)*
Normally the [build](#build) API automatically discovers `tsconfig.json` files and reads their contents during a build. However, you can also configure a custom `tsconfig.json` file to use instead. This can be useful if you need to do multiple builds of the same code with different settings:
```
esbuild app.ts --bundle --tsconfig=custom-tsconfig.json
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.ts'],
bundle: true,
tsconfig: 'custom-tsconfig.json',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Bundle: true,
Tsconfig: "custom-tsconfig.json",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Tsconfig raw
*Supported by: [Transform](#transform)*
This option can be used to pass your `tsconfig.json` file to the [transform](#transform) API, which doesn't access the file system. Using it looks like this:
```
echo 'class Foo { foo }' | esbuild --loader=ts --tsconfig-raw='{"compilerOptions":{"useDefineForClassFields":true}}'
```
```
import * as esbuild from 'esbuild'
let ts = 'class Foo { foo }'
let result = await esbuild.transform(ts, {
loader: 'ts',
tsconfigRaw: `{
"compilerOptions": {
"useDefineForClassFields": true,
},
}`,
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
ts := "class Foo { foo }"
result := api.Transform(ts, api.TransformOptions{
Loader: api.LoaderTS,
TsconfigRaw: `{
"compilerOptions": {
"useDefineForClassFields": true,
},
}`,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
### Watch
*Supported by: [Build](#build)*
Enabling watch mode tells esbuild to listen for changes on the file system and to automatically rebuild whenever a file changes that could invalidate the build. Using it looks like this:
```
esbuild app.js --outfile=out.js --bundle --watch
[watch] build finished, watching for changes...
```
```
import * as esbuild from 'esbuild'
let ctx = await esbuild.context({
entryPoints: ['app.js'],
outfile: 'out.js',
bundle: true,
})
await ctx.watch()
console.log('watching...')
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"app.js"},
Outfile: "out.js",
Bundle: true,
Write: true,
})
if err != nil {
os.Exit(1)
}
err2 := ctx.Watch(api.WatchOptions{})
if err2 != nil {
os.Exit(1)
}
fmt.Printf("watching...\n")
// Returning from main() exits immediately in Go.
// Block forever so we keep watching and don't exit.
<-make(chan struct{})
}
```
If you want to stop watch mode at some point in the future, you can call `dispose` on the context object to terminate the file watcher:
```
# Use Ctrl+C to stop the CLI in watch mode
```
```
import * as esbuild from 'esbuild'
let ctx = await esbuild.context({
entryPoints: ['app.js'],
outfile: 'out.js',
bundle: true,
})
await ctx.watch()
console.log('watching...')
await new Promise(r => setTimeout(r, 10 * 1000))
await ctx.dispose()
console.log('stopped watching')
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
import "os"
import "time"
func main() {
ctx, err := api.Context(api.BuildOptions{
EntryPoints: []string{"app.js"},
Outfile: "out.js",
Bundle: true,
Write: true,
})
if err != nil {
os.Exit(1)
}
err2 := ctx.Watch(api.WatchOptions{})
if err2 != nil {
os.Exit(1)
}
fmt.Printf("watching...\n")
time.Sleep(10 * time.Second)
ctx.Dispose()
fmt.Printf("stopped watching\n")
}
```
Watch mode in esbuild is implemented using polling instead of OS-specific file system APIs for portability. The polling system is designed to use relatively little CPU vs. a more traditional polling system that scans the whole directory tree at once. The file system is still scanned regularly but each scan only checks a random subset of your files, which means a change to a file will be picked up soon after the change is made but not necessarily instantly.
With the current heuristics, large projects should be completely scanned around every 2 seconds so in the worst case it could take up to 2 seconds for a change to be noticed. However, after a change has been noticed the change's path goes on a short list of recently changed paths which are checked on every scan, so further changes to recently changed files should be noticed almost instantly.
Note that it is still possible to implement watch mode yourself using esbuild's [rebuild](#rebuild) API and a file watcher library of your choice if you don't want to use a polling-based approach.
If you are using the CLI, keep in mind that watch mode will be terminated when esbuild's stdin is closed. This prevents esbuild from accidentally outliving the parent process and unexpectedly continuing to consume resources on the system. If you have a use case that requires esbuild to continue to watch forever even when the parent process has finished, you may use `--watch=forever` instead of `--watch`.
Input
-----
### Entry points
*Supported by: [Build](#build)*
This is an array of files that each serve as an input to the bundling algorithm. They are called "entry points" because each one is meant to be the initial script that is evaluated which then loads all other aspects of the code that it represents. Instead of loading many libraries in your page with `<script>` tags, you would instead use `import` statements to import them into your entry point (or into another file that is then imported into your entry point).
Simple apps only need one entry point but additional entry points can be useful if there are multiple logically-independent groups of code such as a main thread and a worker thread, or an app with separate relatively unrelated areas such as a landing page, an editor page, and a settings page. Separate entry points helps introduce separation of concerns and helps reduce the amount of unnecessary code that the browser needs to download. If applicable, enabling [code splitting](#splitting) can further reduce download sizes when browsing to a second page whose entry point shares some already-downloaded code with a first page that has already been visited.
The simple way to specify entry points is to just pass an array of file paths:
```
esbuild home.ts settings.ts --bundle --outdir=out
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['home.ts', 'settings.ts'],
bundle: true,
write: true,
outdir: 'out',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"home.ts", "settings.ts"},
Bundle: true,
Write: true,
Outdir: "out",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
This will generate two output files, `out/home.js` and `out/settings.js` corresponding to the two entry points `home.ts` and `settings.ts`.
For further control over how the paths of the output files are derived from the corresponding input entry points, you should look into these options:
* [Entry names](#entry-names)
* [Out extension](#out-extension)
* [Outbase](#outbase)
* [Outdir](#outdir)
* [Outfile](#outfile)
In addition, you can also specify a fully custom output path for each individual entry point using an alternative entry point syntax:
```
esbuild out1=home.ts out2=settings.ts --bundle --outdir=out
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: [
{ out: 'out1', in: 'home.ts'},
{ out: 'out2', in: 'settings.ts'},
],
bundle: true,
write: true,
outdir: 'out',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPointsAdvanced: []api.EntryPoint{{
OutputPath: "out1",
InputPath: "home.ts",
}, {
OutputPath: "out2",
InputPath: "settings.ts",
}},
Bundle: true,
Write: true,
Outdir: "out",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
This will generate two output files, `out/out1.js` and `out/out2.js` corresponding to the two entry points `home.ts` and `settings.ts`.
### Loader
*Supported by: [Build](#build) and [Transform](#transform)*
This option changes how a given input file is interpreted. For example, the [`js`](../content-types/index#javascript) loader interprets the file as JavaScript and the [`css`](../content-types/index#css) loader interprets the file as CSS. See the [content types](../content-types/index) page for a complete list of all built-in loaders.
Configuring a loader for a given file type lets you load that file type with an `import` statement or a `require` call. For example, configuring the `.png` file extension to use the [data URL](../content-types/index#data-url) loader means importing a `.png` file gives you a data URL containing the contents of that image:
```
import url from './example.png'
let image = new Image
image.src = url
document.body.appendChild(image)
import svg from './example.svg'
let doc = new DOMParser().parseFromString(svg, 'application/xml')
let node = document.importNode(doc.documentElement, true)
document.body.appendChild(node)
```
The above code can be bundled using the [build](#build) API call like this:
```
esbuild app.js --bundle --loader:.png=dataurl --loader:.svg=text
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
loader: {
'.png': 'dataurl',
'.svg': 'text',
},
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".png": api.LoaderDataURL,
".svg": api.LoaderText,
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
This option is specified differently if you are using the build API with input from [stdin](#stdin), since stdin does not have a file extension. Configuring a loader for stdin with the build API looks like this:
```
echo 'import pkg = require("./pkg")' | esbuild --loader=ts --bundle
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
stdin: {
contents: 'import pkg = require("./pkg")',
loader: 'ts',
resolveDir: '.',
},
bundle: true,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
Stdin: &api.StdinOptions{
Contents: "import pkg = require('./pkg')",
Loader: api.LoaderTS,
ResolveDir: ".",
},
Bundle: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
The [transform](#transform) API call just takes a single loader since it doesn't involve interacting with the file system, and therefore doesn't deal with file extensions. Configuring a loader (in this case the [`ts`](../content-types/index#typescript) loader) for the transform API looks like this:
```
echo 'let x: number = 1' | esbuild --loader=ts
let x = 1;
```
```
import * as esbuild from 'esbuild'
let ts = 'let x: number = 1'
let result = await esbuild.transform(ts, {
loader: 'ts',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
ts := "let x: number = 1"
result := api.Transform(ts, api.TransformOptions{
Loader: api.LoaderTS,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
### Stdin
*Supported by: [Build](#build)*
Normally the build API call takes one or more file names as input. However, this option can be used to run a build without a module existing on the file system at all. It's called "stdin" because it corresponds to piping a file to stdin on the command line.
In addition to specifying the contents of the stdin file, you can optionally also specify the resolve directory (used to determine where relative imports are located), the [sourcefile](#sourcefile) (the file name to use in error messages and source maps), and the [loader](#loader) (which determines how the file contents are interpreted). The CLI doesn't have a way to specify the resolve directory. Instead, it's automatically set to the current working directory.
Here's how to use this feature:
```
echo 'export * from "./another-file"' | esbuild --bundle --sourcefile=imaginary-file.js --loader=ts --format=cjs
```
```
import * as esbuild from 'esbuild'
let result = await esbuild.build({
stdin: {
contents: `export * from "./another-file"`,
// These are all optional:
resolveDir: './src',
sourcefile: 'imaginary-file.js',
loader: 'ts',
},
format: 'cjs',
write: false,
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
Stdin: &api.StdinOptions{
Contents: "export * from './another-file'",
// These are all optional:
ResolveDir: "./src",
Sourcefile: "imaginary-file.js",
Loader: api.LoaderTS,
},
Format: api.FormatCommonJS,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Output contents
---------------
### Banner
*Supported by: [Build](#build) and [Transform](#transform)*
Use this to insert an arbitrary string at the beginning of generated JavaScript and CSS files. This is commonly used to insert comments:
```
esbuild app.js --banner:js=//comment --banner:css=/*comment*/
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
banner: {
js: '//comment',
css: '/*comment*/',
},
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Banner: map[string]string{
"js": "//comment",
"css": "/*comment*/",
},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
This is similar to [footer](#footer) which inserts at the end instead of the beginning.
Note that if you are inserting non-comment code into a CSS file, be aware that CSS ignores all `@import` rules that come after a non-`@import` rule (other than a `@charset` rule), so using a banner to inject CSS rules may accidentally disable imports of external stylesheets.
### Charset
*Supported by: [Build](#build) and [Transform](#transform)*
By default esbuild's output is ASCII-only. Any non-ASCII characters are escaped using backslash escape sequences. One reason is because non-ASCII characters are misinterpreted by the browser by default, which causes confusion. You have to explicitly add `<meta charset="utf-8">` to your HTML or serve it with the correct `Content-Type` header for the browser to not mangle your code. Another reason is that non-ASCII characters can significantly [slow down the browser's parser](https://v8.dev/blog/scanner). However, using escape sequences makes the generated output slightly bigger, and also makes it harder to read.
If you would like for esbuild to print the original characters without using escape sequences and you have ensured that the browser will interpret your code as UTF-8, you can disable character escaping by setting the charset:
```
echo 'let π = Math.PI' | esbuild
let \u03C0 = Math.PI;
echo 'let π = Math.PI' | esbuild --charset=utf8
let π = Math.PI;
```
```
import * as esbuild from 'esbuild'
let js = 'let π = Math.PI'
(await esbuild.transform(js)).code
'let \\u03C0 = Math.PI;\n'
(await esbuild.transform(js, {
charset: 'utf8',
})).code
'let π = Math.PI;\n'
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "let π = Math.PI"
result1 := api.Transform(js, api.TransformOptions{})
if len(result1.Errors) == 0 {
fmt.Printf("%s", result1.Code)
}
result2 := api.Transform(js, api.TransformOptions{
Charset: api.CharsetUTF8,
})
if len(result2.Errors) == 0 {
fmt.Printf("%s", result2.Code)
}
}
```
Some caveats:
* This does not yet escape non-ASCII characters embedded in regular expressions. This is because esbuild does not currently parse the contents of regular expressions at all. The flag was added despite this limitation because it's still useful for code that doesn't contain cases like this.
* This flag does not apply to comments. I believe preserving non-ASCII data in comments should be fine because even if the encoding is wrong, the run time environment should completely ignore the contents of all comments. For example, the [V8 blog post](https://v8.dev/blog/scanner) mentions an optimization that avoids decoding comment contents completely. And all comments other than license-related comments are stripped out by esbuild anyway.
* This option simultaneously applies to all output file types (JavaScript, CSS, and JSON). So if you configure your web server to send the correct `Content-Type` header and want to use the UTF-8 charset, make sure your web server is configured to treat both `.js` and `.css` files as UTF-8.
### Footer
*Supported by: [Build](#build) and [Transform](#transform)*
Use this to insert an arbitrary string at the end of generated JavaScript and CSS files. This is commonly used to insert comments:
```
esbuild app.js --footer:js=//comment --footer:css=/*comment*/
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
footer: {
js: '//comment',
css: '/*comment*/',
},
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Footer: map[string]string{
"js": "//comment",
"css": "/*comment*/",
},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
This is similar to [banner](#banner) which inserts at the beginning instead of the end.
### Format
*Supported by: [Build](#build) and [Transform](#transform)*
This sets the output format for the generated JavaScript files. There are currently three possible values that can be configured: `iife`, `cjs`, and `esm`. When no output format is specified, esbuild picks an output format for you if [bundling](#bundle) is enabled (as described below), or doesn't do any format conversion if [bundling](#bundle) is disabled.
#### IIFE
The `iife` format stands for "immediately-invoked function expression" and is intended to be run in the browser. Wrapping your code in a function expression ensures that any variables in your code don't accidentally conflict with variables in the global scope. If your entry point has exports that you want to expose as a global in the browser, you can configure that global's name using the [global name](#global-name) setting. The `iife` format will automatically be enabled when no output format is specified, [bundling](#bundle) is enabled, and [platform](#platform) is set to `browser` (which it is by default). Specifying the `iife` format looks like this:
```
echo 'alert("test")' | esbuild --format=iife
(() => {
alert("test");
})();
```
```
import * as esbuild from 'esbuild'
let js = 'alert("test")'
let result = await esbuild.transform(js, {
format: 'iife',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "alert(\"test\")"
result := api.Transform(js, api.TransformOptions{
Format: api.FormatIIFE,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
#### CommonJS
The `cjs` format stands for "CommonJS" and is intended to be run in node. It assumes the environment contains `exports`, `require`, and `module`. Entry points with exports in ECMAScript module syntax will be converted to a module with a getter on `exports` for each export name. The `cjs` format will automatically be enabled when no output format is specified, [bundling](#bundle) is enabled, and [platform](#platform) is set to `node`. Specifying the `cjs` format looks like this:
```
echo 'export default "test"' | esbuild --format=cjs
...
var stdin_exports = {};
__export(stdin_exports, {
default: () => stdin_default
});
module.exports = __toCommonJS(stdin_exports);
var stdin_default = "test";
```
```
import * as esbuild from 'esbuild'
let js = 'export default "test"'
let result = await esbuild.transform(js, {
format: 'cjs',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "export default 'test'"
result := api.Transform(js, api.TransformOptions{
Format: api.FormatCommonJS,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
#### ESM
The `esm` format stands for "ECMAScript module". It assumes the environment supports `import` and `export` syntax. Entry points with exports in CommonJS module syntax will be converted to a single `default` export of the value of `module.exports`. The `esm` format will automatically be enabled when no output format is specified, [bundling](#bundle) is enabled, and [platform](#platform) is set to `neutral`. Specifying the `esm` format looks like this:
```
echo 'module.exports = "test"' | esbuild --format=esm
...
var require_stdin = __commonJS({
"<stdin>"(exports, module) {
module.exports = "test";
}
});
export default require_stdin();
```
```
import * as esbuild from 'esbuild'
let js = 'module.exports = "test"'
let result = await esbuild.transform(js, {
format: 'esm',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "module.exports = 'test'"
result := api.Transform(js, api.TransformOptions{
Format: api.FormatESModule,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
The `esm` format can be used either in the browser or in node, but you have to explicitly load it as a module. This happens automatically if you `import` it from another module. Otherwise:
* In the browser, you can load a module using `<script src="file.js" type="module"></script>`.
* In node, you can load a module using `node --experimental-modules file.mjs`. Note that node requires the `.mjs` extension unless you have configured `"type": "module"` in your `package.json` file. You can use the [out extension](#out-extension) setting in esbuild to customize the output extension for the files esbuild generates. You can read more about using ECMAScript modules in node [here](https://nodejs.org/api/esm.html).
### Global name
*Supported by: [Build](#build) and [Transform](#transform)*
This option only matters when the [format](#format) setting is `iife` (which stands for immediately-invoked function expression). It sets the name of the global variable which is used to store the exports from the entry point:
```
echo 'module.exports = "test"' | esbuild --format=iife --global-name=xyz
```
```
import * as esbuild from 'esbuild'
let js = 'module.exports = "test"'
let result = await esbuild.transform(js, {
format: 'iife',
globalName: 'xyz',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "module.exports = 'test'"
result := api.Transform(js, api.TransformOptions{
Format: api.FormatIIFE,
GlobalName: "xyz",
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
Specifying the global name with the `iife` format will generate code that looks something like this:
```
var xyz = (() => {
...
var require_stdin = __commonJS((exports, module) => {
module.exports = "test";
});
return require_stdin();
})();
```
The global name can also be a compound property expression, in which case esbuild will generate a global variable with that property. Existing global variables that conflict will not be overwritten. This can be used to implement "namespacing" where multiple independent scripts add their exports onto the same global object. For example:
```
echo 'module.exports = "test"' | esbuild --format=iife --global-name='example.versions["1.0"]'
```
```
import * as esbuild from 'esbuild'
let js = 'module.exports = "test"'
let result = await esbuild.transform(js, {
format: 'iife',
globalName: 'example.versions["1.0"]',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "module.exports = 'test'"
result := api.Transform(js, api.TransformOptions{
Format: api.FormatIIFE,
GlobalName: `example.versions["1.0"]`,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
The compound global name used above generates code that looks like this:
```
var example = example || {};
example.versions = example.versions || {};
example.versions["1.0"] = (() => {
...
var require_stdin = __commonJS((exports, module) => {
module.exports = "test";
});
return require_stdin();
})();
```
### Legal comments
*Supported by: [Build](#build) and [Transform](#transform)*
A "legal comment" is considered to be any statement-level comment in JS or rule-level comment in CSS that contains `@license` or `@preserve` or that starts with `//!` or `/*!`. These comments are preserved in output files by default since that follows the intent of the original authors of the code. However, this behavior can be configured by using one of the following options:
* `none`
Do not preserve any legal comments.
* `inline`
Preserve all legal comments.
* `eof`
Move all legal comments to the end of the file.
* `linked`
Move all legal comments to a `.LEGAL.txt` file and link to them with a comment.
* `external`
Move all legal comments to a `.LEGAL.txt` file but to not link to them.
The default behavior is `eof` when [bundling](#bundle) is enabled and `inline` otherwise. Setting the legal comment mode looks like this:
```
esbuild app.js --legal-comments=eof
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
legalComments: 'eof',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
LegalComments: api.LegalCommentsEndOfFile,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Note that "statement-level" for JS and "rule-level" for CSS means the comment must appear in a context where multiple statements or rules are allowed such as in the top-level scope or in a statement or rule block. So comments inside expressions or at the declaration level are not considered legal comments.
### Splitting
*Supported by: [Build](#build)*
Code splitting is still a work in progress. It currently only works with the `esm` output [format](#format). There is also a known [ordering issue](https://github.com/evanw/esbuild/issues/399) with `import` statements across code splitting chunks. You can follow [the tracking issue](https://github.com/evanw/esbuild/issues/16) for updates about this feature.
This enables "code splitting" which serves two purposes:
* Code shared between multiple entry points is split off into a separate shared file that both entry points import. That way if the user first browses to one page and then to another page, they don't have to download all of the JavaScript for the second page from scratch if the shared part has already been downloaded and cached by their browser.
* Code referenced through an asynchronous `import()` expression will be split off into a separate file and only loaded when that expression is evaluated. This allows you to improve the initial download time of your app by only downloading the code you need at startup, and then lazily downloading additional code if needed later.
Without code splitting enabled, an `import()` expression becomes `Promise.resolve().then(() => require())` instead. This still preserves the asynchronous semantics of the expression but it means the imported code is included in the same bundle instead of being split off into a separate file.
When you enable code splitting you must also configure the output directory using the [outdir](#outdir) setting:
```
esbuild home.ts about.ts --bundle --splitting --outdir=out --format=esm
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['home.ts', 'about.ts'],
bundle: true,
splitting: true,
outdir: 'out',
format: 'esm',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"home.ts", "about.ts"},
Bundle: true,
Splitting: true,
Outdir: "out",
Format: api.FormatESModule,
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Output location
---------------
### Allow overwrite
*Supported by: [Build](#build)*
Enabling this setting allows output files to overwrite input files. It's not enabled by default because doing so means overwriting your source code, which can lead to data loss if your code is not checked in. But supporting this makes certain workflows easier by avoiding the need for a temporary directory. So you can enable this when you want to deliberately overwrite your source code:
```
esbuild app.js --outdir=. --allow-overwrite
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
outdir: '.',
allowOverwrite: true,
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Outdir: ".",
AllowOverwrite: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Asset names
*Supported by: [Build](#build)*
This option controls the file names of the additional output files generated when the [loader](#loader) is set to [`file`](../content-types/index#external-file). It configures the output paths using a template with placeholders that will be substituted with values specific to the file when the output path is generated. For example, specifying an asset name template of `assets/[name]-[hash]` puts all assets into a subdirectory called `assets` inside of the output directory and includes the content hash of the asset in the file name. Doing that looks like this:
```
esbuild app.js --asset-names=assets/[name]-[hash] --loader:.png=file --bundle --outdir=out
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
assetNames: 'assets/[name]-[hash]',
loader: { '.png': 'file' },
bundle: true,
outdir: 'out',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
AssetNames: "assets/[name]-[hash]",
Loader: map[string]api.Loader{
".png": api.LoaderFile,
},
Bundle: true,
Outdir: "out",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
There are four placeholders that can be used in asset path templates:
* `[dir]` This is the relative path from the directory containing the asset file to the [outbase](#outbase) directory. Its purpose is to help asset output paths look more aesthetically pleasing by mirroring the input directory structure inside of the output directory.
* `[name]` This is the original file name of the asset without the extension. For example, if the asset was originally named `image.png` then `[name]` will be substituted with `image` in the template. It is not necessary to use this placeholder; it only exists to provide human-friendly asset names to make debugging easier.
* `[hash]` This is the content hash of the asset, which is useful to avoid name collisions. For example, your code may import `components/button/icon.png` and `components/select/icon.png` in which case you'll need the hash to distinguish between the two assets that are both named `icon`.
* `[ext]` This is the file extension of the asset (i.e. everything after the end of the last `.` character). It can be used to put different types of assets into different directories. For example, `--asset-names=assets/[ext]/[name]-[hash]` might write out an asset named `image.png` as `assets/png/image-CQFGD2NG.png`.
Asset path templates do not need to include a file extension. The original file extension of the asset will be automatically added to the end of the output path after template substitution.
This option is similar to the [chunk names](#chunk-names) and [entry names](#entry-names) options.
### Chunk names
*Supported by: [Build](#build)*
This option controls the file names of the chunks of shared code that are automatically generated when [code splitting](#splitting) is enabled. It configures the output paths using a template with placeholders that will be substituted with values specific to the chunk when the output path is generated. For example, specifying a chunk name template of `chunks/[name]-[hash]` puts all generated chunks into a subdirectory called `chunks` inside of the output directory and includes the content hash of the chunk in the file name. Doing that looks like this:
```
esbuild app.js --chunk-names=chunks/[name]-[hash] --bundle --outdir=out --splitting --format=esm
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
chunkNames: 'chunks/[name]-[hash]',
bundle: true,
outdir: 'out',
splitting: true,
format: 'esm',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
ChunkNames: "chunks/[name]-[hash]",
Bundle: true,
Outdir: "out",
Splitting: true,
Format: api.FormatESModule,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
There are three placeholders that can be used in chunk path templates:
* `[name]` This will currently always be the text `chunk`, although this placeholder may take on additional values in future releases.
* `[hash]` This is the content hash of the chunk. Including this is necessary to distinguish different chunks from each other in the case where multiple chunks of shared code are generated.
* `[ext]` This is the file extension of the chunk (i.e. everything after the end of the last `.` character). It can be used to put different types of chunks into different directories. For example, `--chunk-names=chunks/[ext]/[name]-[hash]` might write out a chunk as `chunks/css/chunk-DEFJT7KY.css`.
Chunk path templates do not need to include a file extension. The configured [out extension](#out-extension) for the appropriate content type will be automatically added to the end of the output path after template substitution.
Note that this option only controls the names for automatically-generated chunks of shared code. It does *not* control the names for output files related to entry points. The names of these are currently determined from the path of the original entry point file relative to the [outbase](#outbase) directory, and this behavior cannot be changed. An additional API option will be added in the future to let you change the file names of entry point output files.
This option is similar to the [asset names](#asset-names) and [entry names](#entry-names) options.
### Entry names
*Supported by: [Build](#build)*
This option controls the file names of the output files corresponding to each input entry point file. It configures the output paths using a template with placeholders that will be substituted with values specific to the file when the output path is generated. For example, specifying an entry name template of `[dir]/[name]-[hash]` includes a hash of the output file in the file name and puts the files into the output directory, potentially under a subdirectory (see the details about `[dir]` below). Doing that looks like this:
```
esbuild src/main-app/app.js --entry-names=[dir]/[name]-[hash] --outbase=src --bundle --outdir=out
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['src/main-app/app.js'],
entryNames: '[dir]/[name]-[hash]',
outbase: 'src',
bundle: true,
outdir: 'out',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"src/main-app/app.js"},
EntryNames: "[dir]/[name]-[hash]",
Outbase: "src",
Bundle: true,
Outdir: "out",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
There are four placeholders that can be used in entry path templates:
* `[dir]` This is the relative path from the directory containing the input entry point file to the [outbase](#outbase) directory. Its purpose is to help you avoid collisions between identically-named entry points in different subdirectories.
For example, if there are two entry points `src/pages/home/index.ts` and `src/pages/about/index.ts`, the outbase directory is `src`, and the entry names template is `[dir]/[name]`, the output directory will contain `pages/home/index.js` and `pages/about/index.js`. If the entry names template had been just `[name]` instead, bundling would have failed because there would have been two output files with the same output path `index.js` inside the output directory.
* `[name]` This is the original file name of the entry point without the extension. For example, if the input entry point file is named `app.js` then `[name]` will be substituted with `app` in the template.
* `[hash]` This is the content hash of the output file, which can be used to take optimal advantage of browser caching. Adding `[hash]` to your entry point names means esbuild will calculate a hash that relates to all content in the corresponding output file (and any output file it imports if [code splitting](#splitting) is active). The hash is designed to change if and only if any of the input files relevant to that output file are changed.
After that, you can have your web server tell browsers that to cache these files forever (in practice you can say they expire a very long time from now such as in a year). You can then use the information in the [metafile](#metafile) to determine which output file path corresponds to which input entry point so you know what path to include in your `<script>` tag.
* `[ext]` This is the file extension that the entry point file will be written out to (i.e. the [out extension](#out-extension) setting, not the original file extension). It can be used to put different types of entry points into different directories. For example, `--entry-names=entries/[ext]/[name]` might write the output file for `app.ts` to `entries/js/app.js`.
Entry path templates do not need to include a file extension. The appropriate [out extension](#out-extension) based on the file type will be automatically added to the end of the output path after template substitution.
This option is similar to the [asset names](#asset-names) and [chunk names](#chunk-names) options.
### Out extension
*Supported by: [Build](#build)*
This option lets you customize the file extension of the files that esbuild generates to something other than `.js` or `.css`. In particular, the `.mjs` and `.cjs` file extensions have special meaning in node (they indicate a file in ESM and CommonJS format, respectively). This option is useful if you are using esbuild to generate multiple files and you have to use the [outdir](#outdir) option instead of the [outfile](#outfile) option. You can use it like this:
```
esbuild app.js --bundle --outdir=dist --out-extension:.js=.mjs
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outdir: 'dist',
outExtension: { '.js': '.mjs' },
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outdir: "dist",
OutExtension: map[string]string{
".js": ".mjs",
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Outbase
*Supported by: [Build](#build)*
If your build contains multiple entry points in separate directories, the directory structure will be replicated into the [output directory](#outdir) relative to the outbase directory. For example, if there are two entry points `src/pages/home/index.ts` and `src/pages/about/index.ts` and the outbase directory is `src`, the output directory will contain `pages/home/index.js` and `pages/about/index.js`. Here's how to use it:
```
esbuild src/pages/home/index.ts src/pages/about/index.ts --bundle --outdir=out --outbase=src
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: [
'src/pages/home/index.ts',
'src/pages/about/index.ts',
],
bundle: true,
outdir: 'out',
outbase: 'src',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{
"src/pages/home/index.ts",
"src/pages/about/index.ts",
},
Bundle: true,
Outdir: "out",
Outbase: "src",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
If the outbase directory isn't specified, it defaults to the [lowest common ancestor](https://en.wikipedia.org/wiki/Lowest_common_ancestor) directory among all input entry point paths. This is `src/pages` in the example above, which means by default the output directory will contain `home/index.js` and `about/index.js` instead.
### Outdir
*Supported by: [Build](#build)*
This option sets the output directory for the build operation. For example, this command will generate a directory called `out`:
```
esbuild app.js --bundle --outdir=out
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outdir: 'out',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outdir: "out",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
The output directory will be generated if it does not already exist, but it will not be cleared if it already contains some files. Any generated files will silently overwrite existing files with the same name. You should clear the output directory yourself before running esbuild if you want the output directory to only contain files from the current run of esbuild.
If your build contains multiple entry points in separate directories, the directory structure will be replicated into the output directory starting from the [lowest common ancestor](https://en.wikipedia.org/wiki/Lowest_common_ancestor) directory among all input entry point paths. For example, if there are two entry points `src/home/index.ts` and `src/about/index.ts`, the output directory will contain `home/index.js` and `about/index.js`. If you want to customize this behavior, you should change the [outbase directory](#outbase).
### Outfile
*Supported by: [Build](#build)*
This option sets the output file name for the build operation. This is only applicable if there is a single entry point. If there are multiple entry points, you must use the [outdir](#outdir) option instead to specify an output directory. Using outfile looks like this:
```
esbuild app.js --bundle --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Outdir: "out.js",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Public path
*Supported by: [Build](#build)*
This is useful in combination with the [external file](../content-types/index#external-file) loader. By default that loader exports the name of the imported file as a string using the `default` export. The public path option lets you prepend a base path to the exported string of each file loaded by this loader:
```
esbuild app.js --bundle --loader:.png=file --public-path=https://www.example.com/v1 --outdir=out
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
loader: { '.png': 'file' },
publicPath: 'https://www.example.com/v1',
outdir: 'out',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".png": api.LoaderFile,
},
Outdir: "out",
PublicPath: "https://www.example.com/v1",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Write
*Supported by: [Build](#build)*
The build API call can either write to the file system directly or return the files that would have been written as in-memory buffers. By default the CLI and JavaScript APIs write to the file system and the Go API doesn't. To use the in-memory buffers:
```
import * as esbuild from 'esbuild'
let result = await esbuild.build({
entryPoints: ['app.js'],
sourcemap: 'external',
write: false,
outdir: 'out',
})
for (let out of result.outputFiles) {
console.log(out.path, out.contents, out.text)
}
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Sourcemap: api.SourceMapExternal,
Write: false,
Outdir: "out",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
for _, out := range result.OutputFiles {
fmt.Printf("%v %v\n", out.Path, out.Contents)
}
}
```
Path resolution
---------------
### Alias
*Supported by: [Build](#build)*
This feature lets you substitute one package for another when bundling. The example below substitutes the package `oldpkg` with the package `newpkg`:
```
esbuild app.js --bundle --alias:oldpkg=newpkg
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
write: true,
alias: {
'oldpkg': 'newpkg',
},
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Write: true,
Alias: map[string]string{
"oldpkg": "newpkg",
},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
These new substitutions happen first before all of esbuild's other path resolution logic. One use case for this feature is replacing a node-only package with a browser-friendly package in third-party code that you don't control.
Note that when an import path is substituted using an alias, the resulting import path is resolved in the working directory instead of in the directory containing the source file with the import path. If needed, the working directory that esbuild uses can be set with the [working directory](#working-directory) feature.
### Conditions
*Supported by: [Build](#build)*
This feature controls how the `exports` field in `package.json` is interpreted. Custom conditions can be added using the conditions setting. You can specify as many of these as you want and the meaning of these is entirely up to package authors. Node has currently only endorsed the `development` and `production` custom conditions for recommended use. Here is an example of adding the custom conditions `custom1` and `custom2`:
```
esbuild src/app.js --bundle --conditions=custom1,custom2
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['src/app.js'],
bundle: true,
conditions: ['custom1', 'custom2'],
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"src/app.js"},
Bundle: true,
Conditions: []string{"custom1", "custom2"},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
#### How conditions work
Conditions allow you to redirect the same import path to different file locations in different situations. The redirect map containing the conditions and paths is stored in the `exports` field in the package's `package.json` file. For example, this would remap `require('pkg/foo')` to `pkg/required.cjs` and `import 'pkg/foo'` to `pkg/imported.mjs` using the `import` and `require` conditions:
```
{
"name": "pkg",
"exports": {
"./foo": {
"import": "./imported.mjs",
"require": "./required.cjs",
"default": "./fallback.js"
}
}
}
```
Conditions are checked in the order that they appear within the JSON file. So the example above behaves sort of like this:
```
if (importPath === './foo') {
if (conditions.has('import')) return './imported.mjs'
if (conditions.has('require')) return './required.cjs'
return './fallback.js'
}
```
By default there are five conditions with special behavior that are built in to esbuild, and cannot be disabled:
* `default` This condition is always active. It is intended to come last and lets you provide a fallback for when no other condition applies. This condition is also active when you run your code natively in node.
* `import` This condition is only active when the import path is from an ESM `import` statement or `import()` expression. It can be used to provide ESM-specific code. This condition is also active when you run your code natively in node (but only in an ESM context).
* `require` This condition is only active when the import path is from a CommonJS `require()` call. It can be used to provide CommonJS-specific code. This condition is also active when you run your code natively in node (but only in a CommonJS context).
* `browser` This condition is only active when esbuild's [platform](#platform) setting is set to `browser`. It can be used to provide browser-specific code. This condition is not active when you run your code natively in node.
* `node` This condition is only active when esbuild's [platform](#platform) setting is set to `node`. It can be used to provide node-specific code. This condition is also active when you run your code natively in node.
The following condition is also automatically included when the [platform](#platform) is set to either `browser` or `node` and no custom conditions are configured. If there are any custom conditions configured (even an empty list) then this condition will no longer be automatically included:
* `module` This condition can be used to tell esbuild to pick the ESM variant for a given import path to provide better tree-shaking when bundling. This condition is not active when you run your code natively in node. It is specific to bundlers, and originated from Webpack.
Note that when you use the `require` and `import` conditions, *your package may end up in the bundle multiple times!* This is a subtle issue that can cause bugs due to duplicate copies of your code's state in addition to bloating the resulting bundle. This is commonly known as the [dual package hazard](https://nodejs.org/docs/latest/api/packages.html#packages_dual_package_hazard).
One way of avoiding the dual package hazard that works both for bundlers and when running natively in node is to put all of your code in the `require` condition as CommonJS and have the `import` condition just be a light ESM wrapper that calls `require` on your package and re-exports the package using ESM syntax. This approach doesn't provide good tree-shaking, however, as esbuild doesn't tree-shake CommonJS modules.
Another way of avoiding a dual package hazard is to use the bundler-specific `module` condition to direct bundlers to always load the ESM version of your package while letting node always fall back to the CommonJS version of your package. Both `import` and `module` are intended to be used with ESM but unlike `import`, the `module` condition is always active even if the import path was loaded using a `require` call. This works well with bundlers because bundlers support loading ESM using `require`, but it's not something that can work with node because node deliberately doesn't implement loading ESM using `require`.
### External
*Supported by: [Build](#build)*
You can mark a file or a package as external to exclude it from your build. Instead of being bundled, the import will be preserved (using `require` for the `iife` and `cjs` formats and using `import` for the `esm` format) and will be evaluated at run time instead.
This has several uses. First of all, it can be used to trim unnecessary code from your bundle for a code path that you know will never be executed. For example, a package may contain code that only runs in node but you will only be using that package in the browser. It can also be used to import code in node at run time from a package that cannot be bundled. For example, the `fsevents` package contains a native extension, which esbuild doesn't support. Marking something as external looks like this:
```
echo 'require("fsevents")' > app.js
esbuild app.js --bundle --external:fsevents --platform=node
// app.js
require("fsevents");
```
```
import * as esbuild from 'esbuild'
import fs from 'node:fs'
fs.writeFileSync('app.js', 'require("fsevents")')
await esbuild.build({
entryPoints: ['app.js'],
outfile: 'out.js',
bundle: true,
platform: 'node',
external: ['fsevents'],
})
```
```
package main
import "io/ioutil"
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
ioutil.WriteFile("app.js", []byte("require(\"fsevents\")"), 0644)
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Outfile: "out.js",
Bundle: true,
Write: true,
Platform: api.PlatformNode,
External: []string{"fsevents"},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
You can also use the `*` wildcard character in an external path to mark all files matching that pattern as external. For example, you can use `*.png` to remove all `.png` files or `/images/*` to remove all paths starting with `/images/`:
```
esbuild app.js --bundle "--external:*.png" "--external:/images/*"
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
outfile: 'out.js',
bundle: true,
external: ['*.png', '/images/*'],
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Outfile: "out.js",
Bundle: true,
Write: true,
External: []string{"*.png", "/images/*"},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
External paths are applied both before and after path resolution, which lets you match against both the import path in the source code and the absolute file system path. The path is considered to be external if the external path matches in either case. The specific behavior is as follows:
* Before path resolution begins, import paths are checked against all external paths. In addition, if the external path looks like a package path (i.e. doesn't start with `/` or `./` or `../`), import paths are checked to see if they have that package path as a path prefix.
This means that `--external:@foo/bar` implicitly also means `--external:@foo/bar/*` which matches the import path `@foo/bar/baz`. So it marks all paths inside the `@foo/bar` package as external too.
* After path resolution ends, the resolved absolute paths are checked against all external paths that don't look like a package path (i.e. those that start with `/` or `./` or `../`). But before checking, the external path is joined with the current working directory and then normalized, becoming an absolute path (even if it contains a `*` wildcard character).
This means that you can mark everything in the directory `dir` as external using `--external:./dir/*`. Note that the leading `./` is important. Using `--external:dir/*` instead is treated as a package path and is not checked for after path resolution ends.
### Main fields
*Supported by: [Build](#build)*
When you import a package in node, the `main` field in that package's `package.json` file determines which file is imported (along with [a lot of other rules](https://nodejs.org/api/modules.html#all-together)). Major JavaScript bundlers including esbuild let you specify additional `package.json` fields to try when resolving a package. There are at least three such fields commonly in use:
* `main` This is [the standard field](https://docs.npmjs.com/files/package.json#main) for all packages that are meant to be used with node. The name `main` is hard-coded in to node's module resolution logic itself. Because it's intended for use with node, it's reasonable to expect that the file path in this field is a CommonJS-style module.
* `module` This field came from [a proposal](https://github.com/dherman/defense-of-dot-js/blob/f31319be735b21739756b87d551f6711bd7aa283/proposal.md) for how to integrate ECMAScript modules into node. Because of this, it's reasonable to expect that the file path in this field is an ECMAScript-style module. This proposal wasn't adopted by node (node uses `"type": "module"` instead) but it was adopted by major bundlers because ECMAScript-style modules lead to better [tree shaking](#tree-shaking), or dead code removal.
For package authors: Some packages incorrectly use the `module` field for browser-specific code, leaving node-specific code for the `main` field. This is probably because node ignores the `module` field and people typically only use bundlers for browser-specific code. However, bundling node-specific code is valuable too (e.g. it decreases download and boot time) and packages that put browser-specific code in `module` prevent bundlers from being able to do tree shaking effectively. If you are trying to publish browser-specific code in a package, use the `browser` field instead.
* `browser` This field came from [a proposal](https://gist.github.com/defunctzombie/4339901/49493836fb873ddaa4b8a7aa0ef2352119f69211) that allows bundlers to replace node-specific files or modules with their browser-friendly versions. It lets you specify an alternate browser-specific entry point. Note that it is possible for a package to use both the `browser` and `module` field together (see the note below).
The default main fields depend on the current [platform](#platform) setting. These defaults should be the most widely compatible with the existing package ecosystem. But you can customize them like this if you want to:
```
esbuild app.js --bundle --main-fields=module,main
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
mainFields: ['module', 'main'],
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
MainFields: []string{"module", "main"},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
#### For package authors
If you want to author a package that uses the `browser` field in combination with the `module` field, then you'll probably want to fill out ***all four entries*** in the full CommonJS-vs-ESM and browser-vs-node compatibility matrix. For that you'll need to use the expanded form of the `browser` field that is a map instead of just a string:
```
{
"main": "./node-cjs.js",
"module": "./node-esm.js",
"browser": {
"./node-cjs.js": "./browser-cjs.js",
"./node-esm.js": "./browser-esm.js"
}
}
```
The `main` field is expected to be CommonJS while the `module` field is expected to be ESM. The decision about which module format to use is independent from the decision about whether to use a browser-specific or node-specific variant. If you omit one of these four entries, then you risk the wrong variant being chosen. For example, if you omit the entry for the CommonJS browser build, then the CommonJS node build could be chosen instead.
Note that using `main`, `module`, and `browser` is the old way of doing this. There is also a newer way to do this that you may prefer to use instead: the [`exports` field](#how-conditions-work) in `package.json`. It provides a different set of trade-offs. For example, it gives you more precise control over imports for all sub-paths in your package (while `main` fields only give you control over the entry point), but it may cause your package to be imported multiple times depending on how you configure it.
### Node paths
*Supported by: [Build](#build)*
Node's module resolution algorithm supports an environment variable called [`NODE_PATH`](https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders) that contains a list of global directories to use when resolving import paths. These paths are searched for packages in addition to the `node_modules` directories in all parent directories. You can pass this list of directories to esbuild using an environment variable with the CLI and using an array with the JS and Go APIs:
```
NODE_PATH=someDir esbuild app.js --bundle --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
nodePaths: ['someDir'],
entryPoints: ['app.js'],
bundle: true,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
NodePaths: []string{"someDir"},
EntryPoints: []string{"app.js"},
Bundle: true,
Outfile: "out.js",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
If you are using the CLI and want to pass multiple directories using `NODE_PATH`, you will have to separate them with `:` on Unix and `;` on Windows. This is the same format that Node itself uses.
### Packages
*Supported by: [Build](#build)*
Use this setting to exclude all of your package's dependencies from the bundle. This is useful when [bundling for node](../getting-started/index#bundling-for-node) because many npm packages use node-specific features that esbuild doesn't support while bundling (such as `__dirname`, `import.meta.url`, `fs.readFileSync`, and `*.node` native binary modules). Using it looks like this:
```
esbuild app.js --bundle --packages=external
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
packages: 'external',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Packages: api.PackagesExternal,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Enabling this automatically marks all import paths that look like npm packages (i.e. that don't start with a `.` or `..` path component and that aren't absolute paths) as external. It has the same effect as manually passing each dependency to [external](#external) but is more concise. If you want to customize which of your dependencies are external and which ones aren't, then you should be using [external](#external) instead of this setting.
Note that this setting only has an effect when [bundling](#bundle) is enabled. Also note that marking an import path as external happens after the import path is rewritten by any configured [aliases](#alias), so the alias feature still has an effect when this setting is used.
### Preserve symlinks
*Supported by: [Build](#build)*
This setting mirrors the [`--preserve-symlinks`](https://nodejs.org/api/cli.html#cli_preserve_symlinks) setting in node. If you use that setting (or the similar [`resolve.symlinks`](https://webpack.js.org/configuration/resolve/#resolvesymlinks) setting in Webpack), you will likely need to enable this setting in esbuild too. It can be enabled like this:
```
esbuild app.js --bundle --preserve-symlinks --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
preserveSymlinks: true,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
PreserveSymlinks: true,
Outfile: "out.js",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Enabling this setting causes esbuild to determine file identity by the original file path (i.e. the path without following symlinks) instead of the real file path (i.e. the path after following symlinks). This can be beneficial with certain directory structures. Keep in mind that this means a file may be given multiple identities if there are multiple symlinks pointing to it, which can result in it appearing multiple times in generated output files.
*Note: The term "symlink" means [symbolic link](https://en.wikipedia.org/wiki/Symbolic_link) and refers to a file system feature where a path can redirect to another path.*
### Resolve extensions
*Supported by: [Build](#build)*
The [resolution algorithm used by node](https://nodejs.org/api/modules.html#modules_file_modules) supports implicit file extensions. You can `require('./file')` and it will check for `./file`, `./file.js`, `./file.json`, and `./file.node` in that order. Modern bundlers including esbuild extend this concept to other file types as well. The full order of implicit file extensions in esbuild can be customized using the resolve extensions setting, which defaults to `.tsx,.ts,.jsx,.js,.css,.json`:
```
esbuild app.js --bundle --resolve-extensions=.ts,.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
resolveExtensions: ['.ts', '.js'],
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
ResolveExtensions: []string{".ts", ".js"},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Note that esbuild deliberately does not include the new `.mjs` and `.cjs` extensions in this list. Node's resolution algorithm doesn't treat these as implicit file extensions, so esbuild doesn't either. If you want to import files with these extensions you should either explicitly add the extensions in your import paths or change this setting to include the additional extensions that you want to be implicit.
### Working directory
*Supported by: [Build](#build)*
This API option lets you specify the working directory to use for the build. It normally defaults to the current [working directory](https://en.wikipedia.org/wiki/Working_directory) of the process you are using to call esbuild's API. The working directory is used by esbuild for a few different things including resolving relative paths given as API options to absolute paths and pretty-printing absolute paths as relative paths in log messages. Here is how to customize esbuild's working directory:
```
cd "/var/tmp/custom/working/directory"
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['file.js'],
absWorkingDir: '/var/tmp/custom/working/directory',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"file.js"},
AbsWorkingDir: "/var/tmp/custom/working/directory",
Outfile: "out.js",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Note: If you are using [Yarn Plug'n'Play](https://yarnpkg.com/features/pnp/), keep in mind that this working directory is used to search for Yarn's manifest file. If you are running esbuild from an unrelated directory, you will have to set this working directory to the directory containing the manifest file (or one of its child directories) for the manifest file to be found by esbuild.
Transformation
--------------
### JSX
*Supported by: [Build](#build) and [Transform](#transform)*
This option tells esbuild what to do about JSX syntax. Here are the available options:
* `transform` This tells esbuild to transform JSX to JS using a general-purpose transform that's shared between many libraries that use JSX syntax. Each JSX element is turned into a call to the [JSX factory](#jsx-factory) function with the element's component (or with the [JSX fragment](#jsx-fragment) for fragments) as the first argument. The second argument is an array of props (or `null` if there are no props). Any child elements present become additional arguments after the second argument.
If you want to configure this setting on a per-file basis, you can do that by using a `// @jsxRuntime classic` comment. This is a convention from [Babel's JSX plugin](https://babeljs.io/docs/en/babel-preset-react/) that esbuild follows.
* `preserve` This preserves the JSX syntax in the output instead of transforming it into function calls. JSX elements are treated as first-class syntax and are still affected by other settings such as [minification](#minify) and [property mangling](#mangle-props).
Note that this means the output files are no longer valid JavaScript code. This feature is intended to be used when you want to transform the JSX syntax in esbuild's output files by another tool after bundling.
* `automatic` This transform was [introduced in React 17+](https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html) and is very specific to React. It automatically generates `import` statements from the [JSX import source](#jsx-import-source) and introduces many special cases regarding how the syntax is handled. The details are too complicated to describe here. For more information, please read [React's documentation about their new JSX transform](https://github.com/reactjs/rfcs/blob/createlement-rfc/text/0000-create-element-changes.md). If you want to enable the development mode version of this transform, you need to additionally enable the [JSX dev](#jsx-dev) setting.
If you want to configure this setting on a per-file basis, you can do that by using a `// @jsxRuntime automatic` comment. This is a convention from [Babel's JSX plugin](https://babeljs.io/docs/en/babel-preset-react/) that esbuild follows.
Here's an example of setting the JSX transform to `preserve`:
```
echo '<div/>' | esbuild --jsx=preserve --loader=jsx
<div />;
```
```
import * as esbuild from 'esbuild'
let result = await esbuild.transform('<div/>', {
jsx: 'preserve',
loader: 'jsx',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
result := api.Transform("<div/>", api.TransformOptions{
JSX: api.JSXPreserve,
Loader: api.LoaderJSX,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
### JSX dev
*Supported by: [Build](#build) and [Transform](#transform)*
If the [JSX](#jsx) transform has been set to `automatic`, then enabling this setting causes esbuild to automatically inject the file name and source location into each JSX element. Your JSX library can then use this information to help with debugging. If the JSX transform has been set to something other than `automatic`, then this setting does nothing. Here's an example of enabling this setting:
```
echo '<a/>' | esbuild --loader=jsx --jsx=automatic
import { jsx } from "react/jsx-runtime";
/* @__PURE__ */ jsx("a", {});
echo '<a/>' | esbuild --loader=jsx --jsx=automatic --jsx-dev
import { jsxDEV } from "react/jsx-dev-runtime";
/* @__PURE__ */ jsxDEV("a", {}, void 0, false, {
fileName: "<stdin>",
lineNumber: 1,
columnNumber: 1
}, this);
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.jsx'],
jsxDev: true,
jsx: 'automatic',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.jsx"},
JSXDev: true,
JSX: api.JSXAutomatic,
Outfile: "out.js",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### JSX factory
*Supported by: [Build](#build) and [Transform](#transform)*
This sets the function that is called for each JSX element. Normally a JSX expression such as this:
```
<div>Example text</div>
```
is compiled into a function call to `React.createElement` like this:
```
React.createElement("div", null, "Example text");
```
You can call something other than `React.createElement` by changing the JSX factory. For example, to call the function `h` instead (which is used by other libraries such as [Preact](https://preactjs.com/)):
```
echo '<div/>' | esbuild --jsx-factory=h --loader=jsx
/* @__PURE__ */ h("div", null);
```
```
import * as esbuild from 'esbuild'
let result = await esbuild.transform('<div/>', {
jsxFactory: 'h',
loader: 'jsx',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
result := api.Transform("<div/>", api.TransformOptions{
JSXFactory: "h",
Loader: api.LoaderJSX,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
Alternatively, if you are using TypeScript, you can just configure JSX for TypeScript by adding this to your `tsconfig.json` file and esbuild should pick it up automatically without needing to be configured:
```
{
"compilerOptions": {
"jsxFactory": "h"
}
}
```
If you want to configure this on a per-file basis, you can do that by using a `// @jsx h` comment. Note that this setting does not apply when the [JSX](#jsx) transform has been set to `automatic`.
### JSX fragment
*Supported by: [Build](#build) and [Transform](#transform)*
This sets the function that is called for each JSX fragment. Normally a JSX fragment expression such as this:
```
<>Stuff</>
```
is compiled into a use of the `React.Fragment` component like this:
```
React.createElement(React.Fragment, null, "Stuff");
```
You can use a component other than `React.Fragment` by changing the JSX fragment. For example, to use the component `Fragment` instead (which is used by other libraries such as [Preact](https://preactjs.com/)):
```
echo '<>x</>' | esbuild --jsx-fragment=Fragment --loader=jsx
/* @__PURE__ */ React.createElement(Fragment, null, "x");
```
```
import * as esbuild from 'esbuild'
let result = await esbuild.transform('<>x</>', {
jsxFragment: 'Fragment',
loader: 'jsx',
})
console.log(result.code)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
result := api.Transform("<>x</>", api.TransformOptions{
JSXFragment: "Fragment",
Loader: api.LoaderJSX,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
Alternatively, if you are using TypeScript, you can just configure JSX for TypeScript by adding this to your `tsconfig.json` file and esbuild should pick it up automatically without needing to be configured:
```
{
"compilerOptions": {
"jsxFragmentFactory": "Fragment"
}
}
```
If you want to configure this on a per-file basis, you can do that by using a `// @jsxFrag Fragment` comment. Note that this setting does not apply when the [JSX](#jsx) transform has been set to `automatic`.
### JSX import source
*Supported by: [Build](#build) and [Transform](#transform)*
If the [JSX](#jsx) transform has been set to `automatic`, then setting this lets you change which library esbuild uses to automatically import its JSX helper functions from. Note that this only works with the JSX transform that's [specific to React 17+](https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html). If you set the JSX import source to `your-pkg`, then that package must expose at least the following exports:
```
import { createElement } from "your-pkg"
import { Fragment, jsx, jsxs } from "your-pkg/jsx-runtime"
import { Fragment, jsxDEV } from "your-pkg/jsx-dev-runtime"
```
The `/jsx-runtime` and `/jsx-dev-runtime` subpaths are hard-coded by design and cannot be changed. The `jsx` and `jsxs` imports are used when [JSX dev mode](#jsx-dev) is off and the `jsxDEV` import is used when JSX dev mode is on. The meaning of these is described in [React's documentation about their new JSX transform](https://github.com/reactjs/rfcs/blob/createlement-rfc/text/0000-create-element-changes.md). The `createElement` import is used regardless of the JSX dev mode when an element has a prop spread followed by a `key` prop, which looks like this:
```
return <div {...props} key={key} />
```
Here's an example of setting the JSX import source to [`preact`](https://preactjs.com/):
```
esbuild app.jsx --jsx-import-source=preact --jsx=automatic
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.jsx'],
jsxImportSource: 'preact',
jsx: 'automatic',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.jsx"},
JSXImportSource: "preact",
JSX: api.JSXAutomatic,
Outfile: "out.js",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Alternatively, if you are using TypeScript, you can just configure the JSX import source for TypeScript by adding this to your `tsconfig.json` file and esbuild should pick it up automatically without needing to be configured:
```
{
"compilerOptions": {
"jsx": "react-jsx",
"jsxImportSource": "preact"
}
}
```
And if you want to control this setting on the per-file basis, you can do that with a `// @jsxImportSource your-pkg` comment in each file. You may also need to add a `// @jsxRuntime automatic` comment as well if the [JSX](#jsx) transform has not already been set by other means, or if you want that to be set on a per-file basis as well.
### JSX side effects
*Supported by: [Build](#build) and [Transform](#transform)*
By default esbuild assumes that JSX expressions are side-effect free, which means they are annoated with [`/* @__PURE__ */` comments](#pure) and are removed during bundling when they are unused. This follows the common use of JSX for virtual DOM and applies to the vast majority of JSX libraries. However, some people have written JSX libraries that don't have this property (specifically JSX expressions can have arbitrary side effects and can't be removed when unused). If you are using such a library, you can use this setting to tell esbuild that JSX expressions have side effects:
```
esbuild app.jsx --jsx-side-effects
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.jsx'],
outfile: 'out.js',
jsxSideEffects: true,
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.jsx"},
Outfile: "out.js",
JSXSideEffects: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Supported
*Supported by: [Build](#build) and [Transform](#transform)*
This setting lets you customize esbuild's set of unsupported syntax features at the individual syntax feature level. For example, you can use this to tell esbuild that [BigInts](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt) are not supported so that esbuild generates an error when you try to use one. Usually this is configured for you when you use the [`target`](#target) setting, which you should typically be using instead of this setting. If the target is specified in addition to this setting, this setting will override whatever is specified by the target.
Here are some examples of why you might want to use this setting instead of or in addition to setting the target:
* JavaScript runtimes often do a quick implementation of newer syntax features that is slower than the equivalent older JavaScript, and you can get a speedup by telling esbuild to pretend this syntax feature isn't supported. For example, [V8](https://v8.dev/) has a [long-standing performance bug regarding object spread](https://bugs.chromium.org/p/v8/issues/detail?id=11536) that can be avoided by manually copying properties instead of using object spread syntax.
* There are many other JavaScript implementations in addition to the ones that esbuild's `target` setting recognizes, and they may not support certain features. If you are targeting such an implementation, you can use this setting to configure esbuild with a custom syntax feature compatibility set without needing to change esbuild itself. For example, [TypeScript's](https://www.typescriptlang.org/) JavaScript parser may not support [arbitrary module namespace identifier names](https://github.com/microsoft/TypeScript/issues/40594) so you may want to turn those off when targeting TypeScript's JavaScript parser.
* You may be processing esbuild's output with another tool, and you may want esbuild to transform certain features and the other tool to transform certain other features. For example, if you are using esbuild to transform files individually to ES5 but you are then feeding the output into [Webpack](https://webpack.js.org/) for bundling, you may want to preserve `import()` expressions even though they are a syntax error in ES5.
If you want esbuild to consider a certain syntax feature to be unsupported, you can specify that like this:
```
esbuild app.js --supported:bigint=false
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
supported: {
'bigint': false,
},
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Supported: map[string]bool{
"bigint": false,
},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Syntax features are specified using esbuild-specific feature names. The full set of feature names is as follows:
**JavaScript:**
* `arbitrary-module-namespace-names`
* `array-spread`
* `arrow`
* `async-await`
* `async-generator`
* `bigint`
* `class-field`
* `class-private-accessor`
* `class-private-brand-check`
* `class-private-field`
* `class-private-method`
* `class-private-static-accessor`
* `class-private-static-field`
* `class-private-static-method`
* `class-static-blocks`
* `class-static-field`
* `class`
* `const-and-let`
* `default-argument`
* `destructuring`
* `dynamic-import`
* `exponent-operator`
* `export-star-as`
* `for-await`
* `for-of`
* `generator`
* `hashbang`
* `import-assertions`
* `import-meta`
* `inline-script`
* `logical-assignment`
* `nested-rest-binding`
* `new-target`
* `node-colon-prefix-import`
* `node-colon-prefix-require`
* `nullish-coalescing`
* `object-accessors`
* `object-extensions`
* `object-rest-spread`
* `optional-catch-binding`
* `optional-chain`
* `regexp-dot-all-flag`
* `regexp-lookbehind-assertions`
* `regexp-match-indices`
* `regexp-named-capture-groups`
* `regexp-sticky-and-unicode-flags`
* `regexp-unicode-property-escapes`
* `rest-argument`
* `template-literal`
* `top-level-await`
* `typeof-exotic-object-is-object`
* `unicode-escapes`
**CSS:**
* `hex-rgba`
* `inline-style`
* `inset-property`
* `modern-rgb-hsl`
* `nesting`
* `rebecca-purple`
### Target
*Supported by: [Build](#build) and [Transform](#transform)*
This sets the target environment for the generated JavaScript and/or CSS code. It tells esbuild to transform JavaScript syntax that is too new for these environments into older JavaScript syntax that will work in these environments. For example, the `??` operator was introduced in Chrome 80 so esbuild will convert it into an equivalent (but more verbose) conditional expression when targeting Chrome 79 or earlier.
Note that this is only concerned with syntax features, not APIs. It does *not* automatically add [polyfills](https://developer.mozilla.org/en-US/docs/Glossary/Polyfill) for new APIs that are not used by these environments. You will have to explicitly import polyfills for the APIs you need (e.g. by importing [`core-js`](https://www.npmjs.com/package/core-js)). Automatic polyfill injection is outside of esbuild's scope.
Each target environment is an environment name followed by a version number. The following environment names are currently supported:
* `chrome`
* `deno`
* `edge`
* `firefox`
* `hermes`
* `ie`
* `ios`
* `node`
* `opera`
* `rhino`
* `safari`
In addition, you can also specify JavaScript language versions such as `es2020`. The default target is `esnext` which means that by default, esbuild will assume all of the latest JavaScript and CSS features are supported. Here is an example that configures multiple target environments. You don't need to specify all of them; you can just specify the subset of target environments that your project cares about. You can also be more precise about version numbers if you'd like (e.g. `node12.19.0` instead of just `node12`):
```
esbuild app.js --target=es2020,chrome58,edge16,firefox57,node12,safari11
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
target: [
'es2020',
'chrome58',
'edge16',
'firefox57',
'node12',
'safari11',
],
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Target: api.ES2020,
Engines: []api.Engine{
{Name: api.EngineChrome, Version: "58"},
{Name: api.EngineEdge, Version: "16"},
{Name: api.EngineFirefox, Version: "57"},
{Name: api.EngineNode, Version: "12"},
{Name: api.EngineSafari, Version: "11"},
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
You can refer to the [JavaScript loader](../content-types/index#javascript) for the details about which syntax features were introduced with which language versions. Keep in mind that while JavaScript language versions such as `es2020` are identified by year, that is the year the specification is approved. It has nothing to do with the year all major browsers implement that specification which often happens earlier or later than that year.
If you use a syntax feature that esbuild doesn't yet have support for transforming to your current language target, esbuild will generate an error where the unsupported syntax is used. This is often the case when targeting the `es5` language version, for example, since esbuild only supports transforming most newer JavaScript syntax features to `es6`.
If you need to customize the set of supported syntax features at the individual feature level in addition to or instead of what `target` provides, you can do that with the [`supported`](#supported) setting.
Optimization
------------
### Define
*Supported by: [Build](#build) and [Transform](#transform)*
This feature provides a way to replace global identifiers with constant expressions. It can be a way to change the behavior some code between builds without changing the code itself:
```
echo 'hooks = DEBUG && require("hooks")' | esbuild --define:DEBUG=true
hooks = require("hooks");
echo 'hooks = DEBUG && require("hooks")' | esbuild --define:DEBUG=false
hooks = false;
```
```
import * as esbuild from 'esbuild'let js = 'hooks = DEBUG && require("hooks")'(await esbuild.transform(js, {
define: { DEBUG: 'true' },
})).code
'hooks = require("hooks");\n'
(await esbuild.transform(js, {
define: { DEBUG: 'false' },
})).code
'hooks = false;\n'
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "hooks = DEBUG && require('hooks')"
result1 := api.Transform(js, api.TransformOptions{
Define: map[string]string{"DEBUG": "true"},
})
if len(result1.Errors) == 0 {
fmt.Printf("%s", result1.Code)
}
result2 := api.Transform(js, api.TransformOptions{
Define: map[string]string{"DEBUG": "false"},
})
if len(result2.Errors) == 0 {
fmt.Printf("%s", result2.Code)
}
}
```
Replacement expressions must either be a JSON object (null, boolean, number, string, array, or object) or a single identifier. Replacement expressions other than arrays and objects are substituted inline, which means that they can participate in constant folding. Array and object replacement expressions are stored in a variable and then referenced using an identifier instead of being substituted inline, which avoids substituting repeated copies of the value but means that the values don't participate in constant folding.
If you want to replace something with a string literal, keep in mind that the replacement value passed to esbuild must itself contain quotes. Omitting the quotes means the replacement value is an identifier instead:
```
echo 'id, str' | esbuild --define:id=text --define:str=\"text\"
text, "text";
```
```
import * as esbuild from 'esbuild'(await esbuild.transform('id, str', {
define: { id: 'text', str: '"text"' },
})).code
'text, "text";\n'
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
result := api.Transform("id, text", api.TransformOptions{
Define: map[string]string{
"id": "text",
"str": "\"text\"",
},
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
If you're using the CLI, keep in mind that different shells have different rules for how to escape double-quote characters (which are necessary when the replacement value is a string). Use a `\"` backslash escape because it works in both bash and Windows command prompt. Other methods of escaping double quotes that work in bash such as surrounding them with single quotes will not work on Windows, since Windows command prompt does not remove the single quotes. This is relevant when using the CLI from a npm script in your `package.json` file, which people will expect to work on all platforms:
```
{
"scripts": {
"build": "esbuild --define:process.env.NODE_ENV=\\\"production\\\" app.js"
}
}
```
If you still run into cross-platform quote escaping issues with different shells, you will probably want to switch to using the [JavaScript API](index) instead. There you can use regular JavaScript syntax to eliminate cross-platform differences.
### Drop
*Supported by: [Build](#build) and [Transform](#transform)*
This tells esbuild to edit your source code before building to drop certain constructs. There are currently two possible things that can be dropped:
* `debugger` Passing this flag causes all [`debugger` statements](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/debugger) to be removed from the output. This is similar to the `drop_debugger: true` flag available in the popular [UglifyJS](https://github.com/mishoo/UglifyJS) and [Terser](https://github.com/terser/terser) JavaScript minifiers.
JavaScript's `debugger` statements cause the active debugger to treat the statement as an automatically-configured breakpoint. Code containing this statement will automatically be paused when the debugger is open. If no debugger is open, the statement does nothing. Dropping these statements from your code just prevents the debugger from automatically stopping when your code runs.
You can drop `debugger` statements like this:
```
esbuild app.js --drop:debugger
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
drop: ['debugger'],
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Drop: api.DropDebugger,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
* `console` Passing this flag causes all [`console` API calls](https://developer.mozilla.org/en-US/docs/Web/API/console#methods) to be removed from the output. This is similar to the `drop_console: true` flag available in the popular [UglifyJS](https://github.com/mishoo/UglifyJS) and [Terser](https://github.com/terser/terser) JavaScript minifiers.
WARNING: Using this flag can introduce bugs into your code! This flag removes the entire call expression including all call arguments. If any of those arguments had important side effects, using this flag will change the behavior of your code. Be very careful when using this flag.
If you want to remove console API calls without removing the arguments with side effects (so you do not introduce bugs), you should mark the relevant API calls as [pure](#pure) instead. For example, you can mark `console.log` as pure using `--pure:console.log`. This will cause these API calls to be removed safely when minification is enabled.
You can drop `console` API calls like this:
```
esbuild app.js --drop:console
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
drop: ['console'],
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Drop: api.DropConsole,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Ignore annotations
*Supported by: [Build](#build) and [Transform](#transform)*
Since JavaScript is a dynamic language, identifying unused code is sometimes very difficult for a compiler, so the community has developed certain annotations to help tell compilers what code should be considered side-effect free and available for removal. Currently there are two forms of side-effect annotations that esbuild supports:
* Inline `/* @__PURE__ */` comments before function calls tell esbuild that the function call can be removed if the resulting value isn't used. See the [pure](#pure) API option for more information.
* The `sideEffects` field in `package.json` can be used to tell esbuild which files in your package can be removed if all imports from that file end up being unused. This is a convention from Webpack and many libraries published to npm already have this field in their package definition. You can learn more about this field in [Webpack's documentation](https://webpack.js.org/guides/tree-shaking/) for this field.
These annotations can be problematic because the compiler depends completely on developers for accuracy, and developers occasionally publish packages with incorrect annotations. The `sideEffects` field is particularly error-prone for developers because by default it causes all files in your package to be considered dead code if no imports are used. If you add a new file containing side effects and forget to update that field, your package will likely break when people try to bundle it.
This is why esbuild includes a way to ignore side-effect annotations. You should only enable this if you encounter a problem where the bundle is broken because necessary code was unexpectedly removed from the bundle:
```
esbuild app.js --bundle --ignore-annotations
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
ignoreAnnotations: true,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
IgnoreAnnotations: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Enabling this means esbuild will no longer respect `/* @__PURE__ */` comments or the `sideEffects` field. It will still do automatic [tree shaking](#tree-shaking) of unused imports, however, since that doesn't rely on annotations from developers. Ideally this flag is only a temporary workaround. You should report these issues to the maintainer of the package to get them fixed since they indicate a problem with the package and they will likely trip up other people too.
### Inject
*Supported by: [Build](#build)*
This option allows you to automatically replace a global variable with an import from another file. This can be a useful tool for adapting code that you don't control to a new environment. For example, assume you have a file called `process-shim.js` that exports a variable named `process`:
```
// process-shim.js
export let process = {
cwd: () => ''
}
```
```
// entry.js
console.log(process.cwd())
```
This is intended to replace uses of node's `process.cwd()` function to prevent packages that call it from crashing when run in the browser. You can use the inject feature to replace all uses of the global identifier `process` with an import to that file:
```
esbuild entry.js --bundle --inject:./process-shim.js --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['entry.js'],
bundle: true,
inject: ['./process-shim.js'],
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"entry.js"},
Bundle: true,
Inject: []string{"./process-shim.js"},
Outfile: "out.js",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
That results in something like this:
```
// out.js
let process = {cwd: () => ""};
console.log(process.cwd());
```
#### Using inject with [define](#define)
You can also combine this with the [define](#define) feature to be more selective about what you import. For example:
```
// process-shim.js
export function dummy_process_cwd() {
return ''
}
```
```
// entry.js
console.log(process.cwd())
```
You can map `process.cwd` to `dummy_process_cwd` with the [define](#define) feature, then inject `dummy_process_cwd` from `process-shim.js` with the inject feature:
```
esbuild entry.js --bundle --define:process.cwd=dummy_process_cwd --inject:./process-shim.js --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['entry.js'],
bundle: true,
define: { 'process.cwd': 'dummy_process_cwd' },
inject: ['./process-shim.js'],
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"entry.js"},
Bundle: true,
Define: map[string]string{
"process.cwd": "dummy_process_cwd",
},
Inject: []string{"./process-shim.js"},
Outfile: "out.js",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
That results in the following output:
```
// out.js
function dummy_process_cwd() {
return "";
}
console.log(dummy_process_cwd());
```
#### Auto-import for [JSX](../content-types/index#jsx)
You can use the inject feature to automatically provide the implementation for JSX expressions. For example, you can auto-import the `react` package to provide functions such as `React.createElement`. See the [JSX documentation](../content-types/index#auto-import-for-jsx) for details.
#### Injecting files without imports
You can also use this feature with files that have no exports. In that case the injected file just comes first before the rest of the output as if every input file contained `import "./file.js"`. Because of the way ECMAScript modules work, this injection is still "hygienic" in that symbols with the same name in different files are renamed so they don't collide with each other.
#### Conditionally injecting a file
If you want to *conditionally* import a file only if the export is actually used, you should mark the injected file as not having side effects by putting it in a package and adding `"sideEffects": false` in that package's `package.json` file. This setting is a [convention from Webpack](https://webpack.js.org/guides/tree-shaking/#mark-the-file-as-side-effect-free) that esbuild respects for any imported file, not just files used with inject.
### Keep names
*Supported by: [Build](#build) and [Transform](#transform)*
In JavaScript the `name` property on functions and classes defaults to a nearby identifier in the source code. These syntax forms all set the `name` property of the function to `"fn"`:
```
function fn() {}
let fn = function() {};
fn = function() {};
let [fn = function() {}] = [];
let {fn = function() {}} = {};
[fn = function() {}] = [];
({fn = function() {}} = {});
```
However, [minification](#minify) renames symbols to reduce code size and [bundling](#bundle) sometimes need to rename symbols to avoid collisions. That changes value of the `name` property for many of these cases. This is usually fine because the `name` property is normally only used for debugging. However, some frameworks rely on the `name` property for registration and binding purposes. If this is the case, you can enable this option to preserve the original `name` values even in minified code:
```
esbuild app.js --minify --keep-names
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
minify: true,
keepNames: true,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
MinifyWhitespace: true,
MinifyIdentifiers: true,
MinifySyntax: true,
KeepNames: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Mangle props
*Supported by: [Build](#build) and [Transform](#transform)*
**Using this feature can break your code in subtle ways.** Do not use this feature unless you know what you are doing, and you know exactly how it will affect both your code and all of your dependencies.
This setting lets you pass a regular expression to esbuild to tell esbuild to automatically rename all properties that match this regular expression. It's useful when you want to minify certain property names in your code either to make the generated code smaller or to somewhat obfuscate your code's intent.
Here's an example that uses the regular expression `_$` to mangle all properties ending in an underscore, such as `foo_`. This mangles `print({ foo_: 0 }.foo_)` into `print({ a: 0 }.a)`:
```
esbuild app.js --mangle-props=_$
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
mangleProps: /_$/,
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
MangleProps: "_$",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Only mangling properties that end in an underscore is a reasonable heuristic because normal JS code doesn't typically contain identifiers like that. Browser APIs also don't use this naming convention so this also avoids conflicts with browser APIs. If you want to avoid mangling names such as [`__defineGetter__`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/__defineGetter__) you could consider using a more complex regular expression such as `[^_]_$` (i.e. must end in a non-underscore followed by an underscore).
This is a separate setting instead of being part of the [minify](#minify) setting because it's an unsafe transformation that does not work on arbitrary JavaScript code. It only works if the provided regular expression matches all of the properties that you want mangled and does not match any of the properties that you don't want mangled. It also only works if you do not under any circumstances reference a mangled property indirectly. For example, it means you can't use `obj[prop]` to reference a property where `prop` is a string containing the property name. Specifically the following syntax constructs are the only ones eligible for property mangling:
| Syntax | Example |
| --- | --- |
| Dot property accesses | `x.foo_` |
| Dot optional chains | `x?.foo_` |
| Object properties | `x = { foo_: y }` |
| Object methods | `x = { foo_() {} }` |
| Class fields | `class x { foo_ = y }` |
| Class methods | `class x { foo_() {} }` |
| Object destructuring bindings | `let { foo_: x } = y` |
| Object destructuring assignments | `({ foo_: x } = y)` |
| JSX element member expression | `<X.foo_></X.foo_>` |
| JSX attribute names | `<X foo_={y} />` |
| TypeScript namespace exports | `namespace x { export let foo_ = y }` |
| TypeScript parameter properties | `class x { constructor(public foo_) {} }` |
When using this feature, keep in mind that property names are only consistently mangled within a single esbuild API call but not across esbuild API calls. Each esbuild API call does an independent property mangling operation so output files generated by two different API calls may mangle the same property to two different names, which could cause the resulting code to behave incorrectly.
#### Quoted properties
By default, esbuild doesn't modify the contents of string literals. This means you can avoid property mangling for an individual property by quoting it as a string. However, you must consistently use quotes or no quotes for a given property everywhere for this to work. For example, `print({ foo_: 0 }.foo_)` will be mangled into `print({ a: 0 }.a)` while `print({ 'foo_': 0 }['foo_'])` will not be mangled.
If you would like for esbuild to also mangle the contents of string literals, you can explicitly enable that behavior like this:
```
esbuild app.js --mangle-props=_$ --mangle-quoted
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
mangleProps: /_$/,
mangleQuoted: true,
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
MangleProps: "_$",
MangleQuoted: api.MangleQuotedTrue,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Enabling this makes the following syntax constructs also eligible for property mangling:
| Syntax | Example |
| --- | --- |
| Quoted property accesses | `x['foo_']` |
| Quoted optional chains | `x?.['foo_']` |
| Quoted object properties | `x = { 'foo_': y }` |
| Quoted object methods | `x = { 'foo_'() {} }` |
| Quoted class fields | `class x { 'foo_' = y }` |
| Quoted class methods | `class x { 'foo_'() {} }` |
| Quoted object destructuring bindings | `let { 'foo_': x } = y` |
| Quoted object destructuring assignments | `({ 'foo_': x } = y)` |
| String literals to the left of `in` | `'foo_' in x` |
#### Preventing renaming
If you would like to exclude certain properties from mangling, you can reserve them with an additional setting. For example, this uses the regular expression `^__.*__$` to reserve all properties that start and end with two underscores, such as `__foo__`:
```
esbuild app.js --mangle-props=_$ "--reserve-props=^__.*__$"
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
mangleProps: /_$/,
reserveProps: /^__.*__$/,
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
MangleProps: "_$",
ReserveProps: "^__.*__$",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
#### Persisting renaming decisions
Advanced usage of the property mangling feature involves storing the mapping from original name to mangled name in a persistent cache. When enabled, all mangled property renamings are recorded in the cache during the initial build. Subsequent builds reuse the renamings stored in the cache and add additional renamings for any newly-added properties. This has a few consequences:
* You can customize what mangled properties are renamed to by editing the cache before passing it to esbuild.
* The cache serves as a list of all properties that were mangled. You can easily scan it to see if there are any unexpected property renamings.
* You can disable mangling for individual properties by setting the renamed value to `false` instead of to a string. This is similar to the [reserve props](#reserve-props) setting but on a per-property basis.
* You can ensure consistent renaming between builds (e.g. a main-thread file and a web worker, or a library and a plugin). Without this feature, each build would do an independent renaming operation and the mangled property names likely wouldn't be consistent.
For example, consider the following input file:
```
console.log({
someProp_: 1,
customRenaming_: 2,
disabledRenaming_: 3
});
```
If we want `customRenaming_` to be renamed to `cR_` and we don't want `disabledRenaming_` to be renamed at all, we can pass the following mangle cache JSON to esbuild:
```
{
"customRenaming_": "cR_",
"disabledRenaming_": false
}
```
The mangle cache JSON can be passed to esbuild like this:
```
esbuild app.js --mangle-props=_$ --mangle-cache=cache.json
```
```
import * as esbuild from 'esbuild'
let result = await esbuild.build({
entryPoints: ['app.js'],
mangleProps: /_$/,
mangleCache: {
customRenaming_: "cR_",
disabledRenaming_: false
},
})
console.log('updated mangle cache:', result.mangleCache)
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
MangleProps: "_$",
MangleCache: map[string]interface{}{
"customRenaming_": "cR_",
"disabledRenaming_": false,
},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
fmt.Println("updated mangle cache:", result.MangleCache)
}
```
When property naming is enabled, that will result in the following output file:
```
console.log({
a: 1,
cR_: 2,
disabledRenaming_: 3
});
```
And the following updated mangle cache:
```
{
"customRenaming_": "cR_",
"disabledRenaming_": false,
"someProp_": "a"
}
```
### Minify
*Supported by: [Build](#build) and [Transform](#transform)*
When enabled, the generated code will be minified instead of pretty-printed. Minified code is generally equivalent to non-minified code but is smaller, which means it downloads faster but is harder to debug. Usually you minify code in production but not in development.
Enabling minification in esbuild looks like this:
```
echo 'fn = obj => { return obj.x }' | esbuild --minify
fn=n=>n.x;
```
```
import * as esbuild from 'esbuild'var js = 'fn = obj => { return obj.x }'
(await esbuild.transform(js, {
minify: true,
})).code
'fn=n=>n.x;\n'
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "fn = obj => { return obj.x }"
result := api.Transform(js, api.TransformOptions{
MinifyWhitespace: true,
MinifyIdentifiers: true,
MinifySyntax: true,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
This option does three separate things in combination: it removes whitespace, it rewrites your syntax to be more compact, and it renames local variables to be shorter. Usually you want to do all of these things, but these options can also be enabled individually if necessary:
```
echo 'fn = obj => { return obj.x }' | esbuild --minify-whitespace
fn=obj=>{return obj.x};
echo 'fn = obj => { return obj.x }' | esbuild --minify-identifiers
fn = (n) => {
return n.x;
};
echo 'fn = obj => { return obj.x }' | esbuild --minify-syntax
fn = (obj) => obj.x;
```
```
import * as esbuild from 'esbuild'var js = 'fn = obj => { return obj.x }'
(await esbuild.transform(js, {
minifyWhitespace: true,
})).code
'fn=obj=>{return obj.x};\n'
(await esbuild.transform(js, {
minifyIdentifiers: true,
})).code
'fn = (n) => {\n return n.x;\n};\n'
(await esbuild.transform(js, {
minifySyntax: true,
})).code
'fn = (obj) => obj.x;\n'
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
css := "div { color: yellow }"
result1 := api.Transform(css, api.TransformOptions{
Loader: api.LoaderCSS,
MinifyWhitespace: true,
})
if len(result1.Errors) == 0 {
fmt.Printf("%s", result1.Code)
}
result2 := api.Transform(css, api.TransformOptions{
Loader: api.LoaderCSS,
MinifyIdentifiers: true,
})
if len(result2.Errors) == 0 {
fmt.Printf("%s", result2.Code)
}
result3 := api.Transform(css, api.TransformOptions{
Loader: api.LoaderCSS,
MinifySyntax: true,
})
if len(result3.Errors) == 0 {
fmt.Printf("%s", result3.Code)
}
}
```
These same concepts also apply to CSS, not just to JavaScript:
```
echo 'div { color: yellow }' | esbuild --loader=css --minify
div{color:#ff0}
```
```
import * as esbuild from 'esbuild'var css = 'div { color: yellow }'
(await esbuild.transform(css, {
loader: 'css',
minify: true,
})).code
'div{color:#ff0}\n'
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
css := "div { color: yellow }"
result := api.Transform(css, api.TransformOptions{
Loader: api.LoaderCSS,
MinifyWhitespace: true,
MinifyIdentifiers: true,
MinifySyntax: true,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
The JavaScript minification algorithm in esbuild usually generates output that is very close to the minified output size of industry-standard JavaScript minification tools. [This benchmark](https://github.com/privatenumber/minification-benchmarks/tree/cd3e5acb8d38da5f86426d44ac95974812559683#readme) has an example comparison of output sizes between different minifiers. While esbuild is not the optimal JavaScript minifier in all cases (and doesn't try to be), it strives to generate minified output within a few percent of the size of dedicated minification tools for most code, and of course to do so much faster than other tools.
#### Considerations
Here are some things to keep in mind when using esbuild as a minifier:
* You should probably also set the [target](#target) option when minification is enabled. By default esbuild takes advantage of modern JavaScript features to make your code smaller. For example, `a === undefined || a === null ? 1 : a` could be minified to `a ?? 1`. If you do not want esbuild to take advantage of modern JavaScript features when minifying, you should use an older language target such as `--target=es6`.
* The character escape sequence `\n` will be replaced with a newline character in JavaScript template literals. String literals will also be converted into template literals if the [target](#target) supports them and if doing so would result in smaller output. **This is not a bug.** Minification means you are asking for smaller output, and the escape sequence `\n` takes two bytes while the newline character takes one byte.
* By default esbuild won't minify the names of top-level declarations. This is because esbuild doesn't know what you will be doing with the output. You might be injecting the minified code into the middle of some other code, in which case minifying top-level declaration names would be unsafe. Setting an output [format](#format) (or enabling [bundling](#bundle), which picks an output format for you if you haven't set one) tells esbuild that the output will be run within its own scope, which means it's then safe to minify top-level declaration names.
* Minification is not safe for 100% of all JavaScript code. This is true for esbuild as well as for other popular JavaScript minifiers such as [terser](https://github.com/terser/terser). In particular, esbuild is not designed to preserve the value of calling `.toString()` on a function. The reason for this is because if all code inside all functions had to be preserved verbatim, minification would hardly do anything at all and would be virtually useless. However, this means that JavaScript code relying on the return value of `.toString()` will likely break when minified. For example, some patterns in the [AngularJS](https://angularjs.org/) framework break when code is minified because AngularJS uses `.toString()` to read the argument names of functions. A workaround is to use [explicit annotations instead](https://docs.angularjs.org/api/auto/service/%24injector#injection-function-annotation).
* By default esbuild does not preserve the value of `.name` on function and class objects. This is because most code doesn't rely on this property and using shorter names is an important size optimization. However, some code does rely on the `.name` property for registration and binding purposes. If you need to rely on this you should enable the [keep names](#keep-names) option.
* Use of certain JavaScript features can disable many of esbuild's optimizations including minification. Specifically, using direct `eval` and/or the `with` statement prevent esbuild from renaming identifiers to smaller names since these features cause identifier binding to happen at run time instead of compile time. This is almost always unintentional, and only happens because people are unaware of what direct `eval` is and why it's bad.
If you are thinking about writing some code like this:
```
// Direct eval (will disable minification for the whole file)
let result = eval(something)
```
You should probably write your code like this instead so your code can be minified:
```
// Indirect eval (has no effect on the surrounding code)
let result = (0, eval)(something)
```
There is more information about the consequences of direct `eval` and the available alternatives [here](../content-types/index#direct-eval).
* The minification algorithm in esbuild does not yet do advanced code optimizations. In particular, the following code optimizations are possible for JavaScript code but are not done by esbuild (not an exhaustive list):
+ Dead-code elimination within function bodies
+ Function inlining
+ Cross-statement constant propagation
+ Object shape modeling
+ Allocation sinking
+ Method devirtualization
+ Symbolic execution
+ JSX expression hoisting
+ TypeScript enum detection and inlining If your code makes use of patterns that require some of these forms of code optimization to be compact, or if you are searching for the optimal JavaScript minification algorithm for your use case, you should consider using other tools. Some examples of tools that implement some of these advanced code optimizations include [Terser](https://github.com/terser/terser#readme) and [Google Closure Compiler](https://github.com/google/closure-compiler#readme).
### Pure
*Supported by: [Build](#build) and [Transform](#transform)*
There is a convention used by various JavaScript tools where a special comment containing either `/* @__PURE__ */` or `/* #__PURE__ */` before a new or call expression means that that expression can be removed if the resulting value is unused. It looks like this:
```
let button = /* @__PURE__ */ React.createElement(Button, null);
```
This information is used by bundlers such as esbuild during tree shaking (a.k.a. dead code removal) to perform fine-grained removal of unused imports across module boundaries in situations where the bundler is not able to prove by itself that the removal is safe due to the dynamic nature of JavaScript code.
Note that while the comment says "pure", it confusingly does *not* indicate that the function being called is pure. For example, it does not indicate that it is ok to cache repeated calls to that function. The name is essentially just an abstract shorthand for "ok to be removed if unused".
Some expressions such as JSX and certain built-in globals are automatically annotated as `/* @__PURE__ */` in esbuild. You can also configure additional globals to be marked `/* @__PURE__ */` as well. For example, you can mark the global `document.createElement` function as such to have it be automatically removed from your bundle when the bundle is minified as long as the result isn't used.
It's worth mentioning that the effect of the annotation only extends to the call itself, not to the arguments. Arguments with side effects are still kept even when minification is enabled:
```
echo 'document.createElement(elemName())' | esbuild --pure:document.createElement
/* @__PURE__ */ document.createElement(elemName());
echo 'document.createElement(elemName())' | esbuild --pure:document.createElement --minify
elemName();
```
```
import * as esbuild from 'esbuild'let js = 'document.createElement(elemName())'
(await esbuild.transform(js, {
pure: ['document.createElement'],
})).code
'/* @__PURE__ */ document.createElement(elemName());\n'
(await esbuild.transform(js, {
pure: ['document.createElement'],
minify: true,
})).code
'elemName();\n'
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "document.createElement(elemName())"
result1 := api.Transform(js, api.TransformOptions{
Pure: []string{"document.createElement"},
})
if len(result1.Errors) == 0 {
fmt.Printf("%s", result1.Code)
}
result2 := api.Transform(js, api.TransformOptions{
Pure: []string{"document.createElement"},
MinifySyntax: true,
})
if len(result2.Errors) == 0 {
fmt.Printf("%s", result2.Code)
}
}
```
Note that if you are trying to remove all calls to `console` API methods such as `console.log` and also want to remove the evaluation of arguments with side effects, there is a special case available for this: you can use the [drop feature](#drop) instead of marking `console` API calls as pure. However, this mechanism is specific to the `console` API and doesn't work with other call expressions.
### Tree shaking
*Supported by: [Build](#build) and [Transform](#transform)*
Tree shaking is the term the JavaScript community uses for dead code elimination, a common compiler optimization that automatically removes unreachable code. Within esbuild, this term specifically refers to declaration-level dead code removal.
Tree shaking is easiest to explain with an example. Consider the following file. There is one used function and one unused function:
```
// input.js
function one() {
console.log('one')
}
function two() {
console.log('two')
}
one()
```
If you bundle this file with `esbuild --bundle input.js --outfile=output.js`, the unused function will automatically be discarded leaving you with the following output:
```
// input.js
function one() {
console.log("one");
}
one();
```
This even works if we split our functions off into a separate library file and import them using an `import` statement:
```
// lib.js
export function one() {
console.log('one')
}
export function two() {
console.log('two')
}
```
```
// input.js
import * as lib from './lib.js'
lib.one()
```
If you bundle this file with `esbuild --bundle input.js --outfile=output.js`, the unused function and unused import will still be automatically discarded leaving you with the following output:
```
// lib.js
function one() {
console.log("one");
}
// input.js
one();
```
This way esbuild will only bundle the parts of your packages that you actually use, which can sometimes be a substantial size savings. Note that esbuild's tree shaking implementation relies on the use of ECMAScript module `import` and `export` statements. It does not work with CommonJS modules. Many packages on npm include both formats and esbuild tries to pick the format that works with tree shaking by default. You can customize which format esbuild picks using the [main fields](#main-fields) and/or [conditions](#conditions) options depending on the package.
By default, tree shaking is only enabled either when [bundling](#bundle) is enabled or when the output [format](#format) is set to `iife`, otherwise tree shaking is disabled. You can force-enable tree shaking by setting it to `true`:
```
esbuild app.js --tree-shaking=true
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
treeShaking: true,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
TreeShaking: api.TreeShakingTrue,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
You can also force-disable tree shaking by setting it to `false`:
```
esbuild app.js --tree-shaking=false
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
treeShaking: false,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
TreeShaking: api.TreeShakingFalse,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
#### Tree shaking and side effects
The side effect detection used for tree shaking is conservative, meaning that esbuild only considers code removable as dead code if it can be sure that there are no hidden side effects. For example, primitive literals such as `12.34` and `"abcd"` are side-effect free and can be removed while expressions such as `"ab" + cd` and `foo.bar` are not side-effect free (joining strings invokes `toString()` which can have side effects, and member access can invoke a getter which can also have side effects). Even referencing a global identifier is considered to be a side effect because it will throw a `ReferenceError` if there is no global with that name. Here's an example:
```
// These are considered side-effect free
let a = 12.34;
let b = "abcd";
let c = { a: a };
// These are not considered side-effect free
// since they could cause some code to run
let x = "ab" + cd;
let y = foo.bar;
let z = { [x]: x };
```
Sometimes it's desirable to allow some code to be tree shaken even if that code can't be automatically determined to have no side effects. This can be done with a [pure annotation comment](#pure) which tells esbuild to trust the author of the code that there are no side effects within the annotated code. The annotation comment is `/* @__PURE__ */` and can only precede a new or call expression. You can annotate an immediately-invoked function expression and put arbitrary side effects inside the function body:
```
// This is considered side-effect free due to
// the annotation, and will be removed if unused
let gammaTable = /* @__PURE__ */ (() => {
// Side-effect detection is skipped in here
let table = new Uint8Array(256);
for (let i = 0; i < 256; i++)
table[i] = Math.pow(i / 255, 2.2) * 255;
return table;
})();
```
While the fact that `/* @__PURE__ */` only works on call expressions can sometimes make code more verbose, a big benefit of this syntax is that it's portable across many other tools in the JavaScript ecosystem including the popular [UglifyJS](https://github.com/mishoo/uglifyjs) and [Terser](https://github.com/terser/terser) JavaScript minifiers (which are used by other major tools including [Webpack](https://github.com/webpack/webpack) and [Parcel](https://github.com/parcel-bundler/parcel)).
Note that the annotations cause esbuild to assume that the annotated code is side-effect free. If the annotations are wrong and the code actually does have important side effects, these annotations can result in broken code. If you are bundling third-party code with annotations that have been authored incorrectly, you may need to enable [ignoring annotations](#ignore-annotations) to make sure the bundled code is correct.
Source maps
-----------
### Source root
*Supported by: [Build](#build) and [Transform](#transform)*
This feature is only relevant when [source maps](#sourcemap) are enabled. It lets you set the value of the `sourceRoot` field in the source map, which specifies the path that all other paths in the source map are relative to. If this field is not present, all paths in the source map are interpreted as being relative to the directory containing the source map instead.
You can configure `sourceRoot` like this:
```
esbuild app.js --sourcemap --source-root=https://raw.githubusercontent.com/some/repo/v1.2.3/
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
sourcemap: true,
sourceRoot: 'https://raw.githubusercontent.com/some/repo/v1.2.3/',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Sourcemap: api.SourceMapInline,
SourceRoot: "https://raw.githubusercontent.com/some/repo/v1.2.3/",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Sourcefile
*Supported by: [Build](#build) and [Transform](#transform)*
This option sets the file name when using an input which has no file name. This happens when using the transform API and when using the build API with stdin. The configured file name is reflected in error messages and in source maps. If it's not configured, the file name defaults to `<stdin>`. It can be configured like this:
```
cat app.js | esbuild --sourcefile=example.js --sourcemap
```
```
import * as esbuild from 'esbuild'
import fs from 'node:fs'
let js = fs.readFileSync('app.js', 'utf8')
let result = await esbuild.transform(js, {
sourcefile: 'example.js',
sourcemap: 'inline',
})
console.log(result.code)
```
```
package main
import "fmt"
import "io/ioutil"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js, err := ioutil.ReadFile("app.js")
if err != nil {
panic(err)
}
result := api.Transform(string(js),
api.TransformOptions{
Sourcefile: "example.js",
Sourcemap: api.SourceMapInline,
})
if len(result.Errors) == 0 {
fmt.Printf("%s %s", result.Code)
}
}
```
### Sourcemap
*Supported by: [Build](#build) and [Transform](#transform)*
Source maps can make it easier to debug your code. They encode the information necessary to translate from a line/column offset in a generated output file back to a line/column offset in the corresponding original input file. This is useful if your generated code is sufficiently different from your original code (e.g. your original code is TypeScript or you enabled [minification](#minify)). This is also useful if you prefer looking at individual files in your browser's developer tools instead of one big bundled file.
Note that source map output is supported for both JavaScript and CSS, and the same options apply to both. Everything below that talks about `.js` files also applies similarly to `.css` files.
There are four different modes for source map generation:
1. `linked` This mode means the source map is generated into a separate `.js.map` output file alongside the `.js` output file, and the `.js` output file contains a special `//# sourceMappingURL=` comment that points to the `.js.map` output file. That way the browser knows where to find the source map for a given file when you open the debugger. Use `linked` source map mode like this:
```
esbuild app.ts --sourcemap --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.ts'],
sourcemap: true,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Sourcemap: api.SourceMapLinked,
Outfile: "out.js",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
2. `external` This mode means the source map is generated into a separate `.js.map` output file alongside the `.js` output file, but unlike `linked` mode the `.js` output file does not contain a `//# sourceMappingURL=` comment. Use `external` source map mode like this:
```
esbuild app.ts --sourcemap=external --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.ts'],
sourcemap: 'external',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Sourcemap: api.SourceMapExternal,
Outfile: "out.js",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
3. `inline` This mode means the source map is appended to the end of the `.js` output file as a base64 payload inside a `//# sourceMappingURL=` comment. No additional `.js.map` output file is generated. Keep in mind that source maps are usually very big because they contain all of your original source code, so you usually do not want to ship code containing `inline` source maps. To remove the source code from the source map (keeping only the file names and the line/column mappings), use the [sources content](#sources-content) option. Use `inline` source map mode like this:
```
esbuild app.ts --sourcemap=inline --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.ts'],
sourcemap: 'inline',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Sourcemap: api.SourceMapInline,
Outfile: "out.js",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
4. `both` This mode is a combination of `inline` and `external`. The source map is appended inline to the end of the `.js` output file, and another copy of the same source map is written to a separate `.js.map` output file alongside the `.js` output file. Use `both` source map mode like this:
```
esbuild app.ts --sourcemap=both --outfile=out.js
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.ts'],
sourcemap: 'both',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.ts"},
Sourcemap: api.SourceMapInlineAndExternal,
Outfile: "out.js",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
The [build](#build) API supports all four source map modes listed above, but the [transform](#transform) API does not support the `linked` mode. This is because the output returned from the transform API does not have an associated filename. If you want the output of the transform API to have a source map comment, you can append one yourself. In addition, the CLI form of the transform API only supports the `inline` mode because the output is written to stdout so generating multiple output files is not possible.
If you want to "peek under the hood" to see what a source map does (or to debug problems with your source map), you can upload the relevant output file and the associated source map here: [Source Map Visualization](https://evanw.github.io/source-map-visualization/).
#### Using source maps
In the browser, source maps should be automatically picked up by the browser's developer tools as long as the source map setting is enabled. Note that the browser only uses the source maps to alter the display of stack traces when they are logged to the console. The stack traces themselves are not modified so inspecting `error.stack` in your code will still give the unmapped stack trace containing compiled code. Here's how to enable this setting in your browser's developer tools:
* Chrome: ⚙ → Enable JavaScript source maps
* Safari: ⚙ → Sources → Enable source maps
* Firefox: ··· → Enable Source Maps
In node, source maps are supported natively starting with [version v12.12.0](https://nodejs.org/en/blog/release/v12.12.0/). This feature is disabled by default but can be enabled with a flag. Unlike in the browser, the actual stack traces are also modified in node so inspecting `error.stack` in your code will give the mapped stack trace containing your original source code. Here's how to enable this setting in node (the `--enable-source-maps` flag must come before the script file name):
```
node --enable-source-maps app.js
```
### Sources content
*Supported by: [Build](#build) and [Transform](#transform)*
[Source maps](#sourcemap) are generated using [version 3](https://sourcemaps.info/spec.html) of the source map format, which is by far the most widely-supported variant. Each source map will look something like this:
```
{
"version": 3,
"sources": ["bar.js", "foo.js"],
"sourcesContent": ["bar()", "foo()\nimport './bar'"],
"mappings": ";AAAA;;;ACAA;",
"names": []
}
```
The `sourcesContent` field is an optional field that contains all of the original source code. This is helpful for debugging because it means the original source code will be available in the debugger.
However, it's not needed in some scenarios. For example, if you are just using source maps in production to generate stack traces that contain the original file name, you don't need the original source code because there is no debugger involved. In that case it can be desirable to omit the `sourcesContent` field to make the source map smaller:
```
esbuild --bundle app.js --sourcemap --sources-content=false
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
bundle: true,
entryPoints: ['app.js'],
sourcemap: true,
sourcesContent: false,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
Bundle: true,
EntryPoints: []string{"app.js"},
Sourcemap: api.SourceMapInline,
SourcesContent: api.SourcesContentExclude,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Build metadata
--------------
### Analyze
*Supported by: [Build](#build)*
If you're looking for an interactive visualization, try esbuild's [Bundle Size Analyzer](../analyze/index) instead. You can upload your esbuild [metafile](#metafile) to see a bundle size breakdown.
Using the analyze feature generates an easy-to-read report about the contents of your bundle:
```
esbuild --bundle example.jsx --outfile=out.js --minify --analyze
out.js 27.6kb 100.0%
├ node_modules/react-dom/cjs/react-dom-server.browser.production.min.js 19.2kb 69.8%
├ node_modules/react/cjs/react.production.min.js 5.9kb 21.4%
├ node_modules/object-assign/index.js 962b 3.4%
├ example.jsx 137b 0.5%
├ node_modules/react-dom/server.browser.js 50b 0.2%
└ node_modules/react/index.js 50b 0.2%
...
```
```
import * as esbuild from 'esbuild'
let result = await esbuild.build({
entryPoints: ['example.jsx'],
outfile: 'out.js',
minify: true,
metafile: true,
})
console.log(await esbuild.analyzeMetafile(result.metafile))
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "fmt"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"example.jsx"},
Outfile: "out.js",
MinifyWhitespace: true,
MinifyIdentifiers: true,
MinifySyntax: true,
Metafile: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
fmt.Printf("%s", api.AnalyzeMetafile(result.Metafile, api.AnalyzeMetafileOptions{}))
}
```
The information shows which input files ended up in each output file as well as the percentage of the output file they ended up taking up. If you would like additional information, you can enable the "verbose" mode. This currently shows the import path from the entry point to each input file which tells you why a given input file is being included in the bundle:
```
esbuild --bundle example.jsx --outfile=out.js --minify --analyze=verbose
out.js ─────────────────────────────────────────────────────────────────── 27.6kb ─ 100.0%
├ node_modules/react-dom/cjs/react-dom-server.browser.production.min.js ─ 19.2kb ── 69.8%
│ └ node_modules/react-dom/server.browser.js
│ └ example.jsx
├ node_modules/react/cjs/react.production.min.js ───────────────────────── 5.9kb ── 21.4%
│ └ node_modules/react/index.js
│ └ example.jsx
├ node_modules/object-assign/index.js ──────────────────────────────────── 962b ──── 3.4%
│ └ node_modules/react-dom/cjs/react-dom-server.browser.production.min.js
│ └ node_modules/react-dom/server.browser.js
│ └ example.jsx
├ example.jsx ──────────────────────────────────────────────────────────── 137b ──── 0.5%
├ node_modules/react-dom/server.browser.js ──────────────────────────────── 50b ──── 0.2%
│ └ example.jsx
└ node_modules/react/index.js ───────────────────────────────────────────── 50b ──── 0.2%
└ example.jsx
...
```
```
import * as esbuild from 'esbuild'
let result = await esbuild.build({
entryPoints: ['example.jsx'],
outfile: 'out.js',
minify: true,
metafile: true,
})
console.log(await esbuild.analyzeMetafile(result.metafile, {
verbose: true,
}))
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "fmt"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"example.jsx"},
Outfile: "out.js",
MinifyWhitespace: true,
MinifyIdentifiers: true,
MinifySyntax: true,
Metafile: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
fmt.Printf("%s", api.AnalyzeMetafile(result.Metafile, api.AnalyzeMetafileOptions{
Verbose: true,
}))
}
```
This analysis is just a visualization of the information that can be found in the [metafile](#metafile). If this analysis doesn't exactly suit your needs, you are welcome to build your own visualization using the information in the metafile.
Note that this formatted analysis summary is intended for humans, not machines. The specific formatting may change over time which will likely break any tools that try to parse it. You should not write a tool to parse this data. You should be using the information in the [JSON metadata file](#metafile) instead. Everything in this visualization is derived from the JSON metadata so you are not losing out on any information by not parsing esbuild's formatted analysis summary.
### Metafile
*Supported by: [Build](#build)*
This option tells esbuild to produce some metadata about the build in JSON format. The following example puts the metadata in a file called `meta.json`:
```
esbuild app.js --bundle --metafile=meta.json --outfile=out.js
```
```
import * as esbuild from 'esbuild'
import fs from 'node:fs'
let result = await esbuild.build({
entryPoints: ['app.js'],
bundle: true,
metafile: true,
outfile: 'out.js',
})
fs.writeFileSync('meta.json', JSON.stringify(result.metafile))
```
```
package main
import "io/ioutil"
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Metafile: true,
Outfile: "out.js",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
ioutil.WriteFile("meta.json", []byte(result.Metafile), 0644)
}
```
This data can then be analyzed by other tools. For an interactive visualization, you can use esbuild's own [Bundle Size Analyzer](../analyze/index). For a quick textual analysis, you can use esbuild's build-in [analyze](#analyze) feature. Or you can write your own analysis which uses this information.
The metadata JSON format looks like this (described using a TypeScript interface):
```
interface Metafile {
inputs: {
[path: string]: {
bytes: number
imports: {
path: string
kind: string
external?: boolean
original?: string
}[]
format?: string
}
}
outputs: {
[path: string]: {
bytes: number
inputs: {
[path: string]: {
bytesInOutput: number
}
}
imports: {
path: string
kind: string
external?: boolean
}[]
exports: string[]
entryPoint?: string
cssBundle?: string
}
}
}
```
Logging
-------
### Color
*Supported by: [Build](#build) and [Transform](#transform)*
This option enables or disables colors in the error and warning messages that esbuild writes to stderr file descriptor in the terminal. By default, color is automatically enabled if stderr is a TTY session and automatically disabled otherwise. Colored output in esbuild looks like this:
```
▲ [WARNING] The "typeof" operator will never evaluate to "null" [impossible-typeof]
example.js:2:16:
2 │ log(typeof x == "null")
╵ ~~~~~~
The expression "typeof x" actually evaluates to "object" in JavaScript, not "null". You need to
use "x === null" to test for null.
✘ [ERROR] Could not resolve "logger"
example.js:1:16:
1 │ import log from "logger"
╵ ~~~~~~~~
You can mark the path "logger" as external to exclude it from the bundle, which will remove this
error.
```
Colored output can be force-enabled by setting color to `true`. This is useful if you are piping esbuild's stderr output into a TTY yourself:
```
echo 'typeof x == "null"' | esbuild --color=true 2> stderr.txt
```
```
import * as esbuild from 'esbuild'
let js = 'typeof x == "null"'
await esbuild.transform(js, {
color: true,
})
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "typeof x == 'null'"
result := api.Transform(js, api.TransformOptions{
Color: api.ColorAlways,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
Colored output can also be set to `false` to disable colors.
### Format messages
*Supported by: [Build](#build) and [Transform](#transform)*
This API call can be used to format the log errors and warnings returned by the [build](#build) API and [transform](#transform) APIs as a string using the same formatting that esbuild itself uses. This is useful if you want to customize the way esbuild's logging works, such as processing the log messages before they are printed or printing them to somewhere other than to the console. Here's an example:
```
import * as esbuild from 'esbuild'
let formatted = await esbuild.formatMessages([
{
text: 'This is an error',
location: {
file: 'app.js',
line: 10,
column: 4,
length: 3,
lineText: 'let foo = bar',
},
},
], {
kind: 'error',
color: false,
terminalWidth: 100,
})
console.log(formatted.join('\n'))
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
import "strings"
func main() {
formatted := api.FormatMessages([]api.Message{
{
Text: "This is an error",
Location: &api.Location{
File: "app.js",
Line: 10,
Column: 4,
Length: 3,
LineText: "let foo = bar",
},
},
}, api.FormatMessagesOptions{
Kind: api.ErrorMessage,
Color: false,
TerminalWidth: 100,
})
fmt.Printf("%s", strings.Join(formatted, "\n"))
}
```
#### Options
The following options can be provided to control the formatting:
```
interface FormatMessagesOptions {
kind: 'error' | 'warning';
color?: boolean;
terminalWidth?: number;
}
```
```
type FormatMessagesOptions struct {
Kind MessageKind
Color bool
TerminalWidth int
}
```
* `kind` Controls whether these log messages are printed as errors or warnings.
* `color` If this is `true`, Unix-style terminal escape codes are included for colored output.
* `terminalWidth` Provide a positive value to wrap long lines so that they don't overflow past the provided column width. Provide `0` to disable word wrapping.
### Log level
*Supported by: [Build](#build) and [Transform](#transform)*
The log level can be changed to prevent esbuild from printing warning and/or error messages to the terminal. The six log levels are:
* `silent`
Do not show any log output. This is the default log level when using the JS [transform](#transform) API.
* `error`
Only show errors.
* `warning`
Only show warnings and errors. This is the default log level when using the JS [build](#build) API.
* `info`
Show warnings, errors, and an output file summary. This is the default log level when using the CLI.
* `debug`
Log everything from `info` and some additional messages that may help you debug a broken bundle. This log level has a performance impact and some of the messages may be false positives, so this information is not shown by default.
* `verbose`
This generates a torrent of log messages and was added to debug issues with file system drivers. It's not intended for general use.
The log level can be set like this:
```
echo 'typeof x == "null"' | esbuild --log-level=error
```
```
import * as esbuild from 'esbuild'
let js = 'typeof x == "null"'
await esbuild.transform(js, {
logLevel: 'error',
})
```
```
package main
import "fmt"
import "github.com/evanw/esbuild/pkg/api"
func main() {
js := "typeof x == 'null'"
result := api.Transform(js, api.TransformOptions{
LogLevel: api.LogLevelError,
})
if len(result.Errors) == 0 {
fmt.Printf("%s", result.Code)
}
}
```
### Log limit
*Supported by: [Build](#build) and [Transform](#transform)*
By default, esbuild stops reporting log messages after 10 messages have been reported. This avoids the accidental generation of an overwhelming number of log messages, which can easily lock up slower terminal emulators such as Windows command prompt. It also avoids accidentally using up the whole scroll buffer for terminal emulators with limited scroll buffers.
The log limit can be changed to another value, and can also be disabled completely by setting it to zero. This will show all log messages:
```
esbuild app.js --log-limit=0
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
logLimit: 0,
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
LogLimit: 0,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Log override
*Supported by: [Build](#build) and [Transform](#transform)*
This feature lets you change the log level of individual types of log messages. You can use it to silence a particular type of warning, to enable additional warnings that aren't enabled by default, or even to turn warnings into errors.
For example, when targeting older browsers, esbuild automatically transforms regular expression literals which use features that are too new for those browsers into `new RegExp()` calls to allow the generated code to run without being considered a syntax error by the browser. However, these calls will still throw at runtime if you don't add a polyfill for `RegExp` because that regular expression syntax is still unsupported. If you want esbuild to generate a warning when you use newer unsupported regular expression syntax, you can do that like this:
```
esbuild app.js --log-override:unsupported-regexp=warning --target=chrome50
```
```
import * as esbuild from 'esbuild'
await esbuild.build({
entryPoints: ['app.js'],
logOverride: {
'unsupported-regexp': 'warning',
},
target: 'chrome50',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
LogOverride: map[string]api.LogLevel{
"unsupported-regexp": api.LogLevelWarning,
},
Engines: []api.Engine{
{Name: api.EngineChrome, Version: "50"},
},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
The log level for each message type can be overridden to any value supported by the [log level](index#log-level) setting. All currently-available message types are listed below (click on each one for an example log message):
* **JS:**
+ `assign-to-constant`
```
▲ [WARNING] This assignment will throw because "foo" is a constant [assign-to-constant]
example.js:1:15:
1 │ const foo = 1; foo = 2
╵ ~~~
The symbol "foo" was declared a constant here:
example.js:1:6:
1 │ const foo = 1; foo = 2
╵ ~~~
```
+ `assign-to-import`
```
▲ [WARNING] This assignment will throw because "foo" is an import [assign-to-import]
example.js:1:23:
1 │ import foo from "foo"; foo = null
╵ ~~~
Imports are immutable in JavaScript. To modify the value of this import, you must export a setter
function in the imported file (e.g. "setFoo") and then import and call that function here instead.
```
+ `call-import-namespace`
```
▲ [WARNING] Calling "foo" will crash at run-time because it's an import namespace object, not a function [call-import-namespace]
example.js:1:28:
1 │ import * as foo from "foo"; foo()
╵ ~~~
Consider changing "foo" to a default import instead:
example.js:1:7:
1 │ import * as foo from "foo"; foo()
│ ~~~~~~~~
╵ foo
```
+ `commonjs-variable-in-esm`
```
▲ [WARNING] The CommonJS "exports" variable is treated as a global variable in an ECMAScript module and may not work as expected [commonjs-variable-in-esm]
example.js:1:0:
1 │ exports.foo = 1; export let bar = 2
╵ ~~~~~~~
This file is considered to be an ECMAScript module because of the "export" keyword here:
example.js:1:17:
1 │ exports.foo = 1; export let bar = 2
╵ ~~~~~~
```
+ `delete-super-property`
```
▲ [WARNING] Attempting to delete a property of "super" will throw a ReferenceError [delete-super-property]
example.js:1:42:
1 │ class Foo extends Object { foo() { delete super.foo } }
╵ ~~~~~
```
+ `duplicate-case`
```
▲ [WARNING] This case clause will never be evaluated because it duplicates an earlier case clause [duplicate-case]
example.js:1:33:
1 │ switch (foo) { case 1: return 1; case 1: return 2 }
╵ ~~~~
The earlier case clause is here:
example.js:1:15:
1 │ switch (foo) { case 1: return 1; case 1: return 2 }
╵ ~~~~
```
+ `duplicate-object-key`
```
▲ [WARNING] Duplicate key "bar" in object literal [duplicate-object-key]
example.js:1:16:
1 │ foo = { bar: 1, bar: 2 }
╵ ~~~
The original key "bar" is here:
example.js:1:8:
1 │ foo = { bar: 1, bar: 2 }
╵ ~~~
```
+ `empty-import-meta`
```
▲ [WARNING] "import.meta" is not available in the configured target environment ("chrome50") and will be empty [empty-import-meta]
example.js:1:6:
1 │ foo = import.meta
╵ ~~~~~~~~~~~
```
+ `equals-nan`
```
▲ [WARNING] Comparison with NaN using the "!==" operator here is always true [equals-nan]
example.js:1:24:
1 │ foo = foo.filter(x => x !== NaN)
╵ ~~~
Floating-point equality is defined such that NaN is never equal to anything, so "x === NaN" always
returns false. You need to use "Number.isNaN(x)" instead to test for NaN.
```
+ `equals-negative-zero`
```
▲ [WARNING] Comparison with -0 using the "!==" operator will also match 0 [equals-negative-zero]
example.js:1:28:
1 │ foo = foo.filter(x => x !== -0)
╵ ~~
Floating-point equality is defined such that 0 and -0 are equal, so "x === -0" returns true for
both 0 and -0. You need to use "Object.is(x, -0)" instead to test for -0.
```
+ `equals-new-object`
```
▲ [WARNING] Comparison using the "!==" operator here is always true [equals-new-object]
example.js:1:24:
1 │ foo = foo.filter(x => x !== [])
╵ ~~~
Equality with a new object is always false in JavaScript because the equality operator tests
object identity. You need to write code to compare the contents of the object instead. For
example, use "Array.isArray(x) && x.length === 0" instead of "x === []" to test for an empty
array.
```
+ `html-comment-in-js`
```
▲ [WARNING] Treating "<!--" as the start of a legacy HTML single-line comment [html-comment-in-js]
example.js:1:0:
1 │ <!-- comment -->
╵ ~~~~
```
+ `impossible-typeof`
```
▲ [WARNING] The "typeof" operator will never evaluate to "null" [impossible-typeof]
example.js:1:32:
1 │ foo = foo.map(x => typeof x !== "null")
╵ ~~~~~~
The expression "typeof x" actually evaluates to "object" in JavaScript, not "null". You need to
use "x === null" to test for null.
```
+ `indirect-require`
```
▲ [WARNING] Indirect calls to "require" will not be bundled [indirect-require]
example.js:1:8:
1 │ let r = require, fs = r("fs")
╵ ~~~~~~~
```
+ `private-name-will-throw`
```
▲ [WARNING] Writing to getter-only property "#foo" will throw [private-name-will-throw]
example.js:1:39:
1 │ class Foo { get #foo() {} bar() { this.#foo++ } }
╵ ~~~~
```
+ `semicolon-after-return`
```
▲ [WARNING] The following expression is not returned because of an automatically-inserted semicolon [semicolon-after-return]
example.js:1:6:
1 │ return
╵ ^
```
+ `suspicious-boolean-not`
```
▲ [WARNING] Suspicious use of the "!" operator inside the "in" operator [suspicious-boolean-not]
example.js:1:4:
1 │ if (!foo in bar) {
│ ~~~~
╵ (!foo)
The code "!x in y" is parsed as "(!x) in y". You need to insert parentheses to get "!(x in y)"
instead.
```
+ `this-is-undefined-in-esm`
```
▲ [WARNING] Top-level "this" will be replaced with undefined since this file is an ECMAScript module [this-is-undefined-in-esm]
example.js:1:0:
1 │ this.foo = 1; export let bar = 2
│ ~~~~
╵ undefined
This file is considered to be an ECMAScript module because of the "export" keyword here:
example.js:1:14:
1 │ this.foo = 1; export let bar = 2
╵ ~~~~~~
```
+ `unsupported-dynamic-import`
```
▲ [WARNING] This "import" expression will not be bundled because the argument is not a string literal [unsupported-dynamic-import]
example.js:1:0:
1 │ import(foo)
╵ ~~~~~~
```
+ `unsupported-jsx-comment`
```
▲ [WARNING] Invalid JSX factory: 123 [unsupported-jsx-comment]
example.jsx:1:8:
1 │ // @jsx 123
╵ ~~~
```
+ `unsupported-regexp`
```
▲ [WARNING] The regular expression flag "d" is not available in the configured target environment ("chrome50") [unsupported-regexp]
example.js:1:3:
1 │ /./d
╵ ^
This regular expression literal has been converted to a "new RegExp()" constructor to avoid
generating code with a syntax error. However, you will need to include a polyfill for "RegExp" for
your code to have the correct behavior at run-time.
```
+ `unsupported-require-call`
```
▲ [WARNING] This call to "require" will not be bundled because the argument is not a string literal [unsupported-require-call]
example.js:1:0:
1 │ require(foo)
╵ ~~~~~~~
```
* **CSS:**
+ `css-syntax-error`
```
▲ [WARNING] Expected identifier but found "]" [css-syntax-error]
example.css:1:4:
1 │ div[] {
╵ ^
```
+ `invalid-@charset`
```
▲ [WARNING] "@charset" must be the first rule in the file [invalid-@charset]
example.css:1:19:
1 │ div { color: red } @charset "UTF-8";
╵ ~~~~~~~~
This rule cannot come before a "@charset" rule
example.css:1:0:
1 │ div { color: red } @charset "UTF-8";
╵ ^
```
+ `invalid-@import`
```
▲ [WARNING] All "@import" rules must come first [invalid-@import]
example.css:1:19:
1 │ div { color: red } @import "foo.css";
╵ ~~~~~~~
This rule cannot come before an "@import" rule
example.css:1:0:
1 │ div { color: red } @import "foo.css";
╵ ^
```
+ `invalid-@nest`
```
▲ [WARNING] CSS nesting syntax cannot be used outside of a style rule [invalid-@nest]
example.css:1:0:
1 │ & div {
╵ ^
```
+ `invalid-@layer`
```
▲ [WARNING] "initial" cannot be used as a layer name [invalid-@layer]
example.css:1:7:
1 │ @layer initial {
╵ ~~~~~~~
```
+ `invalid-calc`
```
▲ [WARNING] "-" can only be used as an infix operator, not a prefix operator [invalid-calc]
example.css:1:20:
1 │ div { z-index: calc(-(1+2)); }
╵ ^
▲ [WARNING] The "+" operator only works if there is whitespace on both sides [invalid-calc]
example.css:1:23:
1 │ div { z-index: calc(-(1+2)); }
╵ ^
```
+ `js-comment-in-css`
```
▲ [WARNING] Comments in CSS use "/* ... */" instead of "//" [js-comment-in-css]
example.css:1:0:
1 │ // comment
╵ ~~
```
+ `unsupported-@charset`
```
▲ [WARNING] "UTF-8" will be used instead of unsupported charset "ASCII" [unsupported-@charset]
example.css:1:9:
1 │ @charset "ASCII";
╵ ~~~~~~~
```
+ `unsupported-@namespace`
```
▲ [WARNING] "@namespace" rules are not supported [unsupported-@namespace]
example.css:1:0:
1 │ @namespace "ns";
╵ ~~~~~~~~~~
```
+ `unsupported-css-property`
```
▲ [WARNING] "widht" is not a known CSS property [unsupported-css-property]
example.css:1:6:
1 │ div { widht: 1px }
│ ~~~~~
╵ width
Did you mean "width" instead?
```
* **Bundler:**
+ `ambiguous-reexport`
```
▲ [WARNING] Re-export of "foo" in "example.js" is ambiguous and has been removed [ambiguous-reexport]
One definition of "foo" comes from "a.js" here:
a.js:1:11:
1 │ export let foo = 1
╵ ~~~
Another definition of "foo" comes from "b.js" here:
b.js:1:11:
1 │ export let foo = 2
╵ ~~~
```
+ `different-path-case`
```
▲ [WARNING] Use "foo.js" instead of "Foo.js" to avoid issues with case-sensitive file systems [different-path-case]
example.js:2:7:
2 │ import "./Foo.js"
╵ ~~~~~~~~~~
```
+ `ignored-bare-import`
```
▲ [WARNING] Ignoring this import because "node_modules/foo/index.js" was marked as having no side effects [ignored-bare-import]
example.js:1:7:
1 │ import "foo"
╵ ~~~~~
"sideEffects" is false in the enclosing "package.json" file
node_modules/foo/package.json:2:2:
2 │ "sideEffects": false
╵ ~~~~~~~~~~~~~
```
+ `ignored-dynamic-import`
```
▲ [WARNING] Importing "foo" was allowed even though it could not be resolved because dynamic import failures appear to be handled here: [ignored-dynamic-import]
example.js:1:7:
1 │ import("foo").catch(e => {
╵ ~~~~~
The handler for dynamic import failures is here:
example.js:1:14:
1 │ import("foo").catch(e => {
╵ ~~~~~
```
+ `import-is-undefined`
```
▲ [WARNING] Import "foo" will always be undefined because the file "foo.js" has no exports [import-is-undefined]
example.js:1:9:
1 │ import { foo } from "./foo"
╵ ~~~
```
+ `require-resolve-not-external`
```
▲ [WARNING] "foo" should be marked as external for use with "require.resolve" [require-resolve-not-external]
example.js:1:26:
1 │ let foo = require.resolve("foo")
╵ ~~~~~
```
* **Source maps:**
+ `invalid-source-mappings`
```
▲ [WARNING] Bad "mappings" data in source map at character 3: Invalid original column value: -2 [invalid-source-mappings]
example.js.map:2:18:
2 │ "mappings": "aAAFA,UAAU;;"
╵ ^
The source map "example.js.map" was referenced by the file "example.js" here:
example.js:1:21:
1 │ //# sourceMappingURL=example.js.map
╵ ~~~~~~~~~~~~~~
```
+ `sections-in-source-map`
```
▲ [WARNING] Source maps with "sections" are not supported [sections-in-source-map]
example.js.map:2:2:
2 │ "sections": []
╵ ~~~~~~~~~~
The source map "example.js.map" was referenced by the file "example.js" here:
example.js:1:21:
1 │ //# sourceMappingURL=example.js.map
╵ ~~~~~~~~~~~~~~
```
+ `missing-source-map`
```
▲ [WARNING] Cannot read file ".": is a directory [missing-source-map]
example.js:1:21:
1 │ //# sourceMappingURL=.
╵ ^
```
+ `unsupported-source-map-comment`
```
▲ [WARNING] Unsupported source map comment: could not decode percent-escaped data: invalid URL escape "%\"" [unsupported-source-map-comment]
example.js:1:21:
1 │ //# sourceMappingURL=data:application/json,"%"
╵ ~~~~~~~~~~~~~~~~~~~~~~~~~
```
* **Resolver:**
+ `package.json`
```
▲ [WARNING] "esm" is not a valid value for the "type" field [package.json]
package.json:1:10:
1 │ { "type": "esm" }
╵ ~~~~~
The "type" field must be set to either "commonjs" or "module".
```
+ `tsconfig.json`
```
▲ [WARNING] Unrecognized target environment "ES4" [tsconfig.json]
tsconfig.json:1:33:
1 │ { "compilerOptions": { "target": "ES4" } }
╵ ~~~~~
```
These message types should be reasonably stable but new ones may be added and old ones may occasionally be removed in the future. If a message type is removed, any overrides for that message type will just be silently ignored.
| programming_docs |
esbuild Content Types Content Types
=============
All of the built-in content types are listed below. Each content type has an associated "loader" which tells esbuild how to interpret the file contents. Some file extensions already have a loader configured for them by default, although the defaults can be overridden.
JavaScript
----------
Loader: `js`
This loader is enabled by default for `.js`, `.cjs`, and `.mjs` files. The `.cjs` extension is used by node for CommonJS modules and the `.mjs` extension is used by node for ECMAScript modules.
Note that by default, esbuild's output will take advantage of all modern JS features. For example, `a !== void 0 && a !== null ? a : b` will become `a ?? b` when minifying is enabled which makes use of syntax from the [ES2020](https://262.ecma-international.org/11.0/#prod-CoalesceExpression) version of JavaScript. If this is undesired, you must specify esbuild's [target](../api/index#target) setting to say in which browsers you need the output to work correctly. Then esbuild will avoid using JavaScript features that are too modern for those browsers.
All modern JavaScript syntax is supported by esbuild. Newer syntax may not be supported by older browsers, however, so you may want to configure the [target](../api/index#target) option to tell esbuild to convert newer syntax to older syntax as appropriate.
These syntax features are always transformed for older browsers:
| Syntax transform | Language version | Example |
| --- | --- | --- |
| [Trailing commas in function parameter lists and calls](https://github.com/tc39/proposal-trailing-function-commas) | `es2017` | `foo(a, b, )` |
| [Numeric separators](https://github.com/tc39/proposal-numeric-separator) | `esnext` | `1_000_000` |
These syntax features are conditionally transformed for older browsers depending on the configured language target:
| Syntax transform | Transformed when `--target` is below | Example |
| --- | --- | --- |
| [Exponentiation operator](https://github.com/tc39/proposal-exponentiation-operator) | `es2016` | `a ** b` |
| [Async functions](https://github.com/tc39/ecmascript-asyncawait) | `es2017` | `async () => {}` |
| [Asynchronous iteration](https://github.com/tc39/proposal-async-iteration) | `es2018` | `for await (let x of y) {}` |
| [Spread properties](https://github.com/tc39/proposal-object-rest-spread) | `es2018` | `let x = {...y}` |
| [Rest properties](https://github.com/tc39/proposal-object-rest-spread) | `es2018` | `let {...x} = y` |
| [Optional catch binding](https://github.com/tc39/proposal-optional-catch-binding) | `es2019` | `try {} catch {}` |
| [Optional chaining](https://github.com/tc39/proposal-optional-chaining) | `es2020` | `a?.b` |
| [Nullish coalescing](https://github.com/tc39/proposal-nullish-coalescing) | `es2020` | `a ?? b` |
| [`import.meta`](https://github.com/tc39/proposal-import-meta) | `es2020` | `import.meta` |
| [Logical assignment operators](https://github.com/tc39/proposal-logical-assignment) | `es2021` | `a ??= b` |
| [Class instance fields](https://github.com/tc39/proposal-class-fields) | `es2022` | `class { x }` |
| [Static class fields](https://github.com/tc39/proposal-static-class-features) | `es2022` | `class { static x }` |
| [Private instance methods](https://github.com/tc39/proposal-private-methods) | `es2022` | `class { #x() {} }` |
| [Private instance fields](https://github.com/tc39/proposal-class-fields) | `es2022` | `class { #x }` |
| [Private static methods](https://github.com/tc39/proposal-static-class-features) | `es2022` | `class { static #x() {} }` |
| [Private static fields](https://github.com/tc39/proposal-static-class-features) | `es2022` | `class { static #x }` |
| [Ergonomic brand checks](https://github.com/tc39/proposal-private-fields-in-in) | `es2022` | `#x in y` |
| [Class static blocks](https://github.com/tc39/proposal-class-static-block) | `es2022` | `class { static {} }` |
| [Import assertions](https://github.com/tc39/proposal-import-assertions) | `esnext` | `import "x" assert {}` |
These syntax features are currently always passed through un-transformed:
| Syntax transform | Unsupported when `--target` is below | Example |
| --- | --- | --- |
| [Async generators](https://github.com/tc39/proposal-async-iteration) | `es2018` | `async function* foo() {}` |
| [BigInt](https://github.com/tc39/proposal-bigint) | `es2020` | `123n` |
| [Top-level await](https://github.com/tc39/proposal-top-level-await) | `es2022` | `await import(x)` |
| [Arbitrary module namespace identifiers](https://github.com/bmeck/proposal-arbitrary-module-namespace-identifiers) | `es2022` | `export {foo as 'f o o'}` |
| [Hashbang grammar](https://github.com/tc39/proposal-hashbang) | `esnext` | `#!/usr/bin/env node` |
See also [the list of finished ECMAScript proposals](https://github.com/tc39/proposals/blob/main/finished-proposals.md) and [the list of active ECMAScript proposals](https://github.com/tc39/proposals/blob/main/README.md). Note that while transforming code containing top-level await is supported, bundling code containing top-level await is only supported when the [output format](../api/index#format) is set to [`esm`](../api/index#format-esm).
### JavaScript caveats
You should keep the following things in mind when using JavaScript with esbuild:
#### ES5 is not supported well
Transforming ES6+ syntax to ES5 is not supported yet. However, if you're using esbuild to transform ES5 code, you should still set the [target](../api/index#target) to `es5`. This prevents esbuild from introducing ES6 syntax into your ES5 code. For example, without this flag the object literal `{x: x}` will become `{x}` and the string `"a\nb"` will become a multi-line template literal when minifying. Both of these substitutions are done because the resulting code is shorter, but the substitutions will not be performed if the [target](../api/index#target) is `es5`.
#### Private member performance
The private member transform (for the `#name` syntax) uses `WeakMap` and `WeakSet` to preserve the privacy properties of this feature. This is similar to the corresponding transforms in the Babel and TypeScript compilers. Most modern JavaScript engines (V8, JavaScriptCore, and SpiderMonkey but not ChakraCore) may not have good performance characteristics for large `WeakMap` and `WeakSet` objects.
Creating many instances of classes with private fields or private methods with this syntax transform active may cause a lot of overhead for the garbage collector. This is because modern engines (other than ChakraCore) store weak values in an actual map object instead of as hidden properties on the keys themselves, and large map objects can cause performance issues with garbage collection. See [this reference](https://github.com/tc39/ecma262/issues/1657#issuecomment-518916579) for more information.
#### Imports follow ECMAScript module behavior
You might try to modify global state before importing a module which needs that global state and expect it to work. However, JavaScript (and therefore esbuild) effectively "hoists" all `import` statements to the top of the file, so doing this won't work:
```
window.foo = {}
import './something-that-needs-foo'
```
There are some broken implementations of ECMAScript modules out there (e.g. the TypeScript compiler) that don't follow the JavaScript specification in this regard. Code compiled with these tools may "work" since the `import` is replaced with an inline call to `require()`, which ignores the hoisting requirement. But such code will not work with real ECMAScript module implementations such as node, a browser, or esbuild, so writing code like this is non-portable and is not recommended.
The way to do this correctly is to move the global state modification into its own import. That way it *will* be run before the other import:
```
import './assign-to-foo-on-window'
import './something-that-needs-foo'
```
#### Avoid direct `eval` when bundling
Although the expression `eval(x)` looks like a normal function call, it actually takes on special behavior in JavaScript. Using `eval` in this way means that the evaluated code stored in `x` can reference any variable in any containing scope by name. For example, the code `let y = 123; return eval('y')` will return `123`.
This is called "direct eval" and is problematic when bundling your code for many reasons:
* Modern bundlers contain an optimization called "scope hoisting" that merges all bundled files into a single file and renames variables to avoid name collisions. However, this means code evaluated by direct `eval` can read and write variables in any file in the bundle! This is a correctness issue because the evaluated code may try to access a global variable but may accidentally access a private variable with the same name from another file instead. It can potentially even be a security issue if a private variable in another file has sensitive data.
* The evaluated code may not work correctly when it references variables imported using an `import` statement. Imported variables are live bindings to variables in another file. They are not copies of those variables. So when esbuild bundles your code, your imports are replaced with a direct reference to the variable in the imported file. But that variable may have a different name, in which case the code evaluated by direct `eval` will be unable to reference it by the expected name.
* Using direct `eval` forces esbuild to deoptimize all of the code in all of the scopes containing calls to direct `eval`. For correctness, it must assume that the evaluated code might need to access any of the other code in the file reachable from that `eval` call. This means none of that code will be eliminated as dead code and none of that code will be minified.
* Because the code evaluated by the direct `eval` could need to reference any reachable variable by name, esbuild is prevented from renaming all of the variables reachable by the evaluated code. This means it can't rename variables to avoid name collisions with other variables in the bundle. So the direct `eval` causes esbuild to wrap the file in a CommonJS closure, which avoids name collisions by introducing a new scope instead. However, this makes the generated code bigger and slower because exported variables use run-time dynamic binding instead of compile-time static binding.
Luckily it is usually easy to avoid using direct `eval`. There are two commonly-used alternatives that avoid all of the drawbacks mentioned above:
* `(0, eval)('x')` This is known as "indirect eval" because `eval` is not being called directly, and so does not trigger the grammatical special case for direct eval in the JavaScript VM. You can call indirect eval using any syntax at all except for an expression of the exact form `eval('x')`. For example, `var eval2 = eval; eval2('x')` and `[eval][0]('x')` and `window.eval('x')` are all indirect eval calls. When you use indirect eval, the code is evaluated in the global scope instead of in the inline scope of the caller.
* `new Function('x')` This constructs a new function object at run-time. It is as if you wrote `function() { x }` in the global scope except that `x` can be an arbitrary string of code. This form is sometimes convenient because you can add arguments to the function, and use those arguments to expose variables to the evaluated code. For example, `(new Function('env', 'x'))(someEnv)` is as if you wrote `(function(env) { x })(someEnv)`. This is often a sufficient alternative for direct `eval` when the evaluated code needs to access local variables because you can pass the local variables in as arguments.
#### The value of `toString()` is not preserved on functions (and classes)
It's somewhat common to call `toString()` on a JavaScript function object and then pass that string to some form of `eval` to get a new function object. This effectively "rips" the function out of the containing file and breaks links with all variables in that file. Doing this with esbuild is not supported and may not work. In particular, esbuild often uses helper methods to implement certain features and it assumes that JavaScript scope rules have not been tampered with. For example:
```
let pow = (a, b) => a ** b;
let pow2 = (0, eval)(pow.toString());
console.log(pow2(2, 3));
```
When this code is compiled for ES6, where the `**` operator isn't available, the `**` operator is replaced with a call to the `__pow` helper function:
```
let __pow = Math.pow;
let pow = (a, b) => __pow(a, b);
let pow2 = (0, eval)(pow.toString());
console.log(pow2(2, 3));
```
If you try to run this code, you'll get an error such as `ReferenceError: __pow is not defined` because the function `(a, b) => __pow(a, b)` depends on the locally-scoped symbol `__pow` which is not available in the global scope. This is the case for many JavaScript language features including `async` functions, as well as some esbuild-specific features such as the [keep names](../api/index#keep-names) setting.
This problem most often comes up when people get the source code of a function with `.toString()` and then try to use it as the body of a [web worker](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API). If you are doing this and you want to use esbuild, you should instead build the source code for the web worker in a separate build step and then insert the web worker source code as a string into the code that creates the web worker. The [define](../api/index#define) feature is one way to insert the string at build time.
#### The value of `this` is not preserved on functions called from a module namespace object
In JavaScript, the value of `this` in a function is automatically filled in for you based on how the function is called. For example if a function is called using `obj.fn()`, the value of `this` during the function call will be `obj`. This behavior is respected by esbuild with one exception: if you call a function from a module namespace object, the value of `this` may not be correct. For example, consider this code that calls `foo` from the module namespace object `ns`:
```
import * as ns from './foo.js'
ns.foo()
```
If `foo.js` tries to reference the module namespace object using `this`, then it won't necessarily work after the code is bundled with esbuild:
```
// foo.js
export function foo() {
this.bar()
}
export function bar() {
console.log('bar')
}
```
The reason for this is that esbuild automatically rewrites code most code that uses module namespace objects to code that imports things directly instead. That means the example code above will be converted to this instead, which removes the `this` context for the function call:
```
import { foo } from './foo.js'
foo()
```
This transformation dramatically improves [tree shaking](../api/index#tree-shaking) (a.k.a. dead code elimination) because it makes it possible for esbuild to understand which exported symbols are unused. It has the drawback that this changes the behavior of code that uses `this` to access the module's exports, but this isn't an issue because no one should ever write bizarre code like this in the first place. If you need to access an exported function from the same file, just call it directly (i.e. `bar()` instead of `this.bar()` in the example above).
#### The `default` export can be error-prone
The ES module format (i.e. ESM) have a special export called `default` that sometimes behaves differently than all other export names. When code in the ESM format that has a `default` export is converted to the CommonJS format, and then that CommonJS code is imported into another module in ESM format, there are two different interpretations of what should happen that are both widely-used (the [Babel](https://babeljs.io/) way and the [Node](https://nodejs.org/) way). This is very unfortunate because it causes endless compatibility headaches, especially since JavaScript libraries are often authored in ESM and published as CommonJS.
When esbuild [bundles](../api/index#bundle) code that does this, it has to decide which interpretation to use, and there's no perfect answer. The heuristics that esbuild uses are the same heuristics that [Webpack](https://webpack.js.org/) uses (see below for details). Since Webpack is the most widely-used bundler, this means that esbuild is being the most compatible that it can be with the existing ecosystem regarding this compatibility problem. So the good news is that if you can get code with this problem to work with esbuild, it should also work with Webpack.
Here's an example that demonstrates the problem:
```
// index.js
import foo from './somelib.js'
console.log(foo)
```
```
// somelib.js
Object.defineProperty(exports, "__esModule", {
value: true
});
exports["default"] = 'foo';
```
And here are the two interpretations, both of which are widely-used:
* **The Babel interpretation**
If the Babel interpretation is used, this code will print `foo`. Their rationale is that `somelib.js` was converted from ESM into CommonJS (as you can tell by the `__esModule` marker) and the original code looked something like this:
```
// somelib.js
export default 'foo'
```
If `somelib.js` hadn't been converted from ESM into CommonJS, then this code would print `foo`, so it should still print `foo` regardless of the module format. This is accomplished by detecting when a CommonJS module used to be an ES module via the `__esModule` marker (which all module conversion tools set including Babel, TypeScript, Webpack, and esbuild) and setting the default import to `exports.default` if the `__esModule` marker is present. This behavior is important because it's necessary to run cross-compiled ESM correctly in a CommonJS environment, and for a long time that was the only way to run ESM code in Node before Node eventually added native ESM support.
* **The Node interpretation**
If the Node interpretation is used, this code will print `{ default: 'foo' }`. Their rationale is that CommonJS code uses dynamic exports while ESM code uses static exports, so the fully general approach to importing CommonJS into ESM is to expose the CommonJS `exports` object itself somehow. For example, CommonJS code can do `exports[Math.random()] = 'foo'` which has no equivalent in ESM syntax. The `default` export is used for this because that's actually what it was originally designed for by the people who came up with the ES module specification. This interpretation is entirely reasonable for normal CommonJS modules. It only causes compatibility problems for CommonJS modules that used to be ES modules (i.e. when `__esModule` is present) in which case the behavior diverges from the Babel interpretation.
*If you are a library author:* When writing new code, you should strongly consider avoiding the `default` export entirely. It has unfortunately been tainted with compatibility problems and using it will likely cause problems for your users at some point.
*If you are a library user:* By default, esbuild will use the Babel interpretation. If you want esbuild to use the Node interpretation instead, you need to either put your code in a file ending in `.mts` or `.mjs`, or you need to add `"type": "module"` to your `package.json` file. The rationale is that Node's native ESM support can only run ESM code if the file extension is `.mjs` or `"type": "module"` is present, so doing that is a good signal that the code is intended to be run in Node, and should therefore use the Node interpretation of `default` import. This is the same heuristic that Webpack uses.
TypeScript
----------
Loader: `ts` or `tsx`
This loader is enabled by default for `.ts`, `.tsx`, `.mts`, and `.cts` files, which means esbuild has built-in support for parsing TypeScript syntax and discarding the type annotations. However, esbuild *does not* do any type checking so you will still need to run `tsc -noEmit` in parallel with esbuild to check types. This is not something esbuild does itself.
TypeScript type declarations like these are parsed and ignored (a non-exhaustive list):
| Syntax feature | Example |
| --- | --- |
| Interface declarations | `interface Foo {}` |
| Type declarations | `type Foo = number` |
| Function declarations | `function foo(): void;` |
| Ambient declarations | `declare module 'foo' {}` |
| Type-only imports | `import type {Type} from 'foo'` |
| Type-only exports | `export type {Type} from 'foo'` |
| Type-only import specifiers | `import {type Type} from 'foo'` |
| Type-only export specifiers | `export {type Type} from 'foo'` |
TypeScript-only syntax extensions are supported, and are always converted to JavaScript (a non-exhaustive list):
| Syntax feature | Example | Notes |
| --- | --- | --- |
| Namespaces | `namespace Foo {}` | |
| Enums | `enum Foo { A, B }` | |
| Const enums | `const enum Foo { A, B }` | |
| Generic type parameters | `<T>(a: T): T => a` | Not available with the `tsx` loader |
| JSX with types | `<Element<T>/>` | |
| Type casts | `a as B` and `<B>a` | |
| Type imports | `import {Type} from 'foo'` | Handled by removing all unused imports |
| Type exports | `export {Type} from 'foo'` | Handled by ignoring missing exports in TypeScript files |
| Experimental decorators | `@sealed class Foo {}` | The `emitDecoratorMetadata` flag is not supported |
### TypeScript caveats
You should keep the following things in mind when using TypeScript with esbuild (in addition to the [JavaScript caveats](#javascript-caveats)):
#### Files are compiled independently
Even when transpiling a single module, the TypeScript compiler actually still parses imported files so it can tell whether an imported name is a type or a value. However, tools like esbuild and Babel (and the TypeScript compiler's `transpileModule` API) compile each file in isolation so they can't tell if an imported name is a type or a value.
Because of this, you should enable the [`isolatedModules`](https://www.typescriptlang.org/tsconfig#isolatedModules) TypeScript configuration option if you use TypeScript with esbuild. This option prevents you from using features which could cause mis-compilation in environments like esbuild where each file is compiled independently without tracing type references across files. For example, it prevents you from re-exporting types from another module using `export {T} from './types'` (you need to use `export type {T} from './types'` instead).
#### Imports follow ECMAScript module behavior
For historical reasons, the TypeScript compiler compiles ESM (ECMAScript module) syntax to CommonJS syntax by default. For example, `import * as foo from 'foo'` is compiled to `const foo = require('foo')`. Presumably this happened because ECMAScript modules were still a proposal when TypeScript adopted the syntax. However, this is legacy behavior that doesn't match how this syntax behaves on real platforms such as node. For example, the `require` function can return any JavaScript value including a string but the `import * as` syntax always results in an object and cannot be a string.
To avoid problems due to this legacy feature, you should enable the [`esModuleInterop`](https://www.typescriptlang.org/tsconfig#esModuleInterop) TypeScript configuration option if you use TypeScript with esbuild. Enabling it disables this legacy behavior and makes TypeScript's type system compatible with ESM. This option is not enabled by default because it would be a breaking change for existing TypeScript projects, but Microsoft [highly recommends applying it both to new and existing projects](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-7.html#support-for-import-d-from-cjs-from-commonjs-modules-with---esmoduleinterop) (and then updating your code) for better compatibility with the rest of the ecosystem.
Specifically this means that importing a non-object value from a CommonJS module with ESM import syntax must be done using a default import instead of using `import * as`. So if a CommonJS module exports a function via `module.exports = fn`, you need to use `import fn from 'path'` instead of `import * as fn from 'path'`.
#### Features that need a type system are not supported
TypeScript types are treated as comments and are ignored by esbuild, so TypeScript is treated as "type-checked JavaScript." The interpretation of the type annotations is up to the TypeScript type checker, which you should be running in addition to esbuild if you're using TypeScript. This is the same compilation strategy that Babel's TypeScript implementation uses. However, it means that some TypeScript compilation features which require type interpretation to work do not work with esbuild.
Specifically:
* The [`emitDecoratorMetadata`](https://www.typescriptlang.org/tsconfig#emitDecoratorMetadata) TypeScript configuration option is not supported. This feature passes a JavaScript representation of the corresponding TypeScript type to the attached decorator function. Since esbuild does not replicate TypeScript's type system, it does not have enough information to implement this feature.
* The [`declaration`](https://www.typescriptlang.org/tsconfig#declaration) TypeScript configuration option (i.e. generation of `.d.ts` files) is not supported. If you are writing a library in TypeScript and you want to publish the compiled JavaScript code as a package for others to use, you will probably also want to publish type declarations. This is not something that esbuild can do for you because it doesn't retain any type information. You will likely either need to use the TypeScript compiler to generate them or manually write them yourself.
#### Only certain `tsconfig.json` fields are respected
During bundling, the path resolution algorithm in esbuild will consider the contents of the `tsconfig.json` file in the closest parent directory containing one and will modify its behavior accordingly. It is also possible to explicitly set the `tsconfig.json` path with the build API using esbuild's [`tsconfig`](../api/index#tsconfig) setting and to explicitly pass in the contents of a `tsconfig.json` file with the transform API using esbuild's [`tsconfigRaw`](../api/index#tsconfig-raw) setting. However, esbuild currently only inspects the following fields in `tsconfig.json` files:
* [`alwaysStrict`](https://www.typescriptlang.org/tsconfig#alwaysStrict)
* [`baseUrl`](https://www.typescriptlang.org/tsconfig#baseUrl)
* [`extends`](https://www.typescriptlang.org/tsconfig#extends)
* [`importsNotUsedAsValues`](https://www.typescriptlang.org/tsconfig#importsNotUsedAsValues)
* [`jsx`](https://www.typescriptlang.org/tsconfig#jsx)
* [`jsxFactory`](https://www.typescriptlang.org/tsconfig#jsxFactory)
* [`jsxFragmentFactory`](https://www.typescriptlang.org/tsconfig#jsxFragmentFactory)
* [`jsxImportSource`](https://www.typescriptlang.org/tsconfig#jsxImportSource)
* [`paths`](https://www.typescriptlang.org/tsconfig#paths)
* [`preserveValueImports`](https://www.typescriptlang.org/tsconfig/#preserveValueImports)
* [`target`](https://www.typescriptlang.org/tsconfig#target)
* [`useDefineForClassFields`](https://www.typescriptlang.org/tsconfig#useDefineForClassFields) Note: TypeScript silently shipped a breaking change in version 4.3.2 where if the `useDefineForClassFields` option is not specified, it defaults to `true` if you specify `target: "ESNext"` (and later on also `target: "ES2022"` or newer). Before version 4.3.2, the `useDefineForClassFields` option always defaulted to `false`. The latest version of esbuild has been updated to reflect the behavior of TypeScript version 4.3.2. If you need the old behavior, make sure to specify `useDefineForClassFields: false` in addition to `target: "ESNext"`. See TypeScript PR [#42663](https://github.com/microsoft/TypeScript/pull/42663) for more information.
All other fields will be ignored. Note that import path transformation requires [`bundling`](../api/index#bundle) to be enabled, since path resolution only happens during bundling.
#### You cannot use the `tsx` loader for `*.ts` files
The `tsx` loader is *not* a superset of the `ts` loader. They are two different partially-incompatible syntaxes. For example, the character sequence `<a>1</a>/g` parses as `<a>(1 < (/a>/g))` with the `ts` loader and `(<a>1</a>) / g` with the `tsx` loader.
The most common issue this causes is not being able to use generic type parameters on arrow function expressions such as `<T>() => {}` with the `tsx` loader. This is intentional, and matches the behavior of the official TypeScript compiler. That space in the `tsx` grammar is reserved for JSX elements.
JSX
---
Loader: `jsx` or `tsx`
[JSX](https://facebook.github.io/jsx/) is an XML-like syntax extension for JavaScript that was created for [React](https://github.com/facebook/react). It's intended to be converted into normal JavaScript by your build tool. Each XML element becomes a normal JavaScript function call. For example, the following JSX code:
```
import Button from './button'
let button = <Button>Click me</Button>
render(button)
```
Will be converted to the following JavaScript code:
```
import Button from "./button";
let button = React.createElement(Button, null, "Click me");
render(button);
```
This loader is enabled by default for `.jsx` and `.tsx` files. Note that JSX syntax is not enabled in `.js` files by default. If you would like to enable that, you will need to configure it:
```
esbuild app.js --bundle --loader:.js=jsx
```
```
require('esbuild').buildSync({
entryPoints: ['app.js'],
bundle: true,
loader: { '.js': 'jsx' },
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".js": api.LoaderJSX,
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Auto-import for JSX
Using JSX syntax usually requires you to manually import the JSX library you are using. For example, if you are using React, by default you will need to import React into each JSX file like this:
```
import * as React from 'react'
render(<div/>)
```
This is because the JSX transform turns JSX syntax into a call to `React.createElement` but it does not itself import anything, so the `React` variable is not automatically present.
If you would like to avoid having to manually `import` your JSX library into each file, you may be able to do this by setting esbuild's [JSX](../api/index#jsx) transform to `automatic`, which generates import statements for you. Keep in mind that this also completely changes how the JSX transform works, so it may break your code if you are using a JSX library that's not React. Doing that looks like this:
```
esbuild app.jsx --jsx=automatic
```
```
require('esbuild').buildSync({
entryPoints: ['app.jsx'],
jsx: 'automatic',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.jsx"},
JSX: api.JSXAutomatic,
Outfile: "out.js",
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
### Using JSX without React
If you're using JSX with a library other than React (such as [Preact](https://preactjs.com/)), you'll likely need to configure the [JSX factory](../api/index#jsx-factory) and [JSX fragment](../api/index#jsx-fragment) settings since they default to `React.createElement` and `React.Fragment` respectively:
```
esbuild app.jsx --jsx-factory=h --jsx-fragment=Fragment
```
```
require('esbuild').buildSync({
entryPoints: ['app.jsx'],
jsxFactory: 'h',
jsxFragment: 'Fragment',
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.jsx"},
JSXFactory: "h",
JSXFragment: "Fragment",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Alternatively, if you are using TypeScript, you can just configure JSX for TypeScript by adding this to your `tsconfig.json` file and esbuild should pick it up automatically without needing to be configured:
```
{
"compilerOptions": {
"jsxFactory": "h",
"jsxFragmentFactory": "Fragment"
}
}
```
You will also have to add `import {h, Fragment} from 'preact'` in files containing JSX syntax unless you use auto-importing as described above.
JSON
----
Loader: `json`
This loader is enabled by default for `.json` files. It parses the JSON file into a JavaScript object at build time and exports the object as the default export. Using it looks something like this:
```
import object from './example.json'
console.log(object)
```
In addition to the default export, there are also named exports for each top-level property in the JSON object. Importing a named export directly means esbuild can automatically remove unused parts of the JSON file from the bundle, leaving only the named exports that you actually used. For example, this code will only include the `version` field when bundled:
```
import { version } from './package.json'
console.log(version)
```
CSS
---
Loader: `css`
This loader is enabled by default for `.css` files. It loads the file as CSS syntax. CSS is a first-class content type in esbuild, which means esbuild can [bundle](../api/index#bundle) CSS files directly without needing to import your CSS from JavaScript code:
```
esbuild --bundle app.css --outfile=out.css
```
```
require('esbuild').buildSync({
entryPoints: ['app.css'],
bundle: true,
outfile: 'out.css',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.css"},
Bundle: true,
Outfile: "out.css",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
You can `@import` other CSS files and reference image and font files with `url()` and esbuild will bundle everything together. Note that you will have to configure a loader for image and font files, since esbuild doesn't have any pre-configured. Usually this is either the [data URL](#data-url) loader or the [external file](#external-file) loader.
Note that by default, esbuild's output will take advantage of all modern CSS features. For example, `color: rgba(255, 0, 0, 0.4)` will become `color: #f006` when minifying is enabled which makes use of syntax from [CSS Color Module Level 4](https://drafts.csswg.org/css-color-4/#changes-from-3). If this is undesired, you must specify esbuild's [target](../api/index#target) setting to say in which browsers you need the output to work correctly. Then esbuild will avoid using CSS features that are too modern for those browsers.
### Import from JavaScript
You can also import CSS from JavaScript. When you do this, esbuild will gather all CSS files referenced from a given entry point and bundle it into a sibling CSS output file next to the JavaScript output file for that JavaScript entry point. So if esbuild generates `app.js` it would also generate `app.css` containing all CSS files referenced by `app.js`. Here's an example of importing a CSS file from JavaScript:
```
import './button.css'
export let Button = ({ text }) =>
<div className="button">{text}</div>
```
Note that esbuild doesn't yet support CSS modules, so the set of JavaScript export names from a CSS file is currently always empty. Supporting a basic form of CSS modules is on the roadmap.
The bundled JavaScript generated by esbuild will not automatically import the generated CSS into your HTML page for you. Instead, you should import the generated CSS into your HTML page yourself along with the generated JavaScript. This means the browser can download the CSS and JavaScript files in parallel, which is the most efficient way to do it. That looks like this:
```
<html>
<head>
<link href="app.css" rel="stylesheet">
<script src="app.js"></script>
</head>
</html>
```
If the generated output names are not straightforward (for example if you have added `[hash]` to the [entry names](../api/index#entry-names) setting and the output file names have content hashes) then you will likely want to look up the generated output names in the [metafile](../api/index#metafile). To do this, first find the JS file by looking for the output with the matching `entryPoint` property. This file goes in the `<script>` tag. The associated CSS file can then be found using the `cssBundle` property. This file goes in the `<link>` tag.
### CSS caveats
You should keep the following things in mind when using CSS with esbuild:
#### Limited CSS verification
CSS has a [general syntax specification](https://www.w3.org/TR/css-syntax-3/) that all CSS processors use and then [many specifications](https://www.w3.org/Style/CSS/current-work) that define what specific CSS rules mean. While esbuild understands general CSS syntax and can understand some CSS rules (enough to bundle CSS file together and to minify CSS reasonably well), esbuild does not contain complete knowledge of CSS. This means esbuild takes a "garbage in, garbage out" philosophy toward CSS. If you want to verify that your compiled CSS is free of typos, you should be using a CSS linter in addition to esbuild.
####
`@import` order matches the browser
The `@import` rule in CSS behaves differently than the `import` keyword in JavaScript. In JavaScript, an `import` means roughly "make sure the imported file is evaluated before this file is evaluated" but in CSS, `@import` means roughly "re-evaluate the imported file again here" instead. For example, consider the following files:
* `entry.css`
```
@import "foreground.css";@import "background.css";
```
* `foreground.css`
```
@import "reset.css";body { color: white;}
```
* `background.css`
```
@import "reset.css";body { background: black;}
```
* `reset.css`
```
body { color: black; background: white;}
```
Using your intuition from JavaScript, you might think that this code first resets the body to black text on a white background, and then overrides that to white text on a black background. ***This is not what happens.*** Instead, the body will be entirely black (both the foreground and the background). This is because `@import` is supposed to behave as if the import rule was replaced by the imported file[1](#footnote-def-1) (sort of like `#include` in C/C++), which leads to the browser seeing the following code:
```
/* reset.css */
body {
color: black;
background: white;
}
/* foreground.css */
body {
color: white;
}
/* reset.css */
body {
color: black;
background: white;
}
/* background.css */
body {
background: black;
}
```
which ultimately reduces down to this:
```
body {
color: black;
background: black;
}
```
This behavior is unfortunate, but esbuild behaves this way because that's how CSS is specified, and that's how CSS works in browsers. This is important to know about because some other commonly-used CSS processing tools such as [`postcss-import`](https://github.com/postcss/postcss-import/issues/462) incorrectly resolve CSS imports in JavaScript order instead of in CSS order. If you are porting CSS code written for those tools to esbuild (or even just switching over to running your CSS code natively in the browser), you may have appearance changes if your code depends on the incorrect import order.
Text
----
Loader: `text`
This loader is enabled by default for `.txt` files. It loads the file as a string at build time and exports the string as the default export. Using it looks something like this:
```
import string from './example.txt'
console.log(string)
```
Binary
------
Loader: `binary`
This loader will load the file as a binary buffer at build time and embed it into the bundle using Base64 encoding. The original bytes of the file are decoded from Base64 at run time and exported as a `Uint8Array` using the default export. Using it looks like this:
```
import uint8array from './example.data'
console.log(uint8array)
```
If you need an `ArrayBuffer` instead, you can just access `uint8array.buffer`. Note that this loader is not enabled by default. You will need to configure it for the appropriate file extension like this:
```
esbuild app.js --bundle --loader:.data=binary
```
```
require('esbuild').buildSync({
entryPoints: ['app.js'],
bundle: true,
loader: { '.data': 'binary' },
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".data": api.LoaderBinary,
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
Base64
------
Loader: `base64`
This loader will load the file as a binary buffer at build time and embed it into the bundle as a string using Base64 encoding. This string is exported using the default export. Using it looks like this:
```
import base64string from './example.data'
console.log(base64string)
```
Note that this loader is not enabled by default. You will need to configure it for the appropriate file extension like this:
```
esbuild app.js --bundle --loader:.data=base64
```
```
require('esbuild').buildSync({
entryPoints: ['app.js'],
bundle: true,
loader: { '.data': 'base64' },
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".data": api.LoaderBase64,
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
If you intend to turn this into a `Uint8Array` or an `ArrayBuffer`, you should use the `binary` loader instead. It uses an optimized Base64-to-binary converter that is faster than the usual `atob` conversion process.
Data URL
--------
Loader: `dataurl`
This loader will load the file as a binary buffer at build time and embed it into the bundle as a Base64-encoded data URL. This string is exported using the default export. Using it looks like this:
```
import url from './example.png'
let image = new Image
image.src = url
document.body.appendChild(image)
```
The data URL includes a best guess at the MIME type based on the file extension and/or the file contents, and will look something like this for binary data:
```
data:image/png;base64,iVBORw0KGgo=
```
...or like this for textual data:
```
data:image/svg+xml,<svg></svg>%0A
```
Note that this loader is not enabled by default. You will need to configure it for the appropriate file extension like this:
```
esbuild app.js --bundle --loader:.png=dataurl
```
```
require('esbuild').buildSync({
entryPoints: ['app.js'],
bundle: true,
loader: { '.png': 'dataurl' },
outfile: 'out.js',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".png": api.LoaderDataURL,
},
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
External file
-------------
There are two different loaders that can be used for external files depending on the behavior you're looking for. Both loaders are described below:
#### The `file` loader
Loader: `file`
This loader will copy the file to the output directory and embed the file name into the bundle as a string. This string is exported using the default export. Using it looks like this:
```
import url from './example.png'
let image = new Image
image.src = url
document.body.appendChild(image)
```
This behavior is intentionally similar to Webpack's [`file-loader`](https://v4.webpack.js.org/loaders/file-loader/) package. Note that this loader is not enabled by default. You will need to configure it for the appropriate file extension like this:
```
esbuild app.js --bundle --loader:.png=file --outdir=out
```
```
require('esbuild').buildSync({
entryPoints: ['app.js'],
bundle: true,
loader: { '.png': 'file' },
outdir: 'out',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".png": api.LoaderFile,
},
Outdir: "out",
Write: true,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
By default the exported string is just the file name. If you would like to prepend a base path to the exported string, this can be done with the [public path](../api/index#public-path) API option.
#### The `copy` loader
Loader: `copy`
This loader will copy the file to the output directory and rewrite the import path to point to the copied file. This means the import will still exist in the final bundle and the final bundle will still reference the file instead of including the file inside the bundle. This might be useful if you are running additional bundling tools on esbuild's output, if you want to omit a rarely-used data file from the bundle for faster startup performance, or if you want to rely on specific behavior of your runtime that's triggered by an import. For example:
```
import json from './example.json' assert { type: 'json' }
console.log(json)
```
If you bundle the above code with the following command:
```
esbuild app.js --bundle --loader:.json=copy --outdir=out --format=esm
```
```
require('esbuild').buildSync({
entryPoints: ['app.js'],
bundle: true,
loader: { '.json': 'copy' },
outdir: 'out',
format: 'esm',
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".json": api.LoaderCopy,
},
Outdir: "out",
Write: true,
Format: api.FormatESModule,
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
the resulting `out/app.js` file might look something like this:
```
// app.js
import json from "./example-PVCBWCM4.json" assert { type: "json" };
console.log(json);
```
Notice how the import path has been rewritten to point to the copied file `out/example-PVCBWCM4.json` (a content hash has been added due to the default value of the [asset names](../api/index#asset-names) setting), and how the [import assertion](https://v8.dev/features/import-assertions) for JSON has been kept so the runtime will be able to load the JSON file.
Empty file
----------
Loader: `empty`
This loader tells tells esbuild to pretend that a file is empty. It can be a helpful way to remove content from your bundle in certain situations. For example, you can configure `.css` files to load with `empty` to prevent esbuild from bundling CSS files that are imported into JavaScript files:
```
esbuild app.js --bundle --loader:.css=empty
```
```
require('esbuild').buildSync({
entryPoints: ['app.js'],
bundle: true,
loader: { '.css': 'empty' },
})
```
```
package main
import "github.com/evanw/esbuild/pkg/api"
import "os"
func main() {
result := api.Build(api.BuildOptions{
EntryPoints: []string{"app.js"},
Bundle: true,
Loader: map[string]api.Loader{
".css": api.LoaderEmpty,
},
})
if len(result.Errors) > 0 {
os.Exit(1)
}
}
```
This loader also lets you remove imported assets from CSS files. For example, you can configure `.png` files to load with `empty` so that references to `.png` files in CSS code such as `url(image.png)` are replaced with `url()`.
| programming_docs |
react_bootstrap React Bootstrap
React Bootstrap
===============
The most popular front-end framework
**Rebuilt** for React.
[Get started](getting-started/introduction/index)[Components](components/alerts/index)
Current version: 1.5.0
Rebuilt with React
------------------
React-Bootstrap replaces the Bootstrap JavaScript. Each component has been built from scratch as a true React component, without unneeded dependencies like jQuery.
As one of the oldest React libraries, React-Bootstrap has evolved and grown alongside React, making it an excellent choice as your UI foundation.
Bootstrap at its core
---------------------
Built with compatibility in mind, we embrace our bootstrap core and strive to be compatible with the world's largest UI ecosystem.
By relying entirely on the Bootstrap stylesheet, React-Bootstrap just works with the thousands of Bootstrap themes you already love.
Accessible by default
---------------------
The React component model gives us more control over form and function of each component.
Each component is implemented with accessibility in mind. The result is a set of accessible-by-default components, over what is possible from plain Bootstrap.
react_bootstrap Migrating to v1 Migrating to v1
===============
React Bootstrap v1 adds full compatibility with Bootstrap 4. Because bootstrap 4 is a major rewrite of the project there are significant breaking changes from the pre `v1` react-bootstrap.
**PLEASE FIRST READ THE UPSTREAM BOOSTRAP MIGRATION GUIDE**
> <https://getbootstrap.com/docs/4.3/migration/>
>
>
React-Bootstrap *only* contains components that are present in vanilla Bootstrap. If functionality was removed from Bootstrap, then it was also removed from React-Bootstrap. This guide does not repeat information found in the upstream migration guide. Its goal is to document React-Bootstrap-specific API changes and additions.
Versioning
----------
We will continue to provide general maintenance for Bootstrap 3 components, because there are many projects that continue to depend on Bootstrap 3 support in `react-bootstrap`. `react-bootstrap` package versions will be as follows:
* Bootstrap 3 support will continue in react-bootstrap versions < `v1.0.0`
* Bootstrap 4 support will be in react-bootstrap versions >= `v1.0.0`
We are **not** committing to keeping breaking changes in lockstep with bootstraps major releases, there may be a react-bootstrap v2 targeting Bootstrap v4 depending on what's best for the project.
Summary of breaking changes from v0.32.0
----------------------------------------
Below is a *rough* account of the breaking API changes as well as the minimal change to migrate
* `bsStyle` -> `variant`
* `bsClass` -> `bsPrefix`
* `bsRole` has been removed from all components. Components now communicate via context to allow intermediate nesting of child components
* `componentClass` -> `as`
* All utils have been removed from main exports, most were internal already and the rest have been moved to external libraries
### Grid
* renamed to Container
* removed Clearfix
#### Col
* removed visibility props
* consolidated col `span`, `offset`, and `order` into an object value prop per breakpoint.
### Navbar
* removed `Navbar.Header`
* removed `Navbar.Form`
* removed `fluid`, use your own `Container` component in.
* `inverse` removed and replaced with `variant="dark"`
* positioning props have been consolidated into `fixed={top|bottom}` and `sticky={top|bottom}`, staticTop has been removed
#### NavbarHeader
* removed, not present in v4
#### NavbarToggle
* name changed to `Navbar.Toggle`
#### NavbarBrand
* Renders a `<a>` when an `href` is provided
* The presence of `children` does not skip the wrapping `span`, use `as` along with `children` for custom rendering
### Nav
* `activeHref` is removed (only activeKey now)
* `bsStyle` renamed to `variant`
* NavLink hrefs will be used as `eventKey`s when `eventKey` is absent
* Local `onSelect` handlers are ignored when in the context of a TabContainer or Navbar (MAYBE ADD BACK?)
#### Nav.Item
* Renders *only* the outer "item" element, use inconjunction with the new `NavLink` component
* default element changed to `<div>` from a `<li>`
* `active` prop removed and moved to `NavLink`
### InputGroup
* removed InputGroup.Button, and InputGroup.Addon
* added InputGroup.Prepend, InputGroup.Append, InputGroup.Text, InputGroup.Checkbox, InputGroup.Radio
### Badge & Label
* removed `Label`, the `Badge` component covers both
* `bsStyle` renamed to `variant`
### Panel
* removed, replaced with Card components
### Dropdown
* Removed the `disabled` prop on Dropdown, pass it directly to Dropdown.Toggle
* Removed bsRole, use function children to render custom Toggles or Menus
* Removed SplitButton.toggle (replaced with a `split` prop on the basic Toggle)
* `noCaret` is removed because it's not optional with the styles anymore
* bsPrefixes are not passed from the parent Dropdown anymore
* onSelect behavior is now passed to Menu and Toggle via the Context api
* DropdownMenu is not rendered until opened
* `divider` has been split out into `Dropdown.Divider`
* `header` has been split out into `Dropdown.Header`
#### DropdownButton
* Extra props are passed to the underlying Dropdown component, not the Toggle.
#### SplitButton
* Extra props are passed to the underlying Dropdown component, not the Toggle.
### NavButton
* Extra props are passed to the underlying Dropdown component, not the Toggle.
#### MenuItem
* renamed to `DropdownItem` (also exported on `Dropdown` as `Dropdown.Item`)
### Alert
* `onDismiss` renamed to `onClose`
### Well
* removed.
### Pager
* removed.
### ControlLabel
* renamed to `FormLabel` (also exported on `Form` as `Form.Label`)
### Checkbox and Radio
* Consolidated into a single component. Component's name is `FormCheck` (also exported on `Form` as `Form.Check`)
### Glyphicon
* Removed -- icons are not included in Bootstrap 4. Icon support can be provided via react-icons, fontawesome, or a similar external library.
react_bootstrap Grid system Grid system
===========
Bootstrap’s grid system uses a series of containers, rows, and columns to layout and align content. It’s built with [flexbox](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Flexible_Box_Layout/Using_CSS_flexible_boxes) and is fully responsive. Below is an example and an in-depth look at how the grid comes together.
**New to or unfamiliar with flexbox?** [Read this CSS Tricks flexbox guide](https://css-tricks.com/snippets/css/a-guide-to-flexbox/#flexbox-background) for background, terminology, guidelines, and code snippets.
Container
---------
Containers provide a means to center and horizontally pad your site’s contents. Use `Container` for a responsive pixel width.
```
<Container>
<Row>
<Col>1 of 1</Col>
</Row>
</Container>
```
### Fluid Container
You can use `<Container fluid />` for width: 100% across all viewport and device sizes.
```
<Container fluid>
<Row>
<Col>1 of 1</Col>
</Row>
</Container>
```
You can set breakpoints for the `fluid` prop. Setting it to a breakpoint (`sm, md, lg, xl`) will set the `Container` as fluid until the specified breakpoint.
```
<Container fluid="md">
<Row>
<Col>1 of 1</Col>
</Row>
</Container>
```
Auto-layout columns
-------------------
When no column widths are specified the `Col` component will render equal width columns
```
<Container>
<Row>
<Col>1 of 2</Col>
<Col>2 of 2</Col>
</Row>
<Row>
<Col>1 of 3</Col>
<Col>2 of 3</Col>
<Col>3 of 3</Col>
</Row>
</Container>
```
### Setting one column width
Auto-layout for flexbox grid columns also means you can set the width of one column and have the sibling columns automatically resize around it. You may use predefined grid classes (as shown below), grid mixins, or inline widths. Note that the other columns will resize no matter the width of the center column.
```
<Container>
<Row>
<Col>1 of 3</Col>
<Col xs={6}>2 of 3 (wider)</Col>
<Col>3 of 3</Col>
</Row>
<Row>
<Col>1 of 3</Col>
<Col xs={5}>2 of 3 (wider)</Col>
<Col>3 of 3</Col>
</Row>
</Container>
```
### Variable width content
Set the column value (for any breakpoint size) to `"auto"` to size columns based on the natural width of their content.
```
<Container>
<Row className="justify-content-md-center">
<Col xs lg="2">
1 of 3
</Col>
<Col md="auto">Variable width content</Col>
<Col xs lg="2">
3 of 3
</Col>
</Row>
<Row>
<Col>1 of 3</Col>
<Col md="auto">Variable width content</Col>
<Col xs lg="2">
3 of 3
</Col>
</Row>
</Container>
```
Responsive grids
----------------
The `Col` lets you specify column widths across 5 breakpoint sizes (xs, sm, md, lg, and xl). For every breakpoint, you can specify the amount of columns to span, or set the prop to `<Col lg={true} />` for auto layout widths.
```
<Container>
<Row>
<Col sm={8}>sm=8</Col>
<Col sm={4}>sm=4</Col>
</Row>
<Row>
<Col sm>sm=true</Col>
<Col sm>sm=true</Col>
<Col sm>sm=true</Col>
</Row>
</Container>
```
You can also mix and match breakpoints to create different grids depending on the screen size.
```
<Container>
{/* Stack the columns on mobile by making one full-width and the other half-width */}
<Row>
<Col xs={12} md={8}>
xs=12 md=8
</Col>
<Col xs={6} md={4}>
xs=6 md=4
</Col>
</Row>
{/* Columns start at 50% wide on mobile and bump up to 33.3% wide on desktop */}
<Row>
<Col xs={6} md={4}>
xs=6 md=4
</Col>
<Col xs={6} md={4}>
xs=6 md=4
</Col>
<Col xs={6} md={4}>
xs=6 md=4
</Col>
</Row>
{/* Columns are always 50% wide, on mobile and desktop */}
<Row>
<Col xs={6}>xs=6</Col>
<Col xs={6}>xs=6</Col>
</Row>
</Container>
```
The `Col` breakpoint props also have a more complicated `object` prop form: `{span: number, order: number, offset: number}` for specifying offsets and ordering effects.
You can use the `order` property to control the **visual order** of your content.
```
<Container>
<Row>
<Col xs>First, but unordered</Col>
<Col xs={{ order: 12 }}>Second, but last</Col>
<Col xs={{ order: 1 }}>Third, but second</Col>
</Row>
</Container>
```
The `order` property also supports `first` (`order: -1`) and `last` (`order: $columns+1`).
```
<Container>
<Row>
<Col xs={{ order: 'last' }}>First, but last</Col>
<Col xs>Second, but unordered</Col>
<Col xs={{ order: 'first' }}>Third, but first</Col>
</Row>
</Container>
```
For offsetting grid columns you can set an `offset` value or for a more general layout, use the margin class utilities.
```
<Container>
<Row>
<Col md={4}>md=4</Col>
<Col md={{ span: 4, offset: 4 }}>{`md={{ span: 4, offset: 4 }}`}</Col>
</Row>
<Row>
<Col md={{ span: 3, offset: 3 }}>{`md={{ span: 3, offset: 3 }}`}</Col>
<Col md={{ span: 3, offset: 3 }}>{`md={{ span: 3, offset: 3 }}`}</Col>
</Row>
<Row>
<Col md={{ span: 6, offset: 3 }}>{`md={{ span: 6, offset: 3 }}`}</Col>
</Row>
</Container>
```
### Setting column widths in Row
The `Row` lets you specify column widths across 5 breakpoint sizes (xs, sm, md, lg, and xl). For every breakpoint, you can specify the amount of columns that will fit next to each other.
```
<Container>
<Row xs={2} md={4} lg={6}>
<Col>1 of 2</Col>
<Col>2 of 2</Col>
</Row>
<Row xs={1} md={2}>
<Col>1 of 3</Col>
<Col>2 of 3</Col>
<Col>3 of 3</Col>
</Row>
</Container>
```
Note that `Row` column widths will override `Col` widths set on lower breakpoints when viewed on larger screens. The `<Col xs={6} />` size will be overriden by `<Row md={4} />` on medium and larger screens.
```
<Container>
<Row md={4}>
<Col>1 of 3</Col>
<Col xs={6}>2 of 3</Col>
<Col>3 of 3</Col>
</Row>
</Container>
```
API
---
### Container
`import Container from 'react-bootstrap/Container'`Copy import code for the Container component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element for this component |
| fluid | `true` | `"sm"` | `"md"` | `"lg"` | `"xl"` | `false` | Allow the Container to fill all of its available horizontal space. |
| bsPrefix | string | `'container'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Row
`import Row from 'react-bootstrap/Row'`Copy import code for the Row component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| lg | number | { cols: number } | | The number of columns that will fit next to each other on large devices (≥992px) |
| md | number | { cols: number } | | The number of columns that will fit next to each other on medium devices (≥768px) |
| noGutters | boolean | `false` | Removes the gutter spacing between `Col`s as well as any added negative margins. |
| sm | number | { cols: number } | | The number of columns that will fit next to each other on small devices (≥576px) |
| xl | number | { cols: number } | | The number of columns that will fit next to each other on extra large devices (≥1200px) |
| xs | number | { cols: number } | | The number of columns that will fit next to each other on extra small devices (<576px) |
| bsPrefix | string | `'row'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Col
`import Col from 'react-bootstrap/Col'`Copy import code for the Col component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| lg | boolean | "auto" | number | { span: boolean | "auto" | number, offset: number, order: "first" | "last" | number } | | The number of columns to span on large devices (≥992px) |
| md | boolean | "auto" | number | { span: boolean | "auto" | number, offset: number, order: "first" | "last" | number } | | The number of columns to span on medium devices (≥768px) |
| sm | boolean | "auto" | number | { span: boolean | "auto" | number, offset: number, order: "first" | "last" | number } | | The number of columns to span on small devices (≥576px) |
| xl | boolean | "auto" | number | { span: boolean | "auto" | number, offset: number, order: "first" | "last" | number } | | The number of columns to span on extra large devices (≥1200px) |
| xs | boolean | "auto" | number | { span: boolean | "auto" | number, offset: number, order: "first" | "last" | number } | | The number of columns to span on extra small devices (<576px) |
| bsPrefix | string | `'col'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Media objects Media objects
=============
The media object helps build complex and repetitive components (e.g. blog comments, tweets, the like and more) where some media is positioned alongside content that doesn’t wrap around said media. Plus, it does this with only two required classes thanks to flexbox. Below is an example of a single media object. Only two classes are required—the wrapping `Media` and the `Media.Body` around your content. Optional padding and margin can be controlled through spacing utilities.
```
<Media>
<img
width={64}
height={64}
className="mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>Media Heading</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla.
Donec lacinia congue felis in faucibus.
</p>
</Media.Body>
</Media>
```
Media Nesting
-------------
Media objects can be infinitely nested, though we suggest you stop at some point. Place nested `Media` within the `Media.Body` of a parent media object.
```
<Media>
<img
width={64}
height={64}
className="mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>Media Heading</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla.
Donec lacinia congue felis in faucibus.
</p>
<Media>
<img
width={64}
height={64}
className="mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>Media Heading</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus
scelerisque ante sollicitudin commodo. Cras purus odio, vestibulum in
vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi
vulputate fringilla. Donec lacinia congue felis in faucibus.
</p>
</Media.Body>
</Media>
</Media.Body>
</Media>
```
Media Alignment
---------------
Media in a media object can be aligned with flexbox utilities to the top (default), middle, or end of your `Media.Body` content.
```
<>
<Media>
<img
width={64}
height={64}
className="align-self-start mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>Media Heading</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate
fringilla. Donec lacinia congue felis in faucibus.
</p>
<p>
Donec sed odio dui. Nullam quis risus eget urna mollis ornare vel eu
leo. Cum sociis natoque penatibus et magnis dis parturient montes,
nascetur ridiculus mus.
</p>
</Media.Body>
</Media>
<Media>
<img
width={64}
height={64}
className="align-self-center mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>Media Heading</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate
fringilla. Donec lacinia congue felis in faucibus.
</p>
<p>
Donec sed odio dui. Nullam quis risus eget urna mollis ornare vel eu
leo. Cum sociis natoque penatibus et magnis dis parturient montes,
nascetur ridiculus mus.
</p>
</Media.Body>
</Media>
<Media>
<img
width={64}
height={64}
className="align-self-end mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>Media Heading</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate
fringilla. Donec lacinia congue felis in faucibus.
</p>
<p className="mb-0">
Donec sed odio dui. Nullam quis risus eget urna mollis ornare vel eu
leo. Cum sociis natoque penatibus et magnis dis parturient montes,
nascetur ridiculus mus.
</p>
</Media.Body>
</Media>
</>
```
Media Order
-----------
Change the order of content in media objects by modifying the HTML itself, or by adding some custom flexbox CSS to set the `order` property (to an integer of your choosing).
```
<Media>
<Media.Body>
<h5>Media Heading</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla.
Donec lacinia congue felis in faucibus.
</p>
</Media.Body>
<img
width={64}
height={64}
className="ml-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
</Media>
```
Media list
----------
Because the media object has so few structural requirements, you can also use these classes on list HTML elements. On your `ul` or `ol` , add the .list-unstyled to remove any browser default list styles, use `<Media as="li">` to render as a list item. As always, use spacing utilities wherever needed to fine tune.
```
<ul className="list-unstyled">
<Media as="li">
<img
width={64}
height={64}
className="mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>List-based media object</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate
fringilla. Donec lacinia congue felis in faucibus.
</p>
</Media.Body>
</Media>
<Media as="li">
<img
width={64}
height={64}
className="mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>List-based media object</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate
fringilla. Donec lacinia congue felis in faucibus.
</p>
</Media.Body>
</Media>
<Media as="li">
<img
width={64}
height={64}
className="mr-3"
src="holder.js/64x64"
alt="Generic placeholder"
/>
<Media.Body>
<h5>List-based media object</h5>
<p>
Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque
ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at,
tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate
fringilla. Donec lacinia congue felis in faucibus.
</p>
</Media.Body>
</Media>
</ul>
```
Props
-----
### Media
`import Media from 'react-bootstrap/Media'`Copy import code for the Media component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix | string | `'media'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| programming_docs |
react_bootstrap About About
=====
Get to know more about the team maintaining React Bootstrap. Learn a little history of how, why and when the project started and how you can be a part of it.
### Team
React Bootstrap is maintained by a [team of developers](https://github.com/orgs/react-bootstrap/people) on Github. We have a growing team and if you are interested in re-building the most popular front-end framework with React we would love to hear from you.
### Contributors
We welcome community support with both feature and bug reporting. Please don't hesitate to jump in. Join our growing list of [contributors](https://github.com/react-bootstrap/react-bootstrap/graphs/contributors).
### Get Involved
Get involved with React Bootstrap [by opening an issue](https://github.com/react-bootstrap/react-bootstrap/issues/new) or submitting a pull request. See our [contributing guidelines](https://github.com/react-bootstrap/react-bootstrap/blob/master/CONTRIBUTING.md) here.
### External Links
* [Bootstrap](https://getbootstrap.com/)
* [React](https://reactjs.org/)
* [React Router Bootstrap](https://github.com/react-bootstrap/react-router-bootstrap)
* [Awesome React Bootstrap Components](https://github.com/Hermanya/awesome-react-bootstrap-components)
* [React Bootstrap CodeSandbox examples](https://codesandbox.io/s/github/react-bootstrap/code-sandbox-examples/tree/master/basic)
react_bootstrap React Overlays React Overlays
==============
Low-level components and utilities for building beautiful accessible overlay components
Often times you may need a more generic or low-level version of a Bootstrap component. Many of the `react-bootstrap` components are built on top of components from [react-overlays](https://react-bootstrap.github.io/react-overlays/), if you find yourself at the limit of a Bootstrap component, consider using the `react-overlays` base component directly.
react_bootstrap Responsive embed Responsive embed
================
Allow browsers to determine video or slideshow dimensions based on the width of their containing block by creating an intrinsic ratio that will properly scale on any device.
You don't need to include `frameborder="0"` in your `iframe`s.
The aspect ratio is controlled via the `aspectRatio` prop.
```
<div style={{ width: 660, height: 'auto' }}>
<ResponsiveEmbed aspectRatio="16by9">
<embed type="image/svg+xml" src="/TheresaKnott_castle.svg" />
</ResponsiveEmbed>
</div>
```
### API
### ResponsiveEmbed
`import ResponsiveEmbed from 'react-bootstrap/ResponsiveEmbed'`Copy import code for the ResponsiveEmbed component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| aspectRatio | `'21by9'` | `'16by9'` | `'4by3'` | `'1by1'` | `'1by1'` | Set the aspect ration of the embed |
| children required | element | | This component requires a single child element |
| bsPrefix | string | `'embed-responsive'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Transitions Transitions
===========
Bootstrap includes a few general use CSS transitions that can be applied to a number of components. React Bootstrap, bundles them up into a few composable `<Transition>` components from [react-transition-group](https://github.com/reactjs/react-transition-group), a commonly used animation wrapper for React.
Encapsulating animations into components has the added benefit of making them more broadly useful, as well as portable for using in other libraries. All React-bootstrap components that can be animated, support pluggable `<Transition>` components.
Collapse
--------
Add a collapse toggle animation to an element or component.
```
function Example() {
const [open, setOpen] = useState(false);
return (
<>
<Button
onClick={() => setOpen(!open)}
aria-controls="example-collapse-text"
aria-expanded={open}
>
click
</Button>
<Collapse in={open}>
<div id="example-collapse-text">
Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus
terry richardson ad squid. Nihil anim keffiyeh helvetica, craft beer
labore wes anderson cred nesciunt sapiente ea proident.
</div>
</Collapse>
</>
);
}
render(<Example />);
```
Fade
----
Add a fade animation to a child element or component.
```
function Example() {
const [open, setOpen] = useState(false);
return (
<>
<Button
onClick={() => setOpen(!open)}
aria-controls="example-fade-text"
aria-expanded={open}
>
Toggle text
</Button>
<Fade in={open}>
<div id="example-fade-text">
Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus
terry richardson ad squid. Nihil anim keffiyeh helvetica, craft beer
labore wes anderson cred nesciunt sapiente ea proident.
</div>
</Fade>
</>
);
}
render(<Example />);
```
API
---
### Collapse
`import Collapse from 'react-bootstrap/Collapse'`Copy import code for the Collapse component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| appear | boolean | `false` | Run the expand animation when the component mounts, if it is initially shown |
| children required | React.ReactElement | | |
| className | string | | |
| dimension |
`'height'` | `'width'` | function | `'height'` |
The dimension used when collapsing, or a function that returns the dimension *Note: Bootstrap only partially supports 'width'! You will need to supply your own CSS animation for the `.width` CSS class.*
|
| getDimensionValue | function | `element.offsetWidth | element.offsetHeight` |
Function that returns the height or width of the animating DOM node Allows for providing some custom logic for how much the Collapse component should animate in its specified dimension. Called with the current dimension prop value and the DOM node.
|
| in | boolean | `false` | Show the component; triggers the expand or collapse animation |
| mountOnEnter | boolean | `false` | Wait until the first "enter" transition to mount the component (add it to the DOM) |
| onEnter | function | | Callback fired before the component expands |
| onEntered | function | | Callback fired after the component has expanded |
| onEntering | function | | Callback fired after the component starts to expand |
| onExit | function | | Callback fired before the component collapses |
| onExited | function | | Callback fired after the component has collapsed |
| onExiting | function | | Callback fired after the component starts to collapse |
| role | string | | ARIA role of collapsible element |
| timeout | number | `300` | Duration of the collapse animation in milliseconds, to ensure that finishing callbacks are fired even if the original browser transition end events are canceled |
| unmountOnExit | boolean | `false` | Unmount the component (remove it from the DOM) when it is collapsed |
### Fade
`import Fade from 'react-bootstrap/Fade'`Copy import code for the Fade component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| appear | boolean | `false` | Run the fade in animation when the component mounts, if it is initially shown |
| in | boolean | `false` | Show the component; triggers the fade in or fade out animation |
| mountOnEnter | boolean | `false` | Wait until the first "enter" transition to mount the component (add it to the DOM) |
| onEnter | function | | Callback fired before the component fades in |
| onEntered | function | | Callback fired after the has component faded in |
| onEntering | function | | Callback fired after the component starts to fade in |
| onExit | function | | Callback fired before the component fades out |
| onExited | function | | Callback fired after the component has faded out |
| onExiting | function | | Callback fired after the component starts to fade out |
| timeout | number | `300` | Duration of the fade animation in milliseconds, to ensure that finishing callbacks are fired even if the original browser transition end events are canceled |
| unmountOnExit | boolean | `false` | Unmount the component (remove it from the DOM) when it is faded out |
react_bootstrap None Tabbed components
-----------------
Dynamic tabbed interfaces
Examples
--------
Create dynamic tabbed interfaces, as described in the [WAI ARIA Authoring Practices](https://www.w3.org/TR/wai-aria-practices/#tabpanel). `Tabs` is a higher-level component for quickly creating a `Nav` matched with a set of `TabPane`s.
```
<Tabs defaultActiveKey="profile" id="uncontrolled-tab-example">
<Tab eventKey="home" title="Home">
<Sonnet />
</Tab>
<Tab eventKey="profile" title="Profile">
<Sonnet />
</Tab>
<Tab eventKey="contact" title="Contact" disabled>
<Sonnet />
</Tab>
</Tabs>
```
Controlled
----------
`Tabs` can be controlled directly when you want to handle the selection logic personally.
```
function ControlledTabs() {
const [key, setKey] = useState('home');
return (
<Tabs
id="controlled-tab-example"
activeKey={key}
onSelect={(k) => setKey(k)}
>
<Tab eventKey="home" title="Home">
<Sonnet />
</Tab>
<Tab eventKey="profile" title="Profile">
<Sonnet />
</Tab>
<Tab eventKey="contact" title="Contact" disabled>
<Sonnet />
</Tab>
</Tabs>
);
}
render(<ControlledTabs />);
```
No animation
------------
Set the `transition` prop to `false`
```
<Tabs defaultActiveKey="home" transition={false} id="noanim-tab-example">
<Tab eventKey="home" title="Home">
<Sonnet />
</Tab>
<Tab eventKey="profile" title="Profile">
<Sonnet />
</Tab>
<Tab eventKey="contact" title="Contact" disabled>
<Sonnet />
</Tab>
</Tabs>
```
Dropdowns?
----------
Dynamic tabbed interfaces should not contain dropdown menus, as this causes both usability and accessibility issues. From a usability perspective, the fact that the currently displayed tab’s trigger element is not immediately visible (as it’s inside the closed dropdown menu) can cause confusion. From an accessibility point of view, there is currently no sensible way to map this sort of construct to a standard WAI ARIA pattern, meaning that it cannot be easily made understandable to users of assistive technologies.
That said, it Dropdowns do work technically (sans focus management), but we don't make any claims about support.
Custom Tab Layout
-----------------
For more complex layouts the flexible `TabContainer`, `TabContent`, and `TabPane` components along with any style of `Nav` allow you to quickly piece together your own Tabs component with additional markup needed.
Create a set of NavItems each with an `eventKey` corresponding to the eventKey of a `TabPane`. Wrap the whole thing in a `TabContainer` and you have fully functioning custom tabs component. Check out the below example making use of the grid system and pills.
```
<Tab.Container id="left-tabs-example" defaultActiveKey="first">
<Row>
<Col sm={3}>
<Nav variant="pills" className="flex-column">
<Nav.Item>
<Nav.Link eventKey="first">Tab 1</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="second">Tab 2</Nav.Link>
</Nav.Item>
</Nav>
</Col>
<Col sm={9}>
<Tab.Content>
<Tab.Pane eventKey="first">
<Sonnet />
</Tab.Pane>
<Tab.Pane eventKey="second">
<Sonnet />
</Tab.Pane>
</Tab.Content>
</Col>
</Row>
</Tab.Container>
```
API
---
### Tabs
`import Tabs from 'react-bootstrap/Tabs'`Copy import code for the Tabs component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| activeKey | any | | *controlled by: `onSelect`, initial prop: `defaultActivekey`*
Mark the Tab with a matching `eventKey` as active. |
| defaultActiveKey | any | | The default active key that is selected on start |
| id | string | | HTML id attribute, required if no `generateChildId` prop is specified. |
| mountOnEnter | boolean | `false` | Wait until the first "enter" transition to mount tabs (add them to the DOM) |
| onSelect | function | | *controls `activeKey`*
Callback fired when a Tab is selected.
```
function (
Any eventKey,
SyntheticEvent event?
)
```
|
| transition | Transition | false | `{Fade}` | Sets a default animation strategy for all children `<TabPane>`s. Defaults to `<Fade>` animation, else use `false` to disable or a react-transition-group `<Transition/>` component. |
| unmountOnExit | boolean | `false` | Unmount tabs (remove it from the DOM) when it is no longer visible |
| variant | `'tabs'` | `'pills'` | `'tabs'` | Navigation style |
### Tab
`import Tab from 'react-bootstrap/Tab'`Copy import code for the Tab component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| disabled | boolean | | |
| eventKey | string | | A unique identifier for the Component, the `eventKey` makes it distinguishable from others in a set. Similar to React's `key` prop, in that it only needs to be unique amongst the Components siblings, not globally. |
| tabClassName | string | | |
| title required | node | | |
### TabContainer
`import TabContainer from 'react-bootstrap/TabContainer'`Copy import code for the TabContainer component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| activeKey | any | | *controlled by: `onSelect`, initial prop: `defaultActivekey`*
The `eventKey` of the currently active tab. |
| defaultActiveKey | unknown | | |
| generateChildId | function | `(eventKey, type) => `${props.id}-${type}-${eventKey}`` |
A function that takes an `eventKey` and `type` and returns a unique id for child tab `<NavItem>`s and `<TabPane>`s. The function *must* be a pure function, meaning it should always return the *same* id for the same set of inputs. The default value requires that an `id` to be set for the `<TabContainer>`. The `type` argument will either be `"tab"` or `"pane"`.
|
| id | string | | HTML id attribute, required if no `generateChildId` prop is specified. |
| mountOnEnter | boolean | | Wait until the first "enter" transition to mount tabs (add them to the DOM) |
| onSelect | function | | *controls `activeKey`*
A callback fired when a tab is selected. |
| transition | {Transition | false} | `{Fade}` | Sets a default animation strategy for all children `<TabPane>`s. Defaults to `<Fade>` animation; else, use `false` to disable, or a custom react-transition-group `<Transition/>` component. |
| unmountOnExit | boolean | | Unmount tabs (remove it from the DOM) when they are no longer visible |
### TabContent
`import TabContent from 'react-bootstrap/TabContent'`Copy import code for the TabContent component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix | string | `'tab-content'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### TabPane
`import TabPane from 'react-bootstrap/TabPane'`Copy import code for the TabPane component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| active | boolean | | Toggles the active state of the TabPane, this is generally controlled by a TabContainer. |
| aria-labelledby | string | | |
| as | elementType | | You can use a custom element type for this component. |
| eventKey | any | | A key that associates the `TabPane` with it's controlling `NavLink`. |
| id | string | | |
| mountOnEnter | boolean | | Wait until the first "enter" transition to mount the tab (add it to the DOM) |
| onEnter | function | | Transition onEnter callback when animation is not `false` |
| onEntered | function | | Transition onEntered callback when animation is not `false` |
| onEntering | function | | Transition onEntering callback when animation is not `false` |
| onExit | function | | Transition onExit callback when animation is not `false` |
| onExited | function | | Transition onExited callback when animation is not `false` |
| onExiting | function | | Transition onExiting callback when animation is not `false` |
| transition | boolean | elementType | | Use animation when showing or hiding `<TabPane>`s. Defaults to `<Fade>` animation, else use `false` to disable or a react-transition-group `<Transition/>` component. |
| unmountOnExit | boolean | | Unmount the tab (remove it from the DOM) when it is no longer visible |
| bsPrefix | string | `'tab-pane'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Navbars Navbars
=======
A powerful, responsive navigation header, the navbar. Includes support for branding, navigation, and more
Overview
--------
Here’s what you need to know before getting started with the Navbar:
* Use the `expand` prop to allow for collapsing the Navbar at lower breakpoints.
* Navbars and their contents are fluid by default. Use optional [containers](#navbars-containers) to limit their horizontal width.
* Use spacing and flex utilities to size and position content
A responsive navigation header, including support for branding, navigation, and more. Here’s an example of all the sub-components included in a responsive light-themed navbar that automatically collapses at the lg (large) breakpoint.
```
<Navbar bg="light" expand="lg">
<Navbar.Brand href="#home">React-Bootstrap</Navbar.Brand>
<Navbar.Toggle aria-controls="basic-navbar-nav" />
<Navbar.Collapse id="basic-navbar-nav">
<Nav className="mr-auto">
<Nav.Link href="#home">Home</Nav.Link>
<Nav.Link href="#link">Link</Nav.Link>
<NavDropdown title="Dropdown" id="basic-nav-dropdown">
<NavDropdown.Item href="#action/3.1">Action</NavDropdown.Item>
<NavDropdown.Item href="#action/3.2">Another action</NavDropdown.Item>
<NavDropdown.Item href="#action/3.3">Something</NavDropdown.Item>
<NavDropdown.Divider />
<NavDropdown.Item href="#action/3.4">Separated link</NavDropdown.Item>
</NavDropdown>
</Nav>
<Form inline>
<FormControl type="text" placeholder="Search" className="mr-sm-2" />
<Button variant="outline-success">Search</Button>
</Form>
</Navbar.Collapse>
</Navbar>
```
Brand
-----
A simple flexible branding component. Images are supported but will likely require custom styling to work well.
```
<>
<Navbar bg="light">
<Navbar.Brand href="#home">Brand link</Navbar.Brand>
</Navbar>
<br />
<Navbar bg="light">
<Navbar.Brand>Brand text</Navbar.Brand>
</Navbar>
<br />
<Navbar bg="dark">
<Navbar.Brand href="#home">
<img
src="/logo.svg"
width="30"
height="30"
className="d-inline-block align-top"
alt="React Bootstrap logo"
/>
</Navbar.Brand>
</Navbar>
<br />
<Navbar bg="dark" variant="dark">
<Navbar.Brand href="#home">
<img
alt=""
src="/logo.svg"
width="30"
height="30"
className="d-inline-block align-top"
/>{' '}
React Bootstrap
</Navbar.Brand>
</Navbar>
</>
```
Forms
-----
Use `<Form inline>` and your various form controls within the Navbar. Align the contents as needed with utility classes.
```
<Navbar className="bg-light justify-content-between">
<Form inline>
<InputGroup>
<InputGroup.Prepend>
<InputGroup.Text id="basic-addon1">@</InputGroup.Text>
</InputGroup.Prepend>
<FormControl
placeholder="Username"
aria-label="Username"
aria-describedby="basic-addon1"
/>
</InputGroup>
</Form>
<Form inline>
<FormControl type="text" placeholder="Search" className=" mr-sm-2" />
<Button type="submit">Submit</Button>
</Form>
</Navbar>
```
Text and Non-nav links
----------------------
Loose text and links can be wrapped `Navbar.Text` in order to correctly align it vertically.
```
<Navbar>
<Navbar.Brand href="#home">Navbar with text</Navbar.Brand>
<Navbar.Toggle />
<Navbar.Collapse className="justify-content-end">
<Navbar.Text>
Signed in as: <a href="#login">Mark Otto</a>
</Navbar.Text>
</Navbar.Collapse>
</Navbar>
```
Color schemes
-------------
Theming the navbar has never been easier thanks to the combination of theming classes and background-color utilities. Choose from `variant="light"` for use with light background colors, or `variant="dark"` for dark background colors. Then, customize with the `bg` prop or any custom css!
```
<>
<Navbar bg="dark" variant="dark">
<Navbar.Brand href="#home">Navbar</Navbar.Brand>
<Nav className="mr-auto">
<Nav.Link href="#home">Home</Nav.Link>
<Nav.Link href="#features">Features</Nav.Link>
<Nav.Link href="#pricing">Pricing</Nav.Link>
</Nav>
<Form inline>
<FormControl type="text" placeholder="Search" className="mr-sm-2" />
<Button variant="outline-info">Search</Button>
</Form>
</Navbar>
<br />
<Navbar bg="primary" variant="dark">
<Navbar.Brand href="#home">Navbar</Navbar.Brand>
<Nav className="mr-auto">
<Nav.Link href="#home">Home</Nav.Link>
<Nav.Link href="#features">Features</Nav.Link>
<Nav.Link href="#pricing">Pricing</Nav.Link>
</Nav>
<Form inline>
<FormControl type="text" placeholder="Search" className="mr-sm-2" />
<Button variant="outline-light">Search</Button>
</Form>
</Navbar>
<br />
<Navbar bg="light" variant="light">
<Navbar.Brand href="#home">Navbar</Navbar.Brand>
<Nav className="mr-auto">
<Nav.Link href="#home">Home</Nav.Link>
<Nav.Link href="#features">Features</Nav.Link>
<Nav.Link href="#pricing">Pricing</Nav.Link>
</Nav>
<Form inline>
<FormControl type="text" placeholder="Search" className="mr-sm-2" />
<Button variant="outline-primary">Search</Button>
</Form>
</Navbar>
</>
```
Containers
----------
While not required, you can wrap the Navbar in a `<Container>` component to center it on a page, or add one within to only center the contents of a [fixed or static top navbar](#navbars-placement).
```
<Container>
<Navbar expand="lg" variant="light" bg="light">
<Navbar.Brand href="#">Navbar</Navbar.Brand>
</Navbar>
</Container>
```
When the container is within your navbar, its horizontal padding is removed at breakpoints lower than your specified `expand={'sm' | 'md' | 'lg' | 'xl'}` prop. This ensures we’re not doubling up on padding unnecessarily on lower viewports when your navbar is collapsed.
```
<Navbar expand="lg" variant="light" bg="light">
<Container>
<Navbar.Brand href="#">Navbar</Navbar.Brand>
</Container>
</Navbar>
```
Placement
---------
You can use Bootstrap's [position utilities](https://getbootstrap.com/docs/4.6/utilities/position/) to place navbars in non-static positions. Choose from fixed to the top, fixed to the bottom, or stickied to the top (scrolls with the page until it reaches the top, then stays there). Fixed navbars use `position: fixed`, meaning they’re pulled from the normal flow of the DOM and may require custom CSS (e.g., padding-top on the `<body>`) to prevent overlap with other elements. Also note that **`.sticky-top` uses `position: sticky`, which [isn’t fully supported in every browser](https://caniuse.com/#feat=css-sticky)**.
Since these positioning needs are so common for Navbars, we've added convenience props for them
### Fixed top
```
<Navbar fixed="top" />
```
### Fixed bottom
```
<Navbar fixed="bottom" />
```
### Sticky top
```
<Navbar sticky="top" />
```
Responsive behaviors
--------------------
Use the `expand` prop as well as the `Navbar.Toggle` and `Navbar.Collapse` components to control when content collapses behind a button.
Set the `defaultExpanded` prop to make the Navbar start expanded. Set `collapseOnSelect` to make the Navbar collapse automatically when the user selects an item. You can also finely control the collapsing behavior by using the `expanded` and `onToggle` props.
```
<Navbar collapseOnSelect expand="lg" bg="dark" variant="dark">
<Navbar.Brand href="#home">React-Bootstrap</Navbar.Brand>
<Navbar.Toggle aria-controls="responsive-navbar-nav" />
<Navbar.Collapse id="responsive-navbar-nav">
<Nav className="mr-auto">
<Nav.Link href="#features">Features</Nav.Link>
<Nav.Link href="#pricing">Pricing</Nav.Link>
<NavDropdown title="Dropdown" id="collasible-nav-dropdown">
<NavDropdown.Item href="#action/3.1">Action</NavDropdown.Item>
<NavDropdown.Item href="#action/3.2">Another action</NavDropdown.Item>
<NavDropdown.Item href="#action/3.3">Something</NavDropdown.Item>
<NavDropdown.Divider />
<NavDropdown.Item href="#action/3.4">Separated link</NavDropdown.Item>
</NavDropdown>
</Nav>
<Nav>
<Nav.Link href="#deets">More deets</Nav.Link>
<Nav.Link eventKey={2} href="#memes">
Dank memes
</Nav.Link>
</Nav>
</Navbar.Collapse>
</Navbar>
```
API
---
### Navbar
`import Navbar from 'react-bootstrap/Navbar'`Copy import code for the Navbar component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | | Set a custom element for this component. |
| bg | string | |
A convenience prop for adding `bg-*` utility classes since they are so commonly used here. `light` and `dark` are common choices but any `bg-*` class is supported, including any custom ones you might define. Pairs nicely with the `variant` prop.
|
| collapseOnSelect | boolean | `false` |
Toggles `expanded` to `false` after the onSelect event of a descendant of a child `<Nav>` fires. Does nothing if no `<Nav>` or `<Nav>` descendants exist. Manually controlling `expanded` via the onSelect callback is recommended instead, for more complex operations that need to be executed after the `select` event of `<Nav>` descendants.
|
| expand | `true` | `'sm'` | `'md'` | `'lg'` | `'xl'` | `true` | The breakpoint, below which, the Navbar will collapse. When `true` the Navbar will always be expanded regardless of screen size. |
| expanded | boolean | | *controlled by: `onToggle`, initial prop: `defaultExpanded`*
Controls the visiblity of the navbar body |
| fixed | `'top'` | `'bottom'` | | Create a fixed navbar along the top or bottom of the screen, that scrolls with the page. A convenience prop for the `fixed-*` positioning classes. |
| onSelect | function | |
A callback fired when a descendant of a child `<Nav>` is selected. Should be used to execute complex closing or other miscellaneous actions desired after selecting a descendant of `<Nav>`. Does nothing if no `<Nav>` or `<Nav>` descendants exist. The callback is called with an eventKey, which is a prop from the selected `<Nav>` descendant, and an event.
```
function (
eventKey: mixed,
event?: SyntheticEvent
)
```
For basic closing behavior after all `<Nav>` descendant onSelect events in mobile viewports, try using collapseOnSelect. Note: If you are manually closing the navbar using this `OnSelect` prop, ensure that you are setting `expanded` to false and not *toggling* between true and false.
|
| onToggle | function | | *controls `expanded`*
A callback fired when the `<Navbar>` body collapses or expands. Fired when a `<Navbar.Toggle>` is clicked and called with the new `expanded` boolean value. |
| role | string | `'navigation'` | The ARIA role for the navbar, will default to 'navigation' for Navbars whose `as` is something other than `<nav>`. |
| sticky | `'top'` | |
Position the navbar at the top of the viewport, but only after scrolling past it. A convenience prop for the `sticky-top` positioning class. **Not supported in <= IE11 and other older browsers without a polyfill**
|
| variant | `'light'` | `'dark'` | `'light'` | The general visual variant a the Navbar. Use in combination with the `bg` prop, `background-color` utilities, or your own background styles. |
| bsPrefix | string | `'navbar'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Navbar.Brand
`import Navbar from 'react-bootstrap/Navbar'`Copy import code for the Navbar component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | | Set a custom element for this component. |
| href | string | | An href, when provided the Brand will render as an `<a>` element (unless `as` is provided). |
| bsPrefix | string | `'navbar'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Navbar.Toggle
`import Navbar from 'react-bootstrap/Navbar'`Copy import code for the Navbar component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<button>` | You can use a custom element type for this component. |
| children | node | | The toggle content. When empty, the default toggle will be rendered. |
| label | string | `'Toggle navigation'` | An accessible ARIA label for the toggler button. |
| onClick | function | | |
| bsPrefix | string | `'navbar-toggler'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Navbar.Collapse
`import Navbar from 'react-bootstrap/Navbar'`Copy import code for the Navbar component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| bsPrefix | string | `'navbar-collapse'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| programming_docs |
react_bootstrap Pagination Pagination
==========
A set of *presentational* components for building pagination UI.
```
let active = 2;
let items = [];
for (let number = 1; number <= 5; number++) {
items.push(
<Pagination.Item key={number} active={number === active}>
{number}
</Pagination.Item>,
);
}
const paginationBasic = (
<div>
<Pagination>{items}</Pagination>
<br />
<Pagination size="lg">{items}</Pagination>
<br />
<Pagination size="sm">{items}</Pagination>
</div>
);
render(paginationBasic);
```
More options
------------
For building more complex pagination UI, there are few convenient sub-components for adding "First", "Previous", "Next", and "Last" buttons, as well as an `Ellipsis` item for indicating previous or continuing results.
```
<Pagination>
<Pagination.First />
<Pagination.Prev />
<Pagination.Item>{1}</Pagination.Item>
<Pagination.Ellipsis />
<Pagination.Item>{10}</Pagination.Item>
<Pagination.Item>{11}</Pagination.Item>
<Pagination.Item active>{12}</Pagination.Item>
<Pagination.Item>{13}</Pagination.Item>
<Pagination.Item disabled>{14}</Pagination.Item>
<Pagination.Ellipsis />
<Pagination.Item>{20}</Pagination.Item>
<Pagination.Next />
<Pagination.Last />
</Pagination>
```
API
---
### Pagination
`import Pagination from 'react-bootstrap/Pagination'`Copy import code for the Pagination component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| size | `'sm'` | `'lg'` | | Set's the size of all PageItems. |
| bsPrefix | string | `'pagination'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### PageItem
`import PageItem from 'react-bootstrap/PageItem'`Copy import code for the PageItem component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| active | boolean | `false` | Styles PageItem as active, and renders a `<span>` instead of an `<a>`. |
| activeLabel | string | `'(current)'` | An accessible label indicating the active state.. |
| disabled | boolean | `false` | Disables the PageItem |
| href | string | | |
| onClick | function | | A callback function for when this component is clicked |
react_bootstrap Forms Forms
=====
The `<FormControl>` component renders a form control with Bootstrap styling. The `<FormGroup>` component wraps a form control with proper spacing, along with support for a label, help text, and validation state. To ensure accessibility, set `controlId` on `<FormGroup>`, and use `<FormLabel>` for the label.
```
<Form>
<Form.Group controlId="formBasicEmail">
<Form.Label>Email address</Form.Label>
<Form.Control type="email" placeholder="Enter email" />
<Form.Text className="text-muted">
We'll never share your email with anyone else.
</Form.Text>
</Form.Group>
<Form.Group controlId="formBasicPassword">
<Form.Label>Password</Form.Label>
<Form.Control type="password" placeholder="Password" />
</Form.Group>
<Form.Group controlId="formBasicCheckbox">
<Form.Check type="checkbox" label="Check me out" />
</Form.Group>
<Button variant="primary" type="submit">
Submit
</Button>
</Form>
```
The `<FormControl>` component directly renders the `<input>` or other specified component. If you need to access the value of an uncontrolled `<FormControl>`, attach a `ref` to it as you would with an uncontrolled input, then call `ReactDOM.findDOMNode(ref)` to get the DOM node. You can then interact with that node as you would with any other uncontrolled input.
If your application contains a large number of form groups, we recommend building a higher-level component encapsulating a complete field group that renders the label, the control, and any other necessary components. We don't provide this out-of-the-box, because the composition of those field groups is too specific to an individual application to admit a good one-size-fits-all solution.
Form controls
-------------
For textual form controls—like `input`s, `select`s, and `textarea`s—use the `FormControl` component. FormControl adds some additional styles for general appearance, focus state, sizing, and more.
```
<Form>
<Form.Group controlId="exampleForm.ControlInput1">
<Form.Label>Email address</Form.Label>
<Form.Control type="email" placeholder="[email protected]" />
</Form.Group>
<Form.Group controlId="exampleForm.ControlSelect1">
<Form.Label>Example select</Form.Label>
<Form.Control as="select">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</Form.Control>
</Form.Group>
<Form.Group controlId="exampleForm.ControlSelect2">
<Form.Label>Example multiple select</Form.Label>
<Form.Control as="select" multiple>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</Form.Control>
</Form.Group>
<Form.Group controlId="exampleForm.ControlTextarea1">
<Form.Label>Example textarea</Form.Label>
<Form.Control as="textarea" rows={3} />
</Form.Group>
</Form>
```
For file inputs, use `Form.File`.
```
<Form>
<Form.Group>
<Form.File id="exampleFormControlFile1" label="Example file input" />
</Form.Group>
</Form>
```
### Sizing
Use `size` on `<FormControl>` and `<FormLabel>` to change the size of inputs and labels respectively.
```
<Form.Group>
<Form.Control size="lg" type="text" placeholder="Large text" />
<br />
<Form.Control type="text" placeholder="Normal text" />
<br />
<Form.Control size="sm" type="text" placeholder="Small text" />
</Form.Group>
```
```
<Form.Group>
<Form.Control as="select" size="lg">
<option>Large select</option>
</Form.Control>
<br />
<Form.Control as="select">
<option>Default select</option>
</Form.Control>
<br />
<Form.Control size="sm" as="select">
<option>Small select</option>
</Form.Control>
</Form.Group>
```
### Readonly
Add the `readOnly` prop on an input to prevent modification of the input's value. Read-only inputs appear lighter (just like disabled inputs), but retain the standard cursor.
```
<Form.Control type="text" placeholder="Readonly input here..." readOnly />
```
### Readonly plain text
If you want to have readonly elements in your form styled as plain text, use the `plaintext` prop on FormControls to remove the default form field styling and preserve the correct margin and padding.
```
<Form>
<Form.Group as={Row} controlId="formPlaintextEmail">
<Form.Label column sm="2">
Email
</Form.Label>
<Col sm="10">
<Form.Control plaintext readOnly defaultValue="[email protected]" />
</Col>
</Form.Group>
<Form.Group as={Row} controlId="formPlaintextPassword">
<Form.Label column sm="2">
Password
</Form.Label>
<Col sm="10">
<Form.Control type="password" placeholder="Password" />
</Col>
</Form.Group>
</Form>
```
Range Inputs
------------
```
<Form>
<Form.Group controlId="formBasicRange">
<Form.Label>Range</Form.Label>
<Form.Control type="range" />
</Form.Group>
</Form>
```
Checkboxes and Radios
---------------------
For the non-textual checkbox and radio controls, `FormCheck` provides a single component for both types that adds some additional styling and improved layout.
### Default (stacked)
By default, any number of checkboxes and radios that are immediate sibling will be vertically stacked and appropriately spaced with FormCheck.
```
<Form>
{['checkbox', 'radio'].map((type) => (
<div key={`default-${type}`} className="mb-3">
<Form.Check
type={type}
id={`default-${type}`}
label={`default ${type}`}
/>
<Form.Check
disabled
type={type}
label={`disabled ${type}`}
id={`disabled-default-${type}`}
/>
</div>
))}
</Form>
```
### Inline
Group checkboxes or radios on the same horizontal row by adding the `inline` prop.
```
<Form>
{['checkbox', 'radio'].map((type) => (
<div key={`inline-${type}`} className="mb-3">
<Form.Check inline label="1" type={type} id={`inline-${type}-1`} />
<Form.Check inline label="2" type={type} id={`inline-${type}-2`} />
<Form.Check
inline
disabled
label="3 (disabled)"
type={type}
id={`inline-${type}-3`}
/>
</div>
))}
</Form>
```
### Without labels
When you render a FormCheck without a label (no `children`) some additional styling is applied to keep the inputs from collapsing. **Remember to add an `aria-label` when omitting labels!**
```
<>
<Form.Check aria-label="option 1" />
<Form.Check type="radio" aria-label="radio 1" />
</>
```
### Customizing FormCheck rendering
When you need tighter control, or want to customize how the `FormCheck` component renders, it may better to use it's constituent parts directly.
By provided `children` to the `FormCheck` you can forgo the default rendering and handle it yourself. (You can still provide an `id` to the `FormCheck` or `FormGroup` and have it propagate to the label and input).
```
<Form>
{['checkbox', 'radio'].map((type) => (
<div key={type} className="mb-3">
<Form.Check type={type} id={`check-api-${type}`}>
<Form.Check.Input type={type} isValid />
<Form.Check.Label>{`Custom api ${type}`}</Form.Check.Label>
<Form.Control.Feedback type="valid">You did it!</Form.Control.Feedback>
</Form.Check>
</div>
))}
</Form>
```
Layout
------
FormControl and FormCheck both apply `display: block` with `width: 100%` to controls, which means they stack vertically by default. Additional components and props can be used to vary this layout on a per-form basis.
### Form groups
The `FormGroup` component is the easiest way to add some structure to forms. It provides a flexible container for grouping of labels, controls, optional help text, and form validation messaging. By default it only applies margin-bottom, but it picks up additional styles in `<Form inline >` as needed. Use it with `fieldset`s, `div`s, or nearly any other element.
You also add the `controlId` prop to accessibly wire the nested label and input together via the `id`.
```
<Form>
<Form.Group controlId="formGroupEmail">
<Form.Label>Email address</Form.Label>
<Form.Control type="email" placeholder="Enter email" />
</Form.Group>
<Form.Group controlId="formGroupPassword">
<Form.Label>Password</Form.Label>
<Form.Control type="password" placeholder="Password" />
</Form.Group>
</Form>
```
### Form grid
More complex forms can be built using the grid components. Use these for form layouts that require multiple columns, varied widths, and additional alignment options.
```
<Form>
<Row>
<Col>
<Form.Control placeholder="First name" />
</Col>
<Col>
<Form.Control placeholder="Last name" />
</Col>
</Row>
</Form>
```
#### Form row
You may also swap `<Row>` for `<Form.Row>`, a variation of the standard grid row that overrides the default column gutters for tighter and more compact layouts.
```
<Form>
<Form.Row>
<Col>
<Form.Control placeholder="First name" />
</Col>
<Col>
<Form.Control placeholder="Last name" />
</Col>
</Form.Row>
</Form>
```
More complex layouts can also be created with the grid system.
```
<Form>
<Form.Row>
<Form.Group as={Col} controlId="formGridEmail">
<Form.Label>Email</Form.Label>
<Form.Control type="email" placeholder="Enter email" />
</Form.Group>
<Form.Group as={Col} controlId="formGridPassword">
<Form.Label>Password</Form.Label>
<Form.Control type="password" placeholder="Password" />
</Form.Group>
</Form.Row>
<Form.Group controlId="formGridAddress1">
<Form.Label>Address</Form.Label>
<Form.Control placeholder="1234 Main St" />
</Form.Group>
<Form.Group controlId="formGridAddress2">
<Form.Label>Address 2</Form.Label>
<Form.Control placeholder="Apartment, studio, or floor" />
</Form.Group>
<Form.Row>
<Form.Group as={Col} controlId="formGridCity">
<Form.Label>City</Form.Label>
<Form.Control />
</Form.Group>
<Form.Group as={Col} controlId="formGridState">
<Form.Label>State</Form.Label>
<Form.Control as="select" defaultValue="Choose...">
<option>Choose...</option>
<option>...</option>
</Form.Control>
</Form.Group>
<Form.Group as={Col} controlId="formGridZip">
<Form.Label>Zip</Form.Label>
<Form.Control />
</Form.Group>
</Form.Row>
<Form.Group id="formGridCheckbox">
<Form.Check type="checkbox" label="Check me out" />
</Form.Group>
<Button variant="primary" type="submit">
Submit
</Button>
</Form>
```
#### Horizontal form
You may also swap `<Row>` for `<Form.Row>`, a variation of the standard grid row that overrides the default column gutters for tighter and more compact layouts.
```
<Form>
<Form.Group as={Row} controlId="formHorizontalEmail">
<Form.Label column sm={2}>
Email
</Form.Label>
<Col sm={10}>
<Form.Control type="email" placeholder="Email" />
</Col>
</Form.Group>
<Form.Group as={Row} controlId="formHorizontalPassword">
<Form.Label column sm={2}>
Password
</Form.Label>
<Col sm={10}>
<Form.Control type="password" placeholder="Password" />
</Col>
</Form.Group>
<fieldset>
<Form.Group as={Row}>
<Form.Label as="legend" column sm={2}>
Radios
</Form.Label>
<Col sm={10}>
<Form.Check
type="radio"
label="first radio"
name="formHorizontalRadios"
id="formHorizontalRadios1"
/>
<Form.Check
type="radio"
label="second radio"
name="formHorizontalRadios"
id="formHorizontalRadios2"
/>
<Form.Check
type="radio"
label="third radio"
name="formHorizontalRadios"
id="formHorizontalRadios3"
/>
</Col>
</Form.Group>
</fieldset>
<Form.Group as={Row} controlId="formHorizontalCheck">
<Col sm={{ span: 10, offset: 2 }}>
<Form.Check label="Remember me" />
</Col>
</Form.Group>
<Form.Group as={Row}>
<Col sm={{ span: 10, offset: 2 }}>
<Button type="submit">Sign in</Button>
</Col>
</Form.Group>
</Form>
```
#### Horizontal form label sizing
You can size the `<FormLabel>` using the column prop as shown.
```
<Form.Group>
<Form.Row>
<Form.Label column="lg" lg={2}>
Large Text
</Form.Label>
<Col>
<Form.Control size="lg" type="text" placeholder="Large text" />
</Col>
</Form.Row>
<br />
<Form.Row>
<Form.Label column lg={2}>
Normal Text
</Form.Label>
<Col>
<Form.Control type="text" placeholder="Normal text" />
</Col>
</Form.Row>
<br />
<Form.Row>
<Form.Label column="sm" lg={2}>
Small Text
</Form.Label>
<Col>
<Form.Control size="sm" type="text" placeholder="Small text" />
</Col>
</Form.Row>
</Form.Group>
```
#### Column sizing
As shown in the previous examples, our grid system allows you to place any number of `<Col>`s within a `<Row>` or `<Form.Row>`. They'll split the available width equally between them. You may also pick a subset of your columns to take up more or less space, while the remaining `<Col>`s equally split the rest, with specific column classes like `<Col xs={7}>`.
```
<Form>
<Form.Row>
<Col xs={7}>
<Form.Control placeholder="City" />
</Col>
<Col>
<Form.Control placeholder="State" />
</Col>
<Col>
<Form.Control placeholder="Zip" />
</Col>
</Form.Row>
</Form>
```
#### Auto-sizing
The example below uses a flexbox utility to vertically center the contents and changes `<Col>` to `<Col xs="auto">` so that your columns only take up as much space as needed. Put another way, the column sizes itself based on on the contents.
```
<Form>
<Form.Row className="align-items-center">
<Col xs="auto">
<Form.Label htmlFor="inlineFormInput" srOnly>
Name
</Form.Label>
<Form.Control
className="mb-2"
id="inlineFormInput"
placeholder="Jane Doe"
/>
</Col>
<Col xs="auto">
<Form.Label htmlFor="inlineFormInputGroup" srOnly>
Username
</Form.Label>
<InputGroup className="mb-2">
<InputGroup.Prepend>
<InputGroup.Text>@</InputGroup.Text>
</InputGroup.Prepend>
<FormControl id="inlineFormInputGroup" placeholder="Username" />
</InputGroup>
</Col>
<Col xs="auto">
<Form.Check
type="checkbox"
id="autoSizingCheck"
className="mb-2"
label="Remember me"
/>
</Col>
<Col xs="auto">
<Button type="submit" className="mb-2">
Submit
</Button>
</Col>
</Form.Row>
</Form>
```
You can then remix that once again with size-specific column classes.
```
<Form>
<Form.Row className="align-items-center">
<Col sm={3} className="my-1">
<Form.Label htmlFor="inlineFormInputName" srOnly>
Name
</Form.Label>
<Form.Control id="inlineFormInputName" placeholder="Jane Doe" />
</Col>
<Col sm={3} className="my-1">
<Form.Label htmlFor="inlineFormInputGroupUsername" srOnly>
Username
</Form.Label>
<InputGroup>
<InputGroup.Prepend>
<InputGroup.Text>@</InputGroup.Text>
</InputGroup.Prepend>
<FormControl id="inlineFormInputGroupUsername" placeholder="Username" />
</InputGroup>
</Col>
<Col xs="auto" className="my-1">
<Form.Check type="checkbox" id="autoSizingCheck2" label="Remember me" />
</Col>
<Col xs="auto" className="my-1">
<Button type="submit">Submit</Button>
</Col>
</Form.Row>
</Form>
```
And of course [custom form controls](#forms-custom) are supported.
```
<Form>
<Form.Row className="align-items-center">
<Col xs="auto" className="my-1">
<Form.Label className="mr-sm-2" htmlFor="inlineFormCustomSelect" srOnly>
Preference
</Form.Label>
<Form.Control
as="select"
className="mr-sm-2"
id="inlineFormCustomSelect"
custom
>
<option value="0">Choose...</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
</Form.Control>
</Col>
<Col xs="auto" className="my-1">
<Form.Check
type="checkbox"
id="customControlAutosizing"
label="Remember my preference"
custom
/>
</Col>
<Col xs="auto" className="my-1">
<Button type="submit">Submit</Button>
</Col>
</Form.Row>
</Form>
```
### Inline forms
Use the `inline` prop to display a series of labels, form controls, and buttons on a single horizontal row. Form controls within forms vary slightly from their default states.
* Controls are `display: flex`, collapsing any HTML white space and allowing you to provide alignment control with spacing and utilities.
* Controls and input groups receive `width: auto` to override the Bootstrap default `width: 100%`.
* Controls **only appear inline in viewports that are at least 576px wide** to account for narrow viewports on mobile devices.
You may need to manually address the width and alignment of individual form controls with spacing utilities (as shown below). Lastly, be sure to always include a `<Form.Label>` with each form control, even if you need to hide it from non-screenreader visitors with the `srOnly` prop.
```
<Form inline>
<Form.Label htmlFor="inlineFormInputName2" srOnly>
Name
</Form.Label>
<Form.Control
className="mb-2 mr-sm-2"
id="inlineFormInputName2"
placeholder="Jane Doe"
/>
<Form.Label htmlFor="inlineFormInputGroupUsername2" srOnly>
Username
</Form.Label>
<InputGroup className="mb-2 mr-sm-2">
<InputGroup.Prepend>
<InputGroup.Text>@</InputGroup.Text>
</InputGroup.Prepend>
<FormControl id="inlineFormInputGroupUsername2" placeholder="Username" />
</InputGroup>
<Form.Check
type="checkbox"
className="mb-2 mr-sm-2"
id="inlineFormCheck"
label="Remember me"
/>
<Button type="submit" className="mb-2">
Submit
</Button>
</Form>
```
Custom form controls and selects are also supported.
```
<Form inline>
<Form.Label className="my-1 mr-2" htmlFor="inlineFormCustomSelectPref">
Preference
</Form.Label>
<Form.Control
as="select"
className="my-1 mr-sm-2"
id="inlineFormCustomSelectPref"
custom
>
<option value="0">Choose...</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
</Form.Control>
<Form.Check
type="checkbox"
className="my-1 mr-sm-2"
id="customControlInline"
label="Remember my preference"
custom
/>
<Button type="submit" className="my-1">
Submit
</Button>
</Form>
```
Help text
---------
Block-level help text in forms can be created using `<Form.Text>`. Inline help text can be flexibly implemented using any inline HTML element and utility classes like`.text-muted`.
Help text below inputs can be styled with `<Form.Text>`. This component includes `display: block` and adds some top margin for easy spacing from the inputs above.
```
<>
<Form.Label htmlFor="inputPassword5">Password</Form.Label>
<Form.Control
type="password"
id="inputPassword5"
aria-describedby="passwordHelpBlock"
/>
<Form.Text id="passwordHelpBlock" muted>
Your password must be 8-20 characters long, contain letters and numbers, and
must not contain spaces, special characters, or emoji.
</Form.Text>
</>
```
Inline text can use any typical inline HTML element (be it a `<small>`, `<span>`, or something else) with nothing more than a utility class.
```
<Form inline>
<Form.Group>
<Form.Label htmlFor="inputPassword6">Password</Form.Label>
<Form.Control
type="password"
className="mx-sm-3"
id="inputPassword6"
aria-describedby="passwordHelpInline"
/>
<Form.Text id="passwordHelpInline" muted>
Must be 8-20 characters long.
</Form.Text>
</Form.Group>
</Form>
```
Disabled forms
--------------
Add the `disabled` boolean attribute on an input to prevent user interactions and make it appear lighter.
```
<>
<Form.Group>
<Form.Label>Disabled input</Form.Label>
<Form.Control placeholder="Disabled input" disabled />
</Form.Group>
<Form.Group>
<Form.Label>Disabled select menu</Form.Label>
<Form.Control as="select" disabled>
<option>Disabled select</option>
</Form.Control>
</Form.Group>
<Form.Group>
<Form.Check type="checkbox" label="Can't check this" disabled />
</Form.Group>
</>
```
Add the `disabled` attribute to a `<fieldset>` to disable all the controls within.
```
<Form>
<fieldset disabled>
<Form.Group>
<Form.Label htmlFor="disabledTextInput">Disabled input</Form.Label>
<Form.Control id="disabledTextInput" placeholder="Disabled input" />
</Form.Group>
<Form.Group>
<Form.Label htmlFor="disabledSelect">Disabled select menu</Form.Label>
<Form.Control as="select" id="disabledSelect">
<option>Disabled select</option>
</Form.Control>
</Form.Group>
<Form.Group>
<Form.Check
type="checkbox"
id="disabledFieldsetCheck"
label="Can't check this"
/>
</Form.Group>
<Button type="submit">Submit</Button>
</fieldset>
</Form>
```
Validation
----------
Provide valuable, actionable feedback to your users with form validation feedback.
### Native HTML5 form validation
For native HTML form validation–[available in all our supported browsers](https://caniuse.com/#feat=form-validation), the `:valid` and `:invalid` pseudo selectors are used to apply validation styles as well as display feedback messages.
Bootstrap scopes the `:valid` and `:invalid` styles to parent `.was-validated` class, usually applied to the `<Form>` (you can use the `validated` prop as a shortcut). Otherwise, any required field without a value shows up as invalid on page load. This way, you may choose when to activate them (typically after form submission is attempted).
```
function FormExample() {
const [validated, setValidated] = useState(false);
const handleSubmit = (event) => {
const form = event.currentTarget;
if (form.checkValidity() === false) {
event.preventDefault();
event.stopPropagation();
}
setValidated(true);
};
return (
<Form noValidate validated={validated} onSubmit={handleSubmit}>
<Form.Row>
<Form.Group as={Col} md="4" controlId="validationCustom01">
<Form.Label>First name</Form.Label>
<Form.Control
required
type="text"
placeholder="First name"
defaultValue="Mark"
/>
<Form.Control.Feedback>Looks good!</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="4" controlId="validationCustom02">
<Form.Label>Last name</Form.Label>
<Form.Control
required
type="text"
placeholder="Last name"
defaultValue="Otto"
/>
<Form.Control.Feedback>Looks good!</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="4" controlId="validationCustomUsername">
<Form.Label>Username</Form.Label>
<InputGroup hasValidation>
<InputGroup.Prepend>
<InputGroup.Text id="inputGroupPrepend">@</InputGroup.Text>
</InputGroup.Prepend>
<Form.Control
type="text"
placeholder="Username"
aria-describedby="inputGroupPrepend"
required
/>
<Form.Control.Feedback type="invalid">
Please choose a username.
</Form.Control.Feedback>
</InputGroup>
</Form.Group>
</Form.Row>
<Form.Row>
<Form.Group as={Col} md="6" controlId="validationCustom03">
<Form.Label>City</Form.Label>
<Form.Control type="text" placeholder="City" required />
<Form.Control.Feedback type="invalid">
Please provide a valid city.
</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="3" controlId="validationCustom04">
<Form.Label>State</Form.Label>
<Form.Control type="text" placeholder="State" required />
<Form.Control.Feedback type="invalid">
Please provide a valid state.
</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="3" controlId="validationCustom05">
<Form.Label>Zip</Form.Label>
<Form.Control type="text" placeholder="Zip" required />
<Form.Control.Feedback type="invalid">
Please provide a valid zip.
</Form.Control.Feedback>
</Form.Group>
</Form.Row>
<Form.Group>
<Form.Check
required
label="Agree to terms and conditions"
feedback="You must agree before submitting."
/>
</Form.Group>
<Button type="submit">Submit form</Button>
</Form>
);
}
render(<FormExample />);
```
### Form libraries and server-rendered styles
It's often beneficial (especially in React) to handle form validation via a library like Formik, or react-formal. In those cases, `isValid` and `isInvalid` props can be added to form controls to manually apply validation styles. Below is a quick example integrating with [Formik](https://github.com/jaredpalmer/formik).
```
const { Formik } = formik;
const schema = yup.object().shape({
firstName: yup.string().required(),
lastName: yup.string().required(),
username: yup.string().required(),
city: yup.string().required(),
state: yup.string().required(),
zip: yup.string().required(),
terms: yup.bool().required().oneOf([true], 'Terms must be accepted'),
});
function FormExample() {
return (
<Formik
validationSchema={schema}
onSubmit={console.log}
initialValues={{
firstName: 'Mark',
lastName: 'Otto',
username: '',
city: '',
state: '',
zip: '',
terms: false,
}}
>
{({
handleSubmit,
handleChange,
handleBlur,
values,
touched,
isValid,
errors,
}) => (
<Form noValidate onSubmit={handleSubmit}>
<Form.Row>
<Form.Group as={Col} md="4" controlId="validationFormik01">
<Form.Label>First name</Form.Label>
<Form.Control
type="text"
name="firstName"
value={values.firstName}
onChange={handleChange}
isValid={touched.firstName && !errors.firstName}
/>
<Form.Control.Feedback>Looks good!</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="4" controlId="validationFormik02">
<Form.Label>Last name</Form.Label>
<Form.Control
type="text"
name="lastName"
value={values.lastName}
onChange={handleChange}
isValid={touched.lastName && !errors.lastName}
/>
<Form.Control.Feedback>Looks good!</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="4" controlId="validationFormikUsername">
<Form.Label>Username</Form.Label>
<InputGroup hasValidation>
<InputGroup.Prepend>
<InputGroup.Text id="inputGroupPrepend">@</InputGroup.Text>
</InputGroup.Prepend>
<Form.Control
type="text"
placeholder="Username"
aria-describedby="inputGroupPrepend"
name="username"
value={values.username}
onChange={handleChange}
isInvalid={!!errors.username}
/>
<Form.Control.Feedback type="invalid">
{errors.username}
</Form.Control.Feedback>
</InputGroup>
</Form.Group>
</Form.Row>
<Form.Row>
<Form.Group as={Col} md="6" controlId="validationFormik03">
<Form.Label>City</Form.Label>
<Form.Control
type="text"
placeholder="City"
name="city"
value={values.city}
onChange={handleChange}
isInvalid={!!errors.city}
/>
<Form.Control.Feedback type="invalid">
{errors.city}
</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="3" controlId="validationFormik04">
<Form.Label>State</Form.Label>
<Form.Control
type="text"
placeholder="State"
name="state"
value={values.state}
onChange={handleChange}
isInvalid={!!errors.state}
/>
<Form.Control.Feedback type="invalid">
{errors.state}
</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="3" controlId="validationFormik05">
<Form.Label>Zip</Form.Label>
<Form.Control
type="text"
placeholder="Zip"
name="zip"
value={values.zip}
onChange={handleChange}
isInvalid={!!errors.zip}
/>
<Form.Control.Feedback type="invalid">
{errors.zip}
</Form.Control.Feedback>
</Form.Group>
</Form.Row>
<Form.Group>
<Form.Check
required
name="terms"
label="Agree to terms and conditions"
onChange={handleChange}
isInvalid={!!errors.terms}
feedback={errors.terms}
id="validationFormik0"
/>
</Form.Group>
<Button type="submit">Submit form</Button>
</Form>
)}
</Formik>
);
}
render(<FormExample />);
```
### Tooltips
If your form layout allows it, you can use the `tooltip` prop to display validation feedback in a styled tooltip. Be sure to have a parent with `position: relative` on it for tooltip positioning. In the example below, our column classes have this already, but your project may require an alternative setup.
```
const { Formik } = formik;
const schema = yup.object().shape({
firstName: yup.string().required(),
lastName: yup.string().required(),
username: yup.string().required(),
city: yup.string().required(),
state: yup.string().required(),
zip: yup.string().required(),
file: yup.mixed().required(),
terms: yup.bool().required().oneOf([true], 'terms must be accepted'),
});
function FormExample() {
return (
<Formik
validationSchema={schema}
onSubmit={console.log}
initialValues={{
firstName: 'Mark',
lastName: 'Otto',
username: '',
city: '',
state: '',
zip: '',
file: null,
terms: false,
}}
>
{({
handleSubmit,
handleChange,
handleBlur,
values,
touched,
isValid,
errors,
}) => (
<Form noValidate onSubmit={handleSubmit}>
<Form.Row>
<Form.Group as={Col} md="4" controlId="validationFormik101">
<Form.Label>First name</Form.Label>
<Form.Control
type="text"
name="firstName"
value={values.firstName}
onChange={handleChange}
isValid={touched.firstName && !errors.firstName}
/>
<Form.Control.Feedback tooltip>Looks good!</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="4" controlId="validationFormik102">
<Form.Label>Last name</Form.Label>
<Form.Control
type="text"
name="lastName"
value={values.lastName}
onChange={handleChange}
isValid={touched.lastName && !errors.lastName}
/>
<Form.Control.Feedback tooltip>Looks good!</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="4" controlId="validationFormikUsername2">
<Form.Label>Username</Form.Label>
<InputGroup hasValidation>
<InputGroup.Prepend>
<InputGroup.Text id="inputGroupPrepend">@</InputGroup.Text>
</InputGroup.Prepend>
<Form.Control
type="text"
placeholder="Username"
aria-describedby="inputGroupPrepend"
name="username"
value={values.username}
onChange={handleChange}
isInvalid={!!errors.username}
/>
<Form.Control.Feedback type="invalid" tooltip>
{errors.username}
</Form.Control.Feedback>
</InputGroup>
</Form.Group>
</Form.Row>
<Form.Row>
<Form.Group as={Col} md="6" controlId="validationFormik103">
<Form.Label>City</Form.Label>
<Form.Control
type="text"
placeholder="City"
name="city"
value={values.city}
onChange={handleChange}
isInvalid={!!errors.city}
/>
<Form.Control.Feedback type="invalid" tooltip>
{errors.city}
</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="3" controlId="validationFormik104">
<Form.Label>State</Form.Label>
<Form.Control
type="text"
placeholder="State"
name="state"
value={values.state}
onChange={handleChange}
isInvalid={!!errors.state}
/>
<Form.Control.Feedback type="invalid" tooltip>
{errors.state}
</Form.Control.Feedback>
</Form.Group>
<Form.Group as={Col} md="3" controlId="validationFormik105">
<Form.Label>Zip</Form.Label>
<Form.Control
type="text"
placeholder="Zip"
name="zip"
value={values.zip}
onChange={handleChange}
isInvalid={!!errors.zip}
/>
<Form.Control.Feedback type="invalid" tooltip>
{errors.zip}
</Form.Control.Feedback>
</Form.Group>
</Form.Row>
<Form.Group>
<Form.File
className="position-relative"
required
name="file"
label="File"
onChange={handleChange}
isInvalid={!!errors.file}
feedback={errors.file}
id="validationFormik107"
feedbackTooltip
/>
</Form.Group>
<Form.Group>
<Form.Check
required
name="terms"
label="Agree to terms and conditions"
onChange={handleChange}
isInvalid={!!errors.terms}
feedback={errors.terms}
id="validationFormik106"
feedbackTooltip
/>
</Form.Group>
<Button type="submit">Submit form</Button>
</Form>
)}
</Formik>
);
}
render(<FormExample />);
```
### Input group validation
To properly show rounded corners in an `<InputGroup>` with validation, the `<InputGroup>` requires the `hasValidation` prop.
```
<InputGroup hasValidation>
<InputGroup.Prepend>
<InputGroup.Text>@</InputGroup.Text>
</InputGroup.Prepend>
<Form.Control type="text" required isInvalid />
<Form.Control.Feedback type="invalid">
Please choose a username.
</Form.Control.Feedback>
</InputGroup>
```
### Examples
Custom forms
------------
For even more customization and cross browser consistency, use our completely custom form elements to replace the browser defaults. They’re built on top of semantic and accessible markup, so they’re solid replacements for any default form control.
### Checkboxes and radios
Custom checkbox and radio styles are achieved with a resourceful use of the `:checked` selector and `:after` pseudo elements, but are Structurally similar to the default `FormCheck`. By default the checked and indeterminate icons use embedded svg icons from [Open Iconic](https://useiconic.com/open).
Apply Bootstrap's custom elements by adding the `custom` prop.
```
<Form>
{['checkbox', 'radio'].map((type) => (
<div key={`custom-${type}`} className="mb-3">
<Form.Check
custom
type={type}
id={`custom-${type}`}
label={`Check this custom ${type}`}
/>
<Form.Check
custom
disabled
type={type}
label={`disabled ${type}`}
id={`disabled-custom-${type}`}
/>
</div>
))}
</Form>
```
### Switches
A switch has the markup of a custom checkbox but uses `type="switch"` to render a toggle switch. Switches also support the same customizable children as `<FormCheck>`.
```
<Form>
<Form.Check
type="switch"
id="custom-switch"
label="Check this switch"
/>
<Form.Check
disabled
type="switch"
label="disabled switch"
id="disabled-custom-switch"
/>
</Form>
```
### Inline
```
<Form>
{['checkbox', 'radio'].map((type) => (
<div key={`custom-inline-${type}`} className="mb-3">
<Form.Check
custom
inline
label="1"
type={type}
id={`custom-inline-${type}-1`}
/>
<Form.Check
custom
inline
label="2"
type={type}
id={`custom-inline-${type}-2`}
/>
<Form.Check
custom
inline
disabled
label="3 (disabled)"
type={type}
id={`custom-inline-${type}-3`}
/>
</div>
))}
</Form>
```
### Select
For the `select` form control you can pass the `custom` prop to get custom styling of the select element. Custom styles are limited to the `select` initial appearance and cannot modify the `option` styling due to browser limitations.
```
<Form>
<Form.Group controlId="exampleForm.SelectCustom">
<Form.Label>Custom select</Form.Label>
<Form.Control as="select" custom>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</Form.Control>
</Form.Group>
</Form>
```
#### Sizing
The custom `select` element supports sizing.
```
<Form>
<Form.Group controlId="exampleForm.SelectCustomSizeSm">
<Form.Label>Custom select Small</Form.Label>
<Form.Control as="select" size="sm" custom>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</Form.Control>
</Form.Group>
<Form.Group controlId="exampleForm.SelectCustomSizeLg">
<Form.Label>Custom select Large</Form.Label>
<Form.Control as="select" size="lg" custom>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</Form.Control>
</Form.Group>
</Form>
```
#### HTML size
You can also specify the visible options of your `select` element.
```
<Form>
<Form.Group controlId="exampleForm.SelectCustomHtmlSize">
<Form.Label>Select with three visible options</Form.Label>
<Form.Control as="select" htmlSize={3} custom>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</Form.Control>
</Form.Group>
</Form>
```
### Range
For the `range` form control you can pass the `custom` prop to get custom styling of the select element. The track (the background) and thumb (the value) are both styled to appear the same across browsers. As only IE and Firefox support “filling” their track from the left or right of the thumb as a means to visually indicate progress, we do not currently support it.
```
<Form>
<Form.Group controlId="formBasicRangeCustom">
<Form.Label>Range</Form.Label>
<Form.Control type="range" custom />
</Form.Group>
</Form>
```
### File
A custom styled File uploader.
```
<Form>
<Form.File
id="custom-file"
label="Custom file input"
custom
/>
</Form>
```
#### Translating or customizing the strings with HTML
Bootstrap also provides a way to translate the “Browse” text in HTML with the `data-browse` attribute which can be added to the custom input label (example in Dutch):
```
<Form>
<Form.File
id="custom-file-translate-html"
label="Voeg je document toe"
data-browse="Bestand kiezen"
custom
/>
</Form>
```
#### Translating or customizing the strings with SCSS
Please refer to the official [Bootstrap documentation for translating via SCSS](https://getbootstrap.com/docs/4.4/components/forms/#translating-or-customizing-the-strings-with-scss). The `lang` prop can be used to pass the language.
```
<Form>
<Form.File
id="custom-file-translate-scss"
label="Custom file input"
lang="en"
custom
/>
</Form>
```
#### Customizing FormFile rendering
When you need tighter control, or want to customize how the `FormFile` component renders, it may be better to use it's constituent parts directly.
By providing `children` to the `FormFile` you can forgo the default rendering and handle it yourself. (You can still provide an `id` to the `FormFile` and have it propagate to the label and input).
```
<Form>
<div className="mb-3">
<Form.File id="formcheck-api-custom" custom>
<Form.File.Input isValid />
<Form.File.Label data-browse="Button text">
Custom file input
</Form.File.Label>
<Form.Control.Feedback type="valid">You did it!</Form.Control.Feedback>
</Form.File>
</div>
<div className="mb-3">
<Form.File id="formcheck-api-regular">
<Form.File.Label>Regular file input</Form.File.Label>
<Form.File.Input />
</Form.File>
</div>
</Form>
```
API
---
### Form
`import Form from 'react-bootstrap/Form'`Copy import code for the Form component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| ref | ReactRef | | The Form `ref` will be forwarded to the underlying element, which means, unless it's rendered `as` a composite component, it will be a DOM node, when resolved. |
| as | elementType | `<form>` | You can use a custom element type for this component. |
| inline | boolean | `false` | Display the series of labels, form controls, and buttons on a single horizontal row |
| validated | boolean | | Mark a form as having been validated. Setting it to `true` will toggle any validation styles on the forms elements. |
| bsPrefix | string | `{'form'}` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Form.Row
`import Form from 'react-bootstrap/Form'`Copy import code for the Form component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'form-row'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Form.Group
`import Form from 'react-bootstrap/Form'`Copy import code for the Form component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| ref | ReactRef | | The FormGroup `ref` will be forwarded to the underlying element. Unless the FormGroup is rendered `as` a composite component, it will be a DOM node, when resolved. |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| controlId | string | | Sets `id` on `<FormControl>` and `htmlFor` on `<FormGroup.Label>`. |
| bsPrefix | string | `'form-group'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Form.Label
`import Form from 'react-bootstrap/Form'`Copy import code for the Form component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| ref | ReactRef | | The FormLabel `ref` will be forwarded to the underlying element. Unless the FormLabel is rendered `as` a composite component, it will be a DOM node, when resolved. |
| as | elementType | `<label>` | Set a custom element for this component |
| column | boolean | `'sm'` | `'lg'`
| `false` | Renders the FormLabel as a `<Col>` component (accepting all the same props), as well as adding additional styling for horizontal forms. |
| htmlFor | string | | Uses `controlId` from `<FormGroup>` if not explicitly specified. |
| srOnly | boolean | `false` | Hides the label visually while still allowing it to be read by assistive technologies. |
| bsPrefix | string | `'form-label'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Form.Text
`import Form from 'react-bootstrap/Form'`Copy import code for the Form component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| ref | ReactRef | | The FormText `ref` will be forwarded to the underlying element. Unless the FormText is rendered `as` a composite component, it will be a DOM node, when resolved. |
| as | elementType | `<small>` | You can use a custom element type for this component. |
| muted | boolean | | A convenience prop for add the `text-muted` class, since it's so commonly used here. |
| bsPrefix | string | `'form-text'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Form.Control
`import Form from 'react-bootstrap/Form'`Copy import code for the Form component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| ref | ReactRef | | The FormControl `ref` will be forwarded to the underlying input element, which means unless `as` is a composite component, it will be a DOM node, when resolved. |
| as | 'input' | 'textarea' | 'select' | elementType | `'input'` | The underlying HTML element to use when rendering the FormControl. |
| custom | boolean | | Use Bootstrap's custom form elements to replace the browser defaults |
| disabled | boolean | | Make the control disabled |
| htmlSize | number | | The size attribute of the underlying HTML element. Specifies the visible width in characters if `as` is `'input'`. Specifies the number of visible options if `as` is `'select'`. |
| id | string | | Uses `controlId` from `<FormGroup>` if not explicitly specified. |
| isInvalid | boolean | `false` | Add "invalid" validation styles to the control and accompanying label |
| isValid | boolean | `false` | Add "valid" validation styles to the control |
| onChange | function | | A callback fired when the `value` prop changes |
| plaintext | boolean | | Render the input as plain text. Generally used along side `readOnly`. |
| readOnly | boolean | | Make the control readonly |
| size | `'sm'` | `'lg'` | | Input size variants |
| type | string | | The HTML input `type`, which is only relevant if `as` is `'input'` (the default). |
| value | string | arrayOf | number | | *controlled by: `onChange`, initial prop: `defaultValue`*
The `value` attribute of underlying input |
| bsPrefix | string | `{'form-control'}` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| bsCustomPrefix | string | `'custom'` | A seperate bsPrefix used for custom controls |
### FormControl.Feedback
`import FormControl from 'react-bootstrap/FormControl'`Copy import code for the FormControl component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| className | string | | |
| tooltip | boolean | `false` | Display feedback as a tooltip. |
| type | `'valid'` | `'invalid'` | `'valid'` | Specify whether the feedback is for valid or invalid fields |
| bsPrefix | never | | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Form.Check
`import Form from 'react-bootstrap/Form'`Copy import code for the Form component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| ref | ReactRef | | The FormCheck `ref` will be forwarded to the underlying input element, which means it will be a DOM node, when resolved. |
| as | 'input' | elementType | `'input'` | The underlying HTML element to use when rendering the FormCheck. |
| children | node | |
Provide a function child to manually handle the layout of the FormCheck's inner components.
```
<FormCheck><FormCheck.Input isInvalid type={radio} /><FormCheck.Label>Allow us to contact you?</FormCheck.Label><Feedback type="invalid">Yo this is required</Feedback></FormCheck>
```
|
| custom | all(PropTypes.bool, ({ custom, id }) => custom && !id ? Error('Custom check controls require an id to work') : null, ) | | Use Bootstrap's custom form elements to replace the browser defaults |
| disabled | boolean | `false` | Disables the control. |
| feedback | node | | A message to display when the input is in a validation state |
| feedbackTooltip | boolean | `false` | Display feedback as a tooltip. |
| id | string | |
A HTML id attribute, necessary for proper form accessibility. An id is recommended for allowing label clicks to toggle the check control. This is **required** for custom check controls or when `type="switch"` due to how they are rendered.
|
| inline | boolean | `false` | Groups controls horizontally with other `FormCheck`s. |
| isInvalid | boolean | `false` | Manually style the input as invalid |
| isValid | boolean | `false` | Manually style the input as valid |
| label | node | | Label for the control. |
| title | string | `''` | `title` attribute for the underlying `FormCheckLabel`. |
| type | `'radio'` | `'checkbox'` | `'switch'` | `'checkbox'` | The type of checkable. |
| bsPrefix | string | `'form-check'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| bsCustomPrefix | string | `'custom-control'` | A seperate bsPrefix used for custom controls |
### FormCheck.Input
`import FormCheck from 'react-bootstrap/FormCheck'`Copy import code for the FormCheck component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | 'input' | elementType | `'input'` | The underlying HTML element to use when rendering the FormCheckInput. |
| id | string | | A HTML id attribute, necessary for proper form accessibility. |
| isInvalid | boolean | `false` | Manually style the input as invalid |
| isStatic | boolean | | A convenience prop shortcut for adding `position-static` to the input, for correct styling when used without an FormCheckLabel |
| isValid | boolean | `false` | Manually style the input as valid |
| type | `'radio'` | `'checkbox'` | `'checkbox'` | The type of checkable. |
| bsPrefix | string | `'form-check-input'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| bsCustomPrefix | string | `'custom-control'` | A seperate bsPrefix used for custom controls |
### FormCheck.Label
`import FormCheck from 'react-bootstrap/FormCheck'`Copy import code for the FormCheck component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| htmlFor | string | | The HTML for attribute for associating the label with an input |
| bsPrefix | string | `'form-check-input'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| bsCustomPrefix | string | `'custom-control'` | A seperate bsPrefix used for custom controls |
### Form.File
`import Form from 'react-bootstrap/Form'`Copy import code for the Form component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | 'div' | elementType | `'div'` | The wrapping HTML element to use when rendering the FormFile. |
| children | node | |
Provide a function child to manually handle the layout of the FormFile's inner components. If not using the custom prop `FormFile.Label>` should be before `<FormFile.Input isInvalid />`
```
<FormFile><FormFile.Label>Allow us to contact you?</FormFile.Label><FormFile.Input isInvalid /><Feedback type="invalid">Yo this is required</Feedback></FormFile>
```
If using the custom prop `<FormFile.Input isInvalid />` should be before `FormFile.Label>`
```
<FormFile custom><FormFile.Input isInvalid /><FormFile.Label>Allow us to contact you?</FormFile.Label><Feedback type="invalid">Yo this is required</Feedback></FormFile>
```
|
| custom | boolean | | Use Bootstrap's custom form elements to replace the browser defaults |
| data-browse | string | | The string for the "Browse" text label when using custom file input |
| disabled | boolean | `false` | |
| feedback | node | | A message to display when the input is in a validation state |
| feedbackTooltip | boolean | `false` | Display feedback as a tooltip. |
| id | string | | A HTML id attribute, necessary for proper form accessibility. |
| inputAs | 'input' | elementType | `'input'` | The underlying HTML element to use when rendering the FormFile. |
| isInvalid | boolean | `false` | Manually style the input as invalid |
| isValid | boolean | `false` | Manually style the input as valid |
| label | node | | |
| lang | all(PropTypes.string, ({ custom, lang }) => lang && !custom ? Error('`lang` can only be set when custom is `true`') : null, ) | | The language for the button when using custom file input and SCSS based strings |
| bsPrefix | string | `'form-file'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| bsCustomPrefix | string | `'custom-file'` | A seperate bsPrefix used for custom controls |
### FormFile.Input
`import FormFile from 'react-bootstrap/FormFile'`Copy import code for the FormFile component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | 'input' | elementType | `'input'` | The underlying HTML element to use when rendering the FormFileInput. |
| id | string | | A HTML id attribute, necessary for proper form accessibility. |
| isInvalid | boolean | | Manually style the input as invalid |
| isValid | boolean | | Manually style the input as valid |
| lang | string | | The language for the button when using custom file input and SCSS based strings |
| bsPrefix | string | `'form-file-input'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| bsCustomPrefix | string | `'custom-file-input'` | A seperate bsPrefix used for custom controls |
### FormFile.Label
`import FormFile from 'react-bootstrap/FormFile'`Copy import code for the FormFile component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| data-browse | string | | The string for the "Browse" text label when using custom file input |
| htmlFor | string | | The HTML for attribute for associating the label with an input |
| bsPrefix | string | `'form-file-input'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| bsCustomPrefix | string | `'custom-file-label'` | A seperate bsPrefix used for custom controls |
| programming_docs |
react_bootstrap Buttons Buttons
=======
Custom button styles for actions in forms, dialogs, and more with support for multiple sizes, states, and more.
Examples
--------
Use any of the available button style types to quickly create a styled button. Just modify the `variant` prop.
```
<>
<Button variant="primary">Primary</Button>{' '}
<Button variant="secondary">Secondary</Button>{' '}
<Button variant="success">Success</Button>{' '}
<Button variant="warning">Warning</Button>{' '}
<Button variant="danger">Danger</Button> <Button variant="info">Info</Button>{' '}
<Button variant="light">Light</Button> <Button variant="dark">Dark</Button>{' '}
<Button variant="link">Link</Button>
</>
```
### Outline buttons
For a lighter touch, Buttons also come in `outline-*` variants with no background color.
```
<>
<Button variant="outline-primary">Primary</Button>{' '}
<Button variant="outline-secondary">Secondary</Button>{' '}
<Button variant="outline-success">Success</Button>{' '}
<Button variant="outline-warning">Warning</Button>{' '}
<Button variant="outline-danger">Danger</Button>{' '}
<Button variant="outline-info">Info</Button>{' '}
<Button variant="outline-light">Light</Button>{' '}
<Button variant="outline-dark">Dark</Button>
</>
```
Button tags
-----------
Normally `<Button>` components will render a HTML `<button>` element. However you can render whatever you'd like, adding a `href` prop will automatically render an `<a />` element. You can use the `as` prop to render whatever your heart desires. React Bootstrap will take care of the proper ARIA roles for you.
```
<>
<Button href="#">Link</Button> <Button type="submit">Button</Button>{' '}
<Button as="input" type="button" value="Input" />{' '}
<Button as="input" type="submit" value="Submit" />{' '}
<Button as="input" type="reset" value="Reset" />
</>
```
Sizes
-----
Fancy larger or smaller buttons? Add `size="lg"`, `size="sm"` for additional sizes.
```
<>
<div className="mb-2">
<Button variant="primary" size="lg">
Large button
</Button>{' '}
<Button variant="secondary" size="lg">
Large button
</Button>
</div>
<div>
<Button variant="primary" size="sm">
Small button
</Button>{' '}
<Button variant="secondary" size="sm">
Small button
</Button>
</div>
</>
```
Create block level buttons—those that span the full width of a parent—by adding `block`
```
<>
<Button variant="primary" size="lg" block>
Block level button
</Button>
<Button variant="secondary" size="lg" block>
Block level button
</Button>
</>
```
Active state
------------
To set a button's active state simply set the component's `active` prop.
```
<>
<Button variant="primary" size="lg" active>
Primary button
</Button>{' '}
<Button variant="secondary" size="lg" active>
Button
</Button>
</>
```
### Disabled state
Make buttons look inactive by adding the `disabled` prop to.
```
<>
<Button variant="primary" size="lg" disabled>
Primary button
</Button>{' '}
<Button variant="secondary" size="lg" disabled>
Button
</Button>{' '}
<Button href="#" variant="secondary" size="lg" disabled>
Link
</Button>
</>
```
Watch out! `<a>` elements don't naturally support a `disabled` attribute. In browsers that support it this is handled with a `point-events: none` style but not all browsers support it yet.
React Bootstrap will prevent any `onClick` handlers from firing regardless of the rendered element.
Button loading state
--------------------
When activating an asynchronous action from a button it is a good UX pattern to give the user feedback as to the loading state, this can easily be done by updating your `<Button />`s props from a state change like below.
```
function simulateNetworkRequest() {
return new Promise((resolve) => setTimeout(resolve, 2000));
}
function LoadingButton() {
const [isLoading, setLoading] = useState(false);
useEffect(() => {
if (isLoading) {
simulateNetworkRequest().then(() => {
setLoading(false);
});
}
}, [isLoading]);
const handleClick = () => setLoading(true);
return (
<Button
variant="primary"
disabled={isLoading}
onClick={!isLoading ? handleClick : null}
>
{isLoading ? 'Loading…' : 'Click to load'}
</Button>
);
}
render(<LoadingButton />);
```
Checkbox / Radio
----------------
Buttons can also be used to style `checkbox` and `radio` form elements. This is helpful when you want a toggle button that works neatly inside an HTML form.
```
function ToggleButtonExample() {
const [checked, setChecked] = useState(false);
const [radioValue, setRadioValue] = useState('1');
const radios = [
{ name: 'Active', value: '1' },
{ name: 'Radio', value: '2' },
{ name: 'Radio', value: '3' },
];
return (
<>
<ButtonGroup toggle className="mb-2">
<ToggleButton
type="checkbox"
variant="secondary"
checked={checked}
value="1"
onChange={(e) => setChecked(e.currentTarget.checked)}
>
Checked
</ToggleButton>
</ButtonGroup>
<br />
<ButtonGroup toggle>
{radios.map((radio, idx) => (
<ToggleButton
key={idx}
type="radio"
variant="secondary"
name="radio"
value={radio.value}
checked={radioValue === radio.value}
onChange={(e) => setRadioValue(e.currentTarget.value)}
>
{radio.name}
</ToggleButton>
))}
</ButtonGroup>
</>
);
}
render(<ToggleButtonExample />);
```
The above handles styling, But requires manually controlling the `checked` state for each radio or checkbox in the group.
For a nicer experience with checked state management use the `<ToggleButtonGroup>` instead of a `<ButtonGroup toggle>` component. The group behaves as a form component, where the `value` is an array of the selected `value`s for a named checkbox group or the single toggled `value` in a similarly named radio group.
#### Uncontrolled
```
<>
<ToggleButtonGroup type="checkbox" defaultValue={[1, 3]} className="mb-2">
<ToggleButton value={1}>Checkbox 1 (pre-checked)</ToggleButton>
<ToggleButton value={2}>Checkbox 2</ToggleButton>
<ToggleButton value={3}>Checkbox 3 (pre-checked)</ToggleButton>
</ToggleButtonGroup>
<br />
<ToggleButtonGroup type="radio" name="options" defaultValue={1}>
<ToggleButton value={1}>Radio 1 (pre-checked)</ToggleButton>
<ToggleButton value={2}>Radio 2</ToggleButton>
<ToggleButton value={3}>Radio 3</ToggleButton>
</ToggleButtonGroup>
</>
```
#### Controlled
```
function ToggleButtonGroupControlled() {
const [value, setValue] = useState([1, 3]);
/*
* The second argument that will be passed to
* `handleChange` from `ToggleButtonGroup`
* is the SyntheticEvent object, but we are
* not using it in this example so we will omit it.
*/
const handleChange = (val) => setValue(val);
return (
<ToggleButtonGroup type="checkbox" value={value} onChange={handleChange}>
<ToggleButton value={1}>Option 1</ToggleButton>
<ToggleButton value={2}>Option 2</ToggleButton>
<ToggleButton value={3}>Option 3</ToggleButton>
</ToggleButtonGroup>
);
}
render(<ToggleButtonGroupControlled />);
```
API
---
### Button
`import Button from 'react-bootstrap/Button'`Copy import code for the Button component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| active | boolean | `false` | Manually set the visual state of the button to `:active` |
| as | elementType | | You can use a custom element type for this component. |
| block | boolean | | Spans the full width of the Button parent |
| disabled | boolean | `false` | Disables the Button, preventing mouse events, even if the underlying component is an `<a>` element |
| href | string | | Providing a `href` will render an `<a>` element, *styled* as a button. |
| size | `'sm'` | `'lg'` | | Specifies a large or small button. |
| target | any | | |
| type | `'button'` | `'reset'` | `'submit'` | `null` | `'button'` | Defines HTML button type attribute. |
| variant | string | `'primary'` |
One or more button variant combinations buttons may be one of a variety of visual variants such as: `'primary', 'secondary', 'success', 'danger', 'warning', 'info', 'dark', 'light', 'link'` as well as "outline" versions (prefixed by 'outline-\*') `'outline-primary', 'outline-secondary', 'outline-success', 'outline-danger', 'outline-warning', 'outline-info', 'outline-dark', 'outline-light'`
|
| bsPrefix | string | `'btn'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ToggleButtonGroup
`import ToggleButtonGroup from 'react-bootstrap/ToggleButtonGroup'`Copy import code for the ToggleButtonGroup component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| name | string | |
An HTML `<input>` name for each child button. **Required if `type` is set to `'radio'`**
|
| onChange | function | | *controls `value`*
Callback fired when a button is pressed, depending on whether the `type` is `'radio'` or `'checkbox'`, `onChange` will be called with the value or array of active values |
| size | `'sm'` | `'lg'` | | Sets the size for all Buttons in the group. |
| type | `'checkbox'` | `'radio'` | `'radio'` | The input `type` of the rendered buttons, determines the toggle behavior of the buttons |
| value | any | | *controlled by: `onChange`, initial prop: `defaultValue`*
The value, or array of values, of the active (pressed) buttons |
| vertical | boolean | `false` | Make the set of Buttons appear vertically stacked. |
### ToggleButton
`import ToggleButton from 'react-bootstrap/ToggleButton'`Copy import code for the ToggleButton component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| checked | boolean | | The checked state of the input, managed by `<ToggleButtonGroup>` automatically |
| disabled | boolean | | The disabled state of both the label and input |
| inputRef | ReactRef | | A ref attached to the `<input>` element |
| name | string | | The HTML input name, used to group like checkboxes or radio buttons together semantically |
| onChange | function | | A callback fired when the underlying input element changes. This is passed directly to the `<input>` so shares the same signature as a native `onChange` event. |
| type | `'checkbox'` | `'radio'` | | The `<input>` element `type` |
| value required | string | arrayOf | number | | The value of the input, should be unique amongst it's siblings when nested in a `ToggleButtonGroup`. |
react_bootstrap Progress bars Progress bars
=============
Provide up-to-date feedback on the progress of a workflow or action with simple yet flexible progress bars.
Example
-------
Default progress bar.
```
<ProgressBar now={60} />
```
With label
----------
Add a `label` prop to show a visible percentage. For low percentages, consider adding a min-width to ensure the label's text is fully visible.
```
const now = 60;
const progressInstance = <ProgressBar now={now} label={`${now}%`} />;
render(progressInstance);
```
Screenreader only label
-----------------------
Add a `srOnly` prop to hide the label visually.
```
const now = 60;
const progressInstance = <ProgressBar now={now} label={`${now}%`} srOnly />;
render(progressInstance);
```
Contextual alternatives
-----------------------
Progress bars use some of the same button and alert classes for consistent styles.
```
<div>
<ProgressBar variant="success" now={40} />
<ProgressBar variant="info" now={20} />
<ProgressBar variant="warning" now={60} />
<ProgressBar variant="danger" now={80} />
</div>
```
Striped
-------
Uses a gradient to create a striped effect. Not available in IE8.
```
<div>
<ProgressBar striped variant="success" now={40} />
<ProgressBar striped variant="info" now={20} />
<ProgressBar striped variant="warning" now={60} />
<ProgressBar striped variant="danger" now={80} />
</div>
```
Animated
--------
Add `animated` prop to animate the stripes right to left. Not available in IE9 and below.
```
<ProgressBar animated now={45} />
```
Stacked
-------
Nest `<ProgressBar />`s to stack them.
```
<ProgressBar>
<ProgressBar striped variant="success" now={35} key={1} />
<ProgressBar variant="warning" now={20} key={2} />
<ProgressBar striped variant="danger" now={10} key={3} />
</ProgressBar>
```
API
---
### ProgressBar
`import ProgressBar from 'react-bootstrap/ProgressBar'`Copy import code for the ProgressBar component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| animated | boolean | `false` | Animate's the stripes from right to left |
| children | onlyProgressBar | | Child elements (only allows elements of type ) |
| isChild | boolean | `false` | |
| label | node | | Show label that represents visual percentage. EG. 60% |
| max | number | `100` | Maximum value progress can reach |
| min | number | `0` | Minimum value progress can begin from |
| now | number | | Current value of progress |
| srOnly | boolean | `false` | Hide's the label visually. |
| striped | boolean | `false` | Uses a gradient to create a striped effect. |
| variant | `'success'` | `'danger'` | `'warning'` | `'info'` | | Sets the background class of the progress bar. |
| bsPrefix | string | `'progress-bar'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Images Images
======
Shape
-----
Use the `rounded`, `roundedCircle` and `thumbnail` props to customise the image.
```
<Container>
<Row>
<Col xs={6} md={4}>
<Image src="holder.js/171x180" rounded />
</Col>
<Col xs={6} md={4}>
<Image src="holder.js/171x180" roundedCircle />
</Col>
<Col xs={6} md={4}>
<Image src="holder.js/171x180" thumbnail />
</Col>
</Row>
</Container>
```
Fluid
-----
Use the `fluid` to scale image nicely to the parent element.
```
<Image src="holder.js/100px250" fluid />
```
API
---
### Image
`import Image from 'react-bootstrap/Image'`Copy import code for the Image component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| fluid | boolean | `false` | Sets image as fluid image. |
| rounded | boolean | `false` | Sets image shape as rounded. |
| roundedCircle | boolean | `false` | Sets image shape as circle. |
| thumbnail | boolean | `false` | Sets image shape as thumbnail. |
| bsPrefix | string | `'img'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Overlays Overlays
========
A set of components for positioning beautiful overlays, tooltips, popovers, and anything else you need.
Overview
--------
Things to know about the React-Boostrap Overlay components.
* Overlays rely on the third-party library [Popper.js](https://popper.js.org/). It's included automatically with React-Bootstrap, but you should reference the API for more advanced use cases.
* The `<Tooltip>` and `<Popover>` components do not position themselves. Instead the `<Overlay>` (or `<OverlayTrigger>`) components, inject `ref` and `style` props.
* Tooltip expects specific props injected by the `<Overlay>` component
* Tooltips for `disabled` elements must be triggered on a wrapper element.
Overlay
-------
`Overlay` is the fundamental component for positioning and controlling tooltip visibility. It's a wrapper around Popper.js, that adds support for transitions, and visibility toggling.
### Creating an Overlay
Overlays consist of at least two elements, the "overlay", the element to be positioned, as well as a "target", the element the overlay is positioned in relation to. You can also also have an "arrow" element, like the tooltips and popovers, but that is optional. Be sure to **check out the [Popper](https://popper.js.org/docs/v2/) documentation for more details about the injected props.**
```
function Example() {
const [show, setShow] = useState(false);
const target = useRef(null);
return (
<>
<Button variant="danger" ref={target} onClick={() => setShow(!show)}>
Click me to see
</Button>
<Overlay target={target.current} show={show} placement="right">
{({ placement, arrowProps, show: _show, popper, ...props }) => (
<div
{...props}
style={{
backgroundColor: 'rgba(255, 100, 100, 0.85)',
padding: '2px 10px',
color: 'white',
borderRadius: 3,
...props.style,
}}
>
Simple tooltip
</div>
)}
</Overlay>
</>
);
}
render(<Example />);
```
OverlayTrigger
--------------
Since the above pattern is pretty common, but verbose, we've included `<OverlayTrigger>` component to help with common use-cases. It even has functionality to delayed show or hides, and a few different "trigger" events you can mix and match.
Note that triggering components **must be able to accept [a ref](https://reactjs.org/docs/refs-and-the-dom.html)** since `<OverlayTrigger>` will attempt to add one. You can use [forwardRef()](https://reactjs.org/docs/react-api.html#reactforwardref) for function components.
```
const renderTooltip = (props) => (
<Tooltip id="button-tooltip" {...props}>
Simple tooltip
</Tooltip>
);
render(
<OverlayTrigger
placement="right"
delay={{ show: 250, hide: 400 }}
overlay={renderTooltip}
>
<Button variant="success">Hover me to see</Button>
</OverlayTrigger>,
);
```
### Customizing trigger behavior
For more advanced behaviors `<OverlayTrigger>` accepts a function child that passes in the injected `ref` and event handlers that correspond to the configured `trigger` prop.
You can manually apply the props to any element you want or split them up. The example below shows how to position the overlay to a different element than the one that triggers its visibility.
```
render(
<OverlayTrigger
placement="bottom"
overlay={<Tooltip id="button-tooltip-2">Check out this avatar</Tooltip>}
>
{({ ref, ...triggerHandler }) => (
<Button
variant="light"
{...triggerHandler}
className="d-inline-flex align-items-center"
>
<Image
ref={ref}
roundedCircle
src="holder.js/20x20?text=J&bg=28a745&fg=FFF"
/>
<span className="ml-1">Hover to see</span>
</Button>
)}
</OverlayTrigger>,
);
```
Tooltips
--------
A tooltip component for a more stylish alternative to that anchor tag `title` attribute.
### Examples
Hover over the links below to see tooltips.
You can pass the `Overlay` injected props directly to the Tooltip component.
```
function Example() {
const [show, setShow] = useState(false);
const target = useRef(null);
return (
<>
<Button ref={target} onClick={() => setShow(!show)}>
Click me!
</Button>
<Overlay target={target.current} show={show} placement="right">
{(props) => (
<Tooltip id="overlay-example" {...props}>
My Tooltip
</Tooltip>
)}
</Overlay>
</>
);
}
render(<Example />);
```
Or pass a Tooltip element to `OverlayTrigger` instead.
```
<>
{['top', 'right', 'bottom', 'left'].map((placement) => (
<OverlayTrigger
key={placement}
placement={placement}
overlay={
<Tooltip id={`tooltip-${placement}`}>
Tooltip on <strong>{placement}</strong>.
</Tooltip>
}
>
<Button variant="secondary">Tooltip on {placement}</Button>
</OverlayTrigger>
))}
</>
```
Popovers
--------
A popover component, like those found in iOS.
### Examples
```
const popover = (
<Popover id="popover-basic">
<Popover.Title as="h3">Popover right</Popover.Title>
<Popover.Content>
And here's some <strong>amazing</strong> content. It's very engaging.
right?
</Popover.Content>
</Popover>
);
const Example = () => (
<OverlayTrigger trigger="click" placement="right" overlay={popover}>
<Button variant="success">Click me to see</Button>
</OverlayTrigger>
);
render(<Example />);
```
As with `<Tooltip>`s, you can control the placement of the Popover.
```
<>
{['top', 'right', 'bottom', 'left'].map((placement) => (
<OverlayTrigger
trigger="click"
key={placement}
placement={placement}
overlay={
<Popover id={`popover-positioned-${placement}`}>
<Popover.Title as="h3">{`Popover ${placement}`}</Popover.Title>
<Popover.Content>
<strong>Holy guacamole!</strong> Check this info.
</Popover.Content>
</Popover>
}
>
<Button variant="secondary">Popover on {placement}</Button>
</OverlayTrigger>
))}
</>
```
Disabled elements
-----------------
Elements with the `disabled` attribute aren’t interactive, meaning users cannot hover or click them to trigger a popover (or tooltip). As a workaround, you’ll want to trigger the overlay from a wrapper `<div>` or `<span>` and override the `pointer-events` on the disabled element.
```
<OverlayTrigger overlay={<Tooltip id="tooltip-disabled">Tooltip!</Tooltip>}>
<span className="d-inline-block">
<Button disabled style={{ pointerEvents: 'none' }}>
Disabled button
</Button>
</span>
</OverlayTrigger>
```
Changing containers
-------------------
You can specify a `container` to control the DOM element the overlay is appended to. This is especially useful when styles conflict with your Overlay's.
```
function Example() {
const [show, setShow] = useState(false);
const [target, setTarget] = useState(null);
const ref = useRef(null);
const handleClick = (event) => {
setShow(!show);
setTarget(event.target);
};
return (
<div ref={ref}>
<Button onClick={handleClick}>Holy guacamole!</Button>
<Overlay
show={show}
target={target}
placement="bottom"
container={ref.current}
containerPadding={20}
>
<Popover id="popover-contained">
<Popover.Title as="h3">Popover bottom</Popover.Title>
<Popover.Content>
<strong>Holy guacamole!</strong> Check this info.
</Popover.Content>
</Popover>
</Overlay>
</div>
);
}
render(<Example />);
```
Updating position dynamically
-----------------------------
Since we can't know every time your overlay changes size, to reposition it, you need to take manual action if you want to update the position of an Overlay in response to a change.
For this, the Overlay component also injects a a `popper` prop with a `scheduleUpdate()` method that an overlay component can use to reposition itself.
```
const UpdatingPopover = React.forwardRef(
({ popper, children, show: _, ...props }, ref) => {
useEffect(() => {
console.log('updating!');
popper.scheduleUpdate();
}, [children, popper]);
return (
<Popover ref={ref} content {...props}>
{children}
</Popover>
);
},
);
const longContent = `
Very long
Multiline content
that is engaging and what-not
`;
const shortContent = 'Short and sweet!';
function Example() {
const [content, setContent] = useState(shortContent);
useEffect(() => {
const timerId = setInterval(() => {
setContent(content === shortContent ? longContent : shortContent);
}, 3000);
return () => clearInterval(timerId);
});
return (
<OverlayTrigger
trigger="click"
overlay={
<UpdatingPopover id="popover-contained">{content}</UpdatingPopover>
}
>
<Button>Holy guacamole!</Button>
</OverlayTrigger>
);
}
render(<Example />);
```
API
---
### Overlay
`import Overlay from 'react-bootstrap/Overlay'`Copy import code for the Overlay component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| children required | React.ReactElement<OverlayInjectedProps> | ((injected: OverlayInjectedProps) => React.ReactNode) | | |
| container | componentOrElement | function | | A component instance, DOM node, or function that returns either. The `container` element will have the Overlay appended to it via a React portal. |
| onEnter | function | | Callback fired before the Overlay transitions in |
| onEntered | function | | Callback fired after the Overlay finishes transitioning in |
| onEntering | function | | Callback fired as the Overlay begins to transition in |
| onExit | function | | Callback fired right before the Overlay transitions out |
| onExited | function | | Callback fired after the Overlay finishes transitioning out |
| onExiting | function | | Callback fired as the Overlay begins to transition out |
| onHide | function | | A callback invoked by the overlay when it wishes to be hidden. Required if `rootClose` is specified. |
| placement | `'auto-start'` | `'auto'` | `'auto-end'` | `'top-start'` | `'top'` | `'top-end'` | `'right-start'` | `'right'` | `'right-end'` | `'bottom-end'` | `'bottom'` | `'bottom-start'` | `'left-end'` | `'left'` | `'left-start'` | `'top'` | The placement of the Overlay in relation to it's `target`. |
| popperConfig | object | `{}` | A set of popper options and props passed directly to Popper. |
| rootClose | boolean | `false` | Specify whether the overlay should trigger onHide when the user clicks outside the overlay |
| rootCloseEvent | `'click'` | `'mousedown'` | | Specify event for triggering a "root close" toggle. |
| show | boolean | `false` | Set the visibility of the Overlay |
| target | componentOrElement | function | | A component instance, DOM node, or function that returns either. The overlay will be positioned in relation to the `target` |
| transition | boolean | elementType | `Fade` | Animate the entering and exiting of the Overlay. `true` will use the `<Fade>` transition, or a custom react-transition-group `<Transition>` component can be provided. |
### OverlayTrigger
`import OverlayTrigger from 'react-bootstrap/OverlayTrigger'`Copy import code for the OverlayTrigger component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| children required | element | function | | |
| defaultShow | boolean | `false` | The initial visibility state of the Overlay. |
| delay | number | shape | | A millisecond delay amount to show and hide the Overlay once triggered |
| flip | boolean | `placement && placement.indexOf('auto') !== -1` | The initial flip state of the Overlay. |
| onHide | `null` | | |
| onToggle | function | | *controls ``show``*
A callback that fires when the user triggers a change in tooltip visibility. `onToggle` is called with the desired next `show`, and generally should be passed back to the `show` prop. `onToggle` fires *after* the configured `delay`
|
| overlay required | function | element | | An element or text to overlay next to the target. |
| placement | `'auto-start'` | `'auto'` | `'auto-end'` | `'top-start'` | `'top'` | `'top-end'` | `'right-start'` | `'right'` | `'right-end'` | `'bottom-end'` | `'bottom'` | `'bottom-start'` | `'left-end'` | `'left'` | `'left-start'` | | The placement of the Overlay in relation to it's `target`. |
| popperConfig | object | `{}` | A Popper.js config object passed to the the underlying popper instance. |
| show | boolean | | *controlled by: `onToggle`, initial prop: `defaultShow`*
The visibility of the Overlay. `show` is a *controlled* prop so should be paired with `onToggle` to avoid breaking user interactions. Manually toggling `show` does **not** wait for `delay` to change the visibility.
|
| target | `null` | | |
| trigger | 'hover' | 'click' |'focus' | Array<'hover' | 'click' |'focus'> | `['hover', 'focus']` | Specify which action or actions trigger Overlay visibility |
### Tooltip
`import Tooltip from 'react-bootstrap/Tooltip'`Copy import code for the Tooltip component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| arrowProps | { ref: ReactRef, style: Object } | |
An Overlay injected set of props for positioning the tooltip arrow. This is generally provided by the `Overlay` component positioning the tooltip
|
| id required | string|number | | An html id attribute, necessary for accessibility |
| placement | `'auto-start'` | `'auto'` | `'auto-end'` | `'top-start'` | `'top'` | `'top-end'` | `'right-start'` | `'right'` | `'right-end'` | `'bottom-end'` | `'bottom'` | `'bottom-start'` | `'left-end'` | `'left'` | `'left-start'` | `'right'` |
Sets the direction the Tooltip is positioned towards. This is generally provided by the `Overlay` component positioning the tooltip
|
| popper | object | | |
| show | any | | |
| bsPrefix | string | `'tooltip'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Popover
`import Popover from 'react-bootstrap/Popover'`Copy import code for the Popover component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| arrowProps | shape | |
An Overlay injected set of props for positioning the popover arrow. This is generally provided by the `Overlay` component positioning the popover
|
| content | boolean | | When this prop is set, it creates a Popover with a Popover.Content inside passing the children directly to it |
| id required | string|number | | An html id attribute, necessary for accessibility |
| placement | `'auto'` | `'top'` | `'bottom'` | `'left'` | `'right'` | `'right'` |
Sets the direction the Popover is positioned towards. This is generally provided by the `Overlay` component positioning the popover
|
| popper | object | | |
| show | boolean | | |
| title | string | | |
| bsPrefix | string | `'popover'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### PopoverContent
`import PopoverContent from 'react-bootstrap/PopoverContent'`Copy import code for the PopoverContent component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | Set a custom element for this component |
| bsPrefix | string | `'popover-body'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### PopoverTitle
`import PopoverTitle from 'react-bootstrap/PopoverTitle'`Copy import code for the PopoverTitle component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | Set a custom element for this component |
| bsPrefix | string | `'popover-header'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| programming_docs |
react_bootstrap Accordion Accordion
=========
Accordions provide a way to restrict Card components to only open one at a time.
Examples
--------
Accordions use Card components to provide styling of the Accordion components. Use AccordionToggle to provide a button that switches between each AccordionCollapse component.
### Basic Example
```
<Accordion defaultActiveKey="0">
<Card>
<Card.Header>
<Accordion.Toggle as={Button} variant="link" eventKey="0">
Click me!
</Accordion.Toggle>
</Card.Header>
<Accordion.Collapse eventKey="0">
<Card.Body>Hello! I'm the body</Card.Body>
</Accordion.Collapse>
</Card>
<Card>
<Card.Header>
<Accordion.Toggle as={Button} variant="link" eventKey="1">
Click me!
</Accordion.Toggle>
</Card.Header>
<Accordion.Collapse eventKey="1">
<Card.Body>Hello! I'm another body</Card.Body>
</Accordion.Collapse>
</Card>
</Accordion>
```
### Fully Collapsed State
If you want your Accordion to start in a fully-collapsed state, then simply don't pass in a `defaultActiveKey` prop to `Accordion`.
```
<Accordion>
<Card>
<Card.Header>
<Accordion.Toggle as={Button} variant="link" eventKey="0">
Click me!
</Accordion.Toggle>
</Card.Header>
<Accordion.Collapse eventKey="0">
<Card.Body>Hello! I'm the body</Card.Body>
</Accordion.Collapse>
</Card>
<Card>
<Card.Header>
<Accordion.Toggle as={Button} variant="link" eventKey="1">
Click me!
</Accordion.Toggle>
</Card.Header>
<Accordion.Collapse eventKey="1">
<Card.Body>Hello! I'm another body</Card.Body>
</Accordion.Collapse>
</Card>
</Accordion>
```
### Entire Header Clickable
Each of the Card components in the Accordion can have their entire header clickable, by setting the AccordionToggle's underlying component to be a CardHeader component.
```
<Accordion defaultActiveKey="0">
<Card>
<Accordion.Toggle as={Card.Header} eventKey="0">
Click me!
</Accordion.Toggle>
<Accordion.Collapse eventKey="0">
<Card.Body>Hello! I'm the body</Card.Body>
</Accordion.Collapse>
</Card>
<Card>
<Accordion.Toggle as={Card.Header} eventKey="1">
Click me!
</Accordion.Toggle>
<Accordion.Collapse eventKey="1">
<Card.Body>Hello! I'm another body</Card.Body>
</Accordion.Collapse>
</Card>
</Accordion>
```
### Custom Toggle
You can now hook into the Accordion toggle functionality via `useAccordionToggle` to make custom toggle components.
```
function CustomToggle({ children, eventKey }) {
const decoratedOnClick = useAccordionToggle(eventKey, () =>
console.log('totally custom!'),
);
return (
<button
type="button"
style={{ backgroundColor: 'pink' }}
onClick={decoratedOnClick}
>
{children}
</button>
);
}
function Example() {
return (
<Accordion defaultActiveKey="0">
<Card>
<Card.Header>
<CustomToggle eventKey="0">Click me!</CustomToggle>
</Card.Header>
<Accordion.Collapse eventKey="0">
<Card.Body>Hello! I'm the body</Card.Body>
</Accordion.Collapse>
</Card>
<Card>
<Card.Header>
<CustomToggle eventKey="1">Click me!</CustomToggle>
</Card.Header>
<Accordion.Collapse eventKey="1">
<Card.Body>Hello! I'm another body</Card.Body>
</Accordion.Collapse>
</Card>
</Accordion>
);
}
render(<Example />);
```
### Custom Toggle with Expansion Awareness
You may wish to have different styles for the toggle if it's associated section is expanded, this can be achieved with a custom toggle that is context aware and also takes advantage of the `useAccordionToggle` hook.
```
function ContextAwareToggle({ children, eventKey, callback }) {
const currentEventKey = useContext(AccordionContext);
const decoratedOnClick = useAccordionToggle(
eventKey,
() => callback && callback(eventKey),
);
const isCurrentEventKey = currentEventKey === eventKey;
return (
<button
type="button"
style={{ backgroundColor: isCurrentEventKey ? 'pink' : 'lavender' }}
onClick={decoratedOnClick}
>
{children}
</button>
);
}
function Example() {
return (
<Accordion defaultActiveKey="0">
<Card>
<Card.Header>
<ContextAwareToggle eventKey="0">Click me!</ContextAwareToggle>
</Card.Header>
<Accordion.Collapse eventKey="0">
<Card.Body>Hello! I'm the body</Card.Body>
</Accordion.Collapse>
</Card>
<Card>
<Card.Header>
<ContextAwareToggle eventKey="1">Click me!</ContextAwareToggle>
</Card.Header>
<Accordion.Collapse eventKey="1">
<Card.Body>Hello! I'm another body</Card.Body>
</Accordion.Collapse>
</Card>
</Accordion>
);
}
render(<Example />);
```
API
---
### Accordion
`import Accordion from 'react-bootstrap/Accordion'`Copy import code for the Accordion component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| activeKey | string | | The current active key that corresponds to the currently expanded card |
| as | elementType | | Set a custom element for this component |
| defaultActiveKey | string | | The default active key that is expanded on start |
| onSelect | SelectCallback | | |
| bsPrefix | string | `'accordion'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Accordion.Toggle
`import Accordion from 'react-bootstrap/Accordion'`Copy import code for the Accordion component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<button>` | Set a custom element for this component |
| eventKey required | string | | A key that corresponds to the collapse component that gets triggered when this has been clicked. |
| onClick | function | | A callback function for when this component is clicked |
### Accordion.Collapse
`import Accordion from 'react-bootstrap/Accordion'`Copy import code for the Accordion component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| children required | element | | Children prop should only contain a single child, and is enforced as such |
| eventKey required | string | | A key that corresponds to the toggler that triggers this collapse's expand or collapse. |
### useAccordionToggle
```
import { useAccordionToggle } from 'react-bootstrap/AccordionToggle';
const decoratedOnClick = useAccordionToggle(eventKey, onClick);
```
react_bootstrap Toasts Toasts
======
Push notifications to your visitors with a toast, a lightweight and easily customizable alert message.
Toasts are lightweight notifications designed to mimic the push notifications that have been popularized by mobile and desktop operating systems. They’re built with flexbox, so they’re easy to align and position.
Examples
--------
### Basic
To encourage extensible and predictable toasts, we recommend a header and body. Toast headers use display: flex, allowing easy alignment of content thanks to our margin and flexbox utilities.
Toasts are as flexible as you need and have very little required markup. At a minimum, we require a single element to contain your “toasted” content and strongly encourage a dismiss button.
```
<Toast>
<Toast.Header>
<img src="holder.js/20x20?text=%20" className="rounded mr-2" alt="" />
<strong className="mr-auto">Bootstrap</strong>
<small>11 mins ago</small>
</Toast.Header>
<Toast.Body>Hello, world! This is a toast message.</Toast.Body>
</Toast>
```
### Dismissible
```
function Example() {
const [showA, setShowA] = useState(true);
const [showB, setShowB] = useState(true);
const toggleShowA = () => setShowA(!showA);
const toggleShowB = () => setShowB(!showB);
return (
<Row>
<Col xs={6}>
<Toast show={showA} onClose={toggleShowA}>
<Toast.Header>
<img
src="holder.js/20x20?text=%20"
className="rounded mr-2"
alt=""
/>
<strong className="mr-auto">Bootstrap</strong>
<small>11 mins ago</small>
</Toast.Header>
<Toast.Body>Woohoo, you're reading this text in a Toast!</Toast.Body>
</Toast>
</Col>
<Col xs={6}>
<Button onClick={toggleShowA}>
Toggle Toast <strong>with</strong> Animation
</Button>
</Col>
<Col xs={6} className="my-1">
<Toast onClose={toggleShowB} show={showB} animation={false}>
<Toast.Header>
<img
src="holder.js/20x20?text=%20"
className="rounded mr-2"
alt=""
/>
<strong className="mr-auto">Bootstrap</strong>
<small>11 mins ago</small>
</Toast.Header>
<Toast.Body>Woohoo, you're reading this text in a Toast!</Toast.Body>
</Toast>
</Col>
<Col xs={6}>
<Button onClick={toggleShowB}>
Toggle Toast <strong>without</strong> Animation
</Button>
</Col>
</Row>
);
}
render(<Example />);
```
### Stacking
When you have multiple toasts, we default to vertically stacking them in a readable manner.
```
<>
<Toast>
<Toast.Header>
<img src="holder.js/20x20?text=%20" className="rounded mr-2" alt="" />
<strong className="mr-auto">Bootstrap</strong>
<small>just now</small>
</Toast.Header>
<Toast.Body>See? Just like this.</Toast.Body>
</Toast>
<Toast>
<Toast.Header>
<img src="holder.js/20x20?text=%20" className="rounded mr-2" alt="" />
<strong className="mr-auto">Bootstrap</strong>
<small>2 seconds ago</small>
</Toast.Header>
<Toast.Body>Heads up, toasts will stack automatically</Toast.Body>
</Toast>
</>
```
### Placement
Place toasts with custom CSS as you need them. The top right is often used for notifications, as is the top middle.
```
<div
aria-live="polite"
aria-atomic="true"
style={{
position: 'relative',
minHeight: '100px',
}}
>
<Toast
style={{
position: 'absolute',
top: 0,
right: 0,
}}
>
<Toast.Header>
<img src="holder.js/20x20?text=%20" className="rounded mr-2" alt="" />
<strong className="mr-auto">Bootstrap</strong>
<small>just now</small>
</Toast.Header>
<Toast.Body>See? Just like this.</Toast.Body>
</Toast>
</div>
```
For systems that generate more notifications, consider using a wrapping element so they can easily stack.
```
<div
aria-live="polite"
aria-atomic="true"
style={{
position: 'relative',
minHeight: '200px',
}}
>
<div
style={{
position: 'absolute',
top: 0,
right: 0,
}}
>
<Toast>
<Toast.Header>
<img src="holder.js/20x20?text=%20" className="rounded mr-2" alt="" />
<strong className="mr-auto">Bootstrap</strong>
<small>just now</small>
</Toast.Header>
<Toast.Body>See? Just like this.</Toast.Body>
</Toast>
<Toast>
<Toast.Header>
<img src="holder.js/20x20?text=%20" className="rounded mr-2" alt="" />
<strong className="mr-auto">Bootstrap</strong>
<small>2 seconds ago</small>
</Toast.Header>
<Toast.Body>Heads up, toasts will stack automatically</Toast.Body>
</Toast>
</div>
</div>
```
### Autohide
A Toast can also automatically hide after X milliseconds. For that, use the `autohide` prop in combination with `delay` the prop to sepecify the delay. But be aware, that it will only trigger the `onClose` function, you have to set manually the show property.
```
function Example() {
const [show, setShow] = useState(false);
return (
<Row>
<Col xs={6}>
<Toast onClose={() => setShow(false)} show={show} delay={3000} autohide>
<Toast.Header>
<img
src="holder.js/20x20?text=%20"
className="rounded mr-2"
alt=""
/>
<strong className="mr-auto">Bootstrap</strong>
<small>11 mins ago</small>
</Toast.Header>
<Toast.Body>Woohoo, you're reading this text in a Toast!</Toast.Body>
</Toast>
</Col>
<Col xs={6}>
<Button onClick={() => setShow(true)}>Show Toast</Button>
</Col>
</Row>
);
}
render(<Example />);
```
API
---
### Toast
`import Toast from 'react-bootstrap/Toast'`Copy import code for the Toast component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| animation | boolean | `true` | Apply a CSS fade transition to the toast |
| autohide | boolean | `false` | Auto hide the toast |
| delay | number | `3000` | Delay hiding the toast (ms) |
| onClose | function | | A Callback fired when the close button is clicked. |
| show | boolean | `true` | When `true` The modal will show itself. |
| transition | elementType | `<Fade>` | A `react-transition-group` Transition component used to animate the Toast on dismissal. |
| bsPrefix | string | `'toast'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ToastHeader
`import ToastHeader from 'react-bootstrap/ToastHeader'`Copy import code for the ToastHeader component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| closeButton | boolean | `true` | Specify whether the Component should contain a close button |
| closeLabel | string | `'Close'` | Provides an accessible label for the close button. It is used for Assistive Technology when the label text is not readable. |
| bsPrefix | string | | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ToastBody
`import ToastBody from 'react-bootstrap/ToastBody'`Copy import code for the ToastBody component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'toast-body'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Cards Cards
=====
Bootstrap’s cards provide a flexible and extensible content container with multiple variants and options.
Basic Example
-------------
```
<Card style={{ width: '18rem' }}>
<Card.Img variant="top" src="holder.js/100px180" />
<Card.Body>
<Card.Title>Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk of
the card's content.
</Card.Text>
<Button variant="primary">Go somewhere</Button>
</Card.Body>
</Card>
```
Content types
-------------
### Body
Use `<Card.Body>` to pad content inside a `<Card>`.
```
<Card>
<Card.Body>This is some text within a card body.</Card.Body>
</Card>
```
Alternatively, you can use this shorthand version for Cards with body only, and no other children
```
<Card body>This is some text within a card body.</Card>
```
### Title, text, and links
Using `<Card.Title>`, `<Card.Subtitle>`, and `<Card.Text>` inside the `<Card.Body>` will line them up nicely. `<Card.Link>`s are used to line up links next to each other.
`<Card.Text>` outputs `<p>` tags around the content, so you can use multiple `<Card.Text>`s to create separate paragraphs.
```
<Card style={{ width: '18rem' }}>
<Card.Body>
<Card.Title>Card Title</Card.Title>
<Card.Subtitle className="mb-2 text-muted">Card Subtitle</Card.Subtitle>
<Card.Text>
Some quick example text to build on the card title and make up the bulk of
the card's content.
</Card.Text>
<Card.Link href="#">Card Link</Card.Link>
<Card.Link href="#">Another Link</Card.Link>
</Card.Body>
</Card>
```
### List Groups
Create lists of content in a card with a flush list group.
```
<Card style={{ width: '18rem' }}>
<ListGroup variant="flush">
<ListGroup.Item>Cras justo odio</ListGroup.Item>
<ListGroup.Item>Dapibus ac facilisis in</ListGroup.Item>
<ListGroup.Item>Vestibulum at eros</ListGroup.Item>
</ListGroup>
</Card>
```
```
<Card style={{ width: '18rem' }}>
<Card.Header>Featured</Card.Header>
<ListGroup variant="flush">
<ListGroup.Item>Cras justo odio</ListGroup.Item>
<ListGroup.Item>Dapibus ac facilisis in</ListGroup.Item>
<ListGroup.Item>Vestibulum at eros</ListGroup.Item>
</ListGroup>
</Card>
```
### Kitchen Sink
```
<Card style={{ width: '18rem' }}>
<Card.Img variant="top" src="holder.js/100px180?text=Image cap" />
<Card.Body>
<Card.Title>Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk of
the card's content.
</Card.Text>
</Card.Body>
<ListGroup className="list-group-flush">
<ListGroupItem>Cras justo odio</ListGroupItem>
<ListGroupItem>Dapibus ac facilisis in</ListGroupItem>
<ListGroupItem>Vestibulum at eros</ListGroupItem>
</ListGroup>
<Card.Body>
<Card.Link href="#">Card Link</Card.Link>
<Card.Link href="#">Another Link</Card.Link>
</Card.Body>
</Card>
```
### Header and Footer
You may add a header by adding a `<Card.Header>` component.
```
<Card>
<Card.Header>Featured</Card.Header>
<Card.Body>
<Card.Title>Special title treatment</Card.Title>
<Card.Text>
With supporting text below as a natural lead-in to additional content.
</Card.Text>
<Button variant="primary">Go somewhere</Button>
</Card.Body>
</Card>
```
A `<CardHeader>` can be styled by passing a heading element through the `<as>` prop
```
<Card>
<Card.Header as="h5">Featured</Card.Header>
<Card.Body>
<Card.Title>Special title treatment</Card.Title>
<Card.Text>
With supporting text below as a natural lead-in to additional content.
</Card.Text>
<Button variant="primary">Go somewhere</Button>
</Card.Body>
</Card>
```
```
<Card>
<Card.Header>Quote</Card.Header>
<Card.Body>
<blockquote className="blockquote mb-0">
<p>
{' '}
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere
erat a ante.{' '}
</p>
<footer className="blockquote-footer">
Someone famous in <cite title="Source Title">Source Title</cite>
</footer>
</blockquote>
</Card.Body>
</Card>
```
```
<Card className="text-center">
<Card.Header>Featured</Card.Header>
<Card.Body>
<Card.Title>Special title treatment</Card.Title>
<Card.Text>
With supporting text below as a natural lead-in to additional content.
</Card.Text>
<Button variant="primary">Go somewhere</Button>
</Card.Body>
<Card.Footer className="text-muted">2 days ago</Card.Footer>
</Card>
```
Images
------
Cards include a few options for working with images. Choose from appending “image caps” at either end of a card, overlaying images with card content, or simply embedding the image in a card.
### Image caps
Similar to headers and footers, cards can include top and bottom “image caps”—images at the top or bottom of a card.
```
<>
<Card>
<Card.Img variant="top" src="holder.js/100px180" />
<Card.Body>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
<Card>
<Card.Body>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
<Card.Img variant="bottom" src="holder.js/100px180" />
</Card>
</>
```
### Image Overlays
Turn an image into a card background and overlay your card’s text. Depending on the image, you may or may not need additional styles or utilities.
```
<Card className="bg-dark text-white">
<Card.Img src="holder.js/100px270" alt="Card image" />
<Card.ImgOverlay>
<Card.Title>Card title</Card.Title>
<Card.Text>
This is a wider card with supporting text below as a natural lead-in to
additional content. This content is a little bit longer.
</Card.Text>
<Card.Text>Last updated 3 mins ago</Card.Text>
</Card.ImgOverlay>
</Card>
```
Navigation
----------
Add some navigation to a card’s header (or block) with React Bootstrap’s [Nav](../navs/index) components.
```
<Card>
<Card.Header>
<Nav variant="tabs" defaultActiveKey="#first">
<Nav.Item>
<Nav.Link href="#first">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link href="#link">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link href="#disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
</Card.Header>
<Card.Body>
<Card.Title>Special title treatment</Card.Title>
<Card.Text>
With supporting text below as a natural lead-in to additional content.
</Card.Text>
<Button variant="primary">Go somewhere</Button>
</Card.Body>
</Card>
```
```
<Card>
<Card.Header>
<Nav variant="pills" defaultActiveKey="#first">
<Nav.Item>
<Nav.Link href="#first">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link href="#link">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link href="#disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
</Card.Header>
<Card.Body>
<Card.Title>Special title treatment</Card.Title>
<Card.Text>
With supporting text below as a natural lead-in to additional content.
</Card.Text>
<Button variant="primary">Go somewhere</Button>
</Card.Body>
</Card>
```
Card Styles
-----------
### Background Color
You can change a card's appearance by changing their `<bg>`, and `<text>` props.
```
[
'Primary',
'Secondary',
'Success',
'Danger',
'Warning',
'Info',
'Light',
'Dark',
].map((variant, idx) => (
<Card
bg={variant.toLowerCase()}
key={idx}
text={variant.toLowerCase() === 'light' ? 'dark' : 'white'}
style={{ width: '18rem' }}
className="mb-2"
>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>{variant} Card Title </Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
));
```
### Border Color
```
<>
<Card border="primary" style={{ width: '18rem' }}>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>Primary Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
<Card border="secondary" style={{ width: '18rem' }}>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>Secondary Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
<Card border="success" style={{ width: '18rem' }}>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>Success Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
<Card border="danger" style={{ width: '18rem' }}>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>Danger Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
<Card border="warning" style={{ width: '18rem' }}>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>Warning Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
<Card border="info" style={{ width: '18rem' }}>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>Info Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
<Card border="dark" style={{ width: '18rem' }}>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>Dark Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
<Card border="light" style={{ width: '18rem' }}>
<Card.Header>Header</Card.Header>
<Card.Body>
<Card.Title>Light Card Title</Card.Title>
<Card.Text>
Some quick example text to build on the card title and make up the bulk
of the card's content.
</Card.Text>
</Card.Body>
</Card>
<br />
</>
```
Card layout
-----------
### Card Groups
```
<CardGroup>
<Card>
<Card.Img variant="top" src="holder.js/100px160" />
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This is a wider card with supporting text below as a natural lead-in to
additional content. This content is a little bit longer.
</Card.Text>
</Card.Body>
<Card.Footer>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Footer>
</Card>
<Card>
<Card.Img variant="top" src="holder.js/100px160" />
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This card has supporting text below as a natural lead-in to additional
content.{' '}
</Card.Text>
</Card.Body>
<Card.Footer>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Footer>
</Card>
<Card>
<Card.Img variant="top" src="holder.js/100px160" />
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This is a wider card with supporting text below as a natural lead-in to
additional content. This card has even longer content than the first to
show that equal height action.
</Card.Text>
</Card.Body>
<Card.Footer>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Footer>
</Card>
</CardGroup>
```
### Card Deck
```
<CardDeck>
<Card>
<Card.Img variant="top" src="holder.js/100px160" />
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This is a wider card with supporting text below as a natural lead-in to
additional content. This content is a little bit longer.
</Card.Text>
</Card.Body>
<Card.Footer>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Footer>
</Card>
<Card>
<Card.Img variant="top" src="holder.js/100px160" />
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This card has supporting text below as a natural lead-in to additional
content.{' '}
</Card.Text>
</Card.Body>
<Card.Footer>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Footer>
</Card>
<Card>
<Card.Img variant="top" src="holder.js/100px160" />
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This is a wider card with supporting text below as a natural lead-in to
additional content. This card has even longer content than the first to
show that equal height action.
</Card.Text>
</Card.Body>
<Card.Footer>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Footer>
</Card>
</CardDeck>
```
### Card Columns
```
<CardColumns>
<Card>
<Card.Img variant="top" src="holder.js/100px160" />
<Card.Body>
<Card.Title>Card title that wraps to a new line</Card.Title>
<Card.Text>
This is a longer card with supporting text below as a natural lead-in to
additional content. This content is a little bit longer.
</Card.Text>
</Card.Body>
</Card>
<Card className="p-3">
<blockquote className="blockquote mb-0 card-body">
<p>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere
erat a ante.
</p>
<footer className="blockquote-footer">
<small className="text-muted">
Someone famous in <cite title="Source Title">Source Title</cite>
</small>
</footer>
</blockquote>
</Card>
<Card>
<Card.Img variant="top" src="holder.js/100px160" />
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This card has supporting text below as a natural lead-in to additional
content.{' '}
</Card.Text>
</Card.Body>
<Card.Footer>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Footer>
</Card>
<Card bg="primary" text="white" className="text-center p-3">
<blockquote className="blockquote mb-0 card-body">
<p>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere
erat a ante.
</p>
<footer className="blockquote-footer">
<small className="text-muted">
Someone famous in <cite title="Source Title">Source Title</cite>
</small>
</footer>
</blockquote>
</Card>
<Card className="text-center">
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This card has supporting text below as a natural lead-in to additional
content.{' '}
</Card.Text>
<Card.Text>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Text>
</Card.Body>
</Card>
<Card>
<Card.Img src="holder.js/100px160" />
</Card>
<Card className="text-right">
<blockquote className="blockquote mb-0 card-body">
<p>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere
erat a ante.
</p>
<footer className="blockquote-footer">
<small className="text-muted">
Someone famous in <cite title="Source Title">Source Title</cite>
</small>
</footer>
</blockquote>
</Card>
<Card>
<Card.Body>
<Card.Title>Card title</Card.Title>
<Card.Text>
This is a wider card with supporting text below as a natural lead-in to
additional content. This card has even longer content than the first to
show that equal height action.
</Card.Text>
<Card.Text>
<small className="text-muted">Last updated 3 mins ago</small>
</Card.Text>
</Card.Body>
</Card>
</CardColumns>
```
API
---
### Card
`import Card from 'react-bootstrap/Card'`Copy import code for the Card component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bg | `'primary'` | `'secondary'` | `'success'` | `'danger'` | `'warning'` | `'info'` | `'dark'` | `'light'` | | Sets card background |
| body | boolean | `false` | When this prop is set, it creates a Card with a Card.Body inside passing the children directly to it |
| border | `'primary'` | `'secondary'` | `'success'` | `'danger'` | `'warning'` | `'info'` | `'dark'` | `'light'` | | Sets card border color |
| text | `'primary'` | `'secondary'` | `'success'` | `'danger'` | `'warning'` | `'info'` | `'dark'` | `'light'` | `'white'` | `'muted'` | | Sets card text color |
| bsPrefix | string | `'card'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Card.Body
`import Card from 'react-bootstrap/Card'`Copy import code for the Card component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'card-body'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Card.Img
`import Card from 'react-bootstrap/Card'`Copy import code for the Card component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<img>` | You can use a custom element type for this component. |
| variant | `'top'` | `'bottom'` | `null` | Defines image position inside the card. |
| bsPrefix | string | `'card-img'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Card.ImgOverlay
`import Card from 'react-bootstrap/Card'`Copy import code for the Card component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'card-img-overlay'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### CardDeck
`import CardDeck from 'react-bootstrap/CardDeck'`Copy import code for the CardDeck component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'card-deck'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### CardGroup
`import CardGroup from 'react-bootstrap/CardGroup'`Copy import code for the CardGroup component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'card-group'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### CardColumns
`import CardColumns from 'react-bootstrap/CardColumns'`Copy import code for the CardColumns component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'card-columns'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| programming_docs |
react_bootstrap Base Nav Base Nav
========
Navigation bits in Bootstrap all share a general `Nav` component and styles. Swap `variant`s to switch between each style. The base `Nav` component is built with flexbox and provide a strong foundation for building all types of navigation components.
```
<Nav
activeKey="/home"
onSelect={(selectedKey) => alert(`selected ${selectedKey}`)}
>
<Nav.Item>
<Nav.Link href="/home">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-1">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-2">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
```
`<Nav>` markup is very flexible and styling is controlled via classes so you can use whatever elements you like to build your navs. By default `<Nav>` and `<Nav.Item>` both render `<div>`s instead of `<ul>` and `<li>` elements respectively. This because it's possible (and common) to leave off the `<Nav.Item>`'s and render a `<Nav.Link>` directly, which would create invalid markup by default (`ul > a`).
When a `<ul>` is appropriate you can render one via the `as` prop; be sure to also set your items to `<li>` as well!
```
<Nav defaultActiveKey="/home" as="ul">
<Nav.Item as="li">
<Nav.Link href="/home">Active</Nav.Link>
</Nav.Item>
<Nav.Item as="li">
<Nav.Link eventKey="link-1">Link</Nav.Link>
</Nav.Item>
<Nav.Item as="li">
<Nav.Link eventKey="link-2">Link</Nav.Link>
</Nav.Item>
</Nav>
```
Alignment and orientation
-------------------------
You can control the the direction and orientation of the `Nav` by making use of the [flexbox layout](https://getbootstrap.com/docs/4.0/layout/grid/#horizontal-alignment) utility classes. By default, navs are left-aligned, but that is easily changed to center or right-aligned.
```
<>
<Nav className="justify-content-center" activeKey="/home">
<Nav.Item>
<Nav.Link href="/home">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-1">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-2">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
<p className="text-center mt-4 mb-4">Or right-aligned</p>
<Nav className="justify-content-end" activeKey="/home">
<Nav.Item>
<Nav.Link href="/home">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-1">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-2">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
</>
```
### Vertical
Create stacked navs by changing the flex item direction with the `.flex-column` class, or your own css. You can even use the responsive versions to stack in some viewports but not others (e.g. `.flex-sm-column`).
```
<Nav defaultActiveKey="/home" className="flex-column">
<Nav.Link href="/home">Active</Nav.Link>
<Nav.Link eventKey="link-1">Link</Nav.Link>
<Nav.Link eventKey="link-2">Link</Nav.Link>
<Nav.Link eventKey="disabled" disabled>
Disabled
</Nav.Link>
</Nav>
```
Tabs
----
Visually represent nav items as "tabs". This style pairs nicely with tabbable regions created by our [Tab components](../tabs/index).
Note: creating a vertical nav (`.flex-column`) with tabs styling is unsupported by Bootstrap's default stylesheet.
```
<Nav variant="tabs" defaultActiveKey="/home">
<Nav.Item>
<Nav.Link href="/home">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-1">Option 2</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
```
Pills
-----
An alternative visual variant.
```
<Nav variant="pills" defaultActiveKey="/home">
<Nav.Item>
<Nav.Link href="/home">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-1">Option 2</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
```
Fill and justify
----------------
Force the contents of your nav to extend the full available width. To proportionately fill the space use `fill`. Notice that the nav is the entire width but each nav item is a different size.
```
<Nav fill variant="tabs" defaultActiveKey="/home">
<Nav.Item>
<Nav.Link href="/home">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-1">Loooonger NavLink</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-2">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
```
If you want each NavItem to be the same size use `justify`.
```
<Nav justify variant="tabs" defaultActiveKey="/home">
<Nav.Item>
<Nav.Link href="/home">Active</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-1">Loooonger NavLink</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="link-2">Link</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="disabled" disabled>
Disabled
</Nav.Link>
</Nav.Item>
</Nav>
```
Using dropdowns
---------------
You can mix and match the Dropdown components with the NavLink and NavItem components to create a Dropdown that plays well in a Nav component
```
<Dropdown as={NavItem}>
<Dropdown.Toggle as={NavLink}>Click to see more…</Dropdown.Toggle>
<Dropdown.Menu>
<Dropdown.Item>Hello there!</Dropdown.Item>
</Dropdown.Menu>
</Dropdown>;
```
The above demonstrates how flexible the component model can be. But if you didn't want to roll your own versions we've included a straight-forward `<NavDropdown>` that works for most cases.
```
function NavDropdownExample() {
const handleSelect = (eventKey) => alert(`selected ${eventKey}`);
return (
<Nav variant="pills" activeKey="1" onSelect={handleSelect}>
<Nav.Item>
<Nav.Link eventKey="1" href="#/home">
NavLink 1 content
</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="2" title="Item">
NavLink 2 content
</Nav.Link>
</Nav.Item>
<Nav.Item>
<Nav.Link eventKey="3" disabled>
NavLink 3 content
</Nav.Link>
</Nav.Item>
<NavDropdown title="Dropdown" id="nav-dropdown">
<NavDropdown.Item eventKey="4.1">Action</NavDropdown.Item>
<NavDropdown.Item eventKey="4.2">Another action</NavDropdown.Item>
<NavDropdown.Item eventKey="4.3">Something else here</NavDropdown.Item>
<NavDropdown.Divider />
<NavDropdown.Item eventKey="4.4">Separated link</NavDropdown.Item>
</NavDropdown>
</Nav>
);
}
render(<NavDropdownExample />);
```
API
---
### Nav
`import Nav from 'react-bootstrap/Nav'`Copy import code for the Nav component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| activeKey | string | | Marks the NavItem with a matching `eventKey` (or `href` if present) as active. |
| as | elementType | | You can use a custom element type for this component. |
| cardHeaderBsPrefix | string | | |
| defaultActiveKey | unknown | | |
| fill | boolean | `false` | Have all `NavItem`s proportionately fill all available width. |
| justify | boolean | `false` | Have all `NavItem`s evenly fill all available width. |
| navbar | boolean | | Apply styling an alignment for use in a Navbar. This prop will be set automatically when the Nav is used inside a Navbar. |
| navbarBsPrefix | string | | |
| onKeyDown | function | | |
| onSelect | function | |
A callback fired when a NavItem is selected.
```
function (
Any eventKey,
SyntheticEvent event?
)
```
|
| role | string | |
ARIA role for the Nav, in the context of a TabContainer, the default will be set to "tablist", but can be overridden by the Nav when set explicitly. When the role is "tablist", NavLink focus is managed according to the ARIA authoring practices for tabs: <https://www.w3.org/TR/2013/WD-wai-aria-practices-20130307/#tabpanel>
|
| variant | `'tabs'` | `'pills'` | | The visual variant of the nav items. |
| bsPrefix | string | `'nav'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Nav.Item
`import Nav from 'react-bootstrap/Nav'`Copy import code for the Nav component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| role | string | | The ARIA role of the component |
| bsPrefix | string | `'nav-item'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Nav.Link
`import Nav from 'react-bootstrap/Nav'`Copy import code for the Nav component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| active | boolean | | The active state of the NavItem item. |
| as | elementType | `<a>` | You can use a custom element type for this component. |
| disabled | boolean | `false` | The disabled state of the NavItem item. |
| eventKey | any | | Uniquely idenifies the `NavItem` amongst its siblings, used to determine and control the active state of the parent `Nav` |
| href | string | | The HTML href attribute for the `NavLink` |
| onSelect | function | |
A callback fired when the `NavLink` is selected.
```
function (eventKey: any, event: SyntheticEvent) {}
```
|
| role | string | | The ARIA role for the `NavLink`, In the context of a 'tablist' parent Nav, the role defaults to 'tab' |
| bsPrefix | string | `'nav-link'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### NavDropdown
`import NavDropdown from 'react-bootstrap/NavDropdown'`Copy import code for the NavDropdown component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| active | boolean | | Style the toggle NavLink as active |
| disabled | boolean | | Disables the toggle NavLink |
| id required | string|number | | An html id attribute for the Toggle button, necessary for assistive technologies, such as screen readers. |
| menuRole | string | | An ARIA accessible role applied to the Menu component. When set to 'menu', The dropdown |
| onClick | function | | An `onClick` handler passed to the Toggle component |
| renderMenuOnMount | boolean | | Whether to render the dropdown menu in the DOM before the first time it is shown |
| rootCloseEvent | string | |
Which event when fired outside the component will cause it to be closed. *see [DropdownMenu](#menu-props) for more details*
|
| title required | node | | The content of the non-toggle Button. |
| bsPrefix | string | | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Carousels Carousels
=========
A slideshow component for cycling through elements—images or slides of text—like a carousel.
Example
-------
Carousels don’t automatically normalize slide dimensions. As such, you may need to use additional utilities or custom styles to appropriately size content. While carousels support previous/next controls and indicators, they’re not explicitly required. Add and customize as you see fit.
```
<Carousel>
<Carousel.Item>
<img
className="d-block w-100"
src="holder.js/800x400?text=First slide&bg=373940"
alt="First slide"
/>
<Carousel.Caption>
<h3>First slide label</h3>
<p>Nulla vitae elit libero, a pharetra augue mollis interdum.</p>
</Carousel.Caption>
</Carousel.Item>
<Carousel.Item>
<img
className="d-block w-100"
src="holder.js/800x400?text=Second slide&bg=282c34"
alt="Second slide"
/>
<Carousel.Caption>
<h3>Second slide label</h3>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
</Carousel.Caption>
</Carousel.Item>
<Carousel.Item>
<img
className="d-block w-100"
src="holder.js/800x400?text=Third slide&bg=20232a"
alt="Third slide"
/>
<Carousel.Caption>
<h3>Third slide label</h3>
<p>Praesent commodo cursus magna, vel scelerisque nisl consectetur.</p>
</Carousel.Caption>
</Carousel.Item>
</Carousel>
```
Controlled
----------
You can also *control* the Carousel state, via the `activeIndex` prop and `onSelect` handler.
```
function ControlledCarousel() {
const [index, setIndex] = useState(0);
const handleSelect = (selectedIndex, e) => {
setIndex(selectedIndex);
};
return (
<Carousel activeIndex={index} onSelect={handleSelect}>
<Carousel.Item>
<img
className="d-block w-100"
src="holder.js/800x400?text=First slide&bg=373940"
alt="First slide"
/>
<Carousel.Caption>
<h3>First slide label</h3>
<p>Nulla vitae elit libero, a pharetra augue mollis interdum.</p>
</Carousel.Caption>
</Carousel.Item>
<Carousel.Item>
<img
className="d-block w-100"
src="holder.js/800x400?text=Second slide&bg=282c34"
alt="Second slide"
/>
<Carousel.Caption>
<h3>Second slide label</h3>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
</Carousel.Caption>
</Carousel.Item>
<Carousel.Item>
<img
className="d-block w-100"
src="holder.js/800x400?text=Third slide&bg=20232a"
alt="Third slide"
/>
<Carousel.Caption>
<h3>Third slide label</h3>
<p>
Praesent commodo cursus magna, vel scelerisque nisl consectetur.
</p>
</Carousel.Caption>
</Carousel.Item>
</Carousel>
);
}
render(<ControlledCarousel />);
```
Individual Item Intervals
-------------------------
You can specify individual intervals for each carousel item via the `interval` prop.
```
<Carousel>
<Carousel.Item interval={1000}>
<img
className="d-block w-100"
src="holder.js/800x400?text=First slide&bg=373940"
alt="First slide"
/>
<Carousel.Caption>
<h3>First slide label</h3>
<p>Nulla vitae elit libero, a pharetra augue mollis interdum.</p>
</Carousel.Caption>
</Carousel.Item>
<Carousel.Item interval={500}>
<img
className="d-block w-100"
src="holder.js/800x400?text=Second slide&bg=282c34"
alt="Second slide"
/>
<Carousel.Caption>
<h3>Second slide label</h3>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
</Carousel.Caption>
</Carousel.Item>
<Carousel.Item>
<img
className="d-block w-100"
src="holder.js/800x400?text=Third slide&bg=20232a"
alt="Third slide"
/>
<Carousel.Caption>
<h3>Third slide label</h3>
<p>Praesent commodo cursus magna, vel scelerisque nisl consectetur.</p>
</Carousel.Caption>
</Carousel.Item>
</Carousel>
```
API
---
### Carousel
`import Carousel from 'react-bootstrap/Carousel'`Copy import code for the Carousel component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| activeIndex | number | | *controlled by: `onSelect`, initial prop: `defaultActiveindex`*
Controls the current visible slide |
| as | elementType | | You can use a custom element type for this component. |
| controls | boolean | `true` | Show the Carousel previous and next arrows for changing the current slide |
| defaultActiveIndex | number | `0` | |
| fade | boolean | `false` | Cross fade slides instead of the default slide animation |
| indicators | boolean | `true` | Show a set of slide position indicators |
| interval | number | `5000` | The amount of time to delay between automatically cycling an item. If `null`, carousel will not automatically cycle. |
| keyboard | boolean | `true` | Whether the carousel should react to keyboard events. |
| nextIcon | node | `<span aria-hidden="true" className="carousel-control-next-icon" />` | Override the default button icon for the "next" control |
| nextLabel | string | `'Next'` | Label shown to screen readers only, can be used to show the next element in the carousel. Set to null to deactivate. |
| onSelect | function | | *controls `activeIndex`*
Callback fired when the active item changes.
```
(eventKey: number, event: Object | null) => void
```
|
| onSlid | function | |
Callback fired when a slide transition ends.
```
(eventKey: number, direction: 'left' | 'right') => void
```
|
| onSlide | function | |
Callback fired when a slide transition starts.
```
(eventKey: number, direction: 'left' | 'right') => void
```
|
| pause | `'hover'` | `false` | `'hover'` |
If set to `"hover"`, pauses the cycling of the carousel on `mouseenter` and resumes the cycling of the carousel on `mouseleave`. If set to `false`, hovering over the carousel won't pause it. On touch-enabled devices, when set to `"hover"`, cycling will pause on `touchend` (once the user finished interacting with the carousel) for two intervals, before automatically resuming. Note that this is in addition to the above mouse behavior.
|
| prevIcon | node | `<span aria-hidden="true" className="carousel-control-prev-icon" />` | Override the default button icon for the "previous" control |
| prevLabel | string | `'Previous'` | Label shown to screen readers only, can be used to show the previous element in the carousel. Set to null to deactivate. |
| ref | React.Ref<CarouselRef> | | |
| slide | boolean | `true` | Enables animation on the Carousel as it transitions between slides. |
| touch | boolean | `true` | Whether the carousel should support left/right swipe interactions on touchscreen devices. |
| wrap | boolean | `true` | Whether the carousel should cycle continuously or have hard stops. |
| bsPrefix | string | `'carousel'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Carousel.Item
`import Carousel from 'react-bootstrap/Carousel'`Copy import code for the Carousel component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | Set a custom element for this component |
| interval | number | | The amount of time to delay between automatically cycling this specific item. Will default to the Carousel's `interval` prop value if none is specified. |
| bsPrefix | string | `'carousel-item'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Carousel.Caption
`import Carousel from 'react-bootstrap/Carousel'`Copy import code for the Carousel component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'carousel-caption'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap List groups List groups
===========
List groups are a flexible and powerful component for displaying a series of content. Modify and extend them to support just about any content within.
Basic Example
-------------
```
<ListGroup>
<ListGroup.Item>Cras justo odio</ListGroup.Item>
<ListGroup.Item>Dapibus ac facilisis in</ListGroup.Item>
<ListGroup.Item>Morbi leo risus</ListGroup.Item>
<ListGroup.Item>Porta ac consectetur ac</ListGroup.Item>
<ListGroup.Item>Vestibulum at eros</ListGroup.Item>
</ListGroup>
```
### Active items
Set the `active` prop to indicate the list groups current active selection.
```
<ListGroup as="ul">
<ListGroup.Item as="li" active>
Cras justo odio
</ListGroup.Item>
<ListGroup.Item as="li">Dapibus ac facilisis in</ListGroup.Item>
<ListGroup.Item as="li" disabled>
Morbi leo risus
</ListGroup.Item>
<ListGroup.Item as="li">Porta ac consectetur ac</ListGroup.Item>
</ListGroup>
```
### Disabled items
Set the `disabled` prop to prevent actions on a `<ListGroup.Item>`. For elements that aren't naturally disable-able (like anchors) `onClick` handlers are added that call `preventDefault` to mimick disabled behavior.
```
<ListGroup>
<ListGroup.Item disabled>Cras justo odio</ListGroup.Item>
<ListGroup.Item>Dapibus ac facilisis in</ListGroup.Item>
<ListGroup.Item>Morbi leo risus</ListGroup.Item>
<ListGroup.Item>Porta ac consectetur ac</ListGroup.Item>
</ListGroup>
```
### Actionable items
Toggle the `action` prop to create *actionable* list group items, with disabled, hover and active styles. List item actions will render a `<button>` or `<a>` (depending on the presence of an `href`) by default but can be overridden by setting the `as` prop as usual.
List items `actions` are distinct from plain items to ensure that click or tap affordances aren't applied to non-interactive items.
```
function alertClicked() {
alert('You clicked the third ListGroupItem');
}
render(
<ListGroup defaultActiveKey="#link1">
<ListGroup.Item action href="#link1">
Link 1
</ListGroup.Item>
<ListGroup.Item action href="#link2" disabled>
Link 2
</ListGroup.Item>
<ListGroup.Item action onClick={alertClicked}>
This one is a button
</ListGroup.Item>
</ListGroup>,
);
```
### Flush
Add the `flush` variant to remove outer borders and rounded corners to render list group items edge-to-edge in a parent container [such as a `Card`](../cards/index#list-groups).
```
<ListGroup variant="flush">
<ListGroup.Item>Cras justo odio</ListGroup.Item>
<ListGroup.Item>Dapibus ac facilisis in</ListGroup.Item>
<ListGroup.Item>Morbi leo risus</ListGroup.Item>
<ListGroup.Item>Porta ac consectetur ac</ListGroup.Item>
</ListGroup>
```
### Horizontal
Use the `horizontal` prop to make the ListGroup render horizontally. Currently **horizontal list groups cannot be combined with flush list groups.**
```
<ListGroup horizontal>
<ListGroup.Item>This</ListGroup.Item>
<ListGroup.Item>ListGroup</ListGroup.Item>
<ListGroup.Item>renders</ListGroup.Item>
<ListGroup.Item>horizontally!</ListGroup.Item>
</ListGroup>
```
There are responsive variants to `horizontal`: setting it to `{sm|md|lg|xl}` makes the list group horizontal starting at that breakpoint’s `min-width`.
```
['sm', 'md', 'lg', 'xl'].map((breakpoint, idx) => (
<ListGroup horizontal={breakpoint} className="my-2" key={idx}>
<ListGroup.Item>This ListGroup</ListGroup.Item>
<ListGroup.Item>renders horizontally</ListGroup.Item>
<ListGroup.Item>on {breakpoint}</ListGroup.Item>
<ListGroup.Item>and above!</ListGroup.Item>
</ListGroup>
));
```
### Contextual classes
Use contextual variants on `<ListGroup.Item>`s to style them with a stateful background and color.
```
<ListGroup>
<ListGroup.Item>No style</ListGroup.Item>
<ListGroup.Item variant="primary">Primary</ListGroup.Item>
<ListGroup.Item variant="secondary">Secondary</ListGroup.Item>
<ListGroup.Item variant="success">Success</ListGroup.Item>
<ListGroup.Item variant="danger">Danger</ListGroup.Item>
<ListGroup.Item variant="warning">Warning</ListGroup.Item>
<ListGroup.Item variant="info">Info</ListGroup.Item>
<ListGroup.Item variant="light">Light</ListGroup.Item>
<ListGroup.Item variant="dark">Dark</ListGroup.Item>
</ListGroup>
```
When paired with `action`s, additional hover and active styles apply.
```
<ListGroup>
<ListGroup.Item>No style</ListGroup.Item>
<ListGroup.Item variant="primary">Primary</ListGroup.Item>
<ListGroup.Item action variant="secondary">
Secondary
</ListGroup.Item>
<ListGroup.Item action variant="success">
Success
</ListGroup.Item>
<ListGroup.Item action variant="danger">
Danger
</ListGroup.Item>
<ListGroup.Item action variant="warning">
Warning
</ListGroup.Item>
<ListGroup.Item action variant="info">
Info
</ListGroup.Item>
<ListGroup.Item action variant="light">
Light
</ListGroup.Item>
<ListGroup.Item action variant="dark">
Dark
</ListGroup.Item>
</ListGroup>
```
Tabbed Interfaces
-----------------
You can also use the [Tab](../tabs/index) components to create ARIA compliant tabbable interfaces with the `<ListGroup>` component. Swap out the `<Nav>` component for the list group and you are good to go.
```
<Tab.Container id="list-group-tabs-example" defaultActiveKey="#link1">
<Row>
<Col sm={4}>
<ListGroup>
<ListGroup.Item action href="#link1">
Link 1
</ListGroup.Item>
<ListGroup.Item action href="#link2">
Link 2
</ListGroup.Item>
</ListGroup>
</Col>
<Col sm={8}>
<Tab.Content>
<Tab.Pane eventKey="#link1">
<Sonnet />
</Tab.Pane>
<Tab.Pane eventKey="#link2">
<Sonnet />
</Tab.Pane>
</Tab.Content>
</Col>
</Row>
</Tab.Container>
```
API
---
### ListGroup
`import ListGroup from 'react-bootstrap/ListGroup'`Copy import code for the ListGroup component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| activeKey | unknown | | |
| as | elementType | | You can use a custom element type for this component. |
| defaultActiveKey | unknown | | |
| horizontal | `true` | `'sm'` | `'md'` | `'lg'` | `'xl'` | `undefined` | Changes the flow of the list group items from vertical to horizontal. A value of `null` (the default) sets it to vertical for all breakpoints; Just including the prop sets it for all breakpoints, while `{sm|md|lg|xl}` makes the list group horizontal starting at that breakpoint’s `min-width`. |
| onSelect | SelectCallback | | |
| variant | `'flush'` | `undefined` | Adds a variant to the list-group |
| bsPrefix | string | `'list-group'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ListGroup.Item
`import ListGroup from 'react-bootstrap/ListGroup'`Copy import code for the ListGroup component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| action | boolean | | Marks a ListGroupItem as actionable, applying additional hover, active and disabled styles for links and buttons. |
| active | boolean | `false` | Sets list item as active |
| as | elementType | `<{div | a | button}>` | You can use a custom element type for this component. For none `action` items, items render as `li`. For actions the default is an achor or button element depending on whether a `href` is provided. |
| disabled | boolean | `false` | Sets list item state as disabled |
| eventKey | string | | A unique identifier for the Component, the `eventKey` makes it distinguishable from others in a set. Similar to React's `key` prop, in that it only needs to be unique amongst the Components siblings, not globally. |
| href | string | | |
| onClick | function | | |
| variant | `'primary'` | `'secondary'` | `'success'` | `'danger'` | `'warning'` | `'info'` | `'dark'` | `'light'` | `undefined` | Sets contextual classes for list item |
| bsPrefix | string | `'list-group-item'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| programming_docs |
react_bootstrap Alerts Alerts
======
Provide contextual feedback messages for typical user actions with the handful of available and flexible alert messages.
Examples
--------
Alerts are available for any length of text, as well as an optional dismiss button. For proper styling, use one of the eight `variant`s.
```
[
'primary',
'secondary',
'success',
'danger',
'warning',
'info',
'light',
'dark',
].map((variant, idx) => (
<Alert key={idx} variant={variant}>
This is a {variant} alert—check it out!
</Alert>
));
```
### Links
For links, use the `<Alert.Link>` component to provide matching colored links within any alert.
```
[
'primary',
'secondary',
'success',
'danger',
'warning',
'info',
'light',
'dark',
].map((variant, idx) => (
<Alert key={idx} variant={variant}>
This is a {variant} alert with{' '}
<Alert.Link href="#">an example link</Alert.Link>. Give it a click if you
like.
</Alert>
));
```
### Additional content
Alerts can contain whatever content you like. Headers, paragraphs, dividers, go crazy.
```
<Alert variant="success">
<Alert.Heading>Hey, nice to see you</Alert.Heading>
<p>
Aww yeah, you successfully read this important alert message. This example
text is going to run a bit longer so that you can see how spacing within an
alert works with this kind of content.
</p>
<hr />
<p className="mb-0">
Whenever you need to, be sure to use margin utilities to keep things nice
and tidy.
</p>
</Alert>
```
### Dismissing
Add the `dismissible` prop to add a functioning dismiss button to the Alert.
```
function AlertDismissibleExample() {
const [show, setShow] = useState(true);
if (show) {
return (
<Alert variant="danger" onClose={() => setShow(false)} dismissible>
<Alert.Heading>Oh snap! You got an error!</Alert.Heading>
<p>
Change this and that and try again. Duis mollis, est non commodo
luctus, nisi erat porttitor ligula, eget lacinia odio sem nec elit.
Cras mattis consectetur purus sit amet fermentum.
</p>
</Alert>
);
}
return <Button onClick={() => setShow(true)}>Show Alert</Button>;
}
render(<AlertDismissibleExample />);
```
You can also control the visual state directly which is great if you want to build more complicated alerts.
```
function AlertDismissible() {
const [show, setShow] = useState(true);
return (
<>
<Alert show={show} variant="success">
<Alert.Heading>How's it going?!</Alert.Heading>
<p>
Duis mollis, est non commodo luctus, nisi erat porttitor ligula, eget
lacinia odio sem nec elit. Cras mattis consectetur purus sit amet
fermentum.
</p>
<hr />
<div className="d-flex justify-content-end">
<Button onClick={() => setShow(false)} variant="outline-success">
Close me y'all!
</Button>
</div>
</Alert>
{!show && <Button onClick={() => setShow(true)}>Show Alert</Button>}
</>
);
}
render(<AlertDismissible />);
```
API
---
### Alert
`import Alert from 'react-bootstrap/Alert'`Copy import code for the Alert component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| closeLabel | string | `'Close alert'` | Sets the text for alert close button. |
| dismissible | boolean | | Renders a properly aligned dismiss button, as well as adding extra horizontal padding to the Alert. |
| onClose | function | | *controls `show`*
Callback fired when alert is closed. |
| show | boolean | `true` | *controlled by: `onClose`, initial prop: `defaultShow`*
Controls the visual state of the Alert. |
| transition | boolean | elementType | `Fade` | Animate the alert dismissal. Defaults to using `<Fade>` animation or use `false` to disable. A custom `react-transition-group` Transition can also be provided. |
| variant | 'primary' | 'secondary' | 'success' | 'danger' | 'warning' | 'info' | 'dark' | 'light' | | The Alert visual variant |
| bsPrefix | string | `'alert'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Alert.Heading
`import Alert from 'react-bootstrap/Alert'`Copy import code for the Alert component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<DivStyledAsH4>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'alert-heading'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Alert.Link
`import Alert from 'react-bootstrap/Alert'`Copy import code for the Alert component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<SafeAnchor>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'alert-link'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap InputGroup InputGroup
==========
Place one add-on or button on either side of an input. You may also place one on both sides of an input. Remember to place `<label>`s outside the input group.
```
<div>
<InputGroup className="mb-3">
<InputGroup.Prepend>
<InputGroup.Text id="basic-addon1">@</InputGroup.Text>
</InputGroup.Prepend>
<FormControl
placeholder="Username"
aria-label="Username"
aria-describedby="basic-addon1"
/>
</InputGroup>
<InputGroup className="mb-3">
<FormControl
placeholder="Recipient's username"
aria-label="Recipient's username"
aria-describedby="basic-addon2"
/>
<InputGroup.Append>
<InputGroup.Text id="basic-addon2">@example.com</InputGroup.Text>
</InputGroup.Append>
</InputGroup>
<label htmlFor="basic-url">Your vanity URL</label>
<InputGroup className="mb-3">
<InputGroup.Prepend>
<InputGroup.Text id="basic-addon3">
https://example.com/users/
</InputGroup.Text>
</InputGroup.Prepend>
<FormControl id="basic-url" aria-describedby="basic-addon3" />
</InputGroup>
<InputGroup className="mb-3">
<InputGroup.Prepend>
<InputGroup.Text>$</InputGroup.Text>
</InputGroup.Prepend>
<FormControl aria-label="Amount (to the nearest dollar)" />
<InputGroup.Append>
<InputGroup.Text>.00</InputGroup.Text>
</InputGroup.Append>
</InputGroup>
<InputGroup>
<InputGroup.Prepend>
<InputGroup.Text>With textarea</InputGroup.Text>
</InputGroup.Prepend>
<FormControl as="textarea" aria-label="With textarea" />
</InputGroup>
</div>
```
Sizing
------
Add the relative form sizing classes to the `InputGroup` and contents within will automatically resize—no need for repeating the form control size classes on each element.
```
<div>
<InputGroup size="sm" className="mb-3">
<InputGroup.Prepend>
<InputGroup.Text id="inputGroup-sizing-sm">Small</InputGroup.Text>
</InputGroup.Prepend>
<FormControl aria-label="Small" aria-describedby="inputGroup-sizing-sm" />
</InputGroup>
<br />
<InputGroup className="mb-3">
<InputGroup.Prepend>
<InputGroup.Text id="inputGroup-sizing-default">Default</InputGroup.Text>
</InputGroup.Prepend>
<FormControl
aria-label="Default"
aria-describedby="inputGroup-sizing-default"
/>
</InputGroup>
<br />
<InputGroup size="lg">
<InputGroup.Prepend>
<InputGroup.Text id="inputGroup-sizing-lg">Large</InputGroup.Text>
</InputGroup.Prepend>
<FormControl aria-label="Large" aria-describedby="inputGroup-sizing-sm" />
</InputGroup>
</div>
```
Checkboxes and radios
---------------------
Use the `InputGroup.Radio` or `InputGroup.Checkbox` to add options to an input group.
```
<div>
<InputGroup className="mb-3">
<InputGroup.Prepend>
<InputGroup.Checkbox aria-label="Checkbox for following text input" />
</InputGroup.Prepend>
<FormControl aria-label="Text input with checkbox" />
</InputGroup>
<InputGroup>
<InputGroup.Prepend>
<InputGroup.Radio aria-label="Radio button for following text input" />
</InputGroup.Prepend>
<FormControl aria-label="Text input with radio button" />
</InputGroup>
</div>
```
Multiple inputs
---------------
While multiple inputs are supported visually, validation styles are only available for input groups with a single input.
```
<InputGroup className="mb-3">
<InputGroup.Prepend>
<InputGroup.Text>First and last name</InputGroup.Text>
</InputGroup.Prepend>
<FormControl />
<FormControl />
</InputGroup>
```
Multiple addons
---------------
Multiple add-ons are supported and can be mixed
```
<div>
<InputGroup className="mb-3">
<InputGroup.Prepend>
<InputGroup.Text>$</InputGroup.Text>
<InputGroup.Text>0.00</InputGroup.Text>
</InputGroup.Prepend>
<FormControl
placeholder="Recipient's username"
aria-label="Amount (to the nearest dollar)"
/>
</InputGroup>
<InputGroup className="mb-3">
<FormControl
placeholder="Recipient's username"
aria-label="Amount (to the nearest dollar)"
/>
<InputGroup.Append>
<InputGroup.Text>$</InputGroup.Text>
<InputGroup.Text>0.00</InputGroup.Text>
</InputGroup.Append>
</InputGroup>
</div>
```
Button addons
-------------
```
<div>
<InputGroup className="mb-3">
<InputGroup.Prepend>
<Button variant="outline-secondary">Button</Button>
</InputGroup.Prepend>
<FormControl aria-describedby="basic-addon1" />
</InputGroup>
<InputGroup className="mb-3">
<FormControl
placeholder="Recipient's username"
aria-label="Recipient's username"
aria-describedby="basic-addon2"
/>
<InputGroup.Append>
<Button variant="outline-secondary">Button</Button>
</InputGroup.Append>
</InputGroup>
<InputGroup className="mb-3">
<InputGroup.Prepend>
<Button variant="outline-secondary">Button</Button>
<Button variant="outline-secondary">Button</Button>
</InputGroup.Prepend>
<FormControl aria-describedby="basic-addon1" />
</InputGroup>
<InputGroup>
<FormControl
placeholder="Recipient's username"
aria-label="Recipient's username"
aria-describedby="basic-addon2"
/>
<InputGroup.Append>
<Button variant="outline-secondary">Button</Button>
<Button variant="outline-secondary">Button</Button>
</InputGroup.Append>
</InputGroup>
</div>
```
Buttons with Dropdowns
----------------------
```
<>
<InputGroup className="mb-3">
<DropdownButton
as={InputGroup.Prepend}
variant="outline-secondary"
title="Dropdown"
id="input-group-dropdown-1"
>
<Dropdown.Item href="#">Action</Dropdown.Item>
<Dropdown.Item href="#">Another action</Dropdown.Item>
<Dropdown.Item href="#">Something else here</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item href="#">Separated link</Dropdown.Item>
</DropdownButton>
<FormControl aria-describedby="basic-addon1" />
</InputGroup>
<InputGroup>
<FormControl
placeholder="Recipient's username"
aria-label="Recipient's username"
aria-describedby="basic-addon2"
/>
<DropdownButton
as={InputGroup.Append}
variant="outline-secondary"
title="Dropdown"
id="input-group-dropdown-2"
>
<Dropdown.Item href="#">Action</Dropdown.Item>
<Dropdown.Item href="#">Another action</Dropdown.Item>
<Dropdown.Item href="#">Something else here</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item href="#">Separated link</Dropdown.Item>
</DropdownButton>
</InputGroup>
</>
```
API
---
### InputGroup
`import InputGroup from 'react-bootstrap/InputGroup'`Copy import code for the InputGroup component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| hasValidation | boolean | |
Handles the input's rounded corners when using form validation. Use this when your input group contains both an input and feedback element.
|
| size | `'sm'` | `'lg'` | | Control the size of buttons and form elements from the top-level. |
| bsPrefix | string | `'input-group'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Tables Tables
======
Use the `striped`, `bordered` and `hover` props to customise the table.
```
<Table striped bordered hover>
<thead>
<tr>
<th>#</th>
<th>First Name</th>
<th>Last Name</th>
<th>Username</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>Mark</td>
<td>Otto</td>
<td>@mdo</td>
</tr>
<tr>
<td>2</td>
<td>Jacob</td>
<td>Thornton</td>
<td>@fat</td>
</tr>
<tr>
<td>3</td>
<td colSpan="2">Larry the Bird</td>
<td>@twitter</td>
</tr>
</tbody>
</Table>
```
Small Table
-----------
Use `size="sm"` to make tables compact by cutting cell padding in half.
```
<Table striped bordered hover size="sm">
<thead>
<tr>
<th>#</th>
<th>First Name</th>
<th>Last Name</th>
<th>Username</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>Mark</td>
<td>Otto</td>
<td>@mdo</td>
</tr>
<tr>
<td>2</td>
<td>Jacob</td>
<td>Thornton</td>
<td>@fat</td>
</tr>
<tr>
<td>3</td>
<td colSpan="2">Larry the Bird</td>
<td>@twitter</td>
</tr>
</tbody>
</Table>
```
Dark Table
----------
Use `variant="dark"` to invert the colors of the table and get light text on a dark background.
```
<Table striped bordered hover variant="dark">
<thead>
<tr>
<th>#</th>
<th>First Name</th>
<th>Last Name</th>
<th>Username</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>Mark</td>
<td>Otto</td>
<td>@mdo</td>
</tr>
<tr>
<td>2</td>
<td>Jacob</td>
<td>Thornton</td>
<td>@fat</td>
</tr>
<tr>
<td>3</td>
<td colSpan="2">Larry the Bird</td>
<td>@twitter</td>
</tr>
</tbody>
</Table>
```
Responsive
----------
Responsive tables allow tables to be scrolled horizontally with ease.
### Always Responsive
Across every breakpoint, use `responsive` for horizontally scrolling tables. Responsive tables are wrapped automatically in a `div`. The following example has 12 columns that are scrollable horizontally.
```
<Table responsive>
<thead>
<tr>
<th>#</th>
{Array.from({ length: 12 }).map((_, index) => (
<th key={index}>Table heading</th>
))}
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
{Array.from({ length: 12 }).map((_, index) => (
<td key={index}>Table cell {index}</td>
))}
</tr>
<tr>
<td>2</td>
{Array.from({ length: 12 }).map((_, index) => (
<td key={index}>Table cell {index}</td>
))}
</tr>
<tr>
<td>3</td>
{Array.from({ length: 12 }).map((_, index) => (
<td key={index}>Table cell {index}</td>
))}
</tr>
</tbody>
</Table>
```
### Breakpoint specific
Use `responsive="sm"`, `responsive="md"`, `responsive="lg"`, or `responsive="xl"` as needed to create responsive tables up to a particular breakpoint. From that breakpoint and up, the table will behave normally and not scroll horizontally.
```
<div>
<Table responsive="sm">
<thead>
<tr>
<th>#</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
<tr>
<td>2</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
<tr>
<td>3</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
</tbody>
</Table>
<Table responsive="md">
<thead>
<tr>
<th>#</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
<tr>
<td>2</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
<tr>
<td>3</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
</tbody>
</Table>
<Table responsive="lg">
<thead>
<tr>
<th>#</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
<tr>
<td>2</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
<tr>
<td>3</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
</tbody>
</Table>
<Table responsive="xl">
<thead>
<tr>
<th>#</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
<th>Table heading</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
<tr>
<td>2</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
<tr>
<td>3</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
<td>Table cell</td>
</tr>
</tbody>
</Table>
</div>
```
API
---
### Table
`import Table from 'react-bootstrap/Table'`Copy import code for the Table component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| bordered | boolean | | Adds borders on all sides of the table and cells. |
| borderless | boolean | | Removes all borders on the table and cells, including table header. |
| hover | boolean | | Enable a hover state on table rows within a `<tbody>`. |
| responsive | boolean | string | | Responsive tables allow tables to be scrolled horizontally with ease. Across every breakpoint, use `responsive` for horizontally scrolling tables. Responsive tables are wrapped automatically in a `div`. Use `responsive="sm"`, `responsive="md"`, `responsive="lg"`, or `responsive="xl"` as needed to create responsive tables up to a particular breakpoint. From that breakpoint and up, the table will behave normally and not scroll horizontally. |
| size | string | | Make tables more compact by cutting cell padding in half by setting size as `sm`. |
| striped | boolean | | Adds zebra-striping to any table row within the `<tbody>`. |
| variant | string | | Invert the colors of the table — with light text on dark backgrounds by setting variant as `dark`. |
| bsPrefix | string | `'table'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| programming_docs |
react_bootstrap Figures Figures
=======
Anytime you need to display a piece of content, like an image with an optional caption, consider using a `Figure`.
Figure
------
Displaying related images and text with the Figure component.
```
<Figure>
<Figure.Image
width={171}
height={180}
alt="171x180"
src="holder.js/171x180"
/>
<Figure.Caption>
Nulla vitae elit libero, a pharetra augue mollis interdum.
</Figure.Caption>
</Figure>
```
API
---
### Figure
`import Figure from 'react-bootstrap/Figure'`Copy import code for the Figure component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<figure>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'figure'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### FigureImage
`import FigureImage from 'react-bootstrap/FigureImage'`Copy import code for the FigureImage component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
### FigureCaption
`import FigureCaption from 'react-bootstrap/FigureCaption'`Copy import code for the FigureCaption component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<figcaption>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'figure-caption'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap None Breadcrumbs
-----------
Indicate the current page’s location within a navigational hierarchy that automatically adds separators via CSS. Add `active` prop to active `Breadcrumb.Item` . Do not set both `active` and `href` attributes. `active` overrides `href` and `span` element is rendered instead of `a` .
### Example
```
<Breadcrumb>
<Breadcrumb.Item href="#">Home</Breadcrumb.Item>
<Breadcrumb.Item href="https://getbootstrap.com/docs/4.0/components/breadcrumb/">
Library
</Breadcrumb.Item>
<Breadcrumb.Item active>Data</Breadcrumb.Item>
</Breadcrumb>
```
API
---
### Breadcrumb
`import Breadcrumb from 'react-bootstrap/Breadcrumb'`Copy import code for the Breadcrumb component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<nav>` | You can use a custom element type for this component. |
| className | string | | |
| label | string | `'breadcrumb'` | ARIA label for the nav element <https://www.w3.org/TR/wai-aria-practices/#breadcrumb> |
| listProps | object | `{}` | Additional props passed as-is to the underlying `<ol>` element |
| bsPrefix | string | `'breadcrumb'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Breadcrumb.Item
`import Breadcrumb from 'react-bootstrap/Breadcrumb'`Copy import code for the Breadcrumb component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| active | boolean | `false` | Adds a visual "active" state to a Breadcrumb Item and disables the link. |
| as | elementType | `<li>` | You can use a custom element type for this component. |
| href | string | | `href` attribute for the inner `a` element |
| linkAs | elementType | `<SafeAnchor>` | You can use a custom element type for this component's inner link. |
| linkProps | object | `{}` | Additional props passed as-is to the underlying link for non-active items. |
| target | string | | `target` attribute for the inner `a` element |
| title | node | | `title` attribute for the inner `a` element |
| bsPrefix | string | `'breadcrumb-item'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Dropdowns Dropdowns
=========
Toggle contextual overlays for displaying lists of links and more with the Bootstrap dropdown plugin
Overview
--------
Dropdowns are toggleable, contextual overlays for displaying lists of links and more. Like overlays, Dropdowns are built using a third-party library [Popper.js](https://popper.js.org/), which provides dynamic positioning and viewport detection.
Accessibility
-------------
The [WAI ARIA](https://www.w3.org/TR/wai-aria/) standard defines a [`role="menu"` widget](https://www.w3.org/TR/wai-aria-1.1/#menu), but it's very specific to a certain kind of menu. ARIA menus, must only contain `role="menuitem"`, `role="menuitemcheckbox"`, or `role="menuitemradio"`.
On the other hand, Bootstrap's dropdowns are designed to more generic and application in a variety of situations. For this reason we don't automatically add the menu roles to the markup. We do implement some basic keyboard navigation, and if you do provide the "menu" role, react-bootstrap will do its best to ensure the focus management is compliant with the ARIA authoring guidelines for menus.
Examples
--------
### Single button dropdowns
The basic Dropdown is composed of a wrapping `Dropdown` and inner `<DropdownMenu>`, and `<DropdownToggle>`. By default the `<DropdownToggle>` will render a `Button` component and accepts all the same props.
```
<Dropdown>
<Dropdown.Toggle variant="success" id="dropdown-basic">
Dropdown Button
</Dropdown.Toggle>
<Dropdown.Menu>
<Dropdown.Item href="#/action-1">Action</Dropdown.Item>
<Dropdown.Item href="#/action-2">Another action</Dropdown.Item>
<Dropdown.Item href="#/action-3">Something else</Dropdown.Item>
</Dropdown.Menu>
</Dropdown>
```
Since the above is such a common configuration react-bootstrap provides the `<DropdownButton>` component to help reduce typing. Provide a `title` prop and some `<DropdownItem>`s and you're ready to go.
```
<DropdownButton id="dropdown-basic-button" title="Dropdown button">
<Dropdown.Item href="#/action-1">Action</Dropdown.Item>
<Dropdown.Item href="#/action-2">Another action</Dropdown.Item>
<Dropdown.Item href="#/action-3">Something else</Dropdown.Item>
</DropdownButton>
```
DropdownButton will forward Button props to the underlying Toggle component
```
<>
{['Primary', 'Secondary', 'Success', 'Info', 'Warning', 'Danger'].map(
(variant) => (
<DropdownButton
as={ButtonGroup}
key={variant}
id={`dropdown-variants-${variant}`}
variant={variant.toLowerCase()}
title={variant}
>
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3" active>
Active Item
</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</DropdownButton>
),
)}
</>
```
### Split button dropdowns
Similarly, You create a split dropdown by combining the Dropdown components with another Button and a ButtonGroup.
```
<Dropdown as={ButtonGroup}>
<Button variant="success">Split Button</Button>
<Dropdown.Toggle split variant="success" id="dropdown-split-basic" />
<Dropdown.Menu>
<Dropdown.Item href="#/action-1">Action</Dropdown.Item>
<Dropdown.Item href="#/action-2">Another action</Dropdown.Item>
<Dropdown.Item href="#/action-3">Something else</Dropdown.Item>
</Dropdown.Menu>
</Dropdown>
```
As with DropdownButton, `SplitButton` is provided as convenience component.
```
<>
{['Primary', 'Secondary', 'Success', 'Info', 'Warning', 'Danger'].map(
(variant) => (
<SplitButton
key={variant}
id={`dropdown-split-variants-${variant}`}
variant={variant.toLowerCase()}
title={variant}
>
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3" active>
Active Item
</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</SplitButton>
),
)}
</>
```
### Sizing
Dropdowns work with buttons of all sizes.
```
<>
<div className="mb-2">
{[DropdownButton, SplitButton].map((DropdownType, idx) => (
<DropdownType
as={ButtonGroup}
key={idx}
id={`dropdown-button-drop-${idx}`}
size="lg"
title="Drop large"
>
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3">Something else here</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</DropdownType>
))}
</div>
<div>
{[DropdownButton, SplitButton].map((DropdownType, idx) => (
<DropdownType
as={ButtonGroup}
key={idx}
id={`dropdown-button-drop-${idx}`}
size="sm"
variant="secondary"
title="Drop small"
>
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3">Something else here</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</DropdownType>
))}
</div>
</>
```
Drop directions
---------------
Trigger dropdown menus above, below, left, or to the right of their toggle elements, with the `drop` prop.
```
<>
<div className="mb-2">
{['up', 'down', 'left', 'right'].map((direction) => (
<DropdownButton
as={ButtonGroup}
key={direction}
id={`dropdown-button-drop-${direction}`}
drop={direction}
variant="secondary"
title={` Drop ${direction} `}
>
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3">Something else here</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</DropdownButton>
))}
</div>
<div>
{['up', 'down', 'left', 'right'].map((direction) => (
<SplitButton
key={direction}
id={`dropdown-button-drop-${direction}`}
drop={direction}
variant="secondary"
title={`Drop ${direction}`}
>
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3">Something else here</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</SplitButton>
))}
</div>
</>
```
Dropdown items
--------------
Historically dropdown menu contents had to be links, but that’s no longer the case with v4. Now you can optionally use `<button>` elements in your dropdowns instead of just `<a>`s.
You can also create non-interactive dropdown items with `<Dropdown.ItemText>`. Feel free to style further with custom CSS or text utilities.
```
<DropdownButton id="dropdown-item-button" title="Dropdown button">
<Dropdown.ItemText>Dropdown item text</Dropdown.ItemText>
<Dropdown.Item as="button">Action</Dropdown.Item>
<Dropdown.Item as="button">Another action</Dropdown.Item>
<Dropdown.Item as="button">Something else</Dropdown.Item>
</DropdownButton>
```
Menu alignment
--------------
By default, a dropdown menu is aligned to the left, but you can switch it by passing `right` to the `align` prop on a `<DropdownMenu>` or passing `right` to the `menuAlign` prop on the `<DropdownButton>` or `<SplitButton>` as seen below.
```
<DropdownButton
menuAlign="right"
title="Dropdown right"
id="dropdown-menu-align-right"
>
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3">Something else here</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</DropdownButton>
```
### Responsive alignment
If you want to use responsive menu alignment, pass an object to the `align` prop on the `<DropdownMenu>` or the `menuAlign` prop on the `<DropdownButton>` and `<SplitButton>`. You can specify the directions `left` or `right` for the various breakpoints.
```
<>
<div>
<DropdownButton
as={ButtonGroup}
menuAlign={{ lg: 'right' }}
title="Left-aligned but right aligned when large screen"
id="dropdown-menu-align-responsive-1"
>
<Dropdown.Item eventKey="1">Action 1</Dropdown.Item>
<Dropdown.Item eventKey="2">Action 2</Dropdown.Item>
</DropdownButton>
</div>
<div className="mt-2">
<SplitButton
menuAlign={{ lg: 'left' }}
title="Right-aligned but left aligned when large screen"
id="dropdown-menu-align-responsive-2"
>
<Dropdown.Item eventKey="1">Action 1</Dropdown.Item>
<Dropdown.Item eventKey="2">Action 2</Dropdown.Item>
</SplitButton>
</div>
</>
```
Menu headers
------------
Add a header to label sections of actions.
```
<Dropdown.Menu show>
<Dropdown.Header>Dropdown header</Dropdown.Header>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3">Something else here</Dropdown.Item>
</Dropdown.Menu>
```
Menu dividers
-------------
Separate groups of related menu items with a divider.
```
<Dropdown.Menu show>
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3">Something else here</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</Dropdown.Menu>
```
Customization
-------------
If the default handling of the dropdown menu and toggle components aren't to your liking, you can customize them, by using the more basic `<Dropdown>` Component to explicitly specify the Toggle and Menu components
```
<>
<Dropdown as={ButtonGroup}>
<Dropdown.Toggle id="dropdown-custom-1">Pow! Zoom!</Dropdown.Toggle>
<Dropdown.Menu className="super-colors">
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3" active>
Active Item
</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</Dropdown.Menu>
</Dropdown>{' '}
<Dropdown as={ButtonGroup}>
<Button variant="info">mix it up style-wise</Button>
<Dropdown.Toggle split variant="success" id="dropdown-custom-2" />
<Dropdown.Menu className="super-colors">
<Dropdown.Item eventKey="1">Action</Dropdown.Item>
<Dropdown.Item eventKey="2">Another action</Dropdown.Item>
<Dropdown.Item eventKey="3" active>
Active Item
</Dropdown.Item>
<Dropdown.Divider />
<Dropdown.Item eventKey="4">Separated link</Dropdown.Item>
</Dropdown.Menu>
</Dropdown>
</>
```
### Custom Dropdown Components
For those that want to customize everything, you can forgo the included Toggle and Menu components, and create your own. By providing custom components to the `as` prop, you can control how each component behaves. Custom toggle and menu components **must** be able to accept refs.
```
// The forwardRef is important!!
// Dropdown needs access to the DOM node in order to position the Menu
const CustomToggle = React.forwardRef(({ children, onClick }, ref) => (
<a
href=""
ref={ref}
onClick={(e) => {
e.preventDefault();
onClick(e);
}}
>
{children}
▼
</a>
));
// forwardRef again here!
// Dropdown needs access to the DOM of the Menu to measure it
const CustomMenu = React.forwardRef(
({ children, style, className, 'aria-labelledby': labeledBy }, ref) => {
const [value, setValue] = useState('');
return (
<div
ref={ref}
style={style}
className={className}
aria-labelledby={labeledBy}
>
<FormControl
autoFocus
className="mx-3 my-2 w-auto"
placeholder="Type to filter..."
onChange={(e) => setValue(e.target.value)}
value={value}
/>
<ul className="list-unstyled">
{React.Children.toArray(children).filter(
(child) =>
!value || child.props.children.toLowerCase().startsWith(value),
)}
</ul>
</div>
);
},
);
render(
<Dropdown>
<Dropdown.Toggle as={CustomToggle} id="dropdown-custom-components">
Custom toggle
</Dropdown.Toggle>
<Dropdown.Menu as={CustomMenu}>
<Dropdown.Item eventKey="1">Red</Dropdown.Item>
<Dropdown.Item eventKey="2">Blue</Dropdown.Item>
<Dropdown.Item eventKey="3" active>
Orange
</Dropdown.Item>
<Dropdown.Item eventKey="1">Red-Orange</Dropdown.Item>
</Dropdown.Menu>
</Dropdown>,
);
```
API
---
### DropdownButton
`import DropdownButton from 'react-bootstrap/DropdownButton'`Copy import code for the DropdownButton component
A convenience component for simple or general use dropdowns. Renders a `Button` toggle and all `children` are passed directly to the default `Dropdown.Menu`. This component accepts all of [`Dropdown`'s props](#dropdown-props).
*All unknown props are passed through to the `Dropdown` component.* Only the Button `variant`, `size` and `bsPrefix` props are passed to the toggle, along with menu-related props are passed to the `Dropdown.Menu`
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| disabled | boolean | | Disables both Buttons |
| href | string | | An `href` passed to the Toggle component |
| id required | string|number | | An html id attribute for the Toggle button, necessary for assistive technologies, such as screen readers. |
| menuAlign | "left"|"right"|{ sm: "left"|"right" }|{ md: "left"|"right" }|{ lg: "left"|"right" }|{ xl: "left"|"right"} | |
Aligns the dropdown menu responsively. *see [DropdownMenu](#dropdown-menu-props) for more details*
|
| menuRole | string | | An ARIA accessible role applied to the Menu component. When set to 'menu', The dropdown |
| onClick | function | | An `onClick` handler passed to the Toggle component |
| renderMenuOnMount | boolean | | Whether to render the dropdown menu in the DOM before the first time it is shown |
| rootCloseEvent | string | |
Which event when fired outside the component will cause it to be closed. *see [DropdownMenu](#dropdown-menu-props) for more details*
|
| size | string | | Component size variations. |
| title required | node | | The content of the non-toggle Button. |
| variant | string | | Component visual or contextual style variants. |
| bsPrefix | string | | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### SplitButton
`import SplitButton from 'react-bootstrap/SplitButton'`Copy import code for the SplitButton component
A convenience component for simple or general use split button dropdowns. Renders a `ButtonGroup` containing a `Button` and a `Button` toggle for the `Dropdown`. All `children` are passed directly to the default `Dropdown.Menu`. This component accepts all of [`Dropdown`'s props](#dropdown-props).
*All unknown props are passed through to the `Dropdown` component.* The Button `variant`, `size` and `bsPrefix` props are passed to the button and toggle, and menu-related props are passed to the `Dropdown.Menu`
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| disabled | boolean | | Disables both Buttons |
| href | string | | An `href` passed to the non-toggle Button |
| id required | string|number | | An html id attribute for the Toggle button, necessary for assistive technologies, such as screen readers. |
| menuAlign | "left"|"right"|{ sm: "left"|"right" }|{ md: "left"|"right" }|{ lg: "left"|"right" }|{ xl: "left"|"right"} | |
Aligns the dropdown menu responsively. *see [DropdownMenu](#dropdown-menu-props) for more details*
|
| menuRole | string | | An ARIA accessible role applied to the Menu component. When set to 'menu', The dropdown |
| onClick | function | | An `onClick` handler passed to the non-toggle Button |
| renderMenuOnMount | boolean | | Whether to render the dropdown menu in the DOM before the first time it is shown |
| rootCloseEvent | string | |
Which event when fired outside the component will cause it to be closed. *see [DropdownMenu](#dropdown-menu-props) for more details*
|
| size | string | | Component size variations. |
| target | string | | An anchor `target` passed to the non-toggle Button |
| title required | node | | The content of the non-toggle Button. |
| toggleLabel | string | `'Toggle dropdown'` | Accessible label for the toggle; the value of `title` if not specified. |
| type | string | `'button'` | A `type` passed to the non-toggle Button |
| variant | string | | Component visual or contextual style variants. |
| bsPrefix | string | | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Dropdown
`import Dropdown from 'react-bootstrap/Dropdown'`Copy import code for the Dropdown component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| alignRight | boolean | | Align the menu to the right side of the Dropdown toggle |
| as | elementType | | You can use a custom element type for this component. |
| drop | `'up'` | `'left'` | `'right'` | `'down'` | | Determines the direction and location of the Menu in relation to it's Toggle. |
| flip | boolean | | Allow Dropdown to flip in case of an overlapping on the reference element. For more information refer to Popper.js's flip [docs](https://popper.js.org/docs/v2/modifiers/flip/). |
| focusFirstItemOnShow | `false` | `true` | `'keyboard'` | |
Controls the focus behavior for when the Dropdown is opened. Set to `true` to always focus the first menu item, `keyboard` to focus only when navigating via the keyboard, or `false` to disable completely The Default behavior is `false` **unless** the Menu has a `role="menu"` where it will default to `keyboard` to match the recommended [ARIA Authoring practices](https://www.w3.org/TR/wai-aria-practices-1.1/#menubutton).
|
| navbar | boolean | `false` | |
| onSelect | function | |
A callback fired when a menu item is selected.
```
(eventKey: any, event: Object) => any
```
|
| onToggle | function | | *controls `show`*
A callback fired when the Dropdown wishes to change visibility. Called with the requested `show` value, the DOM event, and the source that fired it: `'click'`,`'keydown'`,`'rootClose'`, or `'select'`.
```
function(
isOpen: boolean,
event: SyntheticEvent,
metadata: {
source: 'select' | 'click' | 'rootClose' | 'keydown'
}
): void
```
|
| show | boolean | | *controlled by: `onToggle`, initial prop: `defaultShow`*
Whether or not the Dropdown is visible. |
| bsPrefix | string | `'dropdown'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Dropdown.Toggle
`import Dropdown from 'react-bootstrap/Dropdown'`Copy import code for the Dropdown component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<Button>` | You can use a custom element type for this component. |
| childBsPrefix | string | | to passthrough to the underlying button or whatever from DropdownButton |
| eventKey | any | | A unique identifier for the Component, the `eventKey` makes it distinguishable from others in a set. Similar to React's `key` prop, in that it only needs to be unique amongst the Components siblings, not globally. |
| id required | string|number | | An html id attribute, necessary for assistive technologies, such as screen readers. |
| split | boolean | | |
| bsPrefix | string | `'dropdown-toggle'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Dropdown.Menu
`import Dropdown from 'react-bootstrap/Dropdown'`Copy import code for the Dropdown component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| align | "left"|"right"|{ sm: "left"|"right" }|{ md: "left"|"right" }|{ lg: "left"|"right" }|{ xl: "left"|"right"} | `'left'` |
Aligns the dropdown menu to the specified side of the container. You can also align the menu responsively for breakpoints starting at `sm` and up. The alignment direction will affect the specified breakpoint or larger. *Note: Using responsive alignment will disable Popper usage for positioning.*
|
| alignRight | boolean | `false` | **Deprecated: Use align="right"**
Aligns the Dropdown menu to the right of it's container. |
| as | elementType | `<div>` |
Control the rendering of the DropdownMenu. All non-menu props (listed here) are passed through to the `as` Component. If providing a custom, non DOM, component. the `show`, `close` and `alignRight` props are also injected and should be handled appropriately.
|
| flip | boolean | `true` | Have the dropdown switch to it's opposite placement when necessary to stay on screen. |
| onSelect | function | | |
| popperConfig | object | | A set of popper options and props passed directly to Popper. |
| renderOnMount | boolean | | Whether to render the dropdown menu in the DOM before the first time it is shown |
| rootCloseEvent | `'click'` | `'mousedown'` | |
Which event when fired outside the component will cause it to be closed *Note: For custom dropdown components, you will have to pass the `rootCloseEvent` to `<RootCloseWrapper>` in your custom dropdown menu component ([similarly to how it is implemented in `<Dropdown.Menu>`](https://github.com/react-bootstrap/react-bootstrap/blob/v0.31.5/src/DropdownMenu.js#L115-L119)).*
|
| show | boolean | | Controls the visibility of the Dropdown menu |
| bsPrefix | string | `'dropdown-menu'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Dropdown.Item
`import Dropdown from 'react-bootstrap/Dropdown'`Copy import code for the Dropdown component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| active | boolean | | Highlight the menu item as active. |
| as | elementType | `<SafeAnchor>` | You can use a custom element type for this component. |
| disabled | boolean | `false` | Disable the menu item, making it unselectable. |
| eventKey | any | | Value passed to the `onSelect` handler, useful for identifying the selected menu item. |
| href | string | | HTML `href` attribute corresponding to `a.href`. |
| onClick | function | | Callback fired when the menu item is clicked. |
| onSelect | function | |
Callback fired when the menu item is selected.
```
(eventKey: any, event: Object) => any
```
|
| bsPrefix | string | `'dropdown-item'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Dropdown.Header
`import Dropdown from 'react-bootstrap/Dropdown'`Copy import code for the Dropdown component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'dropdown-header'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### Dropdown.Divider
`import Dropdown from 'react-bootstrap/Dropdown'`Copy import code for the Dropdown component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'dropdown-divider'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| programming_docs |
react_bootstrap Modals Modals
======
Add dialogs to your site for lightboxes, user notifications, or completely custom content.
Overview
--------
* Modals are positioned over everything else in the document and remove scroll from the `<body>` so that modal content scrolls instead.
* Modals are *unmounted* when closed.
* Bootstrap only supports **one** modal window at a time. Nested modals aren’t supported, but if you really need them the underlying `react-overlays` can support them if you're willing.
* Modal's "trap" focus in them, ensuring the keyboard navigation cycles through the modal, and not the rest of the page.
* Unlike vanilla Bootstrap, `autoFocus` works in Modals because React handles the implementation.
Examples
--------
### Static Markup
Below is a *static* modal dialog (without the positioning) to demonstrate the look and feel of the Modal.
```
<Modal.Dialog>
<Modal.Header closeButton>
<Modal.Title>Modal title</Modal.Title>
</Modal.Header>
<Modal.Body>
<p>Modal body text goes here.</p>
</Modal.Body>
<Modal.Footer>
<Button variant="secondary">Close</Button>
<Button variant="primary">Save changes</Button>
</Modal.Footer>
</Modal.Dialog>
```
### Live demo
A modal with header, body, and set of actions in the footer. Use `<Modal/>` in combination with other components to show or hide your Modal. The `<Modal/>` Component comes with a few convenient "sub components": `<Modal.Header/>`, `<Modal.Title/>`, `<Modal.Body/>`, and `<Modal.Footer/>`, which you can use to build the Modal content.
```
function Example() {
const [show, setShow] = useState(false);
const handleClose = () => setShow(false);
const handleShow = () => setShow(true);
return (
<>
<Button variant="primary" onClick={handleShow}>
Launch demo modal
</Button>
<Modal show={show} onHide={handleClose}>
<Modal.Header closeButton>
<Modal.Title>Modal heading</Modal.Title>
</Modal.Header>
<Modal.Body>Woohoo, you're reading this text in a modal!</Modal.Body>
<Modal.Footer>
<Button variant="secondary" onClick={handleClose}>
Close
</Button>
<Button variant="primary" onClick={handleClose}>
Save Changes
</Button>
</Modal.Footer>
</Modal>
</>
);
}
render(<Example />);
```
### Static backdrop
When backdrop is set to static, the modal will not close when clicking outside it. Click the button below to try it.
```
function Example() {
const [show, setShow] = useState(false);
const handleClose = () => setShow(false);
const handleShow = () => setShow(true);
return (
<>
<Button variant="primary" onClick={handleShow}>
Launch static backdrop modal
</Button>
<Modal
show={show}
onHide={handleClose}
backdrop="static"
keyboard={false}
>
<Modal.Header closeButton>
<Modal.Title>Modal title</Modal.Title>
</Modal.Header>
<Modal.Body>
I will not close if you click outside me. Don't even try to press
escape key.
</Modal.Body>
<Modal.Footer>
<Button variant="secondary" onClick={handleClose}>
Close
</Button>
<Button variant="primary">Understood</Button>
</Modal.Footer>
</Modal>
</>
);
}
render(<Example />);
```
### Without Animation
A Modal can also be without an animation. For that set the "animation" prop to `false`.
```
function Example() {
const [show, setShow] = useState(false);
const handleClose = () => setShow(false);
const handleShow = () => setShow(true);
return (
<>
<Button variant="primary" onClick={handleShow}>
Launch demo modal
</Button>
<Modal show={show} onHide={handleClose} animation={false}>
<Modal.Header closeButton>
<Modal.Title>Modal heading</Modal.Title>
</Modal.Header>
<Modal.Body>Woohoo, you're reading this text in a modal!</Modal.Body>
<Modal.Footer>
<Button variant="secondary" onClick={handleClose}>
Close
</Button>
<Button variant="primary" onClick={handleClose}>
Save Changes
</Button>
</Modal.Footer>
</Modal>
</>
);
}
render(<Example />);
```
Additional Import Options
The Modal Header, Title, Body, and Footer components are available as static properties the `<Modal/>` component, but you can also, import them directly like: `require("react-bootstrap/ModalHeader")`.
### Vertically centered
You can vertically center a modal by passing the "centered" prop.
```
function MyVerticallyCenteredModal(props) {
return (
<Modal
{...props}
size="lg"
aria-labelledby="contained-modal-title-vcenter"
centered
>
<Modal.Header closeButton>
<Modal.Title id="contained-modal-title-vcenter">
Modal heading
</Modal.Title>
</Modal.Header>
<Modal.Body>
<h4>Centered Modal</h4>
<p>
Cras mattis consectetur purus sit amet fermentum. Cras justo odio,
dapibus ac facilisis in, egestas eget quam. Morbi leo risus, porta ac
consectetur ac, vestibulum at eros.
</p>
</Modal.Body>
<Modal.Footer>
<Button onClick={props.onHide}>Close</Button>
</Modal.Footer>
</Modal>
);
}
function App() {
const [modalShow, setModalShow] = React.useState(false);
return (
<>
<Button variant="primary" onClick={() => setModalShow(true)}>
Launch vertically centered modal
</Button>
<MyVerticallyCenteredModal
show={modalShow}
onHide={() => setModalShow(false)}
/>
</>
);
}
render(<App />);
```
### Using the grid
You can use grid layouts within a model using regular grid components inside the modal content.
```
function MydModalWithGrid(props) {
return (
<Modal {...props} aria-labelledby="contained-modal-title-vcenter">
<Modal.Header closeButton>
<Modal.Title id="contained-modal-title-vcenter">
Using Grid in Modal
</Modal.Title>
</Modal.Header>
<Modal.Body className="show-grid">
<Container>
<Row>
<Col xs={12} md={8}>
.col-xs-12 .col-md-8
</Col>
<Col xs={6} md={4}>
.col-xs-6 .col-md-4
</Col>
</Row>
<Row>
<Col xs={6} md={4}>
.col-xs-6 .col-md-4
</Col>
<Col xs={6} md={4}>
.col-xs-6 .col-md-4
</Col>
<Col xs={6} md={4}>
.col-xs-6 .col-md-4
</Col>
</Row>
</Container>
</Modal.Body>
<Modal.Footer>
<Button onClick={props.onHide}>Close</Button>
</Modal.Footer>
</Modal>
);
}
function App() {
const [modalShow, setModalShow] = useState(false);
return (
<>
<Button variant="primary" onClick={() => setModalShow(true)}>
Launch modal with grid
</Button>
<MydModalWithGrid show={modalShow} onHide={() => setModalShow(false)} />
</>
);
}
render(<App />);
```
Optional Sizes
--------------
You can specify a bootstrap large or small modal by using the "size" prop.
```
function Example() {
const [smShow, setSmShow] = useState(false);
const [lgShow, setLgShow] = useState(false);
return (
<>
<Button onClick={() => setSmShow(true)}>Small modal</Button>{' '}
<Button onClick={() => setLgShow(true)}>Large modal</Button>
<Modal
size="sm"
show={smShow}
onHide={() => setSmShow(false)}
aria-labelledby="example-modal-sizes-title-sm"
>
<Modal.Header closeButton>
<Modal.Title id="example-modal-sizes-title-sm">
Small Modal
</Modal.Title>
</Modal.Header>
<Modal.Body>...</Modal.Body>
</Modal>
<Modal
size="lg"
show={lgShow}
onHide={() => setLgShow(false)}
aria-labelledby="example-modal-sizes-title-lg"
>
<Modal.Header closeButton>
<Modal.Title id="example-modal-sizes-title-lg">
Large Modal
</Modal.Title>
</Modal.Header>
<Modal.Body>...</Modal.Body>
</Modal>
</>
);
}
render(<Example />);
```
### Sizing modals using custom CSS
You can apply custom css to the modal dialog div using the "dialogClassName" prop. Example is using a custom css class with width set to 90%.
```
function Example() {
const [show, setShow] = useState(false);
return (
<>
<Button variant="primary" onClick={() => setShow(true)}>
Custom Width Modal
</Button>
<Modal
show={show}
onHide={() => setShow(false)}
dialogClassName="modal-90w"
aria-labelledby="example-custom-modal-styling-title"
>
<Modal.Header closeButton>
<Modal.Title id="example-custom-modal-styling-title">
Custom Modal Styling
</Modal.Title>
</Modal.Header>
<Modal.Body>
<p>
Ipsum molestiae natus adipisci modi eligendi? Debitis amet quae unde
commodi aspernatur enim, consectetur. Cumque deleniti temporibus
ipsam atque a dolores quisquam quisquam adipisci possimus
laboriosam. Quibusdam facilis doloribus debitis! Sit quasi quod
accusamus eos quod. Ab quos consequuntur eaque quo rem! Mollitia
reiciendis porro quo magni incidunt dolore amet atque facilis ipsum
deleniti rem!
</p>
</Modal.Body>
</Modal>
</>
);
}
render(<Example />);
```
API
---
### Modal
`import Modal from 'react-bootstrap/Modal'`Copy import code for the Modal component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| animation | boolean | `true` | Open and close the Modal with a slide and fade animation. |
| aria-labelledby | any | | |
| autoFocus | boolean | `true` | When `true` The modal will automatically shift focus to itself when it opens, and replace it to the last focused element when it closes. Generally this should never be set to false as it makes the Modal less accessible to assistive technologies, like screen-readers. |
| backdrop | `'static'` | `true` | `false` | `true` | Include a backdrop component. Specify 'static' for a backdrop that doesn't trigger an "onHide" when clicked. |
| backdropClassName | string | | Add an optional extra class name to .modal-backdrop It could end up looking like class="modal-backdrop foo-modal-backdrop in". |
| centered | boolean | | vertically center the Dialog in the window |
| container | any | | |
| contentClassName | string | | Add an optional extra class name to .modal-content |
| dialogAs | elementType | `<ModalDialog>` | A Component type that provides the modal content Markup. This is a useful prop when you want to use your own styles and markup to create a custom modal component. |
| dialogClassName | string | | A css class to apply to the Modal dialog DOM node. |
| enforceFocus | boolean | `true` | When `true` The modal will prevent focus from leaving the Modal while open. Consider leaving the default value here, as it is necessary to make the Modal work well with assistive technologies, such as screen readers. |
| keyboard | boolean | `true` | Close the modal when escape key is pressed |
| manager | object | | A ModalManager instance used to track and manage the state of open Modals. Useful when customizing how modals interact within a container |
| onEnter | function | | Callback fired before the Modal transitions in |
| onEntered | function | | Callback fired after the Modal finishes transitioning in |
| onEntering | function | | Callback fired as the Modal begins to transition in |
| onEscapeKeyDown | function | | A callback fired when the escape key, if specified in `keyboard`, is pressed. |
| onExit | function | | Callback fired right before the Modal transitions out |
| onExited | function | | Callback fired after the Modal finishes transitioning out |
| onExiting | function | | Callback fired as the Modal begins to transition out |
| onHide | function | | A callback fired when the header closeButton or non-static backdrop is clicked. Required if either are specified. |
| onShow | function | | A callback fired when the Modal is opening. |
| restoreFocus | boolean | `true` | When `true` The modal will restore focus to previously focused element once modal is hidden |
| restoreFocusOptions | shape | | Options passed to focus function when `restoreFocus` is set to `true` |
| scrollable | boolean | | Allows scrolling the `<Modal.Body>` instead of the entire Modal when overflowing. |
| show | boolean | `false` | When `true` The modal will show itself. |
| size | `'sm'` | `'lg','xl'` | | Render a large, extra large or small modal. When not provided, the modal is rendered with medium (default) size. |
| bsPrefix | string | `'modal'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ModalDialog
`import ModalDialog from 'react-bootstrap/ModalDialog'`Copy import code for the ModalDialog component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| centered | boolean | | Specify whether the Component should be vertically centered |
| contentClassName | string | | |
| scrollable | boolean | | Allows scrolling the `<Modal.Body>` instead of the entire Modal when overflowing. |
| size | `'sm'` | `'lg','xl'` | | Render a large, extra large or small modal. |
| bsPrefix | string | `'modal'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ModalHeader
`import ModalHeader from 'react-bootstrap/ModalHeader'`Copy import code for the ModalHeader component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| closeButton | boolean | `false` | Specify whether the Component should contain a close button |
| closeLabel | string | `'Close'` | Provides an accessible label for the close button. It is used for Assistive Technology when the label text is not readable. |
| onHide | function | | A Callback fired when the close button is clicked. If used directly inside a Modal component, the onHide will automatically be propagated up to the parent Modal `onHide`. |
| bsPrefix | string | | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ModalTitle
`import ModalTitle from 'react-bootstrap/ModalTitle'`Copy import code for the ModalTitle component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<DivStyledAsH4>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'modal-title'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ModalBody
`import ModalBody from 'react-bootstrap/ModalBody'`Copy import code for the ModalBody component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'modal-body'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ModalFooter
`import ModalFooter from 'react-bootstrap/ModalFooter'`Copy import code for the ModalFooter component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| bsPrefix required | string | `'modal-footer'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Jumbotron Jumbotron
=========
A lightweight, flexible component that can optionally extend the entire viewport to showcase key content on your site.
```
<Jumbotron>
<h1>Hello, world!</h1>
<p>
This is a simple hero unit, a simple jumbotron-style component for calling
extra attention to featured content or information.
</p>
<p>
<Button variant="primary">Learn more</Button>
</p>
</Jumbotron>
```
```
<Jumbotron fluid>
<Container>
<h1>Fluid jumbotron</h1>
<p>
This is a modified jumbotron that occupies the entire horizontal space of
its parent.
</p>
</Container>
</Jumbotron>
```
API
---
### Jumbotron
`import Jumbotron from 'react-bootstrap/Jumbotron'`Copy import code for the Jumbotron component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| fluid | boolean | `false` | Make the jumbotron full width, and without rounded corners |
| bsPrefix | string | `'jumbotron'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Button groups Button groups
=============
Group a series of buttons together on a single line with the button group.
Basic example
-------------
Wrap a series of `<Button>`s in a `<ButtonGroup>`.
```
<ButtonGroup aria-label="Basic example">
<Button variant="secondary">Left</Button>
<Button variant="secondary">Middle</Button>
<Button variant="secondary">Right</Button>
</ButtonGroup>
```
Button toolbar
--------------
Combine sets of `<ButtonGroup>`s into a `<ButtonToolbar>` for more complex components.
```
<ButtonToolbar aria-label="Toolbar with button groups">
<ButtonGroup className="mr-2" aria-label="First group">
<Button>1</Button> <Button>2</Button> <Button>3</Button> <Button>4</Button>
</ButtonGroup>
<ButtonGroup className="mr-2" aria-label="Second group">
<Button>5</Button> <Button>6</Button> <Button>7</Button>
</ButtonGroup>
<ButtonGroup aria-label="Third group">
<Button>8</Button>
</ButtonGroup>
</ButtonToolbar>
```
Feel free to mix input groups with button groups in your toolbars. Similar to the example above, you’ll likely need some utilities though to space things properly.
```
<>
<ButtonToolbar className="mb-3" aria-label="Toolbar with Button groups">
<ButtonGroup className="mr-2" aria-label="First group">
<Button variant="secondary">1</Button>{' '}
<Button variant="secondary">2</Button>{' '}
<Button variant="secondary">3</Button>{' '}
<Button variant="secondary">4</Button>
</ButtonGroup>
<InputGroup>
<InputGroup.Prepend>
<InputGroup.Text id="btnGroupAddon">@</InputGroup.Text>
</InputGroup.Prepend>
<FormControl
type="text"
placeholder="Input group example"
aria-label="Input group example"
aria-describedby="btnGroupAddon"
/>
</InputGroup>
</ButtonToolbar>
<ButtonToolbar
className="justify-content-between"
aria-label="Toolbar with Button groups"
>
<ButtonGroup aria-label="First group">
<Button variant="secondary">1</Button>{' '}
<Button variant="secondary">2</Button>{' '}
<Button variant="secondary">3</Button>{' '}
<Button variant="secondary">4</Button>
</ButtonGroup>
<InputGroup>
<InputGroup.Prepend>
<InputGroup.Text id="btnGroupAddon2">@</InputGroup.Text>
</InputGroup.Prepend>
<FormControl
type="text"
placeholder="Input group example"
aria-label="Input group example"
aria-describedby="btnGroupAddon2"
/>
</InputGroup>
</ButtonToolbar>
</>
```
Sizing
------
Instead of applying button sizing props to every button in a group, just add `size` prop to the `<ButtonGroup>`.
```
<>
<ButtonGroup size="lg" className="mb-2">
<Button>Left</Button>
<Button>Middle</Button>
<Button>Right</Button>
</ButtonGroup>
<br />
<ButtonGroup className="mb-2">
<Button>Left</Button>
<Button>Middle</Button>
<Button>Right</Button>
</ButtonGroup>
<br />
<ButtonGroup size="sm">
<Button>Left</Button>
<Button>Middle</Button>
<Button>Right</Button>
</ButtonGroup>
</>
```
Nesting
-------
You can place other button types within the `<ButtonGroup>` like `<DropdownButton>`s.
```
<ButtonGroup>
<Button>1</Button>
<Button>2</Button>
<DropdownButton as={ButtonGroup} title="Dropdown" id="bg-nested-dropdown">
<Dropdown.Item eventKey="1">Dropdown link</Dropdown.Item>
<Dropdown.Item eventKey="2">Dropdown link</Dropdown.Item>
</DropdownButton>
</ButtonGroup>
```
Vertical variation
------------------
Make a set of buttons appear vertically stacked rather than horizontally, by adding `vertical` to the `<ButtonGroup>`. **Split button dropdowns are not supported here.**
```
<ButtonGroup vertical>
<Button>Button</Button>
<Button>Button</Button>
<DropdownButton as={ButtonGroup} title="Dropdown" id="bg-vertical-dropdown-1">
<Dropdown.Item eventKey="1">Dropdown link</Dropdown.Item>
<Dropdown.Item eventKey="2">Dropdown link</Dropdown.Item>
</DropdownButton>
<Button>Button</Button>
<Button>Button</Button>
<DropdownButton as={ButtonGroup} title="Dropdown" id="bg-vertical-dropdown-2">
<Dropdown.Item eventKey="1">Dropdown link</Dropdown.Item>
<Dropdown.Item eventKey="2">Dropdown link</Dropdown.Item>
</DropdownButton>
<DropdownButton as={ButtonGroup} title="Dropdown" id="bg-vertical-dropdown-3">
<Dropdown.Item eventKey="1">Dropdown link</Dropdown.Item>
<Dropdown.Item eventKey="2">Dropdown link</Dropdown.Item>
</DropdownButton>
</ButtonGroup>
```
API
---
### ButtonGroup
`import ButtonGroup from 'react-bootstrap/ButtonGroup'`Copy import code for the ButtonGroup component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| role | string | `'group'` | An ARIA role describing the button group. Usually the default "group" role is fine. An `aria-label` or `aria-labelledby` prop is also recommended. |
| size | `'sm'` | `'lg'` | | Sets the size for all Buttons in the group. |
| toggle | boolean | `false` |
Display as a button toggle group. (Generally it's better to use `ToggleButtonGroup` directly)
|
| vertical | boolean | `false` | Make the set of Buttons appear vertically stacked. |
| bsPrefix | string | `'btn-group'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
### ButtonToolbar
`import ButtonToolbar from 'react-bootstrap/ButtonToolbar'`Copy import code for the ButtonToolbar component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| role | string | `'toolbar'` | The ARIA role describing the button toolbar. Generally the default "toolbar" role is correct. An `aria-label` or `aria-labelledby` prop is also recommended. |
| bsPrefix | string | `'btn-toolbar'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
| programming_docs |
react_bootstrap Badges Badges
======
Badges scale to match the size of the immediate parent element by using relative font sizing and em units.
```
<div>
<h1>
Example heading <Badge variant="secondary">New</Badge>
</h1>
<h2>
Example heading <Badge variant="secondary">New</Badge>
</h2>
<h3>
Example heading <Badge variant="secondary">New</Badge>
</h3>
<h4>
Example heading <Badge variant="secondary">New</Badge>
</h4>
<h5>
Example heading <Badge variant="secondary">New</Badge>
</h5>
<h6>
Example heading <Badge variant="secondary">New</Badge>
</h6>
</div>
```
Badges can be used as part of links or buttons to provide a counter.
```
<Button variant="primary">
Profile <Badge variant="light">9</Badge>
<span className="sr-only">unread messages</span>
</Button>
```
Note that depending on how they are used, badges may be confusing for users of screen readers and similar assistive technologies. While the styling of badges provides a visual cue as to their purpose, these users will simply be presented with the content of the badge. Depending on the specific situation, these badges may seem like random additional words or numbers at the end of a sentence, link, or button. Unless the context is clear, consider including additional context with a visually hidden piece of additional text.
Contextual variations
---------------------
Add any of the below mentioned modifier classes to change the appearance of a badge.
```
<div>
<Badge variant="primary">Primary</Badge>{' '}
<Badge variant="secondary">Secondary</Badge>{' '}
<Badge variant="success">Success</Badge>{' '}
<Badge variant="danger">Danger</Badge>{' '}
<Badge variant="warning">Warning</Badge> <Badge variant="info">Info</Badge>{' '}
<Badge variant="light">Light</Badge> <Badge variant="dark">Dark</Badge>
</div>
```
Pill
----
badges Use the `pill` modifier class to make badges more rounded (with a larger `border-radius` and additional horizontal `padding`). Useful if you miss the badges from v3.
```
<div>
<Badge pill variant="primary">
Primary
</Badge>{' '}
<Badge pill variant="secondary">
Secondary
</Badge>{' '}
<Badge pill variant="success">
Success
</Badge>{' '}
<Badge pill variant="danger">
Danger
</Badge>{' '}
<Badge pill variant="warning">
Warning
</Badge>{' '}
<Badge pill variant="info">
Info
</Badge>{' '}
<Badge pill variant="light">
Light
</Badge>{' '}
<Badge pill variant="dark">
Dark
</Badge>
</div>
```
API
---
### Badge
`import Badge from 'react-bootstrap/Badge'`Copy import code for the Badge component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| as | elementType | `<span>` | You can use a custom element type for this component. |
| pill | boolean | `false` | Add the `pill` modifier to make badges more rounded with some additional horizontal padding |
| variant | `'primary'` | `'secondary'` | `'success'` | `'danger'` | `'warning'` | `'info'` | `'light'` | `'dark'` | | The visual style of the badge |
| bsPrefix | string | `'badge'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Spinners Spinners
========
Spinners can be used to show the loading state in your projects.
```
<Spinner animation="border" role="status">
<span className="sr-only">Loading...</span>
</Spinner>
```
Animations
----------
Bootstrap offers two animation styles for spinners. The animation style can be configured with the `animation` property. An animation style must always be provided when creating a spinner.
**Border Spinner - `border`**
```
<Spinner animation="border" />
```
**Grow Spinner - `grow`**
```
<Spinner animation="grow" />
```
Variants
--------
All standard visual variants are available for both animation styles by setting the `variant` property. Alternatively spinners can be custom sized with the `style` property, or custom CSS classes.
```
<>
<Spinner animation="border" variant="primary" />
<Spinner animation="border" variant="secondary" />
<Spinner animation="border" variant="success" />
<Spinner animation="border" variant="danger" />
<Spinner animation="border" variant="warning" />
<Spinner animation="border" variant="info" />
<Spinner animation="border" variant="light" />
<Spinner animation="border" variant="dark" />
<Spinner animation="grow" variant="primary" />
<Spinner animation="grow" variant="secondary" />
<Spinner animation="grow" variant="success" />
<Spinner animation="grow" variant="danger" />
<Spinner animation="grow" variant="warning" />
<Spinner animation="grow" variant="info" />
<Spinner animation="grow" variant="light" />
<Spinner animation="grow" variant="dark" />
</>
```
Sizing
------
In addition to the standard size, a smaller additional preconfigured size is available by configuring the `size` property to `sm`.
```
<>
<Spinner animation="border" size="sm" />
<Spinner animation="border" />
<Spinner animation="grow" size="sm" />
<Spinner animation="grow" />
</>
```
Buttons
-------
Like the original Bootstrap spinners, these can also be used with buttons. To use this component out-of-the-box it is recommended you change the element type to `span` by configuring the `as` property when using spinners inside buttons.
```
<>
<Button variant="primary" disabled>
<Spinner
as="span"
animation="border"
size="sm"
role="status"
aria-hidden="true"
/>
<span className="sr-only">Loading...</span>
</Button>{' '}
<Button variant="primary" disabled>
<Spinner
as="span"
animation="grow"
size="sm"
role="status"
aria-hidden="true"
/>
Loading...
</Button>
</>
```
Accessibility
-------------
To ensure the maximum accessibility for spinner components it is recommended you provide a relevant ARIA `role` property, and include screenreader-only readable text representation of the spinner's meaning inside the component using Bootstrap's `sr-only` class.
The example below provides an example of accessible usage of this component.
```
<Spinner animation="border" role="status">
<span className="sr-only">Loading...</span>
</Spinner>
```
API
---
### Spinner
`import Spinner from 'react-bootstrap/Spinner'`Copy import code for the Spinner component
| Name | Type | Default | Description |
| --- | --- | --- | --- |
| animation required | `'border'` | `'grow'` | `true` | Changes the animation style of the spinner. |
| as | elementType | `<div>` | You can use a custom element type for this component. |
| children | element | | This component may be used to wrap child elements or components. |
| role | string | | An ARIA accessible role applied to the Menu component. This should generally be set to 'status' |
| size | `'sm'` | | Component size variations. |
| variant | `'primary'` | `'secondary'` | `'success'` | `'danger'` | `'warning'` | `'info'` | `'light'` | `'dark'` | | The visual color style of the spinner |
| bsPrefix | string | `'spinner'` | Change the underlying component CSS base class name and modifier class names prefix. **This is an escape hatch** for working with heavily customized bootstrap css. |
react_bootstrap Why React-Bootstrap? Why React-Bootstrap?
====================
React-Bootstrap is a complete re-implementation of the Bootstrap components using React. It has **no dependency on either `bootstrap.js` or jQuery.** If you have React setup and React-Bootstrap installed, you have everything you need.
Methods and events using jQuery is done imperatively by directly manipulating the DOM. In contrast, React uses updates to the state to update the virtual DOM. In this way, React-Bootstrap provides a more reliable solution by incorporating Bootstrap functionality into React's virtual DOM. Below are a few examples of how React-Bootstrap components differ from Bootstrap.
A Simple React Component
------------------------
The CSS and details of Bootstrap components are rather opinionated and lengthy. React-Bootstrap simplifies this by condensing the original Bootstrap into React-styled components.
### Bootstrap
```
import React from 'react';
function Example() {
return (
<div class="alert alert-danger alert-dismissible fade show" role="alert">
<strong>Oh snap! You got an error!</strong>
<p>
Change this and that and try again.
</p>
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
)
}
```
### React-Bootstrap
```
import React, { Component } from 'react';
import Alert from 'react-bootstrap/Alert';
function Example() {
return (
<Alert dismissible variant="danger">
<Alert.Heading>Oh snap! You got an error!</Alert.Heading>
<p>
Change this and that and try again.
</p>
</Alert>
)
}
```
Bootstrap with state
--------------------
Since React-Bootstrap is built with React Javascript, state can be passed within React-Bootstrap components as a prop. It also makes it easier to manage the state as updates are made using React’s state instead of directly manipulating the state of the DOM. This also gives a lot of flexibility when creating more complex components.
### React-bootstrap
```
function AlertDismissible() {
const [show, setShow] = useState(true);
return (
<>
<Alert show={show} variant="success">
<Alert.Heading>How's it going?!</Alert.Heading>
<p>
Duis mollis, est non commodo luctus, nisi erat porttitor ligula, eget
lacinia odio sem nec elit. Cras mattis consectetur purus sit amet
fermentum.
</p>
<hr />
<div className="d-flex justify-content-end">
<Button onClick={() => setShow(false)} variant="outline-success">
Close me y'all!
</Button>
</div>
</Alert>
{!show && <Button onClick={() => setShow(true)}>Show Alert</Button>}
</>
);
}
render(<AlertDismissible />);
```
### Bootstrap
```
// HTML
<div class="alert alert-success alert-dismissible fade show firstCollapsible" role="alert">
<strong>How's it going?!</strong>
<p>
Duis mollis, est non commodo luctus, nisi erat porttitor ligula,
eget lacinia odio sem nec elit. Cras mattis consectetur purus sit
amet fermentum.
</p>
<hr/>
<div class="d-flex justify-content-end">
<button type="button" class="btn btn-outline-success">Close me ya'll!</button>
</div>
</div>
<div class="d-flex justify-content-start alert fade show">
<button type="button" class="btn btn-primary d-none secondCollapsible">Show Alert</button>
</div>
// Javascript
$('.btn-outline-success').on('click', function(e) {
$('.firstCollapsible').addClass('d-none');
$('.secondCollapsible').removeClass('d-none');
})
$('.btn-primary').on('click', function(e) {
$('.firstCollapsible').removeClass('d-none');
$('.secondCollapsible').addClass('d-none');
})
```
react_bootstrap Introduction Introduction
============
Learn how to include React Bootstrap in your project
Installation
------------
The best way to consume React-Bootstrap is via the npm package which you can install with `npm` (or `yarn` if you prefer).
If you plan on customizing the Bootstrap Sass files, or don't want to use a CDN for the stylesheet, it may be helpful to install [vanilla Bootstrap](https://getbootstrap.com/docs/4.6/getting-started/download/#npm) as well.
```
npm install react-bootstrap bootstrap
```
Importing Components
--------------------
You should import individual components like: `react-bootstrap/Button` rather than the entire library. Doing so pulls in only the specific components that you use, which can significantly reduce the amount of code you end up sending to the client.
```
import Button from 'react-bootstrap/Button';
// or less ideally
import { Button } from 'react-bootstrap';
```
### Browser globals
We provide `react-bootstrap.js` and `react-bootstrap.min.js` bundles with all components exported on the `window.ReactBootstrap` object. These bundles are available on [unpkg](https://unpkg.com/react-bootstrap/), as well as in the npm package.
```
<script src="https://unpkg.com/react/umd/react.production.min.js" crossorigin></script>
<script
src="https://unpkg.com/react-dom/umd/react-dom.production.min.js"
crossorigin></script>
<script
src="https://unpkg.com/react-bootstrap@next/dist/react-bootstrap.min.js"
crossorigin></script>
<script>var Alert = ReactBootstrap.Alert;</script>
```
Examples
--------
React-Bootstrap has started a repo with a few basic CodeSandbox examples. [Click here](https://github.com/react-bootstrap/code-sandbox-examples/blob/master/README.md) to check them out.
Stylesheets
-----------
Because React-Bootstrap doesn't depend on a very precise version of Bootstrap, we don't ship with any included CSS. However, some stylesheet **is required** to use these components.
### CSS
```
{/\* The following line can be included in your src/index.js or App.js file\*/}
import 'bootstrap/dist/css/bootstrap.min.css';
```
How and which Bootstrap styles you include is up to you, but the simplest way is to include the latest styles from the CDN. A little more information about the benefits of using a CDN can be found [here](https://www.w3schools.com/bootstrap/bootstrap_get_started.asp).
```
<link
rel="stylesheet"
href="https://maxcdn.bootstrapcdn.com/bootstrap/4.6.0/css/bootstrap.min.css"
integrity="sha384-B0vP5xmATw1+K9KRQjQERJvTumQW0nPEzvF6L/Z6nronJ3oUOFUFpCjEUQouq2+l"
crossorigin="anonymous"
/>
```
### Sass
In case you are using **Sass** the simplest way is to include the Bootstrap’s source Sass files in your main Sass file and then require it on your `src/index.js` or `App.js` file. This applies to a typical `create-react-app` application in other use cases you might have to setup the bundler of your choice to compile Sass/SCSS stylesheets to CSS.
```
/\* The following line can be included in a src/App.scss \*/
@import "~bootstrap/scss/bootstrap";
/\* The following line can be included in your src/index.js or App.js file \*/
import './App.scss';
```
#### Customize Bootstrap
If you wish to customize the Bootstrap theme or any Bootstrap variables you can create a custom Sass file:
```
/\* The following block can be included in a custom.scss \*/
/\* make the customizations \*/
$theme-colors: (
"info": tomato,
"danger": teal
);
/\* import bootstrap to set changes \*/
@import "~bootstrap/scss/bootstrap";
```
... And import it on the main Sass file.
```
/\* The following line can be included in a src/App.scss \*/
@import "custom";
```
### Advanced usage
See [the Bootstrap docs](https://getbootstrap.com/docs/4.4/getting-started/theming/) for more advanced use cases and details about customizing stylesheets.
Themes
------
React-Bootstrap is compatible with existing Bootstrap themes. Just follow the installation instructions for your theme of choice.
Browser support
---------------
We aim to support all browsers supported by both [React](http://facebook.github.io/react/docs/working-with-the-browser.html#browser-support-and-polyfills) and [Bootstrap](https://getbootstrap.com/docs/4.6/getting-started/browsers-devices/#supported-browsers).
react_bootstrap Theming and customizing styles Theming and customizing styles
==============================
Generally, if you stick to the Bootstrap defined classes and variants, there isn't anything you need to do to use a custom theme with React-Bootstrap. It just works. But we also make coloring outside the lines easy to do.
New variants and sizes
----------------------
Custom variants and sizes should follow the pattern of the default bootstrap variants, and define css classes matching: `component-*`. React bootstrap builds the component `classNames` in a consistent way that you can rely on. For instance this custom Button.
```
<>
<style type="text/css">
{`
.btn-flat {
background-color: purple;
color: white;
}
.btn-xxl {
padding: 1rem 1.5rem;
font-size: 1.5rem;
}
`}
</style>
<Button variant="flat" size="xxl">
flat button
</Button>
</>
```
Prefixing components
--------------------
In some cases you may need to change the base class "prefix" of one or more Components. You can control how a Component prefixes its classes locally by changing the `bsPrefix` prop. Or globally via the `ThemeProvider` Component.
```
<>
{/* Hint: inspect the markup to see how the classes differ */}
<ThemeProvider prefixes={{ btn: 'my-btn' }}>
<Button variant="primary">My Button</Button>
</ThemeProvider>{' '}
<Button bsPrefix="super-btn" variant="primary">
Super button
</Button>
</>
```
react_bootstrap Getting help Getting help
============
Stay up to date on the development of React-Bootstrap and reach out to the community with these helpful resources.
Stack Overflow
--------------
[Ask questions](http://stackoverflow.com/questions/ask) about specific problems you have faced, including details about what exactly you are trying to do. Make sure you tag your question with `react-bootstrap`. You can also read through [existing React-Bootstrap questions](http://stackoverflow.com/questions/tagged/react-bootstrap).
Chat rooms
----------
Discuss questions in the `#react-bootstrap` channel on the [Reactiflux Discord](https://discord.gg/AKfs9vpvRW).
GitHub issues
-------------
The issue tracker is the preferred channel for bug reports, features requests and submitting pull requests. See more about how we use issues in the [contribution guidelines](https://github.com/react-bootstrap/react-bootstrap/blob/master/CONTRIBUTING.md#issues).
electron What is Electron? What is Electron?
=================
Electron is a framework for building desktop applications using JavaScript, HTML, and CSS. By embedding [Chromium](https://www.chromium.org/) and [Node.js](https://nodejs.org/) into its binary, Electron allows you to maintain one JavaScript codebase and create cross-platform apps that work on Windows, macOS, and Linux — no native development experience required.
Getting started[](#getting-started "Direct link to heading")
-------------------------------------------------------------
We recommend you to start with the [tutorial](tutorial/tutorial-prerequisites), which guides you through the process of developing an Electron app and distributing it to users. The [examples](tutorial/examples) and [API documentation](api/app) are also good places to browse around and discover new things.
Running examples with Electron Fiddle[](#running-examples-with-electron-fiddle "Direct link to heading")
---------------------------------------------------------------------------------------------------------
[Electron Fiddle](https://electronjs.org/fiddle) is a sandbox app written with Electron and supported by Electron's maintainers. We highly recommend installing it as a learning tool to experiment with Electron's APIs or to prototype features during development.
Fiddle also integrates nicely with our documentation. When browsing through examples in our tutorials, you'll frequently see an "Open in Electron Fiddle" button underneath a code block. If you have Fiddle installed, this button will open a `fiddle.electronjs.org` link that will automatically load the example into Fiddle, no copy-pasting required.
[docs/fiddles/quick-start (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/quick-start)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/quick-start)
* main.js
* preload.js
* index.html
```
const { app, BrowserWindow } = require('electron')
const path = require('path')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
win.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
```
```
window.addEventListener('DOMContentLoaded', () => {
const replaceText = (selector, text) => {
const element = document.getElementById(selector)
if (element) element.innerText = text
}
for (const type of ['chrome', 'node', 'electron']) {
replaceText(`${type}-version`, process.versions[type])
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>
We are using Node.js <span id="node-version"></span>,
Chromium <span id="chrome-version"></span>,
and Electron <span id="electron-version"></span>.
</p>
</body>
</html>
```
What is in the docs?[](#what-is-in-the-docs "Direct link to heading")
----------------------------------------------------------------------
All the official documentation is available from the sidebar. These are the different categories and what you can expect on each one:
* **Tutorial**: An end-to-end guide on how to create and publish your first Electron application.
* **Processes in Electron**: In-depth reference on Electron processes and how to work with them.
* **Best Practices**: Important checklists to keep in mind when developing an Electron app.
* **Examples**: Quick references to add features to your Electron app.
* **Development**: Miscellaneous development guides.
* **Distribution**: Learn how to distribute your app to end users.
* **Testing and debugging**: How to debug JavaScript, write tests, and other tools used to create quality Electron applications.
* **References**: Useful links to better understand how the Electron project works and is organized.
* **Contributing**: Compiling Electron and making contributions can be daunting. We try to make it easier in this section.
Getting help[](#getting-help "Direct link to heading")
-------------------------------------------------------
Are you getting stuck anywhere? Here are a few links to places to look:
* If you need help with developing your app, our [community Discord server](https://discord.com/invite/APGC3k5yaH) is a great place to get advice from other Electron app developers.
* If you suspect you're running into a bug with the `electron` package, please check the [GitHub issue tracker](https://github.com/electron/electron/issues) to see if any existing issues match your problem. If not, feel free to fill out our bug report template and submit a new issue.
| programming_docs |
electron Breaking Changes Breaking Changes
================
Breaking changes will be documented here, and deprecation warnings added to JS code where possible, at least [one major version](tutorial/electron-versioning#semver) before the change is made.
### Types of Breaking Changes[](#types-of-breaking-changes "Direct link to heading")
This document uses the following convention to categorize breaking changes:
* **API Changed:** An API was changed in such a way that code that has not been updated is guaranteed to throw an exception.
* **Behavior Changed:** The behavior of Electron has changed, but not in such a way that an exception will necessarily be thrown.
* **Default Changed:** Code depending on the old default may break, not necessarily throwing an exception. The old behavior can be restored by explicitly specifying the value.
* **Deprecated:** An API was marked as deprecated. The API will continue to function, but will emit a deprecation warning, and will be removed in a future release.
* **Removed:** An API or feature was removed, and is no longer supported by Electron.
Planned Breaking API Changes (20.0)[](#planned-breaking-api-changes-200 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Default Changed: renderers without `nodeIntegration: true` are sandboxed by default[](#default-changed-renderers-without-nodeintegration-true-are-sandboxed-by-default "Direct link to heading")
Previously, renderers that specified a preload script defaulted to being unsandboxed. This meant that by default, preload scripts had access to Node.js. In Electron 20, this default has changed. Beginning in Electron 20, renderers will be sandboxed by default, unless `nodeIntegration: true` or `sandbox: false` is specified.
If your preload scripts do not depend on Node, no action is needed. If your preload scripts *do* depend on Node, either refactor them to remove Node usage from the renderer, or explicitly specify `sandbox: false` for the relevant renderers.
### Removed: `skipTaskbar` on Linux[](#removed-skiptaskbar-on-linux "Direct link to heading")
On X11, `skipTaskbar` sends a `_NET_WM_STATE_SKIP_TASKBAR` message to the X11 window manager. There is not a direct equivalent for Wayland, and the known workarounds have unacceptable tradeoffs (e.g. Window.is\_skip\_taskbar in GNOME requires unsafe mode), so Electron is unable to support this feature on Linux.
### API Changed: `session.setDevicePermissionHandler(handler)`[](#api-changed-sessionsetdevicepermissionhandlerhandler "Direct link to heading")
The handler invoked when `session.setDevicePermissionHandler(handler)` is used has a change to its arguments. This handler no longer is passed a frame `[WebFrameMain](/docs/latest/api/web-frame-main)`, but instead is passed the `origin`, which is the origin that is checking for device permission.
Planned Breaking API Changes (19.0)[](#planned-breaking-api-changes-190 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Removed: IA32 Linux binaries[](#removed-ia32-linux-binaries "Direct link to heading")
This is a result of Chromium 102.0.4999.0 dropping support for IA32 Linux. This concludes the [removal of support for IA32 Linux](#removed-ia32-linux-support).
Planned Breaking API Changes (18.0)[](#planned-breaking-api-changes-180 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Removed: `nativeWindowOpen`[](#removed-nativewindowopen "Direct link to heading")
Prior to Electron 15, `window.open` was by default shimmed to use `BrowserWindowProxy`. This meant that `window.open('about:blank')` did not work to open synchronously scriptable child windows, among other incompatibilities. Since Electron 15, `nativeWindowOpen` has been enabled by default.
See the documentation for [window.open in Electron](api/window-open) for more details.
Planned Breaking API Changes (17.0)[](#planned-breaking-api-changes-170 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Removed: `desktopCapturer.getSources` in the renderer[](#removed-desktopcapturergetsources-in-the-renderer "Direct link to heading")
The `desktopCapturer.getSources` API is now only available in the main process. This has been changed in order to improve the default security of Electron apps.
If you need this functionality, it can be replaced as follows:
```
// Main process
const { ipcMain, desktopCapturer } = require('electron')
ipcMain.handle(
'DESKTOP_CAPTURER_GET_SOURCES',
(event, opts) => desktopCapturer.getSources(opts)
)
```
```
// Renderer process
const { ipcRenderer } = require('electron')
const desktopCapturer = {
getSources: (opts) => ipcRenderer.invoke('DESKTOP_CAPTURER_GET_SOURCES', opts)
}
```
However, you should consider further restricting the information returned to the renderer; for instance, displaying a source selector to the user and only returning the selected source.
### Deprecated: `nativeWindowOpen`[](#deprecated-nativewindowopen "Direct link to heading")
Prior to Electron 15, `window.open` was by default shimmed to use `BrowserWindowProxy`. This meant that `window.open('about:blank')` did not work to open synchronously scriptable child windows, among other incompatibilities. Since Electron 15, `nativeWindowOpen` has been enabled by default.
See the documentation for [window.open in Electron](api/window-open) for more details.
Planned Breaking API Changes (16.0)[](#planned-breaking-api-changes-160 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Behavior Changed: `crashReporter` implementation switched to Crashpad on Linux[](#behavior-changed-crashreporter-implementation-switched-to-crashpad-on-linux "Direct link to heading")
The underlying implementation of the `crashReporter` API on Linux has changed from Breakpad to Crashpad, bringing it in line with Windows and Mac. As a result of this, child processes are now automatically monitored, and calling `process.crashReporter.start` in Node child processes is no longer needed (and is not advisable, as it will start a second instance of the Crashpad reporter).
There are also some subtle changes to how annotations will be reported on Linux, including that long values will no longer be split between annotations appended with `__1`, `__2` and so on, and instead will be truncated at the (new, longer) annotation value limit.
### Deprecated: `desktopCapturer.getSources` in the renderer[](#deprecated-desktopcapturergetsources-in-the-renderer "Direct link to heading")
Usage of the `desktopCapturer.getSources` API in the renderer has been deprecated and will be removed. This change improves the default security of Electron apps.
See [here](#removed-desktopcapturergetsources-in-the-renderer) for details on how to replace this API in your app.
Planned Breaking API Changes (15.0)[](#planned-breaking-api-changes-150 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Default Changed: `nativeWindowOpen` defaults to `true`[](#default-changed-nativewindowopen-defaults-to-true "Direct link to heading")
Prior to Electron 15, `window.open` was by default shimmed to use `BrowserWindowProxy`. This meant that `window.open('about:blank')` did not work to open synchronously scriptable child windows, among other incompatibilities. `nativeWindowOpen` is no longer experimental, and is now the default.
See the documentation for [window.open in Electron](api/window-open) for more details.
Planned Breaking API Changes (14.0)[](#planned-breaking-api-changes-140 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Removed: `remote` module[](#removed-remote-module "Direct link to heading")
The `remote` module was deprecated in Electron 12, and will be removed in Electron 14. It is replaced by the [`@electron/remote`](https://github.com/electron/remote) module.
```
// Deprecated in Electron 12:
const { BrowserWindow } = require('electron').remote
```
```
// Replace with:
const { BrowserWindow } = require('@electron/remote')
// In the main process:
require('@electron/remote/main').initialize()
```
### Removed: `app.allowRendererProcessReuse`[](#removed-appallowrendererprocessreuse "Direct link to heading")
The `app.allowRendererProcessReuse` property will be removed as part of our plan to more closely align with Chromium's process model for security, performance and maintainability.
For more detailed information see [#18397](https://github.com/electron/electron/issues/18397).
### Removed: Browser Window Affinity[](#removed-browser-window-affinity "Direct link to heading")
The `affinity` option when constructing a new `BrowserWindow` will be removed as part of our plan to more closely align with Chromium's process model for security, performance and maintainability.
For more detailed information see [#18397](https://github.com/electron/electron/issues/18397).
### API Changed: `window.open()`[](#api-changed-windowopen "Direct link to heading")
The optional parameter `frameName` will no longer set the title of the window. This now follows the specification described by the [native documentation](https://developer.mozilla.org/en-US/docs/Web/API/Window/open#parameters) under the corresponding parameter `windowName`.
If you were using this parameter to set the title of a window, you can instead use [win.setTitle(title)](api/browser-window#winsettitletitle).
### Removed: `worldSafeExecuteJavaScript`[](#removed-worldsafeexecutejavascript "Direct link to heading")
In Electron 14, `worldSafeExecuteJavaScript` will be removed. There is no alternative, please ensure your code works with this property enabled. It has been enabled by default since Electron 12.
You will be affected by this change if you use either `webFrame.executeJavaScript` or `webFrame.executeJavaScriptInIsolatedWorld`. You will need to ensure that values returned by either of those methods are supported by the [Context Bridge API](api/context-bridge#parameter--error--return-type-support) as these methods use the same value passing semantics.
### Removed: BrowserWindowConstructorOptions inheriting from parent windows[](#removed-browserwindowconstructoroptions-inheriting-from-parent-windows "Direct link to heading")
Prior to Electron 14, windows opened with `window.open` would inherit BrowserWindow constructor options such as `transparent` and `resizable` from their parent window. Beginning with Electron 14, this behavior is removed, and windows will not inherit any BrowserWindow constructor options from their parents.
Instead, explicitly set options for the new window with `setWindowOpenHandler`:
```
webContents.setWindowOpenHandler((details) => {
return {
action: 'allow',
overrideBrowserWindowOptions: {
// ...
}
}
})
```
### Removed: `additionalFeatures`[](#removed-additionalfeatures "Direct link to heading")
The deprecated `additionalFeatures` property in the `new-window` and `did-create-window` events of WebContents has been removed. Since `new-window` uses positional arguments, the argument is still present, but will always be the empty array `[]`. (Though note, the `new-window` event itself is deprecated, and is replaced by `setWindowOpenHandler`.) Bare keys in window features will now present as keys with the value `true` in the options object.
```
// Removed in Electron 14
// Triggered by window.open('...', '', 'my-key')
webContents.on('did-create-window', (window, details) => {
if (details.additionalFeatures.includes('my-key')) {
// ...
}
})
// Replace with
webContents.on('did-create-window', (window, details) => {
if (details.options['my-key']) {
// ...
}
})
```
Planned Breaking API Changes (13.0)[](#planned-breaking-api-changes-130 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### API Changed: `session.setPermissionCheckHandler(handler)`[](#api-changed-sessionsetpermissioncheckhandlerhandler "Direct link to heading")
The `handler` methods first parameter was previously always a `webContents`, it can now sometimes be `null`. You should use the `requestingOrigin`, `embeddingOrigin` and `securityOrigin` properties to respond to the permission check correctly. As the `webContents` can be `null` it can no longer be relied on.
```
// Old code
session.setPermissionCheckHandler((webContents, permission) => {
if (webContents.getURL().startsWith('https://google.com/') && permission === 'notification') {
return true
}
return false
})
// Replace with
session.setPermissionCheckHandler((webContents, permission, requestingOrigin) => {
if (new URL(requestingOrigin).hostname === 'google.com' && permission === 'notification') {
return true
}
return false
})
```
### Removed: `shell.moveItemToTrash()`[](#removed-shellmoveitemtotrash "Direct link to heading")
The deprecated synchronous `shell.moveItemToTrash()` API has been removed. Use the asynchronous `shell.trashItem()` instead.
```
// Removed in Electron 13
shell.moveItemToTrash(path)
// Replace with
shell.trashItem(path).then(/* ... */)
```
### Removed: `BrowserWindow` extension APIs[](#removed-browserwindow-extension-apis "Direct link to heading")
The deprecated extension APIs have been removed:
* `BrowserWindow.addExtension(path)`
* `BrowserWindow.addDevToolsExtension(path)`
* `BrowserWindow.removeExtension(name)`
* `BrowserWindow.removeDevToolsExtension(name)`
* `BrowserWindow.getExtensions()`
* `BrowserWindow.getDevToolsExtensions()`
Use the session APIs instead:
* `ses.loadExtension(path)`
* `ses.removeExtension(extension_id)`
* `ses.getAllExtensions()`
```
// Removed in Electron 13
BrowserWindow.addExtension(path)
BrowserWindow.addDevToolsExtension(path)
// Replace with
session.defaultSession.loadExtension(path)
```
```
// Removed in Electron 13
BrowserWindow.removeExtension(name)
BrowserWindow.removeDevToolsExtension(name)
// Replace with
session.defaultSession.removeExtension(extension_id)
```
```
// Removed in Electron 13
BrowserWindow.getExtensions()
BrowserWindow.getDevToolsExtensions()
// Replace with
session.defaultSession.getAllExtensions()
```
### Removed: methods in `systemPreferences`[](#removed-methods-in-systempreferences "Direct link to heading")
The following `systemPreferences` methods have been deprecated:
* `systemPreferences.isDarkMode()`
* `systemPreferences.isInvertedColorScheme()`
* `systemPreferences.isHighContrastColorScheme()`
Use the following `nativeTheme` properties instead:
* `nativeTheme.shouldUseDarkColors`
* `nativeTheme.shouldUseInvertedColorScheme`
* `nativeTheme.shouldUseHighContrastColors`
```
// Removed in Electron 13
systemPreferences.isDarkMode()
// Replace with
nativeTheme.shouldUseDarkColors
// Removed in Electron 13
systemPreferences.isInvertedColorScheme()
// Replace with
nativeTheme.shouldUseInvertedColorScheme
// Removed in Electron 13
systemPreferences.isHighContrastColorScheme()
// Replace with
nativeTheme.shouldUseHighContrastColors
```
### Deprecated: WebContents `new-window` event[](#deprecated-webcontents-new-window-event "Direct link to heading")
The `new-window` event of WebContents has been deprecated. It is replaced by [`webContents.setWindowOpenHandler()`](api/web-contents#contentssetwindowopenhandlerhandler).
```
// Deprecated in Electron 13
webContents.on('new-window', (event) => {
event.preventDefault()
})
// Replace with
webContents.setWindowOpenHandler((details) => {
return { action: 'deny' }
})
```
Planned Breaking API Changes (12.0)[](#planned-breaking-api-changes-120 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Removed: Pepper Flash support[](#removed-pepper-flash-support "Direct link to heading")
Chromium has removed support for Flash, and so we must follow suit. See Chromium's [Flash Roadmap](https://www.chromium.org/flash-roadmap) for more details.
### Default Changed: `worldSafeExecuteJavaScript` defaults to `true`[](#default-changed-worldsafeexecutejavascript-defaults-to-true "Direct link to heading")
In Electron 12, `worldSafeExecuteJavaScript` will be enabled by default. To restore the previous behavior, `worldSafeExecuteJavaScript: false` must be specified in WebPreferences. Please note that setting this option to `false` is **insecure**.
This option will be removed in Electron 14 so please migrate your code to support the default value.
### Default Changed: `contextIsolation` defaults to `true`[](#default-changed-contextisolation-defaults-to-true "Direct link to heading")
In Electron 12, `contextIsolation` will be enabled by default. To restore the previous behavior, `contextIsolation: false` must be specified in WebPreferences.
We [recommend having contextIsolation enabled](tutorial/security#3-enable-context-isolation) for the security of your application.
Another implication is that `require()` cannot be used in the renderer process unless `nodeIntegration` is `true` and `contextIsolation` is `false`.
For more details see: <https://github.com/electron/electron/issues/23506>
### Removed: `crashReporter.getCrashesDirectory()`[](#removed-crashreportergetcrashesdirectory "Direct link to heading")
The `crashReporter.getCrashesDirectory` method has been removed. Usage should be replaced by `app.getPath('crashDumps')`.
```
// Removed in Electron 12
crashReporter.getCrashesDirectory()
// Replace with
app.getPath('crashDumps')
```
### Removed: `crashReporter` methods in the renderer process[](#removed-crashreporter-methods-in-the-renderer-process "Direct link to heading")
The following `crashReporter` methods are no longer available in the renderer process:
* `crashReporter.start`
* `crashReporter.getLastCrashReport`
* `crashReporter.getUploadedReports`
* `crashReporter.getUploadToServer`
* `crashReporter.setUploadToServer`
* `crashReporter.getCrashesDirectory`
They should be called only from the main process.
See [#23265](https://github.com/electron/electron/pull/23265) for more details.
### Default Changed: `crashReporter.start({ compress: true })`[](#default-changed-crashreporterstart-compress-true- "Direct link to heading")
The default value of the `compress` option to `crashReporter.start` has changed from `false` to `true`. This means that crash dumps will be uploaded to the crash ingestion server with the `Content-Encoding: gzip` header, and the body will be compressed.
If your crash ingestion server does not support compressed payloads, you can turn off compression by specifying `{ compress: false }` in the crash reporter options.
### Deprecated: `remote` module[](#deprecated-remote-module "Direct link to heading")
The `remote` module is deprecated in Electron 12, and will be removed in Electron 14. It is replaced by the [`@electron/remote`](https://github.com/electron/remote) module.
```
// Deprecated in Electron 12:
const { BrowserWindow } = require('electron').remote
```
```
// Replace with:
const { BrowserWindow } = require('@electron/remote')
// In the main process:
require('@electron/remote/main').initialize()
```
### Deprecated: `shell.moveItemToTrash()`[](#deprecated-shellmoveitemtotrash "Direct link to heading")
The synchronous `shell.moveItemToTrash()` has been replaced by the new, asynchronous `shell.trashItem()`.
```
// Deprecated in Electron 12
shell.moveItemToTrash(path)
// Replace with
shell.trashItem(path).then(/* ... */)
```
Planned Breaking API Changes (11.0)[](#planned-breaking-api-changes-110 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Removed: `BrowserView.{destroy, fromId, fromWebContents, getAllViews}` and `id` property of `BrowserView`[](#removed-browserviewdestroy-fromid-fromwebcontents-getallviews-and-id-property-of-browserview "Direct link to heading")
The experimental APIs `BrowserView.{destroy, fromId, fromWebContents, getAllViews}` have now been removed. Additionally, the `id` property of `BrowserView` has also been removed.
For more detailed information, see [#23578](https://github.com/electron/electron/pull/23578).
Planned Breaking API Changes (10.0)[](#planned-breaking-api-changes-100 "Direct link to heading")
--------------------------------------------------------------------------------------------------
### Deprecated: `companyName` argument to `crashReporter.start()`[](#deprecated-companyname-argument-to-crashreporterstart "Direct link to heading")
The `companyName` argument to `crashReporter.start()`, which was previously required, is now optional, and further, is deprecated. To get the same behavior in a non-deprecated way, you can pass a `companyName` value in `globalExtra`.
```
// Deprecated in Electron 10
crashReporter.start({ companyName: 'Umbrella Corporation' })
// Replace with
crashReporter.start({ globalExtra: { _companyName: 'Umbrella Corporation' } })
```
### Deprecated: `crashReporter.getCrashesDirectory()`[](#deprecated-crashreportergetcrashesdirectory "Direct link to heading")
The `crashReporter.getCrashesDirectory` method has been deprecated. Usage should be replaced by `app.getPath('crashDumps')`.
```
// Deprecated in Electron 10
crashReporter.getCrashesDirectory()
// Replace with
app.getPath('crashDumps')
```
### Deprecated: `crashReporter` methods in the renderer process[](#deprecated-crashreporter-methods-in-the-renderer-process "Direct link to heading")
Calling the following `crashReporter` methods from the renderer process is deprecated:
* `crashReporter.start`
* `crashReporter.getLastCrashReport`
* `crashReporter.getUploadedReports`
* `crashReporter.getUploadToServer`
* `crashReporter.setUploadToServer`
* `crashReporter.getCrashesDirectory`
The only non-deprecated methods remaining in the `crashReporter` module in the renderer are `addExtraParameter`, `removeExtraParameter` and `getParameters`.
All above methods remain non-deprecated when called from the main process.
See [#23265](https://github.com/electron/electron/pull/23265) for more details.
### Deprecated: `crashReporter.start({ compress: false })`[](#deprecated-crashreporterstart-compress-false- "Direct link to heading")
Setting `{ compress: false }` in `crashReporter.start` is deprecated. Nearly all crash ingestion servers support gzip compression. This option will be removed in a future version of Electron.
### Default Changed: `enableRemoteModule` defaults to `false`[](#default-changed-enableremotemodule-defaults-to-false "Direct link to heading")
In Electron 9, using the remote module without explicitly enabling it via the `enableRemoteModule` WebPreferences option began emitting a warning. In Electron 10, the remote module is now disabled by default. To use the remote module, `enableRemoteModule: true` must be specified in WebPreferences:
```
const w = new BrowserWindow({
webPreferences: {
enableRemoteModule: true
}
})
```
We [recommend moving away from the remote module](https://medium.com/@nornagon/electrons-remote-module-considered-harmful-70d69500f31).
###
`protocol.unregisterProtocol`[](#protocolunregisterprotocol "Direct link to heading")
###
`protocol.uninterceptProtocol`[](#protocoluninterceptprotocol "Direct link to heading")
The APIs are now synchronous and the optional callback is no longer needed.
```
// Deprecated
protocol.unregisterProtocol(scheme, () => { /* ... */ })
// Replace with
protocol.unregisterProtocol(scheme)
```
###
`protocol.registerFileProtocol`[](#protocolregisterfileprotocol "Direct link to heading")
###
`protocol.registerBufferProtocol`[](#protocolregisterbufferprotocol "Direct link to heading")
###
`protocol.registerStringProtocol`[](#protocolregisterstringprotocol "Direct link to heading")
###
`protocol.registerHttpProtocol`[](#protocolregisterhttpprotocol "Direct link to heading")
###
`protocol.registerStreamProtocol`[](#protocolregisterstreamprotocol "Direct link to heading")
###
`protocol.interceptFileProtocol`[](#protocolinterceptfileprotocol "Direct link to heading")
###
`protocol.interceptStringProtocol`[](#protocolinterceptstringprotocol "Direct link to heading")
###
`protocol.interceptBufferProtocol`[](#protocolinterceptbufferprotocol "Direct link to heading")
###
`protocol.interceptHttpProtocol`[](#protocolintercepthttpprotocol "Direct link to heading")
###
`protocol.interceptStreamProtocol`[](#protocolinterceptstreamprotocol "Direct link to heading")
The APIs are now synchronous and the optional callback is no longer needed.
```
// Deprecated
protocol.registerFileProtocol(scheme, handler, () => { /* ... */ })
// Replace with
protocol.registerFileProtocol(scheme, handler)
```
The registered or intercepted protocol does not have effect on current page until navigation happens.
###
`protocol.isProtocolHandled`[](#protocolisprotocolhandled "Direct link to heading")
This API is deprecated and users should use `protocol.isProtocolRegistered` and `protocol.isProtocolIntercepted` instead.
```
// Deprecated
protocol.isProtocolHandled(scheme).then(() => { /* ... */ })
// Replace with
const isRegistered = protocol.isProtocolRegistered(scheme)
const isIntercepted = protocol.isProtocolIntercepted(scheme)
```
Planned Breaking API Changes (9.0)[](#planned-breaking-api-changes-90 "Direct link to heading")
------------------------------------------------------------------------------------------------
### Default Changed: Loading non-context-aware native modules in the renderer process is disabled by default[](#default-changed-loading-non-context-aware-native-modules-in-the-renderer-process-is-disabled-by-default "Direct link to heading")
As of Electron 9 we do not allow loading of non-context-aware native modules in the renderer process. This is to improve security, performance and maintainability of Electron as a project.
If this impacts you, you can temporarily set `app.allowRendererProcessReuse` to `false` to revert to the old behavior. This flag will only be an option until Electron 11 so you should plan to update your native modules to be context aware.
For more detailed information see [#18397](https://github.com/electron/electron/issues/18397).
### Deprecated: `BrowserWindow` extension APIs[](#deprecated-browserwindow-extension-apis "Direct link to heading")
The following extension APIs have been deprecated:
* `BrowserWindow.addExtension(path)`
* `BrowserWindow.addDevToolsExtension(path)`
* `BrowserWindow.removeExtension(name)`
* `BrowserWindow.removeDevToolsExtension(name)`
* `BrowserWindow.getExtensions()`
* `BrowserWindow.getDevToolsExtensions()`
Use the session APIs instead:
* `ses.loadExtension(path)`
* `ses.removeExtension(extension_id)`
* `ses.getAllExtensions()`
```
// Deprecated in Electron 9
BrowserWindow.addExtension(path)
BrowserWindow.addDevToolsExtension(path)
// Replace with
session.defaultSession.loadExtension(path)
```
```
// Deprecated in Electron 9
BrowserWindow.removeExtension(name)
BrowserWindow.removeDevToolsExtension(name)
// Replace with
session.defaultSession.removeExtension(extension_id)
```
```
// Deprecated in Electron 9
BrowserWindow.getExtensions()
BrowserWindow.getDevToolsExtensions()
// Replace with
session.defaultSession.getAllExtensions()
```
### Removed: `<webview>.getWebContents()`[](#removed-webviewgetwebcontents "Direct link to heading")
This API, which was deprecated in Electron 8.0, is now removed.
```
// Removed in Electron 9.0
webview.getWebContents()
// Replace with
const { remote } = require('electron')
remote.webContents.fromId(webview.getWebContentsId())
```
### Removed: `webFrame.setLayoutZoomLevelLimits()`[](#removed-webframesetlayoutzoomlevellimits "Direct link to heading")
Chromium has removed support for changing the layout zoom level limits, and it is beyond Electron's capacity to maintain it. The function was deprecated in Electron 8.x, and has been removed in Electron 9.x. The layout zoom level limits are now fixed at a minimum of 0.25 and a maximum of 5.0, as defined [here](https://chromium.googlesource.com/chromium/src/+/938b37a6d2886bf8335fc7db792f1eb46c65b2ae/third_party/blink/common/page/page_zoom.cc#11).
### Behavior Changed: Sending non-JS objects over IPC now throws an exception[](#behavior-changed-sending-non-js-objects-over-ipc-now-throws-an-exception "Direct link to heading")
In Electron 8.0, IPC was changed to use the Structured Clone Algorithm, bringing significant performance improvements. To help ease the transition, the old IPC serialization algorithm was kept and used for some objects that aren't serializable with Structured Clone. In particular, DOM objects (e.g. `Element`, `Location` and `DOMMatrix`), Node.js objects backed by C++ classes (e.g. `process.env`, some members of `Stream`), and Electron objects backed by C++ classes (e.g. `WebContents`, `BrowserWindow` and `WebFrame`) are not serializable with Structured Clone. Whenever the old algorithm was invoked, a deprecation warning was printed.
In Electron 9.0, the old serialization algorithm has been removed, and sending such non-serializable objects will now throw an "object could not be cloned" error.
### API Changed: `shell.openItem` is now `shell.openPath`[](#api-changed-shellopenitem-is-now-shellopenpath "Direct link to heading")
The `shell.openItem` API has been replaced with an asynchronous `shell.openPath` API. You can see the original API proposal and reasoning [here](https://github.com/electron/governance/blob/main/wg-api/spec-documents/shell-openitem.md).
Planned Breaking API Changes (8.0)[](#planned-breaking-api-changes-80 "Direct link to heading")
------------------------------------------------------------------------------------------------
### Behavior Changed: Values sent over IPC are now serialized with Structured Clone Algorithm[](#behavior-changed-values-sent-over-ipc-are-now-serialized-with-structured-clone-algorithm "Direct link to heading")
The algorithm used to serialize objects sent over IPC (through `ipcRenderer.send`, `ipcRenderer.sendSync`, `WebContents.send` and related methods) has been switched from a custom algorithm to V8's built-in [Structured Clone Algorithm](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm), the same algorithm used to serialize messages for `postMessage`. This brings about a 2x performance improvement for large messages, but also brings some breaking changes in behavior.
* Sending Functions, Promises, WeakMaps, WeakSets, or objects containing any such values, over IPC will now throw an exception, instead of silently converting the functions to `undefined`.
```
// Previously:
ipcRenderer.send('channel', { value: 3, someFunction: () => {} })
// => results in { value: 3 } arriving in the main process
// From Electron 8:
ipcRenderer.send('channel', { value: 3, someFunction: () => {} })
// => throws Error("() => {} could not be cloned.")
```
* `NaN`, `Infinity` and `-Infinity` will now be correctly serialized, instead of being converted to `null`.
* Objects containing cyclic references will now be correctly serialized, instead of being converted to `null`.
* `Set`, `Map`, `Error` and `RegExp` values will be correctly serialized, instead of being converted to `{}`.
* `BigInt` values will be correctly serialized, instead of being converted to `null`.
* Sparse arrays will be serialized as such, instead of being converted to dense arrays with `null`s.
* `Date` objects will be transferred as `Date` objects, instead of being converted to their ISO string representation.
* Typed Arrays (such as `Uint8Array`, `Uint16Array`, `Uint32Array` and so on) will be transferred as such, instead of being converted to Node.js `Buffer`.
* Node.js `Buffer` objects will be transferred as `Uint8Array`s. You can convert a `Uint8Array` back to a Node.js `Buffer` by wrapping the underlying `ArrayBuffer`:
```
Buffer.from(value.buffer, value.byteOffset, value.byteLength)
```
Sending any objects that aren't native JS types, such as DOM objects (e.g. `Element`, `Location`, `DOMMatrix`), Node.js objects (e.g. `process.env`, `Stream`), or Electron objects (e.g. `WebContents`, `BrowserWindow`, `WebFrame`) is deprecated. In Electron 8, these objects will be serialized as before with a DeprecationWarning message, but starting in Electron 9, sending these kinds of objects will throw a 'could not be cloned' error.
### Deprecated: `<webview>.getWebContents()`[](#deprecated-webviewgetwebcontents "Direct link to heading")
This API is implemented using the `remote` module, which has both performance and security implications. Therefore its usage should be explicit.
```
// Deprecated
webview.getWebContents()
// Replace with
const { remote } = require('electron')
remote.webContents.fromId(webview.getWebContentsId())
```
However, it is recommended to avoid using the `remote` module altogether.
```
// main
const { ipcMain, webContents } = require('electron')
const getGuestForWebContents = (webContentsId, contents) => {
const guest = webContents.fromId(webContentsId)
if (!guest) {
throw new Error(`Invalid webContentsId: ${webContentsId}`)
}
if (guest.hostWebContents !== contents) {
throw new Error('Access denied to webContents')
}
return guest
}
ipcMain.handle('openDevTools', (event, webContentsId) => {
const guest = getGuestForWebContents(webContentsId, event.sender)
guest.openDevTools()
})
// renderer
const { ipcRenderer } = require('electron')
ipcRenderer.invoke('openDevTools', webview.getWebContentsId())
```
### Deprecated: `webFrame.setLayoutZoomLevelLimits()`[](#deprecated-webframesetlayoutzoomlevellimits "Direct link to heading")
Chromium has removed support for changing the layout zoom level limits, and it is beyond Electron's capacity to maintain it. The function will emit a warning in Electron 8.x, and cease to exist in Electron 9.x. The layout zoom level limits are now fixed at a minimum of 0.25 and a maximum of 5.0, as defined [here](https://chromium.googlesource.com/chromium/src/+/938b37a6d2886bf8335fc7db792f1eb46c65b2ae/third_party/blink/common/page/page_zoom.cc#11).
### Deprecated events in `systemPreferences`[](#deprecated-events-in-systempreferences "Direct link to heading")
The following `systemPreferences` events have been deprecated:
* `inverted-color-scheme-changed`
* `high-contrast-color-scheme-changed`
Use the new `updated` event on the `nativeTheme` module instead.
```
// Deprecated
systemPreferences.on('inverted-color-scheme-changed', () => { /* ... */ })
systemPreferences.on('high-contrast-color-scheme-changed', () => { /* ... */ })
// Replace with
nativeTheme.on('updated', () => { /* ... */ })
```
### Deprecated: methods in `systemPreferences`[](#deprecated-methods-in-systempreferences "Direct link to heading")
The following `systemPreferences` methods have been deprecated:
* `systemPreferences.isDarkMode()`
* `systemPreferences.isInvertedColorScheme()`
* `systemPreferences.isHighContrastColorScheme()`
Use the following `nativeTheme` properties instead:
* `nativeTheme.shouldUseDarkColors`
* `nativeTheme.shouldUseInvertedColorScheme`
* `nativeTheme.shouldUseHighContrastColors`
```
// Deprecated
systemPreferences.isDarkMode()
// Replace with
nativeTheme.shouldUseDarkColors
// Deprecated
systemPreferences.isInvertedColorScheme()
// Replace with
nativeTheme.shouldUseInvertedColorScheme
// Deprecated
systemPreferences.isHighContrastColorScheme()
// Replace with
nativeTheme.shouldUseHighContrastColors
```
Planned Breaking API Changes (7.0)[](#planned-breaking-api-changes-70 "Direct link to heading")
------------------------------------------------------------------------------------------------
### Deprecated: Atom.io Node Headers URL[](#deprecated-atomio-node-headers-url "Direct link to heading")
This is the URL specified as `disturl` in a `.npmrc` file or as the `--dist-url` command line flag when building native Node modules. Both will be supported for the foreseeable future but it is recommended that you switch.
Deprecated: <https://atom.io/download/electron>
Replace with: <https://electronjs.org/headers>
### API Changed: `session.clearAuthCache()` no longer accepts options[](#api-changed-sessionclearauthcache-no-longer-accepts-options "Direct link to heading")
The `session.clearAuthCache` API no longer accepts options for what to clear, and instead unconditionally clears the whole cache.
```
// Deprecated
session.clearAuthCache({ type: 'password' })
// Replace with
session.clearAuthCache()
```
### API Changed: `powerMonitor.querySystemIdleState` is now `powerMonitor.getSystemIdleState`[](#api-changed-powermonitorquerysystemidlestate-is-now-powermonitorgetsystemidlestate "Direct link to heading")
```
// Removed in Electron 7.0
powerMonitor.querySystemIdleState(threshold, callback)
// Replace with synchronous API
const idleState = powerMonitor.getSystemIdleState(threshold)
```
### API Changed: `powerMonitor.querySystemIdleTime` is now `powerMonitor.getSystemIdleTime`[](#api-changed-powermonitorquerysystemidletime-is-now-powermonitorgetsystemidletime "Direct link to heading")
```
// Removed in Electron 7.0
powerMonitor.querySystemIdleTime(callback)
// Replace with synchronous API
const idleTime = powerMonitor.getSystemIdleTime()
```
### API Changed: `webFrame.setIsolatedWorldInfo` replaces separate methods[](#api-changed-webframesetisolatedworldinfo-replaces-separate-methods "Direct link to heading")
```
// Removed in Electron 7.0
webFrame.setIsolatedWorldContentSecurityPolicy(worldId, csp)
webFrame.setIsolatedWorldHumanReadableName(worldId, name)
webFrame.setIsolatedWorldSecurityOrigin(worldId, securityOrigin)
// Replace with
webFrame.setIsolatedWorldInfo(
worldId,
{
securityOrigin: 'some_origin',
name: 'human_readable_name',
csp: 'content_security_policy'
})
```
### Removed: `marked` property on `getBlinkMemoryInfo`[](#removed-marked-property-on-getblinkmemoryinfo "Direct link to heading")
This property was removed in Chromium 77, and as such is no longer available.
### Behavior Changed: `webkitdirectory` attribute for `<input type="file"/>` now lists directory contents[](#behavior-changed-webkitdirectory-attribute-for-input-typefile-now-lists-directory-contents "Direct link to heading")
The `webkitdirectory` property on HTML file inputs allows them to select folders. Previous versions of Electron had an incorrect implementation where the `event.target.files` of the input returned a `FileList` that returned one `File` corresponding to the selected folder.
As of Electron 7, that `FileList` is now list of all files contained within the folder, similarly to Chrome, Firefox, and Edge ([link to MDN docs](https://developer.mozilla.org/en-US/docs/Web/API/HTMLInputElement/webkitdirectory)).
As an illustration, take a folder with this structure:
```
folder
├── file1
├── file2
└── file3
```
In Electron <=6, this would return a `FileList` with a `File` object for:
```
path/to/folder
```
In Electron 7, this now returns a `FileList` with a `File` object for:
```
/path/to/folder/file3
/path/to/folder/file2
/path/to/folder/file1
```
Note that `webkitdirectory` no longer exposes the path to the selected folder. If you require the path to the selected folder rather than the folder contents, see the `dialog.showOpenDialog` API ([link](api/dialog#dialogshowopendialogbrowserwindow-options)).
### API Changed: Callback-based versions of promisified APIs[](#api-changed-callback-based-versions-of-promisified-apis "Direct link to heading")
Electron 5 and Electron 6 introduced Promise-based versions of existing asynchronous APIs and deprecated their older, callback-based counterparts. In Electron 7, all deprecated callback-based APIs are now removed.
These functions now only return Promises:
* `app.getFileIcon()` [#15742](https://github.com/electron/electron/pull/15742)
* `app.dock.show()` [#16904](https://github.com/electron/electron/pull/16904)
* `contentTracing.getCategories()` [#16583](https://github.com/electron/electron/pull/16583)
* `contentTracing.getTraceBufferUsage()` [#16600](https://github.com/electron/electron/pull/16600)
* `contentTracing.startRecording()` [#16584](https://github.com/electron/electron/pull/16584)
* `contentTracing.stopRecording()` [#16584](https://github.com/electron/electron/pull/16584)
* `contents.executeJavaScript()` [#17312](https://github.com/electron/electron/pull/17312)
* `cookies.flushStore()` [#16464](https://github.com/electron/electron/pull/16464)
* `cookies.get()` [#16464](https://github.com/electron/electron/pull/16464)
* `cookies.remove()` [#16464](https://github.com/electron/electron/pull/16464)
* `cookies.set()` [#16464](https://github.com/electron/electron/pull/16464)
* `debugger.sendCommand()` [#16861](https://github.com/electron/electron/pull/16861)
* `dialog.showCertificateTrustDialog()` [#17181](https://github.com/electron/electron/pull/17181)
* `inAppPurchase.getProducts()` [#17355](https://github.com/electron/electron/pull/17355)
* `inAppPurchase.purchaseProduct()`[#17355](https://github.com/electron/electron/pull/17355)
* `netLog.stopLogging()` [#16862](https://github.com/electron/electron/pull/16862)
* `session.clearAuthCache()` [#17259](https://github.com/electron/electron/pull/17259)
* `session.clearCache()` [#17185](https://github.com/electron/electron/pull/17185)
* `session.clearHostResolverCache()` [#17229](https://github.com/electron/electron/pull/17229)
* `session.clearStorageData()` [#17249](https://github.com/electron/electron/pull/17249)
* `session.getBlobData()` [#17303](https://github.com/electron/electron/pull/17303)
* `session.getCacheSize()` [#17185](https://github.com/electron/electron/pull/17185)
* `session.resolveProxy()` [#17222](https://github.com/electron/electron/pull/17222)
* `session.setProxy()` [#17222](https://github.com/electron/electron/pull/17222)
* `shell.openExternal()` [#16176](https://github.com/electron/electron/pull/16176)
* `webContents.loadFile()` [#15855](https://github.com/electron/electron/pull/15855)
* `webContents.loadURL()` [#15855](https://github.com/electron/electron/pull/15855)
* `webContents.hasServiceWorker()` [#16535](https://github.com/electron/electron/pull/16535)
* `webContents.printToPDF()` [#16795](https://github.com/electron/electron/pull/16795)
* `webContents.savePage()` [#16742](https://github.com/electron/electron/pull/16742)
* `webFrame.executeJavaScript()` [#17312](https://github.com/electron/electron/pull/17312)
* `webFrame.executeJavaScriptInIsolatedWorld()` [#17312](https://github.com/electron/electron/pull/17312)
* `webviewTag.executeJavaScript()` [#17312](https://github.com/electron/electron/pull/17312)
* `win.capturePage()` [#15743](https://github.com/electron/electron/pull/15743)
These functions now have two forms, synchronous and Promise-based asynchronous:
* `dialog.showMessageBox()`/`dialog.showMessageBoxSync()` [#17298](https://github.com/electron/electron/pull/17298)
* `dialog.showOpenDialog()`/`dialog.showOpenDialogSync()` [#16973](https://github.com/electron/electron/pull/16973)
* `dialog.showSaveDialog()`/`dialog.showSaveDialogSync()` [#17054](https://github.com/electron/electron/pull/17054)
Planned Breaking API Changes (6.0)[](#planned-breaking-api-changes-60 "Direct link to heading")
------------------------------------------------------------------------------------------------
### API Changed: `win.setMenu(null)` is now `win.removeMenu()`[](#api-changed-winsetmenunull-is-now-winremovemenu "Direct link to heading")
```
// Deprecated
win.setMenu(null)
// Replace with
win.removeMenu()
```
### API Changed: `electron.screen` in the renderer process should be accessed via `remote`[](#api-changed-electronscreen-in-the-renderer-process-should-be-accessed-via-remote "Direct link to heading")
```
// Deprecated
require('electron').screen
// Replace with
require('electron').remote.screen
```
### API Changed: `require()`ing node builtins in sandboxed renderers no longer implicitly loads the `remote` version[](#api-changed-requireing-node-builtins-in-sandboxed-renderers-no-longer-implicitly-loads-the-remote-version "Direct link to heading")
```
// Deprecated
require('child_process')
// Replace with
require('electron').remote.require('child_process')
// Deprecated
require('fs')
// Replace with
require('electron').remote.require('fs')
// Deprecated
require('os')
// Replace with
require('electron').remote.require('os')
// Deprecated
require('path')
// Replace with
require('electron').remote.require('path')
```
### Deprecated: `powerMonitor.querySystemIdleState` replaced with `powerMonitor.getSystemIdleState`[](#deprecated-powermonitorquerysystemidlestate-replaced-with-powermonitorgetsystemidlestate "Direct link to heading")
```
// Deprecated
powerMonitor.querySystemIdleState(threshold, callback)
// Replace with synchronous API
const idleState = powerMonitor.getSystemIdleState(threshold)
```
### Deprecated: `powerMonitor.querySystemIdleTime` replaced with `powerMonitor.getSystemIdleTime`[](#deprecated-powermonitorquerysystemidletime-replaced-with-powermonitorgetsystemidletime "Direct link to heading")
```
// Deprecated
powerMonitor.querySystemIdleTime(callback)
// Replace with synchronous API
const idleTime = powerMonitor.getSystemIdleTime()
```
### Deprecated: `app.enableMixedSandbox()` is no longer needed[](#deprecated-appenablemixedsandbox-is-no-longer-needed "Direct link to heading")
```
// Deprecated
app.enableMixedSandbox()
```
Mixed-sandbox mode is now enabled by default.
### Deprecated: `Tray.setHighlightMode`[](#deprecated-traysethighlightmode "Direct link to heading")
Under macOS Catalina our former Tray implementation breaks. Apple's native substitute doesn't support changing the highlighting behavior.
```
// Deprecated
tray.setHighlightMode(mode)
// API will be removed in v7.0 without replacement.
```
Planned Breaking API Changes (5.0)[](#planned-breaking-api-changes-50 "Direct link to heading")
------------------------------------------------------------------------------------------------
### Default Changed: `nodeIntegration` and `webviewTag` default to false, `contextIsolation` defaults to true[](#default-changed-nodeintegration-and-webviewtag-default-to-false-contextisolation-defaults-to-true "Direct link to heading")
The following `webPreferences` option default values are deprecated in favor of the new defaults listed below.
| Property | Deprecated Default | New Default |
| --- | --- | --- |
| `contextIsolation` | `false` | `true` |
| `nodeIntegration` | `true` | `false` |
| `webviewTag` | `nodeIntegration` if set else `true` | `false` |
E.g. Re-enabling the webviewTag
```
const w = new BrowserWindow({
webPreferences: {
webviewTag: true
}
})
```
### Behavior Changed: `nodeIntegration` in child windows opened via `nativeWindowOpen`[](#behavior-changed-nodeintegration-in-child-windows-opened-via-nativewindowopen "Direct link to heading")
Child windows opened with the `nativeWindowOpen` option will always have Node.js integration disabled, unless `nodeIntegrationInSubFrames` is `true`.
### API Changed: Registering privileged schemes must now be done before app ready[](#api-changed-registering-privileged-schemes-must-now-be-done-before-app-ready "Direct link to heading")
Renderer process APIs `webFrame.registerURLSchemeAsPrivileged` and `webFrame.registerURLSchemeAsBypassingCSP` as well as browser process API `protocol.registerStandardSchemes` have been removed. A new API, `protocol.registerSchemesAsPrivileged` has been added and should be used for registering custom schemes with the required privileges. Custom schemes are required to be registered before app ready.
### Deprecated: `webFrame.setIsolatedWorld*` replaced with `webFrame.setIsolatedWorldInfo`[](#deprecated-webframesetisolatedworld-replaced-with-webframesetisolatedworldinfo "Direct link to heading")
```
// Deprecated
webFrame.setIsolatedWorldContentSecurityPolicy(worldId, csp)
webFrame.setIsolatedWorldHumanReadableName(worldId, name)
webFrame.setIsolatedWorldSecurityOrigin(worldId, securityOrigin)
// Replace with
webFrame.setIsolatedWorldInfo(
worldId,
{
securityOrigin: 'some_origin',
name: 'human_readable_name',
csp: 'content_security_policy'
})
```
### API Changed: `webFrame.setSpellCheckProvider` now takes an asynchronous callback[](#api-changed-webframesetspellcheckprovider-now-takes-an-asynchronous-callback "Direct link to heading")
The `spellCheck` callback is now asynchronous, and `autoCorrectWord` parameter has been removed.
```
// Deprecated
webFrame.setSpellCheckProvider('en-US', true, {
spellCheck: (text) => {
return !spellchecker.isMisspelled(text)
}
})
// Replace with
webFrame.setSpellCheckProvider('en-US', {
spellCheck: (words, callback) => {
callback(words.filter(text => spellchecker.isMisspelled(text)))
}
})
```
### API Changed: `webContents.getZoomLevel` and `webContents.getZoomFactor` are now synchronous[](#api-changed-webcontentsgetzoomlevel-and-webcontentsgetzoomfactor-are-now-synchronous "Direct link to heading")
`webContents.getZoomLevel` and `webContents.getZoomFactor` no longer take callback parameters, instead directly returning their number values.
```
// Deprecated
webContents.getZoomLevel((level) => {
console.log(level)
})
// Replace with
const level = webContents.getZoomLevel()
console.log(level)
```
```
// Deprecated
webContents.getZoomFactor((factor) => {
console.log(factor)
})
// Replace with
const factor = webContents.getZoomFactor()
console.log(factor)
```
Planned Breaking API Changes (4.0)[](#planned-breaking-api-changes-40 "Direct link to heading")
------------------------------------------------------------------------------------------------
The following list includes the breaking API changes made in Electron 4.0.
###
`app.makeSingleInstance`[](#appmakesingleinstance "Direct link to heading")
```
// Deprecated
app.makeSingleInstance((argv, cwd) => {
/* ... */
})
// Replace with
app.requestSingleInstanceLock()
app.on('second-instance', (event, argv, cwd) => {
/* ... */
})
```
###
`app.releaseSingleInstance`[](#appreleasesingleinstance "Direct link to heading")
```
// Deprecated
app.releaseSingleInstance()
// Replace with
app.releaseSingleInstanceLock()
```
###
`app.getGPUInfo`[](#appgetgpuinfo "Direct link to heading")
```
app.getGPUInfo('complete')
// Now behaves the same with `basic` on macOS
app.getGPUInfo('basic')
```
###
`win_delay_load_hook`[](#win_delay_load_hook "Direct link to heading")
When building native modules for windows, the `win_delay_load_hook` variable in the module's `binding.gyp` must be true (which is the default). If this hook is not present, then the native module will fail to load on Windows, with an error message like `Cannot find module`. See the [native module guide](tutorial/using-native-node-modules) for more.
### Removed: IA32 Linux support[](#removed-ia32-linux-support "Direct link to heading")
Electron 18 will no longer run on 32-bit Linux systems. See [discontinuing support for 32-bit Linux](https://www.electronjs.org/blog/linux-32bit-support) for more information.
Breaking API Changes (3.0)[](#breaking-api-changes-30 "Direct link to heading")
--------------------------------------------------------------------------------
The following list includes the breaking API changes in Electron 3.0.
###
`app`[](#app "Direct link to heading")
```
// Deprecated
app.getAppMemoryInfo()
// Replace with
app.getAppMetrics()
// Deprecated
const metrics = app.getAppMetrics()
const { memory } = metrics[0] // Deprecated property
```
###
`BrowserWindow`[](#browserwindow "Direct link to heading")
```
// Deprecated
const optionsA = { webPreferences: { blinkFeatures: '' } }
const windowA = new BrowserWindow(optionsA)
// Replace with
const optionsB = { webPreferences: { enableBlinkFeatures: '' } }
const windowB = new BrowserWindow(optionsB)
// Deprecated
window.on('app-command', (e, cmd) => {
if (cmd === 'media-play_pause') {
// do something
}
})
// Replace with
window.on('app-command', (e, cmd) => {
if (cmd === 'media-play-pause') {
// do something
}
})
```
###
`clipboard`[](#clipboard "Direct link to heading")
```
// Deprecated
clipboard.readRtf()
// Replace with
clipboard.readRTF()
// Deprecated
clipboard.writeRtf()
// Replace with
clipboard.writeRTF()
// Deprecated
clipboard.readHtml()
// Replace with
clipboard.readHTML()
// Deprecated
clipboard.writeHtml()
// Replace with
clipboard.writeHTML()
```
###
`crashReporter`[](#crashreporter "Direct link to heading")
```
// Deprecated
crashReporter.start({
companyName: 'Crashly',
submitURL: 'https://crash.server.com',
autoSubmit: true
})
// Replace with
crashReporter.start({
companyName: 'Crashly',
submitURL: 'https://crash.server.com',
uploadToServer: true
})
```
###
`nativeImage`[](#nativeimage "Direct link to heading")
```
// Deprecated
nativeImage.createFromBuffer(buffer, 1.0)
// Replace with
nativeImage.createFromBuffer(buffer, {
scaleFactor: 1.0
})
```
###
`process`[](#process "Direct link to heading")
```
// Deprecated
const info = process.getProcessMemoryInfo()
```
###
`screen`[](#screen "Direct link to heading")
```
// Deprecated
screen.getMenuBarHeight()
// Replace with
screen.getPrimaryDisplay().workArea
```
###
`session`[](#session "Direct link to heading")
```
// Deprecated
ses.setCertificateVerifyProc((hostname, certificate, callback) => {
callback(true)
})
// Replace with
ses.setCertificateVerifyProc((request, callback) => {
callback(0)
})
```
###
`Tray`[](#tray "Direct link to heading")
```
// Deprecated
tray.setHighlightMode(true)
// Replace with
tray.setHighlightMode('on')
// Deprecated
tray.setHighlightMode(false)
// Replace with
tray.setHighlightMode('off')
```
###
`webContents`[](#webcontents "Direct link to heading")
```
// Deprecated
webContents.openDevTools({ detach: true })
// Replace with
webContents.openDevTools({ mode: 'detach' })
// Removed
webContents.setSize(options)
// There is no replacement for this API
```
###
`webFrame`[](#webframe "Direct link to heading")
```
// Deprecated
webFrame.registerURLSchemeAsSecure('app')
// Replace with
protocol.registerStandardSchemes(['app'], { secure: true })
// Deprecated
webFrame.registerURLSchemeAsPrivileged('app', { secure: true })
// Replace with
protocol.registerStandardSchemes(['app'], { secure: true })
```
###
`<webview>`[](#webview "Direct link to heading")
```
// Removed
webview.setAttribute('disableguestresize', '')
// There is no replacement for this API
// Removed
webview.setAttribute('guestinstance', instanceId)
// There is no replacement for this API
// Keyboard listeners no longer work on webview tag
webview.onkeydown = () => { /* handler */ }
webview.onkeyup = () => { /* handler */ }
```
### Node Headers URL[](#node-headers-url "Direct link to heading")
This is the URL specified as `disturl` in a `.npmrc` file or as the `--dist-url` command line flag when building native Node modules.
Deprecated: <https://atom.io/download/atom-shell>
Replace with: <https://atom.io/download/electron>
Breaking API Changes (2.0)[](#breaking-api-changes-20 "Direct link to heading")
--------------------------------------------------------------------------------
The following list includes the breaking API changes made in Electron 2.0.
###
`BrowserWindow`[](#browserwindow-1 "Direct link to heading")
```
// Deprecated
const optionsA = { titleBarStyle: 'hidden-inset' }
const windowA = new BrowserWindow(optionsA)
// Replace with
const optionsB = { titleBarStyle: 'hiddenInset' }
const windowB = new BrowserWindow(optionsB)
```
###
`menu`[](#menu "Direct link to heading")
```
// Removed
menu.popup(browserWindow, 100, 200, 2)
// Replaced with
menu.popup(browserWindow, { x: 100, y: 200, positioningItem: 2 })
```
###
`nativeImage`[](#nativeimage-1 "Direct link to heading")
```
// Removed
nativeImage.toPng()
// Replaced with
nativeImage.toPNG()
// Removed
nativeImage.toJpeg()
// Replaced with
nativeImage.toJPEG()
```
###
`process`[](#process-1 "Direct link to heading")
* `process.versions.electron` and `process.version.chrome` will be made read-only properties for consistency with the other `process.versions` properties set by Node.
###
`webContents`[](#webcontents-1 "Direct link to heading")
```
// Removed
webContents.setZoomLevelLimits(1, 2)
// Replaced with
webContents.setVisualZoomLevelLimits(1, 2)
```
###
`webFrame`[](#webframe-1 "Direct link to heading")
```
// Removed
webFrame.setZoomLevelLimits(1, 2)
// Replaced with
webFrame.setVisualZoomLevelLimits(1, 2)
```
###
`<webview>`[](#webview-1 "Direct link to heading")
```
// Removed
webview.setZoomLevelLimits(1, 2)
// Replaced with
webview.setVisualZoomLevelLimits(1, 2)
```
### Duplicate ARM Assets[](#duplicate-arm-assets "Direct link to heading")
Each Electron release includes two identical ARM builds with slightly different filenames, like `electron-v1.7.3-linux-arm.zip` and `electron-v1.7.3-linux-armv7l.zip`. The asset with the `v7l` prefix was added to clarify to users which ARM version it supports, and to disambiguate it from future armv6l and arm64 assets that may be produced.
The file *without the prefix* is still being published to avoid breaking any setups that may be consuming it. Starting at 2.0, the unprefixed file will no longer be published.
For details, see [6986](https://github.com/electron/electron/pull/6986) and [7189](https://github.com/electron/electron/pull/7189).
| programming_docs |
electron Glossary Glossary
========
This page defines some terminology that is commonly used in Electron development.
### ASAR[](#asar "Direct link to heading")
ASAR stands for Atom Shell Archive Format. An [asar](https://github.com/electron/asar) archive is a simple `tar`-like format that concatenates files into a single file. Electron can read arbitrary files from it without unpacking the whole file.
The ASAR format was created primarily to improve performance on Windows when reading large quantities of small files (e.g. when loading your app's JavaScript dependency tree from `node_modules`).
### code signing[](#code-signing "Direct link to heading")
Code signing is a process where an app developer digitally signs their code to ensure that it hasn't been tampered with after packaging. Both Windows and macOS implement their own version of code signing. As a desktop app developer, it's important that you sign your code if you plan on distributing it to the general public.
For more information, read the [Code Signing](tutorial/code-signing) tutorial.
### context isolation[](#context-isolation "Direct link to heading")
Context isolation is a security measure in Electron that ensures that your preload script cannot leak privileged Electron or Node.js APIs to the web contents in your renderer process. With context isolation enabled, the only way to expose APIs from your preload script is through the `contextBridge` API.
For more information, read the [Context Isolation](tutorial/context-isolation) tutorial.
See also: [preload script](#preload-script), [renderer process](#renderer-process)
### CRT[](#crt "Direct link to heading")
The C Runtime Library (CRT) is the part of the C++ Standard Library that incorporates the ISO C99 standard library. The Visual C++ libraries that implement the CRT support native code development, and both mixed native and managed code, and pure managed code for .NET development.
### DMG[](#dmg "Direct link to heading")
An Apple Disk Image is a packaging format used by macOS. DMG files are commonly used for distributing application "installers".
### IME[](#ime "Direct link to heading")
Input Method Editor. A program that allows users to enter characters and symbols not found on their keyboard. For example, this allows users of Latin keyboards to input Chinese, Japanese, Korean and Indic characters.
### IDL[](#idl "Direct link to heading")
Interface description language. Write function signatures and data types in a format that can be used to generate interfaces in Java, C++, JavaScript, etc.
### IPC[](#ipc "Direct link to heading")
IPC stands for inter-process communication. Electron uses IPC to send serialized JSON messages between the main and renderer processes.
see also: [main process](#main-process), [renderer process](#renderer-process)
### main process[](#main-process "Direct link to heading")
The main process, commonly a file named `main.js`, is the entry point to every Electron app. It controls the life of the app, from open to close. It also manages native elements such as the Menu, Menu Bar, Dock, Tray, etc. The main process is responsible for creating each new renderer process in the app. The full Node API is built in.
Every app's main process file is specified in the `main` property in `package.json`. This is how `electron .` knows what file to execute at startup.
In Chromium, this process is referred to as the "browser process". It is renamed in Electron to avoid confusion with renderer processes.
See also: [process](#process), [renderer process](#renderer-process)
### MAS[](#mas "Direct link to heading")
Acronym for Apple's Mac App Store. For details on submitting your app to the MAS, see the [Mac App Store Submission Guide](tutorial/mac-app-store-submission-guide).
### Mojo[](#mojo "Direct link to heading")
An IPC system for communicating intra- or inter-process, and that's important because Chrome is keen on being able to split its work into separate processes or not, depending on memory pressures etc.
See <https://chromium.googlesource.com/chromium/src/+/main/mojo/README.md>
See also: [IPC](#ipc)
### MSI[](#msi "Direct link to heading")
On Windows, MSI packages are used by the Windows Installer (also known as Microsoft Installer) service to install and configure applications.
More information can be found in [Microsoft's documentation](https://docs.microsoft.com/en-us/windows/win32/msi/windows-installer-portal).
### native modules[](#native-modules "Direct link to heading")
Native modules (also called [addons](https://nodejs.org/api/addons.html) in Node.js) are modules written in C or C++ that can be loaded into Node.js or Electron using the require() function, and used as if they were an ordinary Node.js module. They are used primarily to provide an interface between JavaScript running in Node.js and C/C++ libraries.
Native Node modules are supported by Electron, but since Electron is very likely to use a different V8 version from the Node binary installed in your system, you have to manually specify the location of Electron’s headers when building native modules.
For more information, read the [Native Node Modules] tutorial.
### notarization[](#notarization "Direct link to heading")
Notarization is a macOS-specific process where a developer can send a code-signed app to Apple servers to get verified for malicious components through an automated service.
See also: [code signing](#code-signing)
### OSR[](#osr "Direct link to heading")
OSR (offscreen rendering) can be used for loading heavy page in background and then displaying it after (it will be much faster). It allows you to render page without showing it on screen.
For more information, read the [Offscreen Rendering][osr] tutorial.
### preload script[](#preload-script "Direct link to heading")
Preload scripts contain code that executes in a renderer process before its web contents begin loading. These scripts run within the renderer context, but are granted more privileges by having access to Node.js APIs.
See also: [renderer process](#renderer-process), [context isolation](#context-isolation)
### process[](#process "Direct link to heading")
A process is an instance of a computer program that is being executed. Electron apps that make use of the [main](#main-process) and one or many [renderer](#renderer-process) process are actually running several programs simultaneously.
In Node.js and Electron, each running process has a `process` object. This object is a global that provides information about, and control over, the current process. As a global, it is always available to applications without using require().
See also: [main process](#main-process), [renderer process](#renderer-process)
### renderer process[](#renderer-process "Direct link to heading")
The renderer process is a browser window in your app. Unlike the main process, there can be multiple of these and each is run in a separate process. They can also be hidden.
See also: [process](#process), [main process](#main-process)
### sandbox[](#sandbox "Direct link to heading")
The sandbox is a security feature inherited from Chromium that restricts your renderer processes to a limited set of permissions.
For more information, read the [Process Sandboxing](tutorial/sandbox) tutorial.
See also: [process](#process)
### Squirrel[](#squirrel "Direct link to heading")
Squirrel is an open-source framework that enables Electron apps to update automatically as new versions are released. See the [autoUpdater](api/auto-updater) API for info about getting started with Squirrel.
### userland[](#userland "Direct link to heading")
This term originated in the Unix community, where "userland" or "userspace" referred to programs that run outside of the operating system kernel. More recently, the term has been popularized in the Node and npm community to distinguish between the features available in "Node core" versus packages published to the npm registry by the much larger "user" community.
Like Node, Electron is focused on having a small set of APIs that provide all the necessary primitives for developing multi-platform desktop applications. This design philosophy allows Electron to remain a flexible tool without being overly prescriptive about how it should be used. Userland enables users to create and share tools that provide additional functionality on top of what is available in "core".
### V8[](#v8 "Direct link to heading")
V8 is Google's open source JavaScript engine. It is written in C++ and is used in Google Chrome. V8 can run standalone, or can be embedded into any C++ application.
Electron builds V8 as part of Chromium and then points Node to that V8 when building it.
V8's version numbers always correspond to those of Google Chrome. Chrome 59 includes V8 5.9, Chrome 58 includes V8 5.8, etc.
* [v8.dev](https://v8.dev/)
* [nodejs.org/api/v8.html](https://nodejs.org/api/v8.html)
* [docs/development/v8-development.md](development/v8-development)
### webview[](#webview "Direct link to heading")
`webview` tags are used to embed 'guest' content (such as external web pages) in your Electron app. They are similar to `iframe`s, but differ in that each webview runs in a separate process. It doesn't have the same permissions as your web page and all interactions between your app and embedded content will be asynchronous. This keeps your app safe from the embedded content.
electron Electron FAQ Electron FAQ
============
Why am I having trouble installing Electron?[](#why-am-i-having-trouble-installing-electron "Direct link to heading")
----------------------------------------------------------------------------------------------------------------------
When running `npm install electron`, some users occasionally encounter installation errors.
In almost all cases, these errors are the result of network problems and not actual issues with the `electron` npm package. Errors like `ELIFECYCLE`, `EAI_AGAIN`, `ECONNRESET`, and `ETIMEDOUT` are all indications of such network problems. The best resolution is to try switching networks, or wait a bit and try installing again.
You can also attempt to download Electron directly from [electron/electron/releases](https://github.com/electron/electron/releases) if installing via `npm` is failing.
When will Electron upgrade to latest Chrome?[](#when-will-electron-upgrade-to-latest-chrome "Direct link to heading")
----------------------------------------------------------------------------------------------------------------------
The Chrome version of Electron is usually bumped within one or two weeks after a new stable Chrome version gets released. This estimate is not guaranteed and depends on the amount of work involved with upgrading.
Only the stable channel of Chrome is used. If an important fix is in beta or dev channel, we will back-port it.
For more information, please see the [security introduction](tutorial/security).
When will Electron upgrade to latest Node.js?[](#when-will-electron-upgrade-to-latest-nodejs "Direct link to heading")
-----------------------------------------------------------------------------------------------------------------------
When a new version of Node.js gets released, we usually wait for about a month before upgrading the one in Electron. So we can avoid getting affected by bugs introduced in new Node.js versions, which happens very often.
New features of Node.js are usually brought by V8 upgrades, since Electron is using the V8 shipped by Chrome browser, the shiny new JavaScript feature of a new Node.js version is usually already in Electron.
How to share data between web pages?[](#how-to-share-data-between-web-pages "Direct link to heading")
------------------------------------------------------------------------------------------------------
To share data between web pages (the renderer processes) the simplest way is to use HTML5 APIs which are already available in browsers. Good candidates are [Storage API](https://developer.mozilla.org/en-US/docs/Web/API/Storage), [`localStorage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage), [`sessionStorage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/sessionStorage), and [IndexedDB](https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_API).
Alternatively, you can use the IPC primitives that are provided by Electron. To share data between the main and renderer processes, you can use the [`ipcMain`](api/ipc-main) and [`ipcRenderer`](api/ipc-renderer) modules. To communicate directly between web pages, you can send a [`MessagePort`](https://developer.mozilla.org/en-US/docs/Web/API/MessagePort) from one to the other, possibly via the main process using [`ipcRenderer.postMessage()`](api/ipc-renderer#ipcrendererpostmessagechannel-message-transfer). Subsequent communication over message ports is direct and does not detour through the main process.
My app's tray disappeared after a few minutes.[](#my-apps-tray-disappeared-after-a-few-minutes "Direct link to heading")
-------------------------------------------------------------------------------------------------------------------------
This happens when the variable which is used to store the tray gets garbage collected.
If you encounter this problem, the following articles may prove helpful:
* [Memory Management](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Memory_Management)
* [Variable Scope](https://msdn.microsoft.com/library/bzt2dkta(v=vs.94).aspx)
If you want a quick fix, you can make the variables global by changing your code from this:
```
const { app, Tray } = require('electron')
app.whenReady().then(() => {
const tray = new Tray('/path/to/icon.png')
tray.setTitle('hello world')
})
```
to this:
```
const { app, Tray } = require('electron')
let tray = null
app.whenReady().then(() => {
tray = new Tray('/path/to/icon.png')
tray.setTitle('hello world')
})
```
I can not use jQuery/RequireJS/Meteor/AngularJS in Electron.[](#i-can-not-use-jqueryrequirejsmeteorangularjs-in-electron "Direct link to heading")
---------------------------------------------------------------------------------------------------------------------------------------------------
Due to the Node.js integration of Electron, there are some extra symbols inserted into the DOM like `module`, `exports`, `require`. This causes problems for some libraries since they want to insert the symbols with the same names.
To solve this, you can turn off node integration in Electron:
```
// In the main process.
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({
webPreferences: {
nodeIntegration: false
}
})
win.show()
```
But if you want to keep the abilities of using Node.js and Electron APIs, you have to rename the symbols in the page before including other libraries:
```
<head>
<script>
window.nodeRequire = require;
delete window.require;
delete window.exports;
delete window.module;
</script>
<script type="text/javascript" src="jquery.js"></script>
</head>
```
`require('electron').xxx` is undefined.[](#requireelectronxxx-is-undefined "Direct link to heading")
------------------------------------------------------------------------------------------------------
When using Electron's built-in module you might encounter an error like this:
```
> require('electron').webFrame.setZoomFactor(1.0)
Uncaught TypeError: Cannot read property 'setZoomLevel' of undefined
```
It is very likely you are using the module in the wrong process. For example `electron.app` can only be used in the main process, while `electron.webFrame` is only available in renderer processes.
The font looks blurry, what is this and what can I do?[](#the-font-looks-blurry-what-is-this-and-what-can-i-do "Direct link to heading")
-----------------------------------------------------------------------------------------------------------------------------------------
If [sub-pixel anti-aliasing](https://alienryderflex.com/sub_pixel/) is deactivated, then fonts on LCD screens can look blurry. Example:
Sub-pixel anti-aliasing needs a non-transparent background of the layer containing the font glyphs. (See [this issue](https://github.com/electron/electron/issues/6344#issuecomment-420371918) for more info).
To achieve this goal, set the background in the constructor for [BrowserWindow](api/browser-window):
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({
backgroundColor: '#fff'
})
```
The effect is visible only on (some?) LCD screens. Even if you don't see a difference, some of your users may. It is best to always set the background this way, unless you have reasons not to do so.
Notice that just setting the background in the CSS does not have the desired effect.
electron Application Debugging Application Debugging
=====================
Whenever your Electron application is not behaving the way you wanted it to, an array of debugging tools might help you find coding errors, performance bottlenecks, or optimization opportunities.
Renderer Process[](#renderer-process "Direct link to heading")
---------------------------------------------------------------
The most comprehensive tool to debug individual renderer processes is the Chromium Developer Toolset. It is available for all renderer processes, including instances of `BrowserWindow`, `BrowserView`, and `WebView`. You can open them programmatically by calling the `openDevTools()` API on the `webContents` of the instance:
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.webContents.openDevTools()
```
Google offers [excellent documentation for their developer tools](https://developer.chrome.com/devtools). We recommend that you make yourself familiar with them - they are usually one of the most powerful utilities in any Electron Developer's tool belt.
Main Process[](#main-process "Direct link to heading")
-------------------------------------------------------
Debugging the main process is a bit trickier, since you cannot open developer tools for them. The Chromium Developer Tools can [be used to debug Electron's main process](https://nodejs.org/en/docs/inspector/) thanks to a closer collaboration between Google / Chrome and Node.js, but you might encounter oddities like `require` not being present in the console.
For more information, see the [Debugging the Main Process documentation](debugging-main-process).
V8 Crashes[](#v8-crashes "Direct link to heading")
---------------------------------------------------
If the V8 context crashes, the DevTools will display this message.
`DevTools was disconnected from the page. Once page is reloaded, DevTools will automatically reconnect.`
Chromium logs can be enabled via the `ELECTRON_ENABLE_LOGGING` environment variable. For more information, see the [environment variables documentation](../api/environment-variables#electron_enable_logging).
Alternatively, the command line argument `--enable-logging` can be passed. More information is available in the [command line switches documentation](../api/command-line-switches#--enable-loggingfile).
electron Distribution Overview Once your app is ready for production, there are a couple steps you need to take before you can deliver it to your users.
Packaging[](#packaging "Direct link to heading")
-------------------------------------------------
To distribute your app with Electron, you need to package all your resources and assets into an executable and rebrand it. To do this, you can either use specialized tooling or do it manually. See the [Application Packaging](application-distribution) tutorial for more information.
Code signing[](#code-signing "Direct link to heading")
-------------------------------------------------------
Code signing is a security technology that you use to certify that an app was created by you. You should sign your application so it does not trigger the security checks of your user's operating system.
To get started with each operating system's code signing process, please read the [Code Signing](code-signing) docs.
Publishing[](#publishing "Direct link to heading")
---------------------------------------------------
Once your app is packaged and signed, you can freely distribute your app directly to users by uploading your installers online.
To reach more users, you can also choose to upload your app to each operating system's digital distribution platform (i.e. app store). These require another build step aside from your direct download app. For more information, check out each individual app store guide:
* [Mac App Store](mac-app-store-submission-guide)
* [Windows Store](windows-store-guide)
* [Snapcraft (Linux)](snapcraft)
Updating[](#updating "Direct link to heading")
-----------------------------------------------
Electron's auto-updater allows you to deliver application updates to users without forcing them to manually download new versions of your application. Check out the [Updating Applications](updates) guide for details on implementing automatic updates with Electron.
| programming_docs |
electron Application Packaging To distribute your app with Electron, you need to package and rebrand it. To do this, you can either use specialized tooling or manual approaches.
With tooling[](#with-tooling "Direct link to heading")
-------------------------------------------------------
There are a couple tools out there that exist to package and distribute your Electron app. We recommend using [Electron Forge](https://www.electronforge.io). You can check out its documentation directly, or refer to the [Packaging and Distribution](tutorial-packaging) part of the Electron tutorial.
Manual packaging[](#manual-packaging "Direct link to heading")
---------------------------------------------------------------
If you prefer the manual approach, there are 2 ways to distribute your application:
* With prebuilt binaries
* With an app source code archive
### With prebuilt binaries[](#with-prebuilt-binaries "Direct link to heading")
To distribute your app manually, you need to download Electron's [prebuilt binaries](https://github.com/electron/electron/releases). Next, the folder containing your app should be named `app` and placed in Electron's resources directory as shown in the following examples.
note
The location of Electron's prebuilt binaries is indicated with `electron/` in the examples below.
macOS
```
electron/Electron.app/Contents/Resources/app/
├── package.json
├── main.js
└── index.html
```
Windows and Linux
```
electron/resources/app
├── package.json
├── main.js
└── index.html
```
Then execute `Electron.app` on macOS, `electron` on Linux, or `electron.exe` on Windows, and Electron will start as your app. The `electron` directory will then be your distribution to deliver to users.
### With an app source code archive (asar)[](#with-an-app-source-code-archive-asar "Direct link to heading")
Instead of shipping your app by copying all of its source files, you can package your app into an [asar](https://github.com/electron/asar) archive to improve the performance of reading files on platforms like Windows, if you are not already using a bundler such as Parcel or Webpack.
To use an `asar` archive to replace the `app` folder, you need to rename the archive to `app.asar`, and put it under Electron's resources directory like below, and Electron will then try to read the archive and start from it.
macOS
```
electron/Electron.app/Contents/Resources/
└── app.asar
```
Windows
```
electron/resources/
└── app.asar
```
You can find more details on how to use `asar` in the [`electron/asar` repository](https://github.com/electron/asar).
### Rebranding with downloaded binaries[](#rebranding-with-downloaded-binaries "Direct link to heading")
After bundling your app into Electron, you will want to rebrand Electron before distributing it to users.
* **Windows:** You can rename `electron.exe` to any name you like, and edit its icon and other information with tools like [rcedit](https://github.com/electron/rcedit).
* **Linux:** You can rename the `electron` executable to any name you like.
* **macOS:** You can rename `Electron.app` to any name you want, and you also have to rename the `CFBundleDisplayName`, `CFBundleIdentifier` and `CFBundleName` fields in the following files:
+ `Electron.app/Contents/Info.plist`
+ `Electron.app/Contents/Frameworks/Electron Helper.app/Contents/Info.plist`You can also rename the helper app to avoid showing `Electron Helper` in the Activity Monitor, but make sure you have renamed the helper app's executable file's name.
The structure of a renamed app would be like:
```
MyApp.app/Contents
├── Info.plist
├── MacOS/
│ └── MyApp
└── Frameworks/
└── MyApp Helper.app
├── Info.plist
└── MacOS/
└── MyApp Helper
```
note
it is also possible to rebrand Electron by changing the product name and building it from source. To do this you need to set the build argument corresponding to the product name (`electron_product_name = "YourProductName"`) in the `args.gn` file and rebuild.
Keep in mind this is not recommended as setting up the environment to compile from source is not trivial and takes significant time.
electron Accessibility Accessibility
=============
Accessibility concerns in Electron applications are similar to those of websites because they're both ultimately HTML.
Manually enabling accessibility features[](#manually-enabling-accessibility-features "Direct link to heading")
---------------------------------------------------------------------------------------------------------------
Electron applications will automatically enable accessibility features in the presence of assistive technology (e.g. [JAWS](https://www.freedomscientific.com/products/software/jaws/) on Windows or [VoiceOver](https://help.apple.com/voiceover/mac/10.15/) on macOS). See Chrome's [accessibility documentation](https://www.chromium.org/developers/design-documents/accessibility#TOC-How-Chrome-detects-the-presence-of-Assistive-Technology) for more details.
You can also manually toggle these features either within your Electron application or by setting flags in third-party native software.
### Using Electron's API[](#using-electrons-api "Direct link to heading")
By using the [`app.setAccessibilitySupportEnabled(enabled)`](../api/app#appsetaccessibilitysupportenabledenabled-macos-windows) API, you can manually expose Chrome's accessibility tree to users in the application preferences. Note that the user's system assistive utilities have priority over this setting and will override it.
### Within third-party software[](#within-third-party-software "Direct link to heading")
#### macOS[](#macos "Direct link to heading")
On macOS, third-party assistive technology can toggle accessibility features inside Electron applications by setting the `AXManualAccessibility` attribute programmatically:
```
CFStringRef kAXManualAccessibility = CFSTR("AXManualAccessibility");
+ (void)enableAccessibility:(BOOL)enable inElectronApplication:(NSRunningApplication *)app
{
AXUIElementRef appRef = AXUIElementCreateApplication(app.processIdentifier);
if (appRef == nil)
return;
CFBooleanRef value = enable ? kCFBooleanTrue : kCFBooleanFalse;
AXUIElementSetAttributeValue(appRef, kAXManualAccessibility, value);
CFRelease(appRef);
}
```
electron Electron Versioning Electron Versioning
===================
> A detailed look at our versioning policy and implementation.
>
>
As of version 2.0.0, Electron follows the [SemVer](#semver) spec. The following command will install the most recent stable build of Electron:
* npm
* Yarn
```
npm install --save-dev electron
```
```
yarn add --dev electron
```
To update an existing project to use the latest stable version:
* npm
* Yarn
```
npm install --save-dev electron@latest
```
```
yarn add --dev electron@latest
```
Versioning scheme[](#versioning-scheme "Direct link to heading")
-----------------------------------------------------------------
There are several major changes from our 1.x strategy outlined below. Each change is intended to satisfy the needs and priorities of developers/maintainers and app developers.
1. Strict use of the the [SemVer](#semver) spec
2. Introduction of semver-compliant `-beta` tags
3. Introduction of [conventional commit messages](https://conventionalcommits.org/)
4. Well-defined stabilization branches
5. The `main` branch is versionless; only stabilization branches contain version information
We will cover in detail how git branching works, how npm tagging works, what developers should expect to see, and how one can backport changes.
SemVer[](#semver "Direct link to heading")
-------------------------------------------
Below is a table explicitly mapping types of changes to their corresponding category of SemVer (e.g. Major, Minor, Patch).
| Major Version Increments | Minor Version Increments | Patch Version Increments |
| --- | --- | --- |
| Electron breaking API changes | Electron non-breaking API changes | Electron bug fixes |
| Node.js major version updates | Node.js minor version updates | Node.js patch version updates |
| Chromium version updates | | fix-related chromium patches |
For more information, see the [Semantic Versioning 2.0.0](https://semver.org/) spec.
Note that most Chromium updates will be considered breaking. Fixes that can be backported will likely be cherry-picked as patches.
Stabilization branches[](#stabilization-branches "Direct link to heading")
---------------------------------------------------------------------------
Stabilization branches are branches that run parallel to `main`, taking in only cherry-picked commits that are related to security or stability. These branches are never merged back to `main`.
Since Electron 8, stabilization branches are always **major** version lines, and named against the following template `$MAJOR-x-y` e.g. `8-x-y`. Prior to that we used **minor** version lines and named them as `$MAJOR-$MINOR-x` e.g. `2-0-x`.
We allow for multiple stabilization branches to exist simultaneously, one for each supported version. For more details on which versions are supported, see our [Electron Releases](electron-timelines) doc.
Older lines will not be supported by the Electron project, but other groups can take ownership and backport stability and security fixes on their own. We discourage this, but recognize that it makes life easier for many app developers.
Beta releases and bug fixes[](#beta-releases-and-bug-fixes "Direct link to heading")
-------------------------------------------------------------------------------------
Developers want to know which releases are *safe* to use. Even seemingly innocent features can introduce regressions in complex applications. At the same time, locking to a fixed version is dangerous because you’re ignoring security patches and bug fixes that may have come out since your version. Our goal is to allow the following standard semver ranges in `package.json` :
* Use `~2.0.0` to admit only stability or security related fixes to your `2.0.0` release.
* Use `^2.0.0` to admit non-breaking *reasonably stable* feature work as well as security and bug fixes.
What’s important about the second point is that apps using `^` should still be able to expect a reasonable level of stability. To accomplish this, SemVer allows for a *pre-release identifier* to indicate a particular version is not yet *safe* or *stable*.
Whatever you choose, you will periodically have to bump the version in your `package.json` as breaking changes are a fact of Chromium life.
The process is as follows:
1. All new major and minor releases lines begin with a beta series indicated by SemVer prerelease tags of `beta.N`, e.g. `2.0.0-beta.1`. After the first beta, subsequent beta releases must meet all of the following conditions:
1. The change is backwards API-compatible (deprecations are allowed)
2. The risk to meeting our stability timeline must be low.
2. If allowed changes need to be made once a release is beta, they are applied and the prerelease tag is incremented, e.g. `2.0.0-beta.2`.
3. If a particular beta release is *generally regarded* as stable, it will be re-released as a stable build, changing only the version information. e.g. `2.0.0`. After the first stable, all changes must be backwards-compatible bug or security fixes.
4. If future bug fixes or security patches need to be made once a release is stable, they are applied and the *patch* version is incremented e.g. `2.0.1`.
Specifically, the above means:
1. Admitting non-breaking-API changes before Week 3 in the beta cycle is okay, even if those changes have the potential to cause moderate side-effects.
2. Admitting feature-flagged changes, that do not otherwise alter existing code paths, at most points in the beta cycle is okay. Users can explicitly enable those flags in their apps.
3. Admitting features of any sort after Week 3 in the beta cycle is 👎 without a very good reason.
For each major and minor bump, you should expect to see something like the following:
```
2.0.0-beta.1
2.0.0-beta.2
2.0.0-beta.3
2.0.0
2.0.1
2.0.2
```
An example lifecycle in pictures:
* A new release branch is created that includes the latest set of features. It is published as `2.0.0-beta.1`.
* A bug fix comes into master that can be backported to the release branch. The patch is applied, and a new beta is published as `2.0.0-beta.2`.
* The beta is considered *generally stable* and it is published again as a non-beta under `2.0.0`.
* Later, a zero-day exploit is revealed and a fix is applied to master. We backport the fix to the `2-0-x` line and release `2.0.1`.
A few examples of how various SemVer ranges will pick up new releases:
### Backport request process[](#backport-request-process "Direct link to heading")
All supported release lines will accept external pull requests to backport fixes previously merged to `main`, though this may be on a case-by-case basis for some older supported lines. All contested decisions around release line backports will be resolved by the [Releases Working Group](https://github.com/electron/governance/tree/main/wg-releases) as an agenda item at their weekly meeting the week the backport PR is raised.
Feature flags[](#feature-flags "Direct link to heading")
---------------------------------------------------------
Feature flags are a common practice in Chromium, and are well-established in the web-development ecosystem. In the context of Electron, a feature flag or **soft branch** must have the following properties:
* it is enabled/disabled either at runtime, or build-time; we do not support the concept of a request-scoped feature flag
* it completely segments new and old code paths; refactoring old code to support a new feature *violates* the feature-flag contract
* feature flags are eventually removed after the feature is released
Semantic commits[](#semantic-commits "Direct link to heading")
---------------------------------------------------------------
All pull requests must adhere to the [Conventional Commits](https://conventionalcommits.org/) spec, which can be summarized as follows:
* Commits that would result in a SemVer **major** bump must start their body with `BREAKING CHANGE:`.
* Commits that would result in a SemVer **minor** bump must start with `feat:`.
* Commits that would result in a SemVer **patch** bump must start with `fix:`.
The `electron/electron` repository also enforces squash merging, so you only need to make sure that your pull request has the correct title prefix.
Versioned `main` branch[](#versioned-main-branch "Direct link to heading")
---------------------------------------------------------------------------
* The `main` branch will always contain the next major version `X.0.0-nightly.DATE` in its `package.json`.
* Release branches are never merged back to `main`.
* Release branches *do* contain the correct version in their `package.json`.
* As soon as a release branch is cut for a major, `main` must be bumped to the next major (i.e. `main` is always versioned as the next theoretical release branch).
Historical versioning (Electron 1.X)[](#historical-versioning-electron-1x "Direct link to heading")
----------------------------------------------------------------------------------------------------
Electron versions *< 2.0* did not conform to the [SemVer](https://semver.org) spec: major versions corresponded to end-user API changes, minor versions corresponded to Chromium major releases, and patch versions corresponded to new features and bug fixes. While convenient for developers merging features, it creates problems for developers of client-facing applications. The QA testing cycles of major apps like Slack, Teams, Skype, VS Code, and GitHub Desktop can be lengthy and stability is a highly desired outcome. There is a high risk in adopting new features while trying to absorb bug fixes.
Here is an example of the 1.x strategy:
An app developed with `1.8.1` cannot take the `1.8.3` bug fix without either absorbing the `1.8.2` feature, or by backporting the fix and maintaining a new release line.
electron Debugging in VSCode Debugging in VSCode
===================
This guide goes over how to set up VSCode debugging for both your own Electron project as well as the native Electron codebase.
Debugging your Electron app[](#debugging-your-electron-app "Direct link to heading")
-------------------------------------------------------------------------------------
### Main process[](#main-process "Direct link to heading")
#### 1. Open an Electron project in VSCode.[](#1-open-an-electron-project-in-vscode "Direct link to heading")
```
$ git clone [email protected]:electron/electron-quick-start.git
$ code electron-quick-start
```
#### 2. Add a file `.vscode/launch.json` with the following configuration:[](#2-add-a-file-vscodelaunchjson-with-the-following-configuration "Direct link to heading")
```
{
"version": "0.2.0",
"configurations": [
{
"name": "Debug Main Process",
"type": "node",
"request": "launch",
"cwd": "${workspaceFolder}",
"runtimeExecutable": "${workspaceFolder}/node_modules/.bin/electron",
"windows": {
"runtimeExecutable": "${workspaceFolder}/node_modules/.bin/electron.cmd"
},
"args" : ["."],
"outputCapture": "std"
}
]
}
```
#### 3. Debugging[](#3-debugging "Direct link to heading")
Set some breakpoints in `main.js`, and start debugging in the [Debug View](https://code.visualstudio.com/docs/editor/debugging). You should be able to hit the breakpoints.
Here is a pre-configured project that you can download and directly debug in VSCode: <https://github.com/octref/vscode-electron-debug/tree/master/electron-quick-start>
Debugging the Electron codebase[](#debugging-the-electron-codebase "Direct link to heading")
---------------------------------------------------------------------------------------------
If you want to build Electron from source and modify the native Electron codebase, this section will help you in testing your modifications.
For those unsure where to acquire this code or how to build it, [Electron's Build Tools](https://github.com/electron/build-tools) automates and explains most of this process. If you wish to manually set up the environment, you can instead use these [build instructions](../development/build-instructions-gn).
### Windows (C++)[](#windows-c "Direct link to heading")
#### 1. Open an Electron project in VSCode.[](#1-open-an-electron-project-in-vscode-1 "Direct link to heading")
```
$ git clone [email protected]:electron/electron-quick-start.git
$ code electron-quick-start
```
#### 2. Add a file `.vscode/launch.json` with the following configuration:[](#2-add-a-file-vscodelaunchjson-with-the-following-configuration-1 "Direct link to heading")
```
{
"version": "0.2.0",
"configurations": [
{
"name": "(Windows) Launch",
"type": "cppvsdbg",
"request": "launch",
"program": "${workspaceFolder}\\out\\your-executable-location\\electron.exe",
"args": ["your-electron-project-path"],
"stopAtEntry": false,
"cwd": "${workspaceFolder}",
"environment": [
{"name": "ELECTRON_ENABLE_LOGGING", "value": "true"},
{"name": "ELECTRON_ENABLE_STACK_DUMPING", "value": "true"},
{"name": "ELECTRON_RUN_AS_NODE", "value": ""},
],
"externalConsole": false,
"sourceFileMap": {
"o:\\": "${workspaceFolder}",
},
},
]
}
```
**Configuration Notes**
* `cppvsdbg` requires the [built-in C/C++ extension](https://marketplace.visualstudio.com/items?itemName=ms-vscode.cpptools) be enabled.
* `${workspaceFolder}` is the full path to Chromium's `src` directory.
* `your-executable-location` will be one of the following depending on a few items:
+ `Testing`: If you are using the default settings of [Electron's Build-Tools](https://github.com/electron/build-tools) or the default instructions when [building from source](../development/build-instructions-gn#building).
+ `Release`: If you built a Release build rather than a Testing build.
+ `your-directory-name`: If you modified this during your build process from the default, this will be whatever you specified.
* The `args` array string `"your-electron-project-path"` should be the absolute path to either the directory or `main.js` file of the Electron project you are using for testing. In this example, it should be your path to `electron-quick-start`.
#### 3. Debugging[](#3-debugging-1 "Direct link to heading")
Set some breakpoints in the .cc files of your choosing in the native Electron C++ code, and start debugging in the [Debug View](https://code.visualstudio.com/docs/editor/debugging).
| programming_docs |
electron Online/Offline Event Detection Online/Offline Event Detection
==============================
Overview[](#overview "Direct link to heading")
-----------------------------------------------
[Online and offline event](https://developer.mozilla.org/en-US/docs/Online_and_offline_events) detection can be implemented in the Renderer process using the [`navigator.onLine`](http://html5index.org/Offline%20-%20NavigatorOnLine.html) attribute, part of standard HTML5 API.
The `navigator.onLine` attribute returns:
* `false` if all network requests are guaranteed to fail (e.g. when disconnected from the network).
* `true` in all other cases.
Since many cases return `true`, you should treat with care situations of getting false positives, as we cannot always assume that `true` value means that Electron can access the Internet. For example, in cases when the computer is running a virtualization software that has virtual Ethernet adapters in "always connected" state. Therefore, if you want to determine the Internet access status of Electron, you should develop additional means for this check.
Example[](#example "Direct link to heading")
---------------------------------------------
Starting with an HTML file `index.html`, this example will demonstrate how the `navigator.onLine` API can be used to build a connection status indicator.
index.html
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Connection status: <strong id='status'></strong></h1>
<script src="renderer.js"></script>
</body>
</html>
```
In order to mutate the DOM, create a `renderer.js` file that adds event listeners to the `'online'` and `'offline'` `window` events. The event handler sets the content of the `<strong id='status'>` element depending on the result of `navigator.onLine`.
renderer.js
```
const updateOnlineStatus = () => {
document.getElementById('status').innerHTML = navigator.onLine ? 'online' : 'offline'
}
window.addEventListener('online', updateOnlineStatus)
window.addEventListener('offline', updateOnlineStatus)
updateOnlineStatus()
```
Finally, create a `main.js` file for main process that creates the window.
main.js
```
const { app, BrowserWindow } = require('electron')
const createWindow = () => {
const onlineStatusWindow = new BrowserWindow({
width: 400,
height: 100
})
onlineStatusWindow.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
```
After launching the Electron application, you should see the notification:
> Note: If you need to communicate the connection status to the main process, use the [IPC renderer](../api/ipc-renderer) API.
>
>
electron Prerequisites
Follow along the tutorial
This is **part 1** of the Electron tutorial.
1. **[Prerequisites](tutorial-prerequisites)**
2. [Building your First App](tutorial-first-app)
3. [Using Preload Scripts](tutorial-preload)
4. [Adding Features](tutorial-adding-features)
5. [Packaging Your Application](tutorial-packaging)
6. [Publishing and Updating](tutorial-publishing-updating)
Electron is a framework for building desktop applications using JavaScript, HTML, and CSS. By embedding [Chromium](https://www.chromium.org/) and [Node.js](https://nodejs.org/) into a single binary file, Electron allows you to create cross-platform apps that work on Windows, macOS, and Linux with a single JavaScript codebase.
This tutorial will guide you through the process of developing a desktop application with Electron and distributing it to end users.
Assumptions[](#assumptions "Direct link to heading")
-----------------------------------------------------
Electron is a native wrapper layer for web apps and is run in a Node.js environment. Therefore, this tutorial assumes you are generally familiar with Node and front-end web development basics. If you need to do some background reading before continuing, we recommend the following resources:
* [Getting started with the Web (MDN Web Docs)](https://developer.mozilla.org/en-US/docs/Learn/)
* [Introduction to Node.js](https://nodejs.dev/learn)
Required tools[](#required-tools "Direct link to heading")
-----------------------------------------------------------
### Code editor[](#code-editor "Direct link to heading")
You will need a text editor to write your code. We recommend using [Visual Studio Code](https://code.visualstudio.com/), although you can choose whichever one you prefer.
### Command line[](#command-line "Direct link to heading")
Throughout the tutorial, we will ask you to use various command-line interfaces (CLIs). You can type these commands into your system's default terminal:
* Windows: Command Prompt or PowerShell
* macOS: Terminal
* Linux: varies depending on distribution (e.g. GNOME Terminal, Konsole)
Most code editors also come with an integrated terminal, which you can also use.
### Git and GitHub[](#git-and-github "Direct link to heading")
Git is a commonly-used version control system for source code, and GitHub is a collaborative development platform built on top of it. Although neither is strictly necessary to building an Electron application, we will use GitHub releases to set up automatic updates later on in the tutorial. Therefore, we'll require you to:
* [Create a GitHub account](https://github.com/join)
* [Install Git](https://github.com/git-guides/install-git)
If you're unfamiliar with how Git works, we recommend reading GitHub's [Git guides](https://github.com/git-guides/). You can also use the [GitHub Desktop](https://desktop.github.com/) app if you prefer using a visual interface over the command line.
We recommend that you create a local Git repository and publish it to GitHub before starting the tutorial, and commit your code after every step.
Installing Git via GitHub Desktop
GitHub Desktop will install the latest version of Git on your system if you don't already have it installed.
### Node.js and npm[](#nodejs-and-npm "Direct link to heading")
To begin developing an Electron app, you need to install the [Node.js](https://nodejs.org/en/download/) runtime and its bundled npm package manager onto your system. We recommend that you use the latest long-term support (LTS) version.
tip
Please install Node.js using pre-built installers for your platform. You may encounter incompatibility issues with different development tools otherwise. If you are using macOS, we recommend using a package manager like [Homebrew](https://brew.sh/) or [nvm](https://github.com/nvm-sh/nvm) to avoid any directory permission issues.
To check that Node.js was installed correctly, you can use the `-v` flag when running the `node` and `npm` commands. These should print out the installed versions.
```
$ node -v
v16.14.2
$ npm -v
8.7.0
```
caution
Although you need Node.js installed locally to scaffold an Electron project, Electron **does not use your system's Node.js installation to run its code**. Instead, it comes bundled with its own Node.js runtime. This means that your end users do not need to install Node.js themselves as a prerequisite to running your app.
To check which version of Node.js is running in your app, you can access the global [`process.versions`](https://nodejs.org/api/process.html#processversions) variable in the main process or preload script. You can also reference the list of versions in the [electron/releases](https://github.com/electron/releases/blob/master/readme.md#releases) repository.
electron Testing Widevine CDM Testing Widevine CDM
====================
In Electron you can use the Widevine CDM library shipped with Chrome browser.
Widevine Content Decryption Modules (CDMs) are how streaming services protect content using HTML5 video to web browsers without relying on an NPAPI plugin like Flash or Silverlight. Widevine support is an alternative solution for streaming services that currently rely on Silverlight for playback of DRM-protected video content. It will allow websites to show DRM-protected video content in Firefox without the use of NPAPI plugins. The Widevine CDM runs in an open-source CDM sandbox providing better user security than NPAPI plugins.
#### Note on VMP[](#note-on-vmp "Direct link to heading")
As of [`Electron v1.8.0 (Chrome v59)`](https://electronjs.org/releases#1.8.1), the below steps are may only be some of the necessary steps to enable Widevine; any app on or after that version intending to use the Widevine CDM may need to be signed using a license obtained from [Widevine](https://www.widevine.com/) itself.
Per [Widevine](https://www.widevine.com/):
>
> Chrome 59 (and later) includes support for Verified Media Path (VMP). VMP provides a method to verify the authenticity of a device platform. For browser deployments, this will provide an additional signal to determine if a browser-based implementation is reliable and secure.
>
>
> The proxy integration guide has been updated with information about VMP and how to issue licenses.
>
>
> Widevine recommends our browser-based integrations (vendors and browser-based applications) add support for VMP.
>
>
>
To enable video playback with this new restriction, [castLabs](https://castlabs.com/open-source/downstream/) has created a [fork](https://github.com/castlabs/electron-releases) that has implemented the necessary changes to enable Widevine to be played in an Electron application if one has obtained the necessary licenses from widevine.
Getting the library[](#getting-the-library "Direct link to heading")
---------------------------------------------------------------------
Open `chrome://components/` in Chrome browser, find `Widevine Content Decryption Module` and make sure it is up to date, then you can find the library files from the application directory.
### On Windows[](#on-windows "Direct link to heading")
The library file `widevinecdm.dll` will be under `Program Files(x86)/Google/Chrome/Application/CHROME_VERSION/WidevineCdm/_platform_specific/win_(x86|x64)/` directory.
### On macOS[](#on-macos "Direct link to heading")
The library file `libwidevinecdm.dylib` will be under `/Applications/Google Chrome.app/Contents/Versions/CHROME_VERSION/Google Chrome Framework.framework/Versions/A/Libraries/WidevineCdm/_platform_specific/mac_(x86|x64)/` directory.
**Note:** Make sure that chrome version used by Electron is greater than or equal to the `min_chrome_version` value of Chrome's widevine cdm component. The value can be found in `manifest.json` under `WidevineCdm` directory.
Using the library[](#using-the-library "Direct link to heading")
-----------------------------------------------------------------
After getting the library files, you should pass the path to the file with `--widevine-cdm-path` command line switch, and the library's version with `--widevine-cdm-version` switch. The command line switches have to be passed before the `ready` event of `app` module gets emitted.
Example code:
```
const { app, BrowserWindow } = require('electron')
// You have to pass the directory that contains widevine library here, it is
// * `libwidevinecdm.dylib` on macOS,
// * `widevinecdm.dll` on Windows.
app.commandLine.appendSwitch('widevine-cdm-path', '/path/to/widevine_library')
// The version of plugin can be got from `chrome://components` page in Chrome.
app.commandLine.appendSwitch('widevine-cdm-version', '1.4.8.866')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow()
win.show()
})
```
Verifying Widevine CDM support[](#verifying-widevine-cdm-support "Direct link to heading")
-------------------------------------------------------------------------------------------
To verify whether widevine works, you can use following ways:
* Open <https://shaka-player-demo.appspot.com/> and load a manifest that uses `Widevine`.
* Open <http://www.dash-player.com/demo/drm-test-area/>, check whether the page says `bitdash uses Widevine in your browser`, then play the video.
electron Snapcraft Guide (Linux) Snapcraft Guide (Linux)
=======================
This guide provides information on how to package your Electron application for any Snapcraft environment, including the Ubuntu Software Center.
Background and Requirements[](#background-and-requirements "Direct link to heading")
-------------------------------------------------------------------------------------
Together with the broader Linux community, Canonical aims to fix many of the common software installation problems with the [`snapcraft`](https://snapcraft.io/) project. Snaps are containerized software packages that include required dependencies, auto-update, and work on all major Linux distributions without system modification.
There are three ways to create a `.snap` file:
1) Using [`electron-forge`](https://github.com/electron-userland/electron-forge) or [`electron-builder`](https://github.com/electron-userland/electron-builder), both tools that come with `snap` support out of the box. This is the easiest option. 2) Using `electron-installer-snap`, which takes `electron-packager`'s output. 3) Using an already created `.deb` package.
In some cases, you will need to have the `snapcraft` tool installed. Instructions to install `snapcraft` for your particular distribution are available [here](https://snapcraft.io/docs/installing-snapcraft).
Using `electron-installer-snap`[](#using-electron-installer-snap "Direct link to heading")
-------------------------------------------------------------------------------------------
The module works like [`electron-winstaller`](https://github.com/electron/windows-installer) and similar modules in that its scope is limited to building snap packages. You can install it with:
```
npm install --save-dev electron-installer-snap
```
### Step 1: Package Your Electron Application[](#step-1-package-your-electron-application "Direct link to heading")
Package the application using [electron-packager](https://github.com/electron/electron-packager) (or a similar tool). Make sure to remove `node_modules` that you don't need in your final application, since any module you don't actually need will increase your application's size.
The output should look roughly like this:
```
.
└── dist
└── app-linux-x64
├── LICENSE
├── LICENSES.chromium.html
├── content_shell.pak
├── app
├── icudtl.dat
├── libgcrypt.so.11
├── libnode.so
├── locales
├── resources
├── v8_context_snapshot.bin
└── version
```
### Step 2: Running `electron-installer-snap`[](#step-2-running-electron-installer-snap "Direct link to heading")
From a terminal that has `snapcraft` in its `PATH`, run `electron-installer-snap` with the only required parameter `--src`, which is the location of your packaged Electron application created in the first step.
```
npx electron-installer-snap --src=out/myappname-linux-x64
```
If you have an existing build pipeline, you can use `electron-installer-snap` programmatically. For more information, see the [Snapcraft API docs](https://docs.snapcraft.io/build-snaps/syntax).
```
const snap = require('electron-installer-snap')
snap(options)
.then(snapPath => console.log(`Created snap at ${snapPath}!`))
```
Using `snapcraft` with `electron-packager`[](#using-snapcraft-with-electron-packager "Direct link to heading")
---------------------------------------------------------------------------------------------------------------
### Step 1: Create Sample Snapcraft Project[](#step-1-create-sample-snapcraft-project "Direct link to heading")
Create your project directory and add the following to `snap/snapcraft.yaml`:
```
name: electron-packager-hello-world
version: '0.1'
summary: Hello World Electron app
description: |
Simple Hello World Electron app as an example
base: core18
confinement: strict
grade: stable
apps:
electron-packager-hello-world:
command: electron-quick-start/electron-quick-start --no-sandbox
extensions: [gnome-3-34]
plugs:
- browser-support
- network
- network-bind
environment:
# Correct the TMPDIR path for Chromium Framework/Electron to ensure
# libappindicator has readable resources.
TMPDIR: $XDG_RUNTIME_DIR
parts:
electron-quick-start:
plugin: nil
source: https://github.com/electron/electron-quick-start.git
override-build: |
npm install electron electron-packager
npx electron-packager . --overwrite --platform=linux --output=release-build --prune=true
cp -rv ./electron-quick-start-linux-* $SNAPCRAFT_PART_INSTALL/electron-quick-start
build-snaps:
- node/14/stable
build-packages:
- unzip
stage-packages:
- libnss3
- libnspr4
```
If you want to apply this example to an existing project:
* Replace `source: https://github.com/electron/electron-quick-start.git` with `source: .`.
* Replace all instances of `electron-quick-start` with your project's name.
### Step 2: Build the snap[](#step-2-build-the-snap "Direct link to heading")
```
$ snapcraft
<output snipped>
Snapped electron-packager-hello-world_0.1_amd64.snap
```
### Step 3: Install the snap[](#step-3-install-the-snap "Direct link to heading")
```
sudo snap install electron-packager-hello-world_0.1_amd64.snap --dangerous
```
### Step 4: Run the snap[](#step-4-run-the-snap "Direct link to heading")
```
electron-packager-hello-world
```
Using an Existing Debian Package[](#using-an-existing-debian-package "Direct link to heading")
-----------------------------------------------------------------------------------------------
Snapcraft is capable of taking an existing `.deb` file and turning it into a `.snap` file. The creation of a snap is configured using a `snapcraft.yaml` file that describes the sources, dependencies, description, and other core building blocks.
### Step 1: Create a Debian Package[](#step-1-create-a-debian-package "Direct link to heading")
If you do not already have a `.deb` package, using `electron-installer-snap` might be an easier path to create snap packages. However, multiple solutions for creating Debian packages exist, including [`electron-forge`](https://github.com/electron-userland/electron-forge), [`electron-builder`](https://github.com/electron-userland/electron-builder) or [`electron-installer-debian`](https://github.com/unindented/electron-installer-debian).
### Step 2: Create a snapcraft.yaml[](#step-2-create-a-snapcraftyaml "Direct link to heading")
For more information on the available configuration options, see the [documentation on the snapcraft syntax](https://docs.snapcraft.io/build-snaps/syntax). Let's look at an example:
```
name: myApp
version: '2.0.0'
summary: A little description for the app.
description: |
You know what? This app is amazing! It does all the things
for you. Some say it keeps you young, maybe even happy.
grade: stable
confinement: classic
parts:
slack:
plugin: dump
source: my-deb.deb
source-type: deb
after:
- desktop-gtk3
stage-packages:
- libasound2
- libnotify4
- libnspr4
- libnss3
- libpcre3
- libpulse0
- libxss1
- libxtst6
electron-launch:
plugin: dump
source: files/
prepare: |
chmod +x bin/electron-launch
apps:
myApp:
command: bin/electron-launch $SNAP/usr/lib/myApp/myApp
desktop: usr/share/applications/myApp.desktop
# Correct the TMPDIR path for Chromium Framework/Electron to ensure
# libappindicator has readable resources.
environment:
TMPDIR: $XDG_RUNTIME_DIR
```
As you can see, the `snapcraft.yaml` instructs the system to launch a file called `electron-launch`. In this example, it passes information on to the app's binary:
```
#!/bin/sh
exec "$@" --executed-from="$(pwd)" --pid=$$ > /dev/null 2>&1 &
```
Alternatively, if you're building your `snap` with `strict` confinement, you can use the `desktop-launch` command:
```
apps:
myApp:
# Correct the TMPDIR path for Chromium Framework/Electron to ensure
# libappindicator has readable resources.
command: env TMPDIR=$XDG_RUNTIME_DIR PATH=/usr/local/bin:${PATH} ${SNAP}/bin/desktop-launch $SNAP/myApp/desktop
desktop: usr/share/applications/desktop.desktop
```
| programming_docs |
electron Dark Mode Dark Mode
=========
Overview[](#overview "Direct link to heading")
-----------------------------------------------
### Automatically update the native interfaces[](#automatically-update-the-native-interfaces "Direct link to heading")
"Native interfaces" include the file picker, window border, dialogs, context menus, and more - anything where the UI comes from your operating system and not from your app. The default behavior is to opt into this automatic theming from the OS.
### Automatically update your own interfaces[](#automatically-update-your-own-interfaces "Direct link to heading")
If your app has its own dark mode, you should toggle it on and off in sync with the system's dark mode setting. You can do this by using the [prefer-color-scheme] CSS media query.
### Manually update your own interfaces[](#manually-update-your-own-interfaces "Direct link to heading")
If you want to manually switch between light/dark modes, you can do this by setting the desired mode in the [themeSource](../api/native-theme#nativethemethemesource) property of the `nativeTheme` module. This property's value will be propagated to your Renderer process. Any CSS rules related to `prefers-color-scheme` will be updated accordingly.
macOS settings[](#macos-settings "Direct link to heading")
-----------------------------------------------------------
In macOS 10.14 Mojave, Apple introduced a new [system-wide dark mode](https://developer.apple.com/design/human-interface-guidelines/macos/visual-design/dark-mode/) for all macOS computers. If your Electron app has a dark mode, you can make it follow the system-wide dark mode setting using [the `nativeTheme` api](../api/native-theme).
In macOS 10.15 Catalina, Apple introduced a new "automatic" dark mode option for all macOS computers. In order for the `nativeTheme.shouldUseDarkColors` and `Tray` APIs to work correctly in this mode on Catalina, you need to use Electron `>=7.0.0`, or set `NSRequiresAquaSystemAppearance` to `false` in your `Info.plist` file for older versions. Both [Electron Packager](https://github.com/electron/electron-packager) and [Electron Forge](https://www.electronforge.io/) have a [`darwinDarkModeSupport` option](https://electron.github.io/electron-packager/main/interfaces/electronpackager.options.html#darwindarkmodesupport) to automate the `Info.plist` changes during app build time.
If you wish to opt-out while using Electron > 8.0.0, you must set the `NSRequiresAquaSystemAppearance` key in the `Info.plist` file to `true`. Please note that Electron 8.0.0 and above will not let you opt-out of this theming, due to the use of the macOS 10.14 SDK.
Example[](#example "Direct link to heading")
---------------------------------------------
This example demonstrates an Electron application that derives its theme colors from the `nativeTheme`. Additionally, it provides theme toggle and reset controls using IPC channels.
[docs/fiddles/features/macos-dark-mode (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/macos-dark-mode)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/macos-dark-mode)
* main.js
* preload.js
* index.html
* renderer.js
* styles.css
```
const { app, BrowserWindow, ipcMain, nativeTheme } = require('electron')
const path = require('path')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
win.loadFile('index.html')
ipcMain.handle('dark-mode:toggle', () => {
if (nativeTheme.shouldUseDarkColors) {
nativeTheme.themeSource = 'light'
} else {
nativeTheme.themeSource = 'dark'
}
return nativeTheme.shouldUseDarkColors
})
ipcMain.handle('dark-mode:system', () => {
nativeTheme.themeSource = 'system'
})
}
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
```
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('darkMode', {
toggle: () => ipcRenderer.invoke('dark-mode:toggle'),
system: () => ipcRenderer.invoke('dark-mode:system')
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
<link rel="stylesheet" type="text/css" href="./styles.css">
</head>
<body>
<h1>Hello World!</h1>
<p>Current theme source: <strong id="theme-source">System</strong></p>
<button id="toggle-dark-mode">Toggle Dark Mode</button>
<button id="reset-to-system">Reset to System Theme</button>
<script src="renderer.js"></script>
</body>
</body>
</html>
```
```
document.getElementById('toggle-dark-mode').addEventListener('click', async () => {
const isDarkMode = await window.darkMode.toggle()
document.getElementById('theme-source').innerHTML = isDarkMode ? 'Dark' : 'Light'
})
document.getElementById('reset-to-system').addEventListener('click', async () => {
await window.darkMode.system()
document.getElementById('theme-source').innerHTML = 'System'
})
```
```
@media (prefers-color-scheme: dark) {
body { background: #333; color: white; }
}
@media (prefers-color-scheme: light) {
body { background: #ddd; color: black; }
}
```
### How does this work?[](#how-does-this-work "Direct link to heading")
Starting with the `index.html` file:
index.html
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
<link rel="stylesheet" type="text/css" href="./styles.css">
</head>
<body>
<h1>Hello World!</h1>
<p>Current theme source: <strong id="theme-source">System</strong></p>
<button id="toggle-dark-mode">Toggle Dark Mode</button>
<button id="reset-to-system">Reset to System Theme</button>
<script src="renderer.js"></script>
</body>
</body>
</html>
```
And the `styles.css` file:
styles.css
```
@media (prefers-color-scheme: dark) {
body { background: #333; color: white; }
}
@media (prefers-color-scheme: light) {
body { background: #ddd; color: black; }
}
```
The example renders an HTML page with a couple elements. The `<strong id="theme-source">` element shows which theme is currently selected, and the two `<button>` elements are the controls. The CSS file uses the [`prefers-color-scheme`](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme) media query to set the `<body>` element background and text colors.
The `preload.js` script adds a new API to the `window` object called `darkMode`. This API exposes two IPC channels to the renderer process, `'dark-mode:toggle'` and `'dark-mode:system'`. It also assigns two methods, `toggle` and `system`, which pass messages from the renderer to the main process.
preload.js
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('darkMode', {
toggle: () => ipcRenderer.invoke('dark-mode:toggle'),
system: () => ipcRenderer.invoke('dark-mode:system')
})
```
Now the renderer process can communicate with the main process securely and perform the necessary mutations to the `nativeTheme` object.
The `renderer.js` file is responsible for controlling the `<button>` functionality.
renderer.js
```
document.getElementById('toggle-dark-mode').addEventListener('click', async () => {
const isDarkMode = await window.darkMode.toggle()
document.getElementById('theme-source').innerHTML = isDarkMode ? 'Dark' : 'Light'
})
document.getElementById('reset-to-system').addEventListener('click', async () => {
await window.darkMode.system()
document.getElementById('theme-source').innerHTML = 'System'
})
```
Using `addEventListener`, the `renderer.js` file adds `'click'` [event listeners](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener) to each button element. Each event listener handler makes calls to the respective `window.darkMode` API methods.
Finally, the `main.js` file represents the main process and contains the actual `nativeTheme` API.
```
const { app, BrowserWindow, ipcMain, nativeTheme } = require('electron')
const path = require('path')
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
win.loadFile('index.html')
ipcMain.handle('dark-mode:toggle', () => {
if (nativeTheme.shouldUseDarkColors) {
nativeTheme.themeSource = 'light'
} else {
nativeTheme.themeSource = 'dark'
}
return nativeTheme.shouldUseDarkColors
})
ipcMain.handle('dark-mode:system', () => {
nativeTheme.themeSource = 'system'
})
}
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
```
The `ipcMain.handle` methods are how the main process responds to the click events from the buttons on the HTML page.
The `'dark-mode:toggle'` IPC channel handler method checks the `shouldUseDarkColors` boolean property, sets the corresponding `themeSource`, and then returns the current `shouldUseDarkColors` property. Looking back on the renderer process event listener for this IPC channel, the return value from this handler is utilized to assign the correct text to the `<strong id='theme-source'>` element.
The `'dark-mode:system'` IPC channel handler method assigns the string `'system'` to the `themeSource` and returns nothing. This also corresponds with the relative renderer process event listener as the method is awaited with no return value expected.
Run the example using Electron Fiddle and then click the "Toggle Dark Mode" button; the app should start alternating between a light and dark background color.
electron Device Access Device Access
=============
Like Chromium based browsers, Electron provides access to device hardware through web APIs. For the most part these APIs work like they do in a browser, but there are some differences that need to be taken into account. The primary difference between Electron and browsers is what happens when device access is requested. In a browser, users are presented with a popup where they can grant access to an individual device. In Electron APIs are provided which can be used by a developer to either automatically pick a device or prompt users to pick a device via a developer created interface.
Web Bluetooth API[](#web-bluetooth-api "Direct link to heading")
-----------------------------------------------------------------
The [Web Bluetooth API](https://web.dev/bluetooth/) can be used to communicate with bluetooth devices. In order to use this API in Electron, developers will need to handle the [`select-bluetooth-device` event on the webContents](../api/web-contents#event-select-bluetooth-device) associated with the device request.
### Example[](#example "Direct link to heading")
This example demonstrates an Electron application that automatically selects the first available bluetooth device when the `Test Bluetooth` button is clicked.
[docs/fiddles/features/web-bluetooth (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/web-bluetooth)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/web-bluetooth)
* main.js
* index.html
* renderer.js
```
const {app, BrowserWindow} = require('electron')
const path = require('path')
function createWindow () {
const mainWindow = new BrowserWindow({
width: 800,
height: 600
})
mainWindow.webContents.on('select-bluetooth-device', (event, deviceList, callback) => {
event.preventDefault()
if (deviceList && deviceList.length > 0) {
callback(deviceList[0].deviceId)
}
})
mainWindow.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
app.on('activate', function () {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Web Bluetooth API</title>
</head>
<body>
<h1>Web Bluetooth API</h1>
<button id="clickme">Test Bluetooth</button>
<p>Currently selected bluetooth device: <strong id="device-name""></strong></p>
<script src="./renderer.js"></script>
</body>
</html>
```
```
async function testIt() {
const device = await navigator.bluetooth.requestDevice({
acceptAllDevices: true
})
document.getElementById('device-name').innerHTML = device.name || `ID: ${device.id}`
}
document.getElementById('clickme').addEventListener('click',testIt)
```
WebHID API[](#webhid-api "Direct link to heading")
---------------------------------------------------
The [WebHID API](https://web.dev/hid/) can be used to access HID devices such as keyboards and gamepads. Electron provides several APIs for working with the WebHID API:
* The [`select-hid-device` event on the Session](../api/session#event-select-hid-device) can be used to select a HID device when a call to `navigator.hid.requestDevice` is made. Additionally the [`hid-device-added`](../api/session#event-hid-device-added) and [`hid-device-removed`](../api/session#event-hid-device-removed) events on the Session can be used to handle devices being plugged in or unplugged when handling the `select-hid-device` event. **Note:** These events only fire until the callback from `select-hid-device` is called. They are not intended to be used as a generic hid device listener.
* [`ses.setDevicePermissionHandler(handler)`](../api/session#sessetdevicepermissionhandlerhandler) can be used to provide default permissioning to devices without first calling for permission to devices via `navigator.hid.requestDevice`. Additionally, the default behavior of Electron is to store granted device permision through the lifetime of the corresponding WebContents. If longer term storage is needed, a developer can store granted device permissions (eg when handling the `select-hid-device` event) and then read from that storage with `setDevicePermissionHandler`.
* [`ses.setPermissionCheckHandler(handler)`](../api/session#sessetpermissioncheckhandlerhandler) can be used to disable HID access for specific origins.
### Blocklist[](#blocklist "Direct link to heading")
By default Electron employs the same [blocklist](https://github.com/WICG/webhid/blob/main/blocklist.txt) used by Chromium. If you wish to override this behavior, you can do so by setting the `disable-hid-blocklist` flag:
```
app.commandLine.appendSwitch('disable-hid-blocklist')
```
### Example[](#example-1 "Direct link to heading")
This example demonstrates an Electron application that automatically selects HID devices through [`ses.setDevicePermissionHandler(handler)`](../api/session#sessetdevicepermissionhandlerhandler) and through [`select-hid-device` event on the Session](../api/session#event-select-hid-device) when the `Test WebHID` button is clicked.
[docs/fiddles/features/web-hid (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/web-hid)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/web-hid)
* main.js
* index.html
* renderer.js
```
const {app, BrowserWindow} = require('electron')
const path = require('path')
function createWindow () {
const mainWindow = new BrowserWindow({
width: 800,
height: 600
})
mainWindow.webContents.session.on('select-hid-device', (event, details, callback) => {
//Add events to handle devices being added or removed before the callback on
//`select-hid-device` is called.
mainWindow.webContents.session.on('hid-device-added', (event, device) => {
console.log('hid-device-added FIRED WITH', device)
//Optionally update details.deviceList
})
mainWindow.webContents.session.on('hid-device-removed', (event, device) => {
console.log('hid-device-removed FIRED WITH', device)
//Optionally update details.deviceList
})
event.preventDefault()
if (details.deviceList && details.deviceList.length > 0) {
callback(details.deviceList[0].deviceId)
}
})
mainWindow.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'hid' && details.securityOrigin === 'file:///') {
return true
}
})
mainWindow.webContents.session.setDevicePermissionHandler((details) => {
if (details.deviceType === 'hid' && details.origin === 'file://') {
return true
}
})
mainWindow.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
app.on('activate', function () {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>WebHID API</title>
</head>
<body>
<h1>WebHID API</h1>
<button id="clickme">Test WebHID</button>
<h3>HID devices automatically granted access via <i>setDevicePermissionHandler</i></h3>
<div id="granted-devices"></div>
<h3>HID devices automatically granted access via <i>select-hid-device</i></h3>
<div id="granted-devices2"></div>
<script src="./renderer.js"></script>
</body>
</html>
```
```
async function testIt() {
const grantedDevices = await navigator.hid.getDevices()
let grantedDeviceList = ''
grantedDevices.forEach(device => {
grantedDeviceList += `<hr>${device.productName}</hr>`
})
document.getElementById('granted-devices').innerHTML = grantedDeviceList
const grantedDevices2 = await navigator.hid.requestDevice({
filters: []
})
grantedDeviceList = ''
grantedDevices2.forEach(device => {
grantedDeviceList += `<hr>${device.productName}</hr>`
})
document.getElementById('granted-devices2').innerHTML = grantedDeviceList
}
document.getElementById('clickme').addEventListener('click',testIt)
```
Web Serial API[](#web-serial-api "Direct link to heading")
-----------------------------------------------------------
The [Web Serial API](https://web.dev/serial/) can be used to access serial devices that are connected via serial port, USB, or Bluetooth. In order to use this API in Electron, developers will need to handle the [`select-serial-port` event on the Session](../api/session#event-select-serial-port) associated with the serial port request.
There are several additional APIs for working with the Web Serial API:
* The [`serial-port-added`](../api/session#event-serial-port-added) and [`serial-port-removed`](../api/session#event-serial-port-removed) events on the Session can be used to handle devices being plugged in or unplugged when handling the `select-serial-port` event. **Note:** These events only fire until the callback from `select-serial-port` is called. They are not intended to be used as a generic serial port listener.
* [`ses.setDevicePermissionHandler(handler)`](../api/session#sessetdevicepermissionhandlerhandler) can be used to provide default permissioning to devices without first calling for permission to devices via `navigator.serial.requestPort`. Additionally, the default behavior of Electron is to store granted device permision through the lifetime of the corresponding WebContents. If longer term storage is needed, a developer can store granted device permissions (eg when handling the `select-serial-port` event) and then read from that storage with `setDevicePermissionHandler`.
* [`ses.setPermissionCheckHandler(handler)`](../api/session#sessetpermissioncheckhandlerhandler) can be used to disable serial access for specific origins.
### Example[](#example-2 "Direct link to heading")
This example demonstrates an Electron application that automatically selects serial devices through [`ses.setDevicePermissionHandler(handler)`](../api/session#sessetdevicepermissionhandlerhandler) as well as demonstrating selecting the first available Arduino Uno serial device (if connected) through [`select-serial-port` event on the Session](../api/session#event-select-serial-port) when the `Test Web Serial` button is clicked.
[docs/fiddles/features/web-serial (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/web-serial)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/web-serial)
* main.js
* index.html
* renderer.js
```
const {app, BrowserWindow} = require('electron')
const path = require('path')
function createWindow () {
const mainWindow = new BrowserWindow({
width: 800,
height: 600
})
mainWindow.webContents.session.on('select-serial-port', (event, portList, webContents, callback) => {
//Add listeners to handle ports being added or removed before the callback for `select-serial-port`
//is called.
mainWindow.webContents.session.on('serial-port-added', (event, port) => {
console.log('serial-port-added FIRED WITH', port)
//Optionally update portList to add the new port
})
mainWindow.webContents.session.on('serial-port-removed', (event, port) => {
console.log('serial-port-removed FIRED WITH', port)
//Optionally update portList to remove the port
})
event.preventDefault()
if (portList && portList.length > 0) {
callback(portList[0].portId)
} else {
callback('') //Could not find any matching devices
}
})
mainWindow.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'serial' && details.securityOrigin === 'file:///') {
return true
}
})
mainWindow.webContents.session.setDevicePermissionHandler((details) => {
if (details.deviceType === 'serial' && details.origin === 'file://') {
return true
}
})
mainWindow.loadFile('index.html')
mainWindow.webContents.openDevTools()
}
app.whenReady().then(() => {
createWindow()
app.on('activate', function () {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Web Serial API</title>
<body>
<h1>Web Serial API</h1>
<button id="clickme">Test Web Serial API</button>
<p>Matching Arduino Uno device: <strong id="device-name""></strong></p>
<script src="./renderer.js"></script>
</body>
</html>
```
```
async function testIt() {
const filters = [
{ usbVendorId: 0x2341, usbProductId: 0x0043 },
{ usbVendorId: 0x2341, usbProductId: 0x0001 }
];
try {
const port = await navigator.serial.requestPort({filters});
const portInfo = port.getInfo();
document.getElementById('device-name').innerHTML = `vendorId: ${portInfo.usbVendorId} | productId: ${portInfo.usbProductId} `
} catch (ex) {
if (ex.name === 'NotFoundError') {
document.getElementById('device-name').innerHTML = 'Device NOT found'
} else {
document.getElementById('device-name').innerHTML = ex
}
}
}
document.getElementById('clickme').addEventListener('click',testIt)
```
| programming_docs |
electron Notifications Notifications
=============
Overview[](#overview "Direct link to heading")
-----------------------------------------------
All three operating systems provide means for applications to send notifications to the user. The technique of showing notifications is different for the Main and Renderer processes.
For the Renderer process, Electron conveniently allows developers to send notifications with the [HTML5 Notification API](https://notifications.spec.whatwg.org/), using the currently running operating system's native notification APIs to display it.
To show notifications in the Main process, you need to use the [Notification](../api/notification) module.
Example[](#example "Direct link to heading")
---------------------------------------------
### Show notifications in the Renderer process[](#show-notifications-in-the-renderer-process "Direct link to heading")
Starting with a working application from the [Quick Start Guide](quick-start), add the following line to the `index.html` file before the closing `</body>` tag:
```
<script src="renderer.js"></script>
```
...and add the `renderer.js` file:
[docs/fiddles/features/notifications/renderer (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/notifications/renderer)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/notifications/renderer)
* main.js
* index.html
* renderer.js
```
const { app, BrowserWindow } = require('electron')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600
})
win.loadFile('index.html')
}
app.whenReady().then(createWindow)
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>After launching this application, you should see the system notification.</p>
<p id="output">Click it to see the effect in this interface.</p>
<script src="renderer.js"></script>
</body>
</html>
```
```
const NOTIFICATION_TITLE = 'Title'
const NOTIFICATION_BODY = 'Notification from the Renderer process. Click to log to console.'
const CLICK_MESSAGE = 'Notification clicked!'
new Notification(NOTIFICATION_TITLE, { body: NOTIFICATION_BODY })
.onclick = () => document.getElementById("output").innerText = CLICK_MESSAGE
```
After launching the Electron application, you should see the notification:
Additionally, if you click on the notification, the DOM will update to show "Notification clicked!".
### Show notifications in the Main process[](#show-notifications-in-the-main-process "Direct link to heading")
Starting with a working application from the [Quick Start Guide](quick-start), update the `main.js` file with the following lines:
[docs/fiddles/features/notifications/main (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/notifications/main)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/notifications/main)
* main.js
* index.html
```
const { app, BrowserWindow, Notification } = require('electron')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600
})
win.loadFile('index.html')
}
const NOTIFICATION_TITLE = 'Basic Notification'
const NOTIFICATION_BODY = 'Notification from the Main process'
function showNotification () {
new Notification({ title: NOTIFICATION_TITLE, body: NOTIFICATION_BODY }).show()
}
app.whenReady().then(createWindow).then(showNotification)
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>After launching this application, you should see the system notification.</p>
</body>
</html>
```
After launching the Electron application, you should see the system notification:
Additional information[](#additional-information "Direct link to heading")
---------------------------------------------------------------------------
While code and user experience across operating systems are similar, there are subtle differences.
### Windows[](#windows "Direct link to heading")
* On Windows 10, a shortcut to your app with an [Application User Model ID](https://msdn.microsoft.com/en-us/library/windows/desktop/dd378459(v=vs.85).aspx) must be installed to the Start Menu. This can be overkill during development, so adding `node_modules\electron\dist\electron.exe` to your Start Menu also does the trick. Navigate to the file in Explorer, right-click and 'Pin to Start Menu'. You will then need to add the line `app.setAppUserModelId(process.execPath)` to your main process to see notifications.
* On Windows 8.1 and Windows 8, a shortcut to your app with an [Application User Model ID](https://msdn.microsoft.com/en-us/library/windows/desktop/dd378459(v=vs.85).aspx) must be installed to the Start screen. Note, however, that it does not need to be pinned to the Start screen.
* On Windows 7, notifications work via a custom implementation which visually resembles the native one on newer systems.
Electron attempts to automate the work around the Application User Model ID. When Electron is used together with the installation and update framework Squirrel, [shortcuts will automatically be set correctly](https://github.com/electron/windows-installer/blob/master/README.md#handling-squirrel-events). Furthermore, Electron will detect that Squirrel was used and will automatically call `app.setAppUserModelId()` with the correct value. During development, you may have to call [`app.setAppUserModelId()`](../api/app#appsetappusermodelidid-windows) yourself.
Furthermore, in Windows 8, the maximum length for the notification body is 250 characters, with the Windows team recommending that notifications should be kept to 200 characters. That said, that limitation has been removed in Windows 10, with the Windows team asking developers to be reasonable. Attempting to send gigantic amounts of text to the API (thousands of characters) might result in instability.
#### Advanced Notifications[](#advanced-notifications "Direct link to heading")
Later versions of Windows allow for advanced notifications, with custom templates, images, and other flexible elements. To send those notifications (from either the main process or the renderer process), use the userland module [electron-windows-notifications](https://github.com/felixrieseberg/electron-windows-notifications), which uses native Node addons to send `ToastNotification` and `TileNotification` objects.
While notifications including buttons work with `electron-windows-notifications`, handling replies requires the use of [`electron-windows-interactive-notifications`](https://github.com/felixrieseberg/electron-windows-interactive-notifications), which helps with registering the required COM components and calling your Electron app with the entered user data.
#### Quiet Hours / Presentation Mode[](#quiet-hours--presentation-mode "Direct link to heading")
To detect whether or not you're allowed to send a notification, use the userland module [electron-notification-state](https://github.com/felixrieseberg/electron-notification-state).
This allows you to determine ahead of time whether or not Windows will silently throw the notification away.
### macOS[](#macos "Direct link to heading")
Notifications are straight-forward on macOS, but you should be aware of [Apple's Human Interface guidelines regarding notifications](https://developer.apple.com/macos/human-interface-guidelines/system-capabilities/notifications/).
Note that notifications are limited to 256 bytes in size and will be truncated if you exceed that limit.
#### Do not disturb / Session State[](#do-not-disturb--session-state "Direct link to heading")
To detect whether or not you're allowed to send a notification, use the userland module [electron-notification-state](https://github.com/felixrieseberg/electron-notification-state).
This will allow you to detect ahead of time whether or not the notification will be displayed.
### Linux[](#linux "Direct link to heading")
Notifications are sent using `libnotify` which can show notifications on any desktop environment that follows [Desktop Notifications Specification](https://developer-old.gnome.org/notification-spec/), including Cinnamon, Enlightenment, Unity, GNOME, KDE.
electron REPL REPL
====
[Read-Eval-Print-Loop](https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop) (REPL) is a simple, interactive computer programming environment that takes single user inputs (i.e. single expressions), evaluates them, and returns the result to the user.
Main process[](#main-process "Direct link to heading")
-------------------------------------------------------
Electron exposes the [Node.js `repl` module](https://nodejs.org/dist/latest/docs/api/repl.html) through the `--interactive` CLI flag. Assuming you have `electron` installed as a local project dependency, you should be able to access the REPL with the following command:
```
./node_modules/.bin/electron --interactive
```
**Note:** `electron --interactive` is not available on Windows (see [electron/electron#5776](https://github.com/electron/electron/pull/5776) for more details).
Renderer process[](#renderer-process "Direct link to heading")
---------------------------------------------------------------
You can use the DevTools Console tab to get a REPL for any renderer process. To learn more, read [the Chrome documentation](https://developer.chrome.com/docs/devtools/console/).
electron Electron Releases Electron Releases
=================
Electron frequently releases major versions alongside every other Chromium release. This document focuses on the release cadence and version support policy. For a more in-depth guide on our git branches and how Electron uses semantic versions, check out our [Electron Versioning](electron-versioning) doc.
Timeline[](#timeline "Direct link to heading")
-----------------------------------------------
| Electron | Alpha | Beta | Stable | Chrome | Node | Supported |
| --- | --- | --- | --- | --- | --- | --- |
| 2.0.0 | -- | 2018-Feb-21 | 2018-May-01 | M61 | v8.9 | 🚫 |
| 3.0.0 | -- | 2018-Jun-21 | 2018-Sep-18 | M66 | v10.2 | 🚫 |
| 4.0.0 | -- | 2018-Oct-11 | 2018-Dec-20 | M69 | v10.11 | 🚫 |
| 5.0.0 | -- | 2019-Jan-22 | 2019-Apr-24 | M73 | v12.0 | 🚫 |
| 6.0.0 | -- | 2019-May-01 | 2019-Jul-30 | M76 | v12.4 | 🚫 |
| 7.0.0 | -- | 2019-Aug-01 | 2019-Oct-22 | M78 | v12.8 | 🚫 |
| 8.0.0 | -- | 2019-Oct-24 | 2020-Feb-04 | M80 | v12.13 | 🚫 |
| 9.0.0 | -- | 2020-Feb-06 | 2020-May-19 | M83 | v12.14 | 🚫 |
| 10.0.0 | -- | 2020-May-21 | 2020-Aug-25 | M85 | v12.16 | 🚫 |
| 11.0.0 | -- | 2020-Aug-27 | 2020-Nov-17 | M87 | v12.18 | 🚫 |
| 12.0.0 | -- | 2020-Nov-19 | 2021-Mar-02 | M89 | v14.16 | 🚫 |
| 13.0.0 | -- | 2021-Mar-04 | 2021-May-25 | M91 | v14.16 | 🚫 |
| 14.0.0 | -- | 2021-May-27 | 2021-Aug-31 | M93 | v14.17 | 🚫 |
| 15.0.0 | 2021-Jul-20 | 2021-Sep-01 | 2021-Sep-21 | M94 | v16.5 | 🚫 |
| 16.0.0 | 2021-Sep-23 | 2021-Oct-20 | 2021-Nov-16 | M96 | v16.9 | 🚫 |
| 17.0.0 | 2021-Nov-18 | 2022-Jan-06 | 2022-Feb-01 | M98 | v16.13 | 🚫 |
| 18.0.0 | 2022-Feb-03 | 2022-Mar-03 | 2022-Mar-29 | M100 | v16.13 | ✅ |
| 19.0.0 | 2022-Mar-31 | 2022-Apr-26 | 2022-May-24 | M102 | v16.14 | ✅ |
| 20.0.0 | 2022-May-26 | 2022-Jun-21 | 2022-Aug-02 | M104 | v16.15 | ✅ |
| 21.0.0 | 2022-Aug-04 | 2022-Aug-30 | 2022-Sep-27 | M106 | TBD | ✅ |
**Notes:**
* The `-alpha.1`, `-beta.1`, and `stable` dates are our solid release dates.
* We strive for weekly alpha/beta releases, but we often release more than scheduled.
* All dates are our goals but there may be reasons for adjusting the stable deadline, such as security bugs.
**Historical changes:**
* Since Electron 5, Electron has been publicizing its release dates ([see blog post](https://electronjs.org/blog/electron-5-0-timeline)).
* Since Electron 6, Electron major versions have been targeting every other Chromium major version. Each Electron stable should happen on the same day as Chrome stable ([see blog post](https://www.electronjs.org/blog/12-week-cadence)).
* Since Electron 16, Electron has been releasing major versions on an 8-week cadence in accordance to Chrome's change to a 4-week release cadence ([see blog post](https://www.electronjs.org/blog/8-week-cadence)).
Chrome release dates
Chromium has the own public release schedule [here](https://chromiumdash.appspot.com/schedule).
Version support policy[](#version-support-policy "Direct link to heading")
---------------------------------------------------------------------------
info
Beginning in September 2021 (Electron 15), the Electron team will temporarily support the latest **four** stable major versions. This extended support is intended to help Electron developers transition to the [new 8-week release cadence](https://electronjs.org/blog/8-week-cadence), and will continue until the release of Electron 19. At that time, the Electron team will drop support back to the latest three stable major versions.
The latest three *stable* major versions are supported by the Electron team. For example, if the latest release is 6.1.x, then the 5.0.x as well as the 4.2.x series are supported. We only support the latest minor release for each stable release series. This means that in the case of a security fix, 6.1.x will receive the fix, but we will not release a new version of 6.0.x.
The latest stable release unilaterally receives all fixes from `main`, and the version prior to that receives the vast majority of those fixes as time and bandwidth warrants. The oldest supported release line will receive only security fixes directly.
### Breaking API changes[](#breaking-api-changes "Direct link to heading")
When an API is changed or removed in a way that breaks existing functionality, the previous functionality will be supported for a minimum of two major versions when possible before being removed. For example, if a function takes three arguments, and that number is reduced to two in major version 10, the three-argument version would continue to work until, at minimum, major version 12. Past the minimum two-version threshold, we will attempt to support backwards compatibility beyond two versions until the maintainers feel the maintenance burden is too high to continue doing so.
### End-of-life[](#end-of-life "Direct link to heading")
When a release branch reaches the end of its support cycle, the series will be deprecated in NPM and a final end-of-support release will be made. This release will add a warning to inform that an unsupported version of Electron is in use.
These steps are to help app developers learn when a branch they're using becomes unsupported, but without being excessively intrusive to end users.
If an application has exceptional circumstances and needs to stay on an unsupported series of Electron, developers can silence the end-of-support warning by omitting the final release from the app's `package.json` `devDependencies`. For example, since the 1-6-x series ended with an end-of-support 1.6.18 release, developers could choose to stay in the 1-6-x series without warnings with `devDependency` of `"electron": 1.6.0 - 1.6.17`.
electron Multithreading Multithreading
==============
With [Web Workers](https://developer.mozilla.org/en/docs/Web/API/Web_Workers_API/Using_web_workers), it is possible to run JavaScript in OS-level threads.
Multi-threaded Node.js[](#multi-threaded-nodejs "Direct link to heading")
--------------------------------------------------------------------------
It is possible to use Node.js features in Electron's Web Workers, to do so the `nodeIntegrationInWorker` option should be set to `true` in `webPreferences`.
```
const win = new BrowserWindow({
webPreferences: {
nodeIntegrationInWorker: true
}
})
```
The `nodeIntegrationInWorker` can be used independent of `nodeIntegration`, but `sandbox` must not be set to `true`.
Available APIs[](#available-apis "Direct link to heading")
-----------------------------------------------------------
All built-in modules of Node.js are supported in Web Workers, and `asar` archives can still be read with Node.js APIs. However none of Electron's built-in modules can be used in a multi-threaded environment.
Native Node.js modules[](#native-nodejs-modules "Direct link to heading")
--------------------------------------------------------------------------
Any native Node.js module can be loaded directly in Web Workers, but it is strongly recommended not to do so. Most existing native modules have been written assuming single-threaded environment, using them in Web Workers will lead to crashes and memory corruptions.
Note that even if a native Node.js module is thread-safe it's still not safe to load it in a Web Worker because the `process.dlopen` function is not thread safe.
The only way to load a native module safely for now, is to make sure the app loads no native modules after the Web Workers get started.
```
process.dlopen = () => {
throw new Error('Load native module is not safe')
}
const worker = new Worker('script.js')
```
electron Web Embeds Web Embeds
==========
Overview[](#overview "Direct link to heading")
-----------------------------------------------
If you want to embed (third-party) web content in an Electron `BrowserWindow`, there are three options available to you: `<iframe>` tags, `<webview>` tags, and `BrowserViews`. Each one offers slightly different functionality and is useful in different situations. To help you choose between these, this guide explains the differences and capabilities of each option.
### Iframes[](#iframes "Direct link to heading")
Iframes in Electron behave like iframes in regular browsers. An `<iframe>` element in your page can show external web pages, provided that their [Content Security Policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP) allows it. To limit the number of capabilities of a site in an `<iframe>` tag, it is recommended to use the [`sandbox` attribute](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-sandbox) and only allow the capabilities you want to support.
### WebViews[](#webviews "Direct link to heading")
> Important Note: [we do not recommend you to use WebViews](../api/webview-tag#warning), as this tag undergoes dramatic architectural changes that may affect stability of your application. Consider switching to alternatives, like `iframe` and Electron's `BrowserView`, or an architecture that avoids embedded content by design.
>
>
[WebViews](../api/webview-tag) are based on Chromium's WebViews and are not explicitly supported by Electron. We do not guarantee that the WebView API will remain available in future versions of Electron. To use `<webview>` tags, you will need to set `webviewTag` to `true` in the `webPreferences` of your `BrowserWindow`.
WebView is a custom element (`<webview>`) that will only work inside Electron. They are implemented as an "out-of-process iframe". This means that all communication with the `<webview>` is done asynchronously using IPC. The `<webview>` element has many custom methods and events, similar to `webContents`, that provide you with greater control over the content.
Compared to an `<iframe>`, `<webview>` tends to be slightly slower but offers much greater control in loading and communicating with the third-party content and handling various events.
### BrowserViews[](#browserviews "Direct link to heading")
[BrowserViews](../api/browser-view) are not a part of the DOM - instead, they are created in and controlled by your Main process. They are simply another layer of web content on top of your existing window. This means that they are completely separate from your own `BrowserWindow` content and their position is not controlled by the DOM or CSS. Instead, it is controlled by setting the bounds in the Main process.
`BrowserViews` offer the greatest control over their contents, since they implement the `webContents` similarly to how the `BrowserWindow` does it. However, as `BrowserViews` are not a part of your DOM, but are rather overlaid on top of them, you will have to manage their position manually.
| programming_docs |
electron Performance Performance
===========
Developers frequently ask about strategies to optimize the performance of Electron applications. Software engineers, consumers, and framework developers do not always agree on one single definition of what "performance" means. This document outlines some of the Electron maintainers' favorite ways to reduce the amount of memory, CPU, and disk resources being used while ensuring that your app is responsive to user input and completes operations as quickly as possible. Furthermore, we want all performance strategies to maintain a high standard for your app's security.
Wisdom and information about how to build performant websites with JavaScript generally applies to Electron apps, too. To a certain extent, resources discussing how to build performant Node.js applications also apply, but be careful to understand that the term "performance" means different things for a Node.js backend than it does for an application running on a client.
This list is provided for your convenience – and is, much like our [security checklist](security) – not meant to exhaustive. It is probably possible to build a slow Electron app that follows all the steps outlined below. Electron is a powerful development platform that enables you, the developer, to do more or less whatever you want. All that freedom means that performance is largely your responsibility.
Measure, Measure, Measure[](#measure-measure-measure "Direct link to heading")
-------------------------------------------------------------------------------
The list below contains a number of steps that are fairly straightforward and easy to implement. However, building the most performant version of your app will require you to go beyond a number of steps. Instead, you will have to closely examine all the code running in your app by carefully profiling and measuring. Where are the bottlenecks? When the user clicks a button, what operations take up the brunt of the time? While the app is simply idling, which objects take up the most memory?
Time and time again, we have seen that the most successful strategy for building a performant Electron app is to profile the running code, find the most resource-hungry piece of it, and to optimize it. Repeating this seemingly laborious process over and over again will dramatically increase your app's performance. Experience from working with major apps like Visual Studio Code or Slack has shown that this practice is by far the most reliable strategy to improve performance.
To learn more about how to profile your app's code, familiarize yourself with the Chrome Developer Tools. For advanced analysis looking at multiple processes at once, consider the [Chrome Tracing](https://www.chromium.org/developers/how-tos/trace-event-profiling-tool) tool.
### Recommended Reading[](#recommended-reading "Direct link to heading")
* [Get Started With Analyzing Runtime Performance](https://developers.google.com/web/tools/chrome-devtools/evaluate-performance/)
* [Talk: "Visual Studio Code - The First Second"](https://www.youtube.com/watch?v=r0OeHRUCCb4)
Checklist: Performance recommendations[](#checklist-performance-recommendations "Direct link to heading")
----------------------------------------------------------------------------------------------------------
Chances are that your app could be a little leaner, faster, and generally less resource-hungry if you attempt these steps.
1. [Carelessly including modules](#1-carelessly-including-modules)
2. [Loading and running code too soon](#2-loading-and-running-code-too-soon)
3. [Blocking the main process](#3-blocking-the-main-process)
4. [Blocking the renderer process](#4-blocking-the-renderer-process)
5. [Unnecessary polyfills](#5-unnecessary-polyfills)
6. [Unnecessary or blocking network requests](#6-unnecessary-or-blocking-network-requests)
7. [Bundle your code](#7-bundle-your-code)
### 1. Carelessly including modules[](#1-carelessly-including-modules "Direct link to heading")
Before adding a Node.js module to your application, examine said module. How many dependencies does that module include? What kind of resources does it need to simply be called in a `require()` statement? You might find that the module with the most downloads on the NPM package registry or the most stars on GitHub is not in fact the leanest or smallest one available.
#### Why?[](#why "Direct link to heading")
The reasoning behind this recommendation is best illustrated with a real-world example. During the early days of Electron, reliable detection of network connectivity was a problem, resulting many apps to use a module that exposed a simple `isOnline()` method.
That module detected your network connectivity by attempting to reach out to a number of well-known endpoints. For the list of those endpoints, it depended on a different module, which also contained a list of well-known ports. This dependency itself relied on a module containing information about ports, which came in the form of a JSON file with more than 100,000 lines of content. Whenever the module was loaded (usually in a `require('module')` statement), it would load all its dependencies and eventually read and parse this JSON file. Parsing many thousands lines of JSON is a very expensive operation. On a slow machine it can take up whole seconds of time.
In many server contexts, startup time is virtually irrelevant. A Node.js server that requires information about all ports is likely actually "more performant" if it loads all required information into memory whenever the server boots at the benefit of serving requests faster. The module discussed in this example is not a "bad" module. Electron apps, however, should not be loading, parsing, and storing in memory information that it does not actually need.
In short, a seemingly excellent module written primarily for Node.js servers running Linux might be bad news for your app's performance. In this particular example, the correct solution was to use no module at all, and to instead use connectivity checks included in later versions of Chromium.
#### How?[](#how "Direct link to heading")
When considering a module, we recommend that you check:
1. the size of dependencies included
2. the resources required to load (`require()`) it
3. the resources required to perform the action you're interested in
Generating a CPU profile and a heap memory profile for loading a module can be done with a single command on the command line. In the example below, we're looking at the popular module `request`.
```
node --cpu-prof --heap-prof -e "require('request')"
```
Executing this command results in a `.cpuprofile` file and a `.heapprofile` file in the directory you executed it in. Both files can be analyzed using the Chrome Developer Tools, using the `Performance` and `Memory` tabs respectively.
In this example, on the author's machine, we saw that loading `request` took almost half a second, whereas `node-fetch` took dramatically less memory and less than 50ms.
### 2. Loading and running code too soon[](#2-loading-and-running-code-too-soon "Direct link to heading")
If you have expensive setup operations, consider deferring those. Inspect all the work being executed right after the application starts. Instead of firing off all operations right away, consider staggering them in a sequence more closely aligned with the user's journey.
In traditional Node.js development, we're used to putting all our `require()` statements at the top. If you're currently writing your Electron application using the same strategy *and* are using sizable modules that you do not immediately need, apply the same strategy and defer loading to a more opportune time.
#### Why?[](#why-1 "Direct link to heading")
Loading modules is a surprisingly expensive operation, especially on Windows. When your app starts, it should not make users wait for operations that are currently not necessary.
This might seem obvious, but many applications tend to do a large amount of work immediately after the app has launched - like checking for updates, downloading content used in a later flow, or performing heavy disk I/O operations.
Let's consider Visual Studio Code as an example. When you open a file, it will immediately display the file to you without any code highlighting, prioritizing your ability to interact with the text. Once it has done that work, it will move on to code highlighting.
#### How?[](#how-1 "Direct link to heading")
Let's consider an example and assume that your application is parsing files in the fictitious `.foo` format. In order to do that, it relies on the equally fictitious `foo-parser` module. In traditional Node.js development, you might write code that eagerly loads dependencies:
parser.js
```
const fs = require('fs')
const fooParser = require('foo-parser')
class Parser {
constructor () {
this.files = fs.readdirSync('.')
}
getParsedFiles () {
return fooParser.parse(this.files)
}
}
const parser = new Parser()
module.exports = { parser }
```
In the above example, we're doing a lot of work that's being executed as soon as the file is loaded. Do we need to get parsed files right away? Could we do this work a little later, when `getParsedFiles()` is actually called?
parser.js
```
// "fs" is likely already being loaded, so the `require()` call is cheap
const fs = require('fs')
class Parser {
async getFiles () {
// Touch the disk as soon as `getFiles` is called, not sooner.
// Also, ensure that we're not blocking other operations by using
// the asynchronous version.
this.files = this.files || await fs.readdir('.')
return this.files
}
async getParsedFiles () {
// Our fictitious foo-parser is a big and expensive module to load, so
// defer that work until we actually need to parse files.
// Since `require()` comes with a module cache, the `require()` call
// will only be expensive once - subsequent calls of `getParsedFiles()`
// will be faster.
const fooParser = require('foo-parser')
const files = await this.getFiles()
return fooParser.parse(files)
}
}
// This operation is now a lot cheaper than in our previous example
const parser = new Parser()
module.exports = { parser }
```
In short, allocate resources "just in time" rather than allocating them all when your app starts.
### 3. Blocking the main process[](#3-blocking-the-main-process "Direct link to heading")
Electron's main process (sometimes called "browser process") is special: It is the parent process to all your app's other processes and the primary process the operating system interacts with. It handles windows, interactions, and the communication between various components inside your app. It also houses the UI thread.
Under no circumstances should you block this process and the UI thread with long-running operations. Blocking the UI thread means that your entire app will freeze until the main process is ready to continue processing.
#### Why?[](#why-2 "Direct link to heading")
The main process and its UI thread are essentially the control tower for major operations inside your app. When the operating system tells your app about a mouse click, it'll go through the main process before it reaches your window. If your window is rendering a buttery-smooth animation, it'll need to talk to the GPU process about that – once again going through the main process.
Electron and Chromium are careful to put heavy disk I/O and CPU-bound operations onto new threads to avoid blocking the UI thread. You should do the same.
#### How?[](#how-2 "Direct link to heading")
Electron's powerful multi-process architecture stands ready to assist you with your long-running tasks, but also includes a small number of performance traps.
1. For long running CPU-heavy tasks, make use of [worker threads](https://nodejs.org/api/worker_threads.html), consider moving them to the BrowserWindow, or (as a last resort) spawn a dedicated process.
2. Avoid using the synchronous IPC and the `@electron/remote` module as much as possible. While there are legitimate use cases, it is far too easy to unknowingly block the UI thread.
3. Avoid using blocking I/O operations in the main process. In short, whenever core Node.js modules (like `fs` or `child_process`) offer a synchronous or an asynchronous version, you should prefer the asynchronous and non-blocking variant.
### 4. Blocking the renderer process[](#4-blocking-the-renderer-process "Direct link to heading")
Since Electron ships with a current version of Chrome, you can make use of the latest and greatest features the Web Platform offers to defer or offload heavy operations in a way that keeps your app smooth and responsive.
#### Why?[](#why-3 "Direct link to heading")
Your app probably has a lot of JavaScript to run in the renderer process. The trick is to execute operations as quickly as possible without taking away resources needed to keep scrolling smooth, respond to user input, or animations at 60fps.
Orchestrating the flow of operations in your renderer's code is particularly useful if users complain about your app sometimes "stuttering".
#### How?[](#how-3 "Direct link to heading")
Generally speaking, all advice for building performant web apps for modern browsers apply to Electron's renderers, too. The two primary tools at your disposal are currently `requestIdleCallback()` for small operations and `Web Workers` for long-running operations.
*`requestIdleCallback()`* allows developers to queue up a function to be executed as soon as the process is entering an idle period. It enables you to perform low-priority or background work without impacting the user experience. For more information about how to use it, [check out its documentation on MDN](https://developer.mozilla.org/en-US/docs/Web/API/Window/requestIdleCallback).
*Web Workers* are a powerful tool to run code on a separate thread. There are some caveats to consider – consult Electron's [multithreading documentation](multithreading) and the [MDN documentation for Web Workers](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Using_web_workers). They're an ideal solution for any operation that requires a lot of CPU power for an extended period of time.
### 5. Unnecessary polyfills[](#5-unnecessary-polyfills "Direct link to heading")
One of Electron's great benefits is that you know exactly which engine will parse your JavaScript, HTML, and CSS. If you're re-purposing code that was written for the web at large, make sure to not polyfill features included in Electron.
#### Why?[](#why-4 "Direct link to heading")
When building a web application for today's Internet, the oldest environments dictate what features you can and cannot use. Even though Electron supports well-performing CSS filters and animations, an older browser might not. Where you could use WebGL, your developers may have chosen a more resource-hungry solution to support older phones.
When it comes to JavaScript, you may have included toolkit libraries like jQuery for DOM selectors or polyfills like the `regenerator-runtime` to support `async/await`.
It is rare for a JavaScript-based polyfill to be faster than the equivalent native feature in Electron. Do not slow down your Electron app by shipping your own version of standard web platform features.
#### How?[](#how-4 "Direct link to heading")
Operate under the assumption that polyfills in current versions of Electron are unnecessary. If you have doubts, check [caniuse.com](https://caniuse.com/) and check if the [version of Chromium used in your Electron version](../api/process#processversionschrome-readonly) supports the feature you desire.
In addition, carefully examine the libraries you use. Are they really necessary? `jQuery`, for example, was such a success that many of its features are now part of the [standard JavaScript feature set available](http://youmightnotneedjquery.com/).
If you're using a transpiler/compiler like TypeScript, examine its configuration and ensure that you're targeting the latest ECMAScript version supported by Electron.
### 6. Unnecessary or blocking network requests[](#6-unnecessary-or-blocking-network-requests "Direct link to heading")
Avoid fetching rarely changing resources from the internet if they could easily be bundled with your application.
#### Why?[](#why-5 "Direct link to heading")
Many users of Electron start with an entirely web-based app that they're turning into a desktop application. As web developers, we are used to loading resources from a variety of content delivery networks. Now that you are shipping a proper desktop application, attempt to "cut the cord" where possible and avoid letting your users wait for resources that never change and could easily be included in your app.
A typical example is Google Fonts. Many developers make use of Google's impressive collection of free fonts, which comes with a content delivery network. The pitch is straightforward: Include a few lines of CSS and Google will take care of the rest.
When building an Electron app, your users are better served if you download the fonts and include them in your app's bundle.
#### How?[](#how-5 "Direct link to heading")
In an ideal world, your application wouldn't need the network to operate at all. To get there, you must understand what resources your app is downloading - and how large those resources are.
To do so, open up the developer tools. Navigate to the `Network` tab and check the `Disable cache` option. Then, reload your renderer. Unless your app prohibits such reloads, you can usually trigger a reload by hitting `Cmd + R` or `Ctrl + R` with the developer tools in focus.
The tools will now meticulously record all network requests. In a first pass, take stock of all the resources being downloaded, focusing on the larger files first. Are any of them images, fonts, or media files that don't change and could be included with your bundle? If so, include them.
As a next step, enable `Network Throttling`. Find the drop-down that currently reads `Online` and select a slower speed such as `Fast 3G`. Reload your renderer and see if there are any resources that your app is unnecessarily waiting for. In many cases, an app will wait for a network request to complete despite not actually needing the involved resource.
As a tip, loading resources from the Internet that you might want to change without shipping an application update is a powerful strategy. For advanced control over how resources are being loaded, consider investing in [Service Workers](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API).
### 7. Bundle your code[](#7-bundle-your-code "Direct link to heading")
As already pointed out in "[Loading and running code too soon](#2-loading-and-running-code-too-soon)", calling `require()` is an expensive operation. If you are able to do so, bundle your application's code into a single file.
#### Why?[](#why-6 "Direct link to heading")
Modern JavaScript development usually involves many files and modules. While that's perfectly fine for developing with Electron, we heavily recommend that you bundle all your code into one single file to ensure that the overhead included in calling `require()` is only paid once when your application loads.
#### How?[](#how-6 "Direct link to heading")
There are numerous JavaScript bundlers out there and we know better than to anger the community by recommending one tool over another. We do however recommend that you use a bundler that is able to handle Electron's unique environment that needs to handle both Node.js and browser environments.
As of writing this article, the popular choices include [Webpack](https://webpack.js.org/), [Parcel](https://parceljs.org/), and [rollup.js](https://rollupjs.org/).
| programming_docs |
electron DevTools Extension DevTools Extension
==================
Electron supports [Chrome DevTools extensions](https://developer.chrome.com/extensions/devtools), which can be used to extend the ability of Chrome's developer tools for debugging popular web frameworks.
Loading a DevTools extension with tooling[](#loading-a-devtools-extension-with-tooling "Direct link to heading")
-----------------------------------------------------------------------------------------------------------------
The easiest way to load a DevTools extension is to use third-party tooling to automate the process for you. [electron-devtools-installer](https://github.com/MarshallOfSound/electron-devtools-installer) is a popular NPM package that does just that.
Manually loading a DevTools extension[](#manually-loading-a-devtools-extension "Direct link to heading")
---------------------------------------------------------------------------------------------------------
If you don't want to use the tooling approach, you can also do all of the necessary operations by hand. To load an extension in Electron, you need to download it via Chrome, locate its filesystem path, and then load it into your [Session](../api/session) by calling the [`ses.loadExtension`] API.
Using the [React Developer Tools](https://chrome.google.com/webstore/detail/react-developer-tools/fmkadmapgofadopljbjfkapdkoienihi) as an example:
1. Install the extension in Google Chrome.
2. Navigate to `chrome://extensions`, and find its extension ID, which is a hash string like `fmkadmapgofadopljbjfkapdkoienihi`.
3. Find out the filesystem location used by Chrome for storing extensions:
* on Windows it is `%LOCALAPPDATA%\Google\Chrome\User Data\Default\Extensions`;
* on Linux it could be:
+ `~/.config/google-chrome/Default/Extensions/`
+ `~/.config/google-chrome-beta/Default/Extensions/`
+ `~/.config/google-chrome-canary/Default/Extensions/`
+ `~/.config/chromium/Default/Extensions/`
* on macOS it is `~/Library/Application Support/Google/Chrome/Default/Extensions`.
4. Pass the location of the extension to the [`ses.loadExtension`](../api/session#sesloadextensionpath-options) API. For React Developer Tools `v4.9.0`, it looks something like:
```
const { app, session } = require('electron')
const path = require('path')
const os = require('os')
// on macOS
const reactDevToolsPath = path.join(
os.homedir(),
'/Library/Application Support/Google/Chrome/Default/Extensions/fmkadmapgofadopljbjfkapdkoienihi/4.9.0_0'
)
app.whenReady().then(async () => {
await session.defaultSession.loadExtension(reactDevToolsPath)
})
```
**Notes:**
* `loadExtension` returns a Promise with an [Extension object](../api/structures/extension), which contains metadata about the extension that was loaded. This promise needs to resolve (e.g. with an `await` expression) before loading a page. Otherwise, the extension won't be guaranteed to load.
* `loadExtension` cannot be called before the `ready` event of the `app` module is emitted, nor can it be called on in-memory (non-persistent) sessions.
* `loadExtension` must be called on every boot of your app if you want the extension to be loaded.
### Removing a DevTools extension[](#removing-a-devtools-extension "Direct link to heading")
You can pass the extension's ID to the [`ses.removeExtension`](../api/session#sesremoveextensionextensionid) API to remove it from your Session. Loaded extensions are not persisted between app launches.
DevTools extension support[](#devtools-extension-support "Direct link to heading")
-----------------------------------------------------------------------------------
Electron only supports [a limited set of `chrome.*` APIs](../api/extensions), so extensions using unsupported `chrome.*` APIs under the hood may not work.
The following Devtools extensions have been tested to work in Electron:
* [Ember Inspector](https://chrome.google.com/webstore/detail/ember-inspector/bmdblncegkenkacieihfhpjfppoconhi)
* [React Developer Tools](https://chrome.google.com/webstore/detail/react-developer-tools/fmkadmapgofadopljbjfkapdkoienihi)
* [Backbone Debugger](https://chrome.google.com/webstore/detail/backbone-debugger/bhljhndlimiafopmmhjlgfpnnchjjbhd)
* [jQuery Debugger](https://chrome.google.com/webstore/detail/jquery-debugger/dbhhnnnpaeobfddmlalhnehgclcmjimi)
* [AngularJS Batarang](https://chrome.google.com/webstore/detail/angularjs-batarang/ighdmehidhipcmcojjgiloacoafjmpfk)
* [Vue.js devtools](https://chrome.google.com/webstore/detail/vuejs-devtools/nhdogjmejiglipccpnnnanhbledajbpd)
* [Cerebral Debugger](https://cerebraljs.com/docs/introduction/devtools.html)
* [Redux DevTools Extension](https://chrome.google.com/webstore/detail/redux-devtools/lmhkpmbekcpmknklioeibfkpmmfibljd)
* [MobX Developer Tools](https://chrome.google.com/webstore/detail/mobx-developer-tools/pfgnfdagidkfgccljigdamigbcnndkod)
### What should I do if a DevTools extension is not working?[](#what-should-i-do-if-a-devtools-extension-is-not-working "Direct link to heading")
First, please make sure the extension is still being maintained and is compatible with the latest version of Google Chrome. We cannot provide additional support for unsupported extensions.
If the extension works on Chrome but not on Electron, file a bug in Electron's [issue tracker](https://github.com/electron/electron/issues) and describe which part of the extension is not working as expected.
electron Recent Documents Recent Documents
================
Overview[](#overview "Direct link to heading")
-----------------------------------------------
Windows and macOS provide access to a list of recent documents opened by the application via JumpList or dock menu, respectively.
**JumpList:**
**Application dock menu:**
Example[](#example "Direct link to heading")
---------------------------------------------
### Managing recent documents[](#managing-recent-documents "Direct link to heading")
[docs/fiddles/features/recent-documents (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/recent-documents)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/recent-documents)
* main.js
* index.html
```
const { app, BrowserWindow } = require('electron')
const fs = require('fs')
const path = require('path')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600
})
win.loadFile('index.html')
}
const fileName = 'recently-used.md'
fs.writeFile(fileName, 'Lorem Ipsum', () => {
app.addRecentDocument(path.join(__dirname, fileName))
})
app.whenReady().then(createWindow)
app.on('window-all-closed', () => {
app.clearRecentDocuments()
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Recent Documents</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Recent Documents</h1>
<p>
Right click on the app icon to see recent documents.
You should see `recently-used.md` added to the list of recent files
</p>
</body>
</html>
```
#### Adding a recent document[](#adding-a-recent-document "Direct link to heading")
To add a file to recent documents, use the [app.addRecentDocument](../api/app#appaddrecentdocumentpath-macos-windows) API.
After launching the Electron application, right click the application icon. In this guide, the item is a Markdown file located in the root of the project. You should see `recently-used.md` added to the list of recent files:
#### Clearing the list of recent documents[](#clearing-the-list-of-recent-documents "Direct link to heading")
To clear the list of recent documents, use the [app.clearRecentDocuments](../api/app#appclearrecentdocuments-macos-windows) API. In this guide, the list of documents is cleared once all windows have been closed.
Additional information[](#additional-information "Direct link to heading")
---------------------------------------------------------------------------
### Windows Notes[](#windows-notes "Direct link to heading")
To use this feature on Windows, your application has to be registered as a handler of the file type of the document, otherwise the file won't appear in JumpList even after you have added it. You can find everything on registering your application in [Application Registration](https://msdn.microsoft.com/en-us/library/cc144104(VS.85).aspx).
When a user clicks a file from the JumpList, a new instance of your application will be started with the path of the file added as a command line argument.
### macOS Notes[](#macos-notes "Direct link to heading")
#### Add the Recent Documents list to the application menu[](#add-the-recent-documents-list-to-the-application-menu "Direct link to heading")
You can add menu items to access and clear recent documents by adding the following code snippet to your menu template:
```
{
"submenu":[
{
"label":"Open Recent",
"role":"recentdocuments",
"submenu":[
{
"label":"Clear Recent",
"role":"clearrecentdocuments"
}
]
}
]
}
```
Make sure the application menu is added after the [`'ready'`](../api/app#event-ready) event and not before, or the menu item will be disabled:
```
const { app, Menu } = require('electron')
const template = [
// Menu template here
]
const menu = Menu.buildFromTemplate(template)
app.whenReady().then(() => {
Menu.setApplicationMenu(menu)
})
```
When a file is requested from the recent documents menu, the `open-file` event of `app` module will be emitted for it.
electron Deep Links Deep Links
==========
Overview[](#overview "Direct link to heading")
-----------------------------------------------
This guide will take you through the process of setting your Electron app as the default handler for a specific [protocol](https://www.electronjs.org/docs/api/protocol).
By the end of this tutorial, we will have set our app to intercept and handle any clicked URLs that start with a specific protocol. In this guide, the protocol we will use will be "`electron-fiddle://`".
Examples[](#examples "Direct link to heading")
-----------------------------------------------
### Main Process (main.js)[](#main-process-mainjs "Direct link to heading")
First, we will import the required modules from `electron`. These modules help control our application lifecycle and create a native browser window.
```
const { app, BrowserWindow, shell } = require('electron')
const path = require('path')
```
Next, we will proceed to register our application to handle all "`electron-fiddle://`" protocols.
```
if (process.defaultApp) {
if (process.argv.length >= 2) {
app.setAsDefaultProtocolClient('electron-fiddle', process.execPath, [path.resolve(process.argv[1])])
}
} else {
app.setAsDefaultProtocolClient('electron-fiddle')
}
```
We will now define the function in charge of creating our browser window and load our application's `index.html` file.
```
const createWindow = () => {
// Create the browser window.
mainWindow = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
mainWindow.loadFile('index.html')
}
```
In this next step, we will create our `BrowserWindow` and tell our application how to handle an event in which an external protocol is clicked.
This code will be different in Windows compared to MacOS and Linux. This is due to Windows requiring additional code in order to open the contents of the protocol link within the same Electron instance. Read more about this [here](https://www.electronjs.org/docs/api/app#apprequestsingleinstancelock).
#### Windows code:[](#windows-code "Direct link to heading")
```
const gotTheLock = app.requestSingleInstanceLock()
if (!gotTheLock) {
app.quit()
} else {
app.on('second-instance', (event, commandLine, workingDirectory) => {
// Someone tried to run a second instance, we should focus our window.
if (mainWindow) {
if (mainWindow.isMinimized()) mainWindow.restore()
mainWindow.focus()
}
})
// Create mainWindow, load the rest of the app, etc...
app.whenReady().then(() => {
createWindow()
})
// Handle the protocol. In this case, we choose to show an Error Box.
app.on('open-url', (event, url) => {
dialog.showErrorBox('Welcome Back', `You arrived from: ${url}`)
})
}
```
#### MacOS and Linux code:[](#macos-and-linux-code "Direct link to heading")
```
// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.whenReady().then(() => {
createWindow()
})
// Handle the protocol. In this case, we choose to show an Error Box.
app.on('open-url', (event, url) => {
dialog.showErrorBox('Welcome Back', `You arrived from: ${url}`)
})
```
Finally, we will add some additional code to handle when someone closes our application.
```
// Quit when all windows are closed, except on macOS. There, it's common
// for applications and their menu bar to stay active until the user quits
// explicitly with Cmd + Q.
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') app.quit()
})
```
Important notes[](#important-notes "Direct link to heading")
-------------------------------------------------------------
### Packaging[](#packaging "Direct link to heading")
On macOS and Linux, this feature will only work when your app is packaged. It will not work when you're launching it in development from the command-line. When you package your app you'll need to make sure the macOS `Info.plist` and the Linux `.desktop` files for the app are updated to include the new protocol handler. Some of the Electron tools for bundling and distributing apps handle this for you.
####
[Electron Forge](https://electronforge.io)[](#electron-forge "Direct link to heading")
If you're using Electron Forge, adjust `packagerConfig` for macOS support, and the configuration for the appropriate Linux makers for Linux support, in your [Forge configuration](https://www.electronforge.io/configuration) *(please note the following example only shows the bare minimum needed to add the configuration changes)*:
```
{
"config": {
"forge": {
"packagerConfig": {
"protocols": [
{
"name": "Electron Fiddle",
"schemes": ["electron-fiddle"]
}
]
},
"makers": [
{
"name": "@electron-forge/maker-deb",
"config": {
"mimeType": ["x-scheme-handler/electron-fiddle"]
}
}
]
}
}
}
```
####
[Electron Packager](https://github.com/electron/electron-packager)[](#electron-packager "Direct link to heading")
For macOS support:
If you're using Electron Packager's API, adding support for protocol handlers is similar to how Electron Forge is handled, except `protocols` is part of the Packager options passed to the `packager` function.
```
const packager = require('electron-packager')
packager({
// ...other options...
protocols: [
{
name: 'Electron Fiddle',
schemes: ['electron-fiddle']
}
]
}).then(paths => console.log(`SUCCESS: Created ${paths.join(', ')}`))
.catch(err => console.error(`ERROR: ${err.message}`))
```
If you're using Electron Packager's CLI, use the `--protocol` and `--protocol-name` flags. For example:
```
npx electron-packager . --protocol=electron-fiddle --protocol-name="Electron Fiddle"
```
Conclusion[](#conclusion "Direct link to heading")
---------------------------------------------------
After you start your Electron app, you can enter in a URL in your browser that contains the custom protocol, for example `"electron-fiddle://open"` and observe that the application will respond and show an error dialog box.
[docs/fiddles/system/protocol-handler/launch-app-from-URL-in-another-app (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/system/protocol-handler/launch-app-from-URL-in-another-app)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/system/protocol-handler/launch-app-from-URL-in-another-app)
* main.js
* preload.js
* index.html
* renderer.js
```
// Modules to control application life and create native browser window
const { app, BrowserWindow, ipcMain, shell, dialog } = require('electron')
const path = require('path')
let mainWindow;
if (process.defaultApp) {
if (process.argv.length >= 2) {
app.setAsDefaultProtocolClient('electron-fiddle', process.execPath, [path.resolve(process.argv[1])])
}
} else {
app.setAsDefaultProtocolClient('electron-fiddle')
}
const gotTheLock = app.requestSingleInstanceLock()
if (!gotTheLock) {
app.quit()
} else {
app.on('second-instance', (event, commandLine, workingDirectory) => {
// Someone tried to run a second instance, we should focus our window.
if (mainWindow) {
if (mainWindow.isMinimized()) mainWindow.restore()
mainWindow.focus()
}
})
// Create mainWindow, load the rest of the app, etc...
app.whenReady().then(() => {
createWindow()
})
app.on('open-url', (event, url) => {
dialog.showErrorBox('Welcome Back', `You arrived from: ${url}`)
})
}
function createWindow () {
// Create the browser window.
mainWindow = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js'),
}
})
mainWindow.loadFile('index.html')
}
// Quit when all windows are closed, except on macOS. There, it's common
// for applications and their menu bar to stay active until the user quits
// explicitly with Cmd + Q.
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
// Handle window controls via IPC
ipcMain.on('shell:open', () => {
const pageDirectory = __dirname.replace('app.asar', 'app.asar.unpacked')
const pagePath = path.join('file://', pageDirectory, 'index.html')
shell.openExternal(pagePath)
})
```
```
// All of the Node.js APIs are available in the preload process.
// It has the same sandbox as a Chrome extension.
const { contextBridge, ipcRenderer } = require('electron')
// Set up context bridge between the renderer process and the main process
contextBridge.exposeInMainWorld(
'shell',
{
open: () => ipcRenderer.send('shell:open'),
}
)
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<meta http-equiv="X-Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>app.setAsDefaultProtocol Demo</title>
</head>
<body>
<h1>App Default Protocol Demo</h1>
<p>The protocol API allows us to register a custom protocol and intercept existing protocol requests.</p>
<p>These methods allow you to set and unset the protocols your app should be the default app for. Similar to when a
browser asks to be your default for viewing web pages.</p>
<p>Open the <a href="https://www.electronjs.org/docs/api/protocol">full protocol API documentation</a> in your
browser.</p>
-----
<h3>Demo</h3>
<p>
First: Launch current page in browser
<button id="open-in-browser" class="js-container-target demo-toggle-button">
Click to Launch Browser
</button>
</p>
<p>
Then: Launch the app from a web link!
<a href="electron-fiddle://open">Click here to launch the app</a>
</p>
----
<p>You can set your app as the default app to open for a specific protocol. For instance, in this demo we set this app
as the default for <code>electron-fiddle://</code>. The demo button above will launch a page in your default
browser with a link. Click that link and it will re-launch this app.</p>
<h3>Packaging</h3>
<p>This feature will only work on macOS when your app is packaged. It will not work when you're launching it in
development from the command-line. When you package your app you'll need to make sure the macOS <code>plist</code>
for the app is updated to include the new protocol handler. If you're using <code>electron-packager</code> then you
can add the flag <code>--extend-info</code> with a path to the <code>plist</code> you've created. The one for this
app is below:</p>
<p>
<h5>macOS plist</h5>
<pre><code>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>CFBundleURLTypes</key>
<array>
<dict>
<key>CFBundleURLSchemes</key>
<array>
<string>electron-api-demos</string>
</array>
<key>CFBundleURLName</key>
<string>Electron API Demos Protocol</string>
</dict>
</array>
<key>ElectronTeamID</key>
<string>VEKTX9H2N7</string>
</dict>
</plist>
</code>
</pre>
<p>
<!-- You can also require other files to run in this process -->
<script src="./renderer.js"></script>
</body>
</html>
```
```
// This file is required by the index.html file and will
// be executed in the renderer process for that window.
// All APIs exposed by the context bridge are available here.
// Binds the buttons to the context bridge API.
document.getElementById('open-in-browser').addEventListener('click', () => {
shell.open();
});
```
| programming_docs |
electron Debugging the Main Process Debugging the Main Process
==========================
The DevTools in an Electron browser window can only debug JavaScript that's executed in that window (i.e. the web pages). To debug JavaScript that's executed in the main process you will need to use an external debugger and launch Electron with the `--inspect` or `--inspect-brk` switch.
Command Line Switches[](#command-line-switches "Direct link to heading")
-------------------------------------------------------------------------
Use one of the following command line switches to enable debugging of the main process:
###
`--inspect=[port]`[](#--inspectport "Direct link to heading")
Electron will listen for V8 inspector protocol messages on the specified `port`, an external debugger will need to connect on this port. The default `port` is `5858`.
```
electron --inspect=5858 your/app
```
###
`--inspect-brk=[port]`[](#--inspect-brkport "Direct link to heading")
Like `--inspect` but pauses execution on the first line of JavaScript.
External Debuggers[](#external-debuggers "Direct link to heading")
-------------------------------------------------------------------
You will need to use a debugger that supports the V8 inspector protocol.
* Connect Chrome by visiting `chrome://inspect` and selecting to inspect the launched Electron app present there.
* [Debugging in VSCode](debugging-vscode)
electron Taskbar Customization Taskbar Customization
=====================
Overview[](#overview "Direct link to heading")
-----------------------------------------------
Electron has APIs to configure the app's icon in the Windows taskbar. This API supports both Windows-only features like [creation of a `JumpList`](#jumplist), [custom thumbnails and toolbars](#thumbnail-toolbars), [icon overlays](#icon-overlays-in-taskbar), and the so-called ["Flash Frame" effect](#flash-frame), and cross-platform features like [recent documents](recent-documents) and [application progress](progress-bar).
JumpList[](#jumplist "Direct link to heading")
-----------------------------------------------
Windows allows apps to define a custom context menu that shows up when users right-click the app's icon in the taskbar. That context menu is called `JumpList`. You specify custom actions in the `Tasks` category of JumpList, as quoted from [MSDN](https://docs.microsoft.com/en-us/windows/win32/shell/taskbar-extensions#tasks):
>
> Applications define tasks based on both the program's features and the key things a user is expected to do with them. Tasks should be context-free, in that the application does not need to be running for them to work. They should also be the statistically most common actions that a normal user would perform in an application, such as compose an email message or open the calendar in a mail program, create a new document in a word processor, launch an application in a certain mode, or launch one of its subcommands. An application should not clutter the menu with advanced features that standard users won't need or one-time actions such as registration. Do not use tasks for promotional items such as upgrades or special offers.
>
>
> It is strongly recommended that the task list be static. It should remain the same regardless of the state or status of the application. While it is possible to vary the list dynamically, you should consider that this could confuse the user who does not expect that portion of the destination list to change.
>
>
>
> NOTE: The screenshot above is an example of general tasks for Microsoft Edge
>
>
Unlike the dock menu in macOS which is a real menu, user tasks in Windows work like application shortcuts. For example, when a user clicks a task, the program will be executed with specified arguments.
To set user tasks for your application, you can use [app.setUserTasks](../api/app#appsetusertaskstasks-windows) API.
#### Examples[](#examples "Direct link to heading")
##### Set user tasks[](#set-user-tasks "Direct link to heading")
Starting with a working application from the [Quick Start Guide](quick-start), update the `main.js` file with the following lines:
```
const { app } = require('electron')
app.setUserTasks([
{
program: process.execPath,
arguments: '--new-window',
iconPath: process.execPath,
iconIndex: 0,
title: 'New Window',
description: 'Create a new window'
}
])
```
##### Clear tasks list[](#clear-tasks-list "Direct link to heading")
To clear your tasks list, you need to call `app.setUserTasks` with an empty array in the `main.js` file.
```
const { app } = require('electron')
app.setUserTasks([])
```
> NOTE: The user tasks will still be displayed even after closing your application, so the icon and program path specified for a task should exist until your application is uninstalled.
>
>
### Thumbnail Toolbars[](#thumbnail-toolbars "Direct link to heading")
On Windows, you can add a thumbnail toolbar with specified buttons to a taskbar layout of an application window. It provides users with a way to access a particular window's command without restoring or activating the window.
As quoted from [MSDN](https://docs.microsoft.com/en-us/windows/win32/shell/taskbar-extensions#thumbnail-toolbars):
>
> This toolbar is the familiar standard toolbar common control. It has a maximum of seven buttons. Each button's ID, image, tooltip, and state are defined in a structure, which is then passed to the taskbar. The application can show, enable, disable, or hide buttons from the thumbnail toolbar as required by its current state.
>
>
> For example, Windows Media Player might offer standard media transport controls such as play, pause, mute, and stop.
>
>
>
> NOTE: The screenshot above is an example of thumbnail toolbar of Windows Media Player
>
>
To set thumbnail toolbar in your application, you need to use [BrowserWindow.setThumbarButtons](../api/browser-window#winsetthumbarbuttonsbuttons-windows)
#### Examples[](#examples-1 "Direct link to heading")
##### Set thumbnail toolbar[](#set-thumbnail-toolbar "Direct link to heading")
Starting with a working application from the [Quick Start Guide](quick-start), update the `main.js` file with the following lines:
```
const { BrowserWindow } = require('electron')
const path = require('path')
const win = new BrowserWindow()
win.setThumbarButtons([
{
tooltip: 'button1',
icon: path.join(__dirname, 'button1.png'),
click () { console.log('button1 clicked') }
}, {
tooltip: 'button2',
icon: path.join(__dirname, 'button2.png'),
flags: ['enabled', 'dismissonclick'],
click () { console.log('button2 clicked.') }
}
])
```
##### Clear thumbnail toolbar[](#clear-thumbnail-toolbar "Direct link to heading")
To clear thumbnail toolbar buttons, you need to call `BrowserWindow.setThumbarButtons` with an empty array in the `main.js` file.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.setThumbarButtons([])
```
### Icon Overlays in Taskbar[](#icon-overlays-in-taskbar "Direct link to heading")
On Windows, a taskbar button can use a small overlay to display application status.
As quoted from [MSDN](https://docs.microsoft.com/en-us/windows/win32/shell/taskbar-extensions#icon-overlays):
> Icon overlays serve as a contextual notification of status, and are intended to negate the need for a separate notification area status icon to communicate that information to the user. For instance, the new mail status in Microsoft Outlook, currently shown in the notification area, can now be indicated through an overlay on the taskbar button. Again, you must decide during your development cycle which method is best for your application. Overlay icons are intended to supply important, long-standing status or notifications such as network status, messenger status, or new mail. The user should not be presented with constantly changing overlays or animations.
>
>
> NOTE: The screenshot above is an example of overlay on a taskbar button
>
>
To set the overlay icon for a window, you need to use the [BrowserWindow.setOverlayIcon](../api/browser-window#winsetoverlayiconoverlay-description-windows) API.
#### Example[](#example "Direct link to heading")
Starting with a working application from the [Quick Start Guide](quick-start), update the `main.js` file with the following lines:
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.setOverlayIcon('path/to/overlay.png', 'Description for overlay')
```
### Flash Frame[](#flash-frame "Direct link to heading")
On Windows, you can highlight the taskbar button to get the user's attention. This is similar to bouncing the dock icon in macOS.
As quoted from [MSDN](https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-flashwindow#remarks):
> Typically, a window is flashed to inform the user that the window requires attention but that it does not currently have the keyboard focus.
>
>
To flash the BrowserWindow taskbar button, you need to use the [BrowserWindow.flashFrame](../api/browser-window#winflashframeflag) API.
#### Example[](#example-1 "Direct link to heading")
Starting with a working application from the [Quick Start Guide](quick-start), update the `main.js` file with the following lines:
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.once('focus', () => win.flashFrame(false))
win.flashFrame(true)
```
> NOTE: Don't forget to call `win.flashFrame(false)` to turn off the flash. In the above example, it is called when the window comes into focus, but you might use a timeout or some other event to disable it.
>
>
electron Tray Tray
====
Overview[](#overview "Direct link to heading")
-----------------------------------------------
This guide will take you through the process of creating a [Tray](https://www.electronjs.org/docs/api/tray) icon with its own context menu to the system's notification area.
On MacOS and Ubuntu, the Tray will be located on the top right corner of your screen, adjacent to your battery and wifi icons. On Windows, the Tray will usually be located in the bottom right corner.
Example[](#example "Direct link to heading")
---------------------------------------------
### main.js[](#mainjs "Direct link to heading")
First we must import `app`, `Tray`, `Menu`, `nativeImage` from `electron`.
```
const { app, Tray, Menu, nativeImage } = require('electron')
```
Next we will create our Tray. To do this, we will use a [`NativeImage`](https://www.electronjs.org/docs/api/native-image) icon, which can be created through any one of these [methods](https://www.electronjs.org/docs/api/native-image#methods). Note that we wrap our Tray creation code within an [`app.whenReady`](https://www.electronjs.org/docs/api/app#appwhenready) as we will need to wait for our electron app to finish initializing.
main.js
```
let tray
app.whenReady().then(() => {
const icon = nativeImage.createFromPath('path/to/asset.png')
tray = new Tray(icon)
// note: your contextMenu, Tooltip and Title code will go here!
})
```
Great! Now we can start attaching a context menu to our Tray, like so:
```
const contextMenu = Menu.buildFromTemplate([
{ label: 'Item1', type: 'radio' },
{ label: 'Item2', type: 'radio' },
{ label: 'Item3', type: 'radio', checked: true },
{ label: 'Item4', type: 'radio' }
])
tray.setContextMenu(contextMenu)
```
The code above will create 4 separate radio-type items in the context menu. To read more about constructing native menus, click [here](https://www.electronjs.org/docs/api/menu#menubuildfromtemplatetemplate).
Finally, let's give our tray a tooltip and a title.
```
tray.setToolTip('This is my application')
tray.setTitle('This is my title')
```
Conclusion[](#conclusion "Direct link to heading")
---------------------------------------------------
After you start your electron app, you should see the Tray residing in either the top or bottom right of your screen, depending on your operating system.
[docs/fiddles/native-ui/tray (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/native-ui/tray)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/native-ui/tray)
* .keep
* main.js
* index.html
```
const { app, Tray, Menu, nativeImage } = require('electron')
let tray
app.whenReady().then(() => {
const icon = nativeImage.createFromDataURL('data:image/png;base64,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')
tray = new Tray(icon)
const contextMenu = Menu.buildFromTemplate([
{ label: 'Item1', type: 'radio' },
{ label: 'Item2', type: 'radio' },
{ label: 'Item3', type: 'radio', checked: true },
{ label: 'Item4', type: 'radio' }
])
tray.setToolTip('This is my application.')
tray.setContextMenu(contextMenu)
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>Tray</title>
</head>
<body>
<div>
<h1>Tray</h1>
<h3>
The <code>tray</code> module allows you to create an icon in the
operating system's notification area.
</h3>
<p>This icon can also have a context menu attached.</p>
<p>
Open the
<a href="https://electronjs.org/docs/api/tray">
full API documentation
</a>
in your browser.
</p>
</div>
<div>
<div>
<h2>ProTip</h2>
<strong>Tray support in Linux.</strong>
<p>
On Linux distributions that only have app indicator support, users
will need to install <code>libappindicator1</code> to make the
tray icon work. See the
<a href="https://electronjs.org/docs/api/tray">
full API documentation
</a>
for more details about using Tray on Linux.
</p>
</div>
</div>
</div>
</div>
<script>
// You can also require other files to run in this process
require("./renderer.js");
</script>
</body>
</html>
```
electron Representing Files in a BrowserWindow Representing Files in a BrowserWindow
=====================================
Overview[](#overview "Direct link to heading")
-----------------------------------------------
On macOS, you can set a represented file for any window in your application. The represented file's icon will be shown in the title bar, and when users `Command-Click` or `Control-Click`, a popup with a path to the file will be shown.
> NOTE: The screenshot above is an example where this feature is used to indicate the currently opened file in the Atom text editor.
>
>
You can also set the edited state for a window so that the file icon can indicate whether the document in this window has been modified.
To set the represented file of window, you can use the [BrowserWindow.setRepresentedFilename](../api/browser-window#winsetrepresentedfilenamefilename-macos) and [BrowserWindow.setDocumentEdited](../api/browser-window#winsetdocumenteditededited-macos) APIs.
Example[](#example "Direct link to heading")
---------------------------------------------
[docs/fiddles/features/represented-file (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/represented-file)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/represented-file)
* main.js
* index.html
```
const { app, BrowserWindow } = require('electron')
const os = require('os');
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600
})
win.loadFile('index.html')
}
app.whenReady().then(() => {
const win = new BrowserWindow()
win.setRepresentedFilename(os.homedir())
win.setDocumentEdited(true)
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
<link rel="stylesheet" type="text/css" href="./styles.css">
</head>
<body>
<h1>Hello World!</h1>
<p>
Click on the title with the <pre>Command</pre> or <pre>Control</pre> key pressed.
You should see a popup with the represented file at the top.
</p>
</body>
</body>
</html>
```
After launching the Electron application, click on the title with `Command` or `Control` key pressed. You should see a popup with the represented file at the top. In this guide, this is the current user's home directory:
| programming_docs |
electron Native File Drag & Drop Native File Drag & Drop
=======================
Overview[](#overview "Direct link to heading")
-----------------------------------------------
Certain kinds of applications that manipulate files might want to support the operating system's native file drag & drop feature. Dragging files into web content is common and supported by many websites. Electron additionally supports dragging files and content out from web content into the operating system's world.
To implement this feature in your app, you need to call the [`webContents.startDrag(item)`](../api/web-contents#contentsstartdragitem) API in response to the `ondragstart` event.
Example[](#example "Direct link to heading")
---------------------------------------------
An example demonstrating how you can create a file on the fly to be dragged out of the window.
### Preload.js[](#preloadjs "Direct link to heading")
In `preload.js` use the [`contextBridge`](../api/context-bridge) to inject a method `window.electron.startDrag(...)` that will send an IPC message to the main process.
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electron', {
startDrag: (fileName) => {
ipcRenderer.send('ondragstart', path.join(process.cwd(), fileName))
}
})
```
### Index.html[](#indexhtml "Direct link to heading")
Add a draggable element to `index.html`, and reference your renderer script:
```
<div style="border:2px solid black;border-radius:3px;padding:5px;display:inline-block" draggable="true" id="drag">Drag me</div>
<script src="renderer.js"></script>
```
### Renderer.js[](#rendererjs "Direct link to heading")
In `renderer.js` set up the renderer process to handle drag events by calling the method you added via the [`contextBridge`](../api/context-bridge) above.
```
document.getElementById('drag').ondragstart = (event) => {
event.preventDefault()
window.electron.startDrag('drag-and-drop.md')
}
```
### Main.js[](#mainjs "Direct link to heading")
In the Main process (`main.js` file), expand the received event with a path to the file that is being dragged and an icon:
[docs/fiddles/features/drag-and-drop (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/drag-and-drop)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/drag-and-drop)
* main.js
* preload.js
* index.html
* renderer.js
```
const { app, BrowserWindow, ipcMain, nativeImage, NativeImage } = require('electron')
const path = require('path')
const fs = require('fs')
const https = require('https')
function createWindow() {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
win.loadFile('index.html')
}
const iconName = path.join(__dirname, 'iconForDragAndDrop.png');
const icon = fs.createWriteStream(iconName);
// Create a new file to copy - you can also copy existing files.
fs.writeFileSync(path.join(__dirname, 'drag-and-drop-1.md'), '# First file to test drag and drop')
fs.writeFileSync(path.join(__dirname, 'drag-and-drop-2.md'), '# Second file to test drag and drop')
https.get('https://img.icons8.com/ios/452/drag-and-drop.png', (response) => {
response.pipe(icon);
});
app.whenReady().then(createWindow)
ipcMain.on('ondragstart', (event, filePath) => {
event.sender.startDrag({
file: path.join(__dirname, filePath),
icon: iconName,
})
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electron', {
startDrag: (fileName) => {
ipcRenderer.send('ondragstart', fileName)
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>Drag the boxes below to somewhere in your OS (Finder/Explorer, Desktop, etc.) to copy an example markdown file.</p>
<div style="border:2px solid black;border-radius:3px;padding:5px;display:inline-block" draggable="true" id="drag1">Drag me - File 1</div>
<div style="border:2px solid black;border-radius:3px;padding:5px;display:inline-block" draggable="true" id="drag2">Drag me - File 2</div>
<script src="renderer.js"></script>
</body>
</html>
```
```
document.getElementById('drag1').ondragstart = (event) => {
event.preventDefault()
window.electron.startDrag('drag-and-drop-1.md')
}
document.getElementById('drag2').ondragstart = (event) => {
event.preventDefault()
window.electron.startDrag('drag-and-drop-2.md')
}
```
After launching the Electron application, try dragging and dropping the item from the BrowserWindow onto your desktop. In this guide, the item is a Markdown file located in the root of the project:
electron Dock Dock
====
Electron has APIs to configure the app's icon in the macOS Dock. A macOS-only API exists to create a custom dock menu, but Electron also uses the app dock icon as the entry point for cross-platform features like [recent documents](recent-documents) and [application progress](progress-bar).
The custom dock is commonly used to add shortcuts to tasks the user wouldn't want to open the whole app window for.
**Dock menu of Terminal.app:**
To set your custom dock menu, you need to use the [`app.dock.setMenu`](../api/dock#docksetmenumenu-macos) API, which is only available on macOS.
[docs/fiddles/features/macos-dock-menu (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/macos-dock-menu)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/macos-dock-menu)
* main.js
* index.html
```
const { app, BrowserWindow, Menu } = require('electron')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600,
})
win.loadFile('index.html')
}
const dockMenu = Menu.buildFromTemplate([
{
label: 'New Window',
click () { console.log('New Window') }
}, {
label: 'New Window with Settings',
submenu: [
{ label: 'Basic' },
{ label: 'Pro' }
]
},
{ label: 'New Command...' }
])
app.whenReady().then(() => {
if (process.platform === 'darwin') {
app.dock.setMenu(dockMenu)
}
}).then(createWindow)
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>Right click the dock icon to see the custom menu options.</p>
</body>
</html>
```
After launching the Electron application, right click the application icon. You should see the custom menu you just defined:
electron Mac App Store Submission Guide Mac App Store Submission Guide
==============================
This guide provides information on:
* How to sign Electron apps on macOS;
* How to submit Electron apps to Mac App Store (MAS);
* The limitations of the MAS build.
Requirements[](#requirements "Direct link to heading")
-------------------------------------------------------
To sign Electron apps, the following tools must be installed first:
* Xcode 11 or above.
* The [electron-osx-sign](https://github.com/electron/electron-osx-sign) npm module.
You also have to register an Apple Developer account and join the [Apple Developer Program](https://developer.apple.com/support/compare-memberships/).
Sign Electron apps[](#sign-electron-apps "Direct link to heading")
-------------------------------------------------------------------
Electron apps can be distributed through Mac App Store or outside it. Each way requires different ways of signing and testing. This guide focuses on distribution via Mac App Store, but will also mention other methods.
The following steps describe how to get the certificates from Apple, how to sign Electron apps, and how to test them.
### Get certificates[](#get-certificates "Direct link to heading")
The simplest way to get signing certificates is to use Xcode:
1. Open Xcode and open "Accounts" preferences;
2. Sign in with your Apple account;
3. Select a team and click "Manage Certificates";
4. In the lower-left corner of the signing certificates sheet, click the Add button (+), and add following certificates:
* "Apple Development"
* "Apple Distribution"
The "Apple Development" certificate is used to sign apps for development and testing, on machines that have been registered on Apple Developer website. The method of registration will be described in [Prepare provisioning profile](#prepare-provisioning-profile).
Apps signed with the "Apple Development" certificate cannot be submitted to Mac App Store. For that purpose, apps must be signed with the "Apple Distribution" certificate instead. But note that apps signed with the "Apple Distribution" certificate cannot run directly, they must be re-signed by Apple to be able to run, which will only be possible after being downloaded from the Mac App Store.
#### Other certificates[](#other-certificates "Direct link to heading")
You may notice that there are also other kinds of certificates.
The "Developer ID Application" certificate is used to sign apps before distributing them outside the Mac App Store.
The "Developer ID Installer" and "Mac Installer Distribution" certificates are used to sign the Mac Installer Package instead of the app itself. Most Electron apps do not use Mac Installer Package so they are generally not needed.
The full list of certificate types can be found [here](https://help.apple.com/xcode/mac/current/#/dev80c6204ec).
Apps signed with "Apple Development" and "Apple Distribution" certificates can only run under [App Sandbox](https://developer.apple.com/app-sandboxing/), so they must use the MAS build of Electron. However, the "Developer ID Application" certificate does not have this restrictions, so apps signed with it can use either the normal build or the MAS build of Electron.
#### Legacy certificate names[](#legacy-certificate-names "Direct link to heading")
Apple has been changing the names of certificates during past years, you might encounter them when reading old documentations, and some utilities are still using one of the old names.
* The "Apple Distribution" certificate was also named as "3rd Party Mac Developer Application" and "Mac App Distribution".
* The "Apple Development" certificate was also named as "Mac Developer" and "Development".
### Prepare provisioning profile[](#prepare-provisioning-profile "Direct link to heading")
If you want to test your app on your local machine before submitting your app to the Mac App Store, you have to sign the app with the "Apple Development" certificate with the provisioning profile embedded in the app bundle.
To [create a provisioning profile](https://help.apple.com/developer-account/#/devf2eb157f8), you can follow the below steps:
1. Open the "Certificates, Identifiers & Profiles" page on the [Apple Developer](https://developer.apple.com/account) website.
2. Add a new App ID for your app in the "Identifiers" page.
3. Register your local machine in the "Devices" page. You can find your machine's "Device ID" in the "Hardware" page of the "System Information" app.
4. Register a new Provisioning Profile in the "Profiles" page, and download it to `/path/to/yourapp.provisionprofile`.
### Enable Apple's App Sandbox[](#enable-apples-app-sandbox "Direct link to heading")
Apps submitted to the Mac App Store must run under Apple's [App Sandbox](https://developer.apple.com/app-sandboxing/), and only the MAS build of Electron can run with the App Sandbox. The standard darwin build of Electron will fail to launch when run under App Sandbox.
When signing the app with `electron-osx-sign`, it will automatically add the necessary entitlements to your app's entitlements, but if you are using custom entitlements, you must ensure App Sandbox capacity is added:
```
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>com.apple.security.app-sandbox</key>
<true/>
</dict>
</plist>
```
#### Extra steps without `electron-osx-sign`[](#extra-steps-without-electron-osx-sign "Direct link to heading")
If you are signing your app without using `electron-osx-sign`, you must ensure the app bundle's entitlements have at least following keys:
```
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>com.apple.security.app-sandbox</key>
<true/>
<key>com.apple.security.application-groups</key>
<array>
<string>TEAM_ID.your.bundle.id</string>
</array>
</dict>
</plist>
```
The `TEAM_ID` should be replaced with your Apple Developer account's Team ID, and the `your.bundle.id` should be replaced with the App ID of the app.
And the following entitlements must be added to the binaries and helpers in the app's bundle:
```
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>com.apple.security.app-sandbox</key>
<true/>
<key>com.apple.security.inherit</key>
<true/>
</dict>
</plist>
```
And the app bundle's `Info.plist` must include `ElectronTeamID` key, which has your Apple Developer account's Team ID as its value:
```
<plist version="1.0">
<dict>
...
<key>ElectronTeamID</key>
<string>TEAM_ID</string>
</dict>
</plist>
```
When using `electron-osx-sign` the `ElectronTeamID` key will be added automatically by extracting the Team ID from the certificate's name. You may need to manually add this key if `electron-osx-sign` could not find the correct Team ID.
### Sign apps for development[](#sign-apps-for-development "Direct link to heading")
To sign an app that can run on your development machine, you must sign it with the "Apple Development" certificate and pass the provisioning profile to `electron-osx-sign`.
```
electron-osx-sign YourApp.app --identity='Apple Development' --provisioning-profile=/path/to/yourapp.provisionprofile
```
If you are signing without `electron-osx-sign`, you must place the provisioning profile to `YourApp.app/Contents/embedded.provisionprofile`.
The signed app can only run on the machines that registered by the provisioning profile, and this is the only way to test the signed app before submitting to Mac App Store.
### Sign apps for submitting to the Mac App Store[](#sign-apps-for-submitting-to-the-mac-app-store "Direct link to heading")
To sign an app that will be submitted to Mac App Store, you must sign it with the "Apple Distribution" certificate. Note that apps signed with this certificate will not run anywhere, unless it is downloaded from Mac App Store.
```
electron-osx-sign YourApp.app --identity='Apple Distribution'
```
### Sign apps for distribution outside the Mac App Store[](#sign-apps-for-distribution-outside-the-mac-app-store "Direct link to heading")
If you don't plan to submit the app to Mac App Store, you can sign it the "Developer ID Application" certificate. In this way there is no requirement on App Sandbox, and you should use the normal darwin build of Electron if you don't use App Sandbox.
```
electron-osx-sign YourApp.app --identity='Developer ID Application' --no-gatekeeper-assess
```
By passing `--no-gatekeeper-assess`, the `electron-osx-sign` will skip the macOS GateKeeper check as your app usually has not been notarized yet by this step.
This guide does not cover [App Notarization](https://developer.apple.com/documentation/security/notarizing_macos_software_before_distribution), but you might want to do it otherwise Apple may prevent users from using your app outside Mac App Store.
Submit Apps to the Mac App Store[](#submit-apps-to-the-mac-app-store "Direct link to heading")
-----------------------------------------------------------------------------------------------
After signing the app with the "Apple Distribution" certificate, you can continue to submit it to Mac App Store.
However, this guide do not ensure your app will be approved by Apple; you still need to read Apple's [Submitting Your App](https://developer.apple.com/library/mac/documentation/IDEs/Conceptual/AppDistributionGuide/SubmittingYourApp/SubmittingYourApp.html) guide on how to meet the Mac App Store requirements.
### Upload[](#upload "Direct link to heading")
The Application Loader should be used to upload the signed app to iTunes Connect for processing, making sure you have [created a record](https://developer.apple.com/library/ios/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/CreatingiTunesConnectRecord.html) before uploading.
If you are seeing errors like private APIs uses, you should check if the app is using the MAS build of Electron.
### Submit for review[](#submit-for-review "Direct link to heading")
After uploading, you should [submit your app for review](https://developer.apple.com/library/ios/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/SubmittingTheApp.html).
Limitations of MAS Build[](#limitations-of-mas-build "Direct link to heading")
-------------------------------------------------------------------------------
In order to satisfy all requirements for app sandboxing, the following modules have been disabled in the MAS build:
* `crashReporter`
* `autoUpdater`
and the following behaviors have been changed:
* Video capture may not work for some machines.
* Certain accessibility features may not work.
* Apps will not be aware of DNS changes.
Also, due to the usage of app sandboxing, the resources which can be accessed by the app are strictly limited; you can read [App Sandboxing](https://developer.apple.com/app-sandboxing/) for more information.
### Additional entitlements[](#additional-entitlements "Direct link to heading")
Depending on which Electron APIs your app uses, you may need to add additional entitlements to your app's entitlements file. Otherwise, the App Sandbox may prevent you from using them.
#### Network access[](#network-access "Direct link to heading")
Enable outgoing network connections to allow your app to connect to a server:
```
<key>com.apple.security.network.client</key>
<true/>
```
Enable incoming network connections to allow your app to open a network listening socket:
```
<key>com.apple.security.network.server</key>
<true/>
```
See the [Enabling Network Access documentation](https://developer.apple.com/library/ios/documentation/Miscellaneous/Reference/EntitlementKeyReference/Chapters/EnablingAppSandbox.html#//apple_ref/doc/uid/TP40011195-CH4-SW9) for more details.
#### dialog.showOpenDialog[](#dialogshowopendialog "Direct link to heading")
```
<key>com.apple.security.files.user-selected.read-only</key>
<true/>
```
See the [Enabling User-Selected File Access documentation](https://developer.apple.com/library/mac/documentation/Miscellaneous/Reference/EntitlementKeyReference/Chapters/EnablingAppSandbox.html#//apple_ref/doc/uid/TP40011195-CH4-SW6) for more details.
#### dialog.showSaveDialog[](#dialogshowsavedialog "Direct link to heading")
```
<key>com.apple.security.files.user-selected.read-write</key>
<true/>
```
See the [Enabling User-Selected File Access documentation](https://developer.apple.com/library/mac/documentation/Miscellaneous/Reference/EntitlementKeyReference/Chapters/EnablingAppSandbox.html#//apple_ref/doc/uid/TP40011195-CH4-SW6) for more details.
Cryptographic Algorithms Used by Electron[](#cryptographic-algorithms-used-by-electron "Direct link to heading")
-----------------------------------------------------------------------------------------------------------------
Depending on the countries in which you are releasing your app, you may be required to provide information on the cryptographic algorithms used in your software. See the [encryption export compliance docs](https://help.apple.com/app-store-connect/#/devc3f64248f) for more information.
Electron uses following cryptographic algorithms:
* AES - [NIST SP 800-38A](https://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf), [NIST SP 800-38D](https://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf), [RFC 3394](https://www.ietf.org/rfc/rfc3394.txt)
* HMAC - [FIPS 198-1](https://csrc.nist.gov/publications/fips/fips198-1/FIPS-198-1_final.pdf)
* ECDSA - ANS X9.62–2005
* ECDH - ANS X9.63–2001
* HKDF - [NIST SP 800-56C](https://csrc.nist.gov/publications/nistpubs/800-56C/SP-800-56C.pdf)
* PBKDF2 - [RFC 2898](https://tools.ietf.org/html/rfc2898)
* RSA - [RFC 3447](https://www.ietf.org/rfc/rfc3447)
* SHA - [FIPS 180-4](https://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf)
* Blowfish - <https://www.schneier.com/cryptography/blowfish/>
* CAST - [RFC 2144](https://tools.ietf.org/html/rfc2144), [RFC 2612](https://tools.ietf.org/html/rfc2612)
* DES - [FIPS 46-3](https://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf)
* DH - [RFC 2631](https://tools.ietf.org/html/rfc2631)
* DSA - [ANSI X9.30](https://webstore.ansi.org/RecordDetail.aspx?sku=ANSI+X9.30-1%3A1997)
* EC - [SEC 1](https://www.secg.org/sec1-v2.pdf)
* IDEA - "On the Design and Security of Block Ciphers" book by X. Lai
* MD2 - [RFC 1319](https://tools.ietf.org/html/rfc1319)
* MD4 - [RFC 6150](https://tools.ietf.org/html/rfc6150)
* MD5 - [RFC 1321](https://tools.ietf.org/html/rfc1321)
* MDC2 - [ISO/IEC 10118-2](https://wiki.openssl.org/index.php/Manual:Mdc2(3))
* RC2 - [RFC 2268](https://tools.ietf.org/html/rfc2268)
* RC4 - [RFC 4345](https://tools.ietf.org/html/rfc4345)
* RC5 - <https://people.csail.mit.edu/rivest/Rivest-rc5rev.pdf>
* RIPEMD - [ISO/IEC 10118-3](https://webstore.ansi.org/RecordDetail.aspx?sku=ISO%2FIEC%2010118-3:2004)
| programming_docs |
electron Progress Bars Progress Bars
=============
Overview[](#overview "Direct link to heading")
-----------------------------------------------
A progress bar enables a window to provide progress information to the user without the need of switching to the window itself.
On Windows, you can use a taskbar button to display a progress bar.
On macOS, the progress bar will be displayed as a part of the dock icon.
On Linux, the Unity graphical interface also has a similar feature that allows you to specify the progress bar in the launcher.
> NOTE: on Windows, each window can have its own progress bar, whereas on macOS and Linux (Unity) there can be only one progress bar for the application.
>
>
---
All three cases are covered by the same API - the [`setProgressBar()`](../api/browser-window#winsetprogressbarprogress-options) method available on an instance of `BrowserWindow`. To indicate your progress, call this method with a number between `0` and `1`. For example, if you have a long-running task that is currently at 63% towards completion, you would call it as `setProgressBar(0.63)`.
Setting the parameter to negative values (e.g. `-1`) will remove the progress bar. Setting it to a value greater than `1` will indicate an indeterminate progress bar in Windows or clamp to 100% in other operating systems. An indeterminate progress bar remains active but does not show an actual percentage, and is used for situations when you do not know how long an operation will take to complete.
See the [API documentation for more options and modes](../api/browser-window#winsetprogressbarprogress-options).
Example[](#example "Direct link to heading")
---------------------------------------------
In this example, we add a progress bar to the main window that increments over time using Node.js timers.
[docs/fiddles/features/progress-bar (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/progress-bar)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/progress-bar)
* main.js
* index.html
```
const { app, BrowserWindow } = require('electron')
let progressInterval
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600
})
win.loadFile('index.html')
const INCREMENT = 0.03
const INTERVAL_DELAY = 100 // ms
let c = 0
progressInterval = setInterval(() => {
// update progress bar to next value
// values between 0 and 1 will show progress, >1 will show indeterminate or stick at 100%
win.setProgressBar(c)
// increment or reset progress bar
if (c < 2) {
c += INCREMENT
} else {
c = (-INCREMENT * 5) // reset to a bit less than 0 to show reset state
}
}, INTERVAL_DELAY)
}
app.whenReady().then(createWindow)
// before the app is terminated, clear both timers
app.on('before-quit', () => {
clearInterval(progressInterval)
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>Keep an eye on the dock (Mac) or taskbar (Windows, Unity) for this application!</p>
<p>It should indicate a progress that advances from 0 to 100%.</p>
<p>It should then show indeterminate (Windows) or pin at 100% (other operating systems)
briefly and then loop.</p>
</body>
</html>
```
After launching the Electron application, the dock (macOS) or taskbar (Windows, Unity) should show a progress bar that starts at zero and progresses through 100% to completion. It should then show indeterminate (Windows) or pin to 100% (other operating systems) briefly and then loop.
For macOS, the progress bar will also be indicated for your application when using [Mission Control](https://support.apple.com/en-us/HT204100):
electron Security Security
========
Reporting security issues
For information on how to properly disclose an Electron vulnerability, see [SECURITY.md](https://github.com/electron/electron/tree/main/SECURITY.md).
For upstream Chromium vulnerabilities: Electron keeps up to date with alternating Chromium releases. For more information, see the [Electron Release Timelines](electron-timelines) document.
Preface[](#preface "Direct link to heading")
---------------------------------------------
As web developers, we usually enjoy the strong security net of the browser — the risks associated with the code we write are relatively small. Our websites are granted limited powers in a sandbox, and we trust that our users enjoy a browser built by a large team of engineers that is able to quickly respond to newly discovered security threats.
When working with Electron, it is important to understand that Electron is not a web browser. It allows you to build feature-rich desktop applications with familiar web technologies, but your code wields much greater power. JavaScript can access the filesystem, user shell, and more. This allows you to build high quality native applications, but the inherent security risks scale with the additional powers granted to your code.
With that in mind, be aware that displaying arbitrary content from untrusted sources poses a severe security risk that Electron is not intended to handle. In fact, the most popular Electron apps (Atom, Slack, Visual Studio Code, etc) display primarily local content (or trusted, secure remote content without Node integration) — if your application executes code from an online source, it is your responsibility to ensure that the code is not malicious.
General guidelines[](#general-guidelines "Direct link to heading")
-------------------------------------------------------------------
### Security is everyone's responsibility[](#security-is-everyones-responsibility "Direct link to heading")
It is important to remember that the security of your Electron application is the result of the overall security of the framework foundation (*Chromium*, *Node.js*), Electron itself, all NPM dependencies and your code. As such, it is your responsibility to follow a few important best practices:
* **Keep your application up-to-date with the latest Electron framework release.** When releasing your product, you’re also shipping a bundle composed of Electron, Chromium shared library and Node.js. Vulnerabilities affecting these components may impact the security of your application. By updating Electron to the latest version, you ensure that critical vulnerabilities (such as *nodeIntegration bypasses*) are already patched and cannot be exploited in your application. For more information, see "[Use a current version of Electron](#16-use-a-current-version-of-electron)".
* **Evaluate your dependencies.** While NPM provides half a million reusable packages, it is your responsibility to choose trusted 3rd-party libraries. If you use outdated libraries affected by known vulnerabilities or rely on poorly maintained code, your application security could be in jeopardy.
* **Adopt secure coding practices.** The first line of defense for your application is your own code. Common web vulnerabilities, such as Cross-Site Scripting (XSS), have a higher security impact on Electron applications hence it is highly recommended to adopt secure software development best practices and perform security testing.
### Isolation for untrusted content[](#isolation-for-untrusted-content "Direct link to heading")
A security issue exists whenever you receive code from an untrusted source (e.g. a remote server) and execute it locally. As an example, consider a remote website being displayed inside a default [`BrowserWindow`](../api/browser-window). If an attacker somehow manages to change said content (either by attacking the source directly, or by sitting between your app and the actual destination), they will be able to execute native code on the user's machine.
danger
Under no circumstances should you load and execute remote code with Node.js integration enabled. Instead, use only local files (packaged together with your application) to execute Node.js code. To display remote content, use the [`<webview>`](../api/webview-tag) tag or [`BrowserView`](../api/browser-view), make sure to disable the `nodeIntegration` and enable `contextIsolation`.
Electron security warnings
Security warnings and recommendations are printed to the developer console. They only show up when the binary's name is Electron, indicating that a developer is currently looking at the console.
You can force-enable or force-disable these warnings by setting `ELECTRON_ENABLE_SECURITY_WARNINGS` or `ELECTRON_DISABLE_SECURITY_WARNINGS` on either `process.env` or the `window` object.
Checklist: Security recommendations[](#checklist-security-recommendations "Direct link to heading")
----------------------------------------------------------------------------------------------------
You should at least follow these steps to improve the security of your application:
1. [Only load secure content](#1-only-load-secure-content)
2. [Disable the Node.js integration in all renderers that display remote content](#2-do-not-enable-nodejs-integration-for-remote-content)
3. [Enable context isolation in all renderers](#3-enable-context-isolation)
4. [Enable process sandboxing](#4-enable-process-sandboxing)
5. [Use `ses.setPermissionRequestHandler()` in all sessions that load remote content](#5-handle-session-permission-requests-from-remote-content)
6. [Do not disable `webSecurity`](#6-do-not-disable-websecurity)
7. [Define a `Content-Security-Policy`](#7-define-a-content-security-policy) and use restrictive rules (i.e. `script-src 'self'`)
8. [Do not enable `allowRunningInsecureContent`](#8-do-not-enable-allowrunninginsecurecontent)
9. [Do not enable experimental features](#9-do-not-enable-experimental-features)
10. [Do not use `enableBlinkFeatures`](#10-do-not-use-enableblinkfeatures)
11. [`<webview>`: Do not use `allowpopups`](#11-do-not-use-allowpopups-for-webviews)
12. [`<webview>`: Verify options and params](#12-verify-webview-options-before-creation)
13. [Disable or limit navigation](#13-disable-or-limit-navigation)
14. [Disable or limit creation of new windows](#14-disable-or-limit-creation-of-new-windows)
15. [Do not use `shell.openExternal` with untrusted content](#15-do-not-use-shellopenexternal-with-untrusted-content)
16. [Use a current version of Electron](#16-use-a-current-version-of-electron)
To automate the detection of misconfigurations and insecure patterns, it is possible to use [Electronegativity](https://github.com/doyensec/electronegativity). For additional details on potential weaknesses and implementation bugs when developing applications using Electron, please refer to this [guide for developers and auditors](https://doyensec.com/resources/us-17-Carettoni-Electronegativity-A-Study-Of-Electron-Security-wp.pdf).
### 1. Only load secure content[](#1-only-load-secure-content "Direct link to heading")
Any resources not included with your application should be loaded using a secure protocol like `HTTPS`. In other words, do not use insecure protocols like `HTTP`. Similarly, we recommend the use of `WSS` over `WS`, `FTPS` over `FTP`, and so on.
#### Why?[](#why "Direct link to heading")
`HTTPS` has three main benefits:
1. It authenticates the remote server, ensuring your app connects to the correct host instead of an impersonator.
2. It ensures data integrity, asserting that the data was not modified while in transit between your application and the host.
3. It encrypts the traffic between your user and the destination host, making it more difficult to eavesdrop on the information sent between your app and the host.
#### How?[](#how "Direct link to heading")
main.js (Main Process)
```
// Bad
browserWindow.loadURL('http://example.com')
// Good
browserWindow.loadURL('https://example.com')
```
index.html (Renderer Process)
```
<!-- Bad -->
<script crossorigin src="http://example.com/react.js"></script>
<link rel="stylesheet" href="http://example.com/style.css">
<!-- Good -->
<script crossorigin src="https://example.com/react.js"></script>
<link rel="stylesheet" href="https://example.com/style.css">
```
### 2. Do not enable Node.js integration for remote content[](#2-do-not-enable-nodejs-integration-for-remote-content "Direct link to heading")
info
This recommendation is the default behavior in Electron since 5.0.0.
It is paramount that you do not enable Node.js integration in any renderer ([`BrowserWindow`](../api/browser-window), [`BrowserView`](../api/browser-view), or [`<webview>`](../api/webview-tag)) that loads remote content. The goal is to limit the powers you grant to remote content, thus making it dramatically more difficult for an attacker to harm your users should they gain the ability to execute JavaScript on your website.
After this, you can grant additional permissions for specific hosts. For example, if you are opening a BrowserWindow pointed at `https://example.com/`, you can give that website exactly the abilities it needs, but no more.
#### Why?[](#why-1 "Direct link to heading")
A cross-site-scripting (XSS) attack is more dangerous if an attacker can jump out of the renderer process and execute code on the user's computer. Cross-site-scripting attacks are fairly common - and while an issue, their power is usually limited to messing with the website that they are executed on. Disabling Node.js integration helps prevent an XSS from being escalated into a so-called "Remote Code Execution" (RCE) attack.
#### How?[](#how-1 "Direct link to heading")
main.js (Main Process)
```
// Bad
const mainWindow = new BrowserWindow({
webPreferences: {
contextIsolation: false,
nodeIntegration: true,
nodeIntegrationInWorker: true
}
})
mainWindow.loadURL('https://example.com')
```
main.js (Main Process)
```
// Good
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(app.getAppPath(), 'preload.js')
}
})
mainWindow.loadURL('https://example.com')
```
index.html (Renderer Process)
```
<!-- Bad -->
<webview nodeIntegration src="page.html"></webview>
<!-- Good -->
<webview src="page.html"></webview>
```
When disabling Node.js integration, you can still expose APIs to your website that do consume Node.js modules or features. Preload scripts continue to have access to `require` and other Node.js features, allowing developers to expose a custom API to remotely loaded content via the [contextBridge API](../api/context-bridge).
### 3. Enable Context Isolation[](#3-enable-context-isolation "Direct link to heading")
info
This recommendation is the default behavior in Electron since 12.0.0.
Context isolation is an Electron feature that allows developers to run code in preload scripts and in Electron APIs in a dedicated JavaScript context. In practice, that means that global objects like `Array.prototype.push` or `JSON.parse` cannot be modified by scripts running in the renderer process.
Electron uses the same technology as Chromium's [Content Scripts](https://developer.chrome.com/extensions/content_scripts#execution-environment) to enable this behavior.
Even when `nodeIntegration: false` is used, to truly enforce strong isolation and prevent the use of Node primitives `contextIsolation` **must** also be used.
info
For more information on what `contextIsolation` is and how to enable it please see our dedicated [Context Isolation](context-isolation) document.
### 4. Enable process sandboxing[](#4-enable-process-sandboxing "Direct link to heading")
[Sandboxing](https://chromium.googlesource.com/chromium/src/+/HEAD/docs/design/sandbox.md) is a Chromium feature that uses the operating system to significantly limit what renderer processes have access to. You should enable the sandbox in all renderers. Loading, reading or processing any untrusted content in an unsandboxed process, including the main process, is not advised.
info
For more information on what `contextIsolation` is and how to enable it please see our dedicated [Process Sandboxing](sandbox) document.
### 5. Handle session permission requests from remote content[](#5-handle-session-permission-requests-from-remote-content "Direct link to heading")
You may have seen permission requests while using Chrome: they pop up whenever the website attempts to use a feature that the user has to manually approve ( like notifications).
The API is based on the [Chromium permissions API](https://developer.chrome.com/extensions/permissions) and implements the same types of permissions.
#### Why?[](#why-2 "Direct link to heading")
By default, Electron will automatically approve all permission requests unless the developer has manually configured a custom handler. While a solid default, security-conscious developers might want to assume the very opposite.
#### How?[](#how-2 "Direct link to heading")
main.js (Main Process)
```
const { session } = require('electron')
const URL = require('url').URL
session
.fromPartition('some-partition')
.setPermissionRequestHandler((webContents, permission, callback) => {
const parsedUrl = new URL(webContents.getURL())
if (permission === 'notifications') {
// Approves the permissions request
callback(true)
}
// Verify URL
if (parsedUrl.protocol !== 'https:' || parsedUrl.host !== 'example.com') {
// Denies the permissions request
return callback(false)
}
})
```
### 6. Do not disable `webSecurity`[](#6-do-not-disable-websecurity "Direct link to heading")
info
This recommendation is Electron's default.
You may have already guessed that disabling the `webSecurity` property on a renderer process ([`BrowserWindow`](../api/browser-window), [`BrowserView`](../api/browser-view), or [`<webview>`](../api/webview-tag)) disables crucial security features.
Do not disable `webSecurity` in production applications.
#### Why?[](#why-3 "Direct link to heading")
Disabling `webSecurity` will disable the same-origin policy and set `allowRunningInsecureContent` property to `true`. In other words, it allows the execution of insecure code from different domains.
#### How?[](#how-3 "Direct link to heading")
main.js (Main Process)
```
// Bad
const mainWindow = new BrowserWindow({
webPreferences: {
webSecurity: false
}
})
```
main.js (Main Process)
```
// Good
const mainWindow = new BrowserWindow()
```
index.html (Renderer Process)
```
<!-- Bad -->
<webview disablewebsecurity src="page.html"></webview>
<!-- Good -->
<webview src="page.html"></webview>
```
### 7. Define a Content Security Policy[](#7-define-a-content-security-policy "Direct link to heading")
A Content Security Policy (CSP) is an additional layer of protection against cross-site-scripting attacks and data injection attacks. We recommend that they be enabled by any website you load inside Electron.
#### Why?[](#why-4 "Direct link to heading")
CSP allows the server serving content to restrict and control the resources Electron can load for that given web page. `https://example.com` should be allowed to load scripts from the origins you defined while scripts from `https://evil.attacker.com` should not be allowed to run. Defining a CSP is an easy way to improve your application's security.
#### How?[](#how-4 "Direct link to heading")
The following CSP will allow Electron to execute scripts from the current website and from `apis.example.com`.
```
// Bad
Content-Security-Policy: '*'
// Good
Content-Security-Policy: script-src 'self' https://apis.example.com
```
#### CSP HTTP headers[](#csp-http-headers "Direct link to heading")
Electron respects the [`Content-Security-Policy` HTTP header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy) which can be set using Electron's [`webRequest.onHeadersReceived`](../api/web-request#webrequestonheadersreceivedfilter-listener) handler:
main.js (Main Process)
```
const { session } = require('electron')
session.defaultSession.webRequest.onHeadersReceived((details, callback) => {
callback({
responseHeaders: {
...details.responseHeaders,
'Content-Security-Policy': ['default-src \'none\'']
}
})
})
```
#### CSP meta tag[](#csp-meta-tag "Direct link to heading")
CSP's preferred delivery mechanism is an HTTP header. However, it is not possible to use this method when loading a resource using the `file://` protocol. It can be useful in some cases to set a policy on a page directly in the markup using a `<meta>` tag:
index.html (Renderer Process)
```
<meta http-equiv="Content-Security-Policy" content="default-src 'none'">
```
### 8. Do not enable `allowRunningInsecureContent`[](#8-do-not-enable-allowrunninginsecurecontent "Direct link to heading")
info
This recommendation is Electron's default.
By default, Electron will not allow websites loaded over `HTTPS` to load and execute scripts, CSS, or plugins from insecure sources (`HTTP`). Setting the property `allowRunningInsecureContent` to `true` disables that protection.
Loading the initial HTML of a website over `HTTPS` and attempting to load subsequent resources via `HTTP` is also known as "mixed content".
#### Why?[](#why-5 "Direct link to heading")
Loading content over `HTTPS` assures the authenticity and integrity of the loaded resources while encrypting the traffic itself. See the section on [only displaying secure content](#1-only-load-secure-content) for more details.
#### How?[](#how-5 "Direct link to heading")
main.js (Main Process)
```
// Bad
const mainWindow = new BrowserWindow({
webPreferences: {
allowRunningInsecureContent: true
}
})
```
main.js (Main Process)
```
// Good
const mainWindow = new BrowserWindow({})
```
### 9. Do not enable experimental features[](#9-do-not-enable-experimental-features "Direct link to heading")
info
This recommendation is Electron's default.
Advanced users of Electron can enable experimental Chromium features using the `experimentalFeatures` property.
#### Why?[](#why-6 "Direct link to heading")
Experimental features are, as the name suggests, experimental and have not been enabled for all Chromium users. Furthermore, their impact on Electron as a whole has likely not been tested.
Legitimate use cases exist, but unless you know what you are doing, you should not enable this property.
#### How?[](#how-6 "Direct link to heading")
main.js (Main Process)
```
// Bad
const mainWindow = new BrowserWindow({
webPreferences: {
experimentalFeatures: true
}
})
```
main.js (Main Process)
```
// Good
const mainWindow = new BrowserWindow({})
```
### 10. Do not use `enableBlinkFeatures`[](#10-do-not-use-enableblinkfeatures "Direct link to heading")
info
This recommendation is Electron's default.
Blink is the name of the rendering engine behind Chromium. As with `experimentalFeatures`, the `enableBlinkFeatures` property allows developers to enable features that have been disabled by default.
#### Why?[](#why-7 "Direct link to heading")
Generally speaking, there are likely good reasons if a feature was not enabled by default. Legitimate use cases for enabling specific features exist. As a developer, you should know exactly why you need to enable a feature, what the ramifications are, and how it impacts the security of your application. Under no circumstances should you enable features speculatively.
#### How?[](#how-7 "Direct link to heading")
main.js (Main Process)
```
// Bad
const mainWindow = new BrowserWindow({
webPreferences: {
enableBlinkFeatures: 'ExecCommandInJavaScript'
}
})
```
main.js (Main Process)
```
// Good
const mainWindow = new BrowserWindow()
```
### 11. Do not use `allowpopups` for WebViews[](#11-do-not-use-allowpopups-for-webviews "Direct link to heading")
info
This recommendation is Electron's default.
If you are using [`<webview>`](../api/webview-tag), you might need the pages and scripts loaded in your `<webview>` tag to open new windows. The `allowpopups` attribute enables them to create new [`BrowserWindows`](../api/browser-window) using the `window.open()` method. `<webview>` tags are otherwise not allowed to create new windows.
#### Why?[](#why-8 "Direct link to heading")
If you do not need popups, you are better off not allowing the creation of new [`BrowserWindows`](../api/browser-window) by default. This follows the principle of minimally required access: Don't let a website create new popups unless you know it needs that feature.
#### How?[](#how-8 "Direct link to heading")
index.html (Renderer Process)
```
<!-- Bad -->
<webview allowpopups src="page.html"></webview>
<!-- Good -->
<webview src="page.html"></webview>
```
### 12. Verify WebView options before creation[](#12-verify-webview-options-before-creation "Direct link to heading")
A WebView created in a renderer process that does not have Node.js integration enabled will not be able to enable integration itself. However, a WebView will always create an independent renderer process with its own `webPreferences`.
It is a good idea to control the creation of new [`<webview>`](../api/webview-tag) tags from the main process and to verify that their webPreferences do not disable security features.
#### Why?[](#why-9 "Direct link to heading")
Since `<webview>` live in the DOM, they can be created by a script running on your website even if Node.js integration is otherwise disabled.
Electron enables developers to disable various security features that control a renderer process. In most cases, developers do not need to disable any of those features - and you should therefore not allow different configurations for newly created [`<webview>`](../api/webview-tag) tags.
#### How?[](#how-9 "Direct link to heading")
Before a [`<webview>`](../api/webview-tag) tag is attached, Electron will fire the `will-attach-webview` event on the hosting `webContents`. Use the event to prevent the creation of `webViews` with possibly insecure options.
main.js (Main Process)
```
app.on('web-contents-created', (event, contents) => {
contents.on('will-attach-webview', (event, webPreferences, params) => {
// Strip away preload scripts if unused or verify their location is legitimate
delete webPreferences.preload
// Disable Node.js integration
webPreferences.nodeIntegration = false
// Verify URL being loaded
if (!params.src.startsWith('https://example.com/')) {
event.preventDefault()
}
})
})
```
Again, this list merely minimizes the risk, but does not remove it. If your goal is to display a website, a browser will be a more secure option.
### 13. Disable or limit navigation[](#13-disable-or-limit-navigation "Direct link to heading")
If your app has no need to navigate or only needs to navigate to known pages, it is a good idea to limit navigation outright to that known scope, disallowing any other kinds of navigation.
#### Why?[](#why-10 "Direct link to heading")
Navigation is a common attack vector. If an attacker can convince your app to navigate away from its current page, they can possibly force your app to open web sites on the Internet. Even if your `webContents` are configured to be more secure (like having `nodeIntegration` disabled or `contextIsolation` enabled), getting your app to open a random web site will make the work of exploiting your app a lot easier.
A common attack pattern is that the attacker convinces your app's users to interact with the app in such a way that it navigates to one of the attacker's pages. This is usually done via links, plugins, or other user-generated content.
#### How?[](#how-10 "Direct link to heading")
If your app has no need for navigation, you can call `event.preventDefault()` in a [`will-navigate`](../api/web-contents#event-will-navigate) handler. If you know which pages your app might navigate to, check the URL in the event handler and only let navigation occur if it matches the URLs you're expecting.
We recommend that you use Node's parser for URLs. Simple string comparisons can sometimes be fooled - a `startsWith('https://example.com')` test would let `https://example.com.attacker.com` through.
main.js (Main Process)
```
const URL = require('url').URL
app.on('web-contents-created', (event, contents) => {
contents.on('will-navigate', (event, navigationUrl) => {
const parsedUrl = new URL(navigationUrl)
if (parsedUrl.origin !== 'https://example.com') {
event.preventDefault()
}
})
})
```
### 14. Disable or limit creation of new windows[](#14-disable-or-limit-creation-of-new-windows "Direct link to heading")
If you have a known set of windows, it's a good idea to limit the creation of additional windows in your app.
#### Why?[](#why-11 "Direct link to heading")
Much like navigation, the creation of new `webContents` is a common attack vector. Attackers attempt to convince your app to create new windows, frames, or other renderer processes with more privileges than they had before; or with pages opened that they couldn't open before.
If you have no need to create windows in addition to the ones you know you'll need to create, disabling the creation buys you a little bit of extra security at no cost. This is commonly the case for apps that open one `BrowserWindow` and do not need to open an arbitrary number of additional windows at runtime.
#### How?[](#how-11 "Direct link to heading")
[`webContents`](../api/web-contents) will delegate to its [window open handler](../api/web-contents#contentssetwindowopenhandlerhandler) before creating new windows. The handler will receive, amongst other parameters, the `url` the window was requested to open and the options used to create it. We recommend that you register a handler to monitor the creation of windows, and deny any unexpected window creation.
main.js (Main Process)
```
const { shell } = require('electron')
app.on('web-contents-created', (event, contents) => {
contents.setWindowOpenHandler(({ url }) => {
// In this example, we'll ask the operating system
// to open this event's url in the default browser.
//
// See the following item for considerations regarding what
// URLs should be allowed through to shell.openExternal.
if (isSafeForExternalOpen(url)) {
setImmediate(() => {
shell.openExternal(url)
})
}
return { action: 'deny' }
})
})
```
### 15. Do not use `shell.openExternal` with untrusted content[](#15-do-not-use-shellopenexternal-with-untrusted-content "Direct link to heading")
The shell module's [`openExternal`](../api/shell#shellopenexternalurl-options) API allows opening a given protocol URI with the desktop's native utilities. On macOS, for instance, this function is similar to the `open` terminal command utility and will open the specific application based on the URI and filetype association.
#### Why?[](#why-12 "Direct link to heading")
Improper use of [`openExternal`](../api/shell#shellopenexternalurl-options) can be leveraged to compromise the user's host. When openExternal is used with untrusted content, it can be leveraged to execute arbitrary commands.
#### How?[](#how-12 "Direct link to heading")
main.js (Main Process)
```
// Bad
const { shell } = require('electron')
shell.openExternal(USER_CONTROLLED_DATA_HERE)
```
main.js (Main Process)
```
// Good
const { shell } = require('electron')
shell.openExternal('https://example.com/index.html')
```
### 16. Use a current version of Electron[](#16-use-a-current-version-of-electron "Direct link to heading")
You should strive for always using the latest available version of Electron. Whenever a new major version is released, you should attempt to update your app as quickly as possible.
#### Why?[](#why-13 "Direct link to heading")
An application built with an older version of Electron, Chromium, and Node.js is an easier target than an application that is using more recent versions of those components. Generally speaking, security issues and exploits for older versions of Chromium and Node.js are more widely available.
Both Chromium and Node.js are impressive feats of engineering built by thousands of talented developers. Given their popularity, their security is carefully tested and analyzed by equally skilled security researchers. Many of those researchers [disclose vulnerabilities responsibly](https://en.wikipedia.org/wiki/Responsible_disclosure), which generally means that researchers will give Chromium and Node.js some time to fix issues before publishing them. Your application will be more secure if it is running a recent version of Electron (and thus, Chromium and Node.js) for which potential security issues are not as widely known.
#### How?[](#how-13 "Direct link to heading")
Migrate your app one major version at a time, while referring to Electron's [Breaking Changes](../breaking-changes) document to see if any code needs to be updated.
### 17. Validate the `sender` of all IPC messages[](#17-validate-the-sender-of-all-ipc-messages "Direct link to heading")
You should always validate incoming IPC messages `sender` property to ensure you aren't performing actions or sending information to untrusted renderers.
#### Why?[](#why-14 "Direct link to heading")
All Web Frames can in theory send IPC messages to the main process, including iframes and child windows in some scenarios. If you have an IPC message that returns user data to the sender via `event.reply` or performs privileged actions that the renderer can't natively, you should ensure you aren't listening to third party web frames.
You should be validating the `sender` of **all** IPC messages by default.
#### How?[](#how-14 "Direct link to heading")
main.js (Main Process)
```
// Bad
ipcMain.handle('get-secrets', () => {
return getSecrets();
});
// Good
ipcMain.handle('get-secrets', (e) => {
if (!validateSender(e.senderFrame)) return null;
return getSecrets();
});
function validateSender(frame) {
// Value the host of the URL using an actual URL parser and an allowlist
if ((new URL(frame.url)).host === 'electronjs.org') return true;
return false;
}
```
| programming_docs |
electron Native Node Modules Native Node Modules
===================
Native Node.js modules are supported by Electron, but since Electron has a different [application binary interface (ABI)](https://en.wikipedia.org/wiki/Application_binary_interface) from a given Node.js binary (due to differences such as using Chromium's BoringSSL instead of OpenSSL), the native modules you use will need to be recompiled for Electron. Otherwise, you will get the following class of error when you try to run your app:
```
Error: The module '/path/to/native/module.node'
was compiled against a different Node.js version using
NODE_MODULE_VERSION $XYZ. This version of Node.js requires
NODE_MODULE_VERSION $ABC. Please try re-compiling or re-installing
the module (for instance, using `npm rebuild` or `npm install`).
```
How to install native modules[](#how-to-install-native-modules "Direct link to heading")
-----------------------------------------------------------------------------------------
There are several different ways to install native modules:
### Installing modules and rebuilding for Electron[](#installing-modules-and-rebuilding-for-electron "Direct link to heading")
You can install modules like other Node projects, and then rebuild the modules for Electron with the [`electron-rebuild`](https://github.com/electron/electron-rebuild) package. This module can automatically determine the version of Electron and handle the manual steps of downloading headers and rebuilding native modules for your app. If you are using [Electron Forge](https://electronforge.io/), this tool is used automatically in both development mode and when making distributables.
For example, to install the standalone `electron-rebuild` tool and then rebuild modules with it via the command line:
```
npm install --save-dev electron-rebuild
# Every time you run "npm install", run this:
./node_modules/.bin/electron-rebuild
# If you have trouble on Windows, try:
.\node_modules\.bin\electron-rebuild.cmd
```
For more information on usage and integration with other tools such as [Electron Packager](https://github.com/electron/electron-packager), consult the project's README.
### Using `npm`[](#using-npm "Direct link to heading")
By setting a few environment variables, you can use `npm` to install modules directly.
For example, to install all dependencies for Electron:
```
# Electron's version.
export npm_config_target=1.2.3
# The architecture of Electron, see https://electronjs.org/docs/tutorial/support#supported-platforms
# for supported architectures.
export npm_config_arch=x64
export npm_config_target_arch=x64
# Download headers for Electron.
export npm_config_disturl=https://electronjs.org/headers
# Tell node-pre-gyp that we are building for Electron.
export npm_config_runtime=electron
# Tell node-pre-gyp to build module from source code.
export npm_config_build_from_source=true
# Install all dependencies, and store cache to ~/.electron-gyp.
HOME=~/.electron-gyp npm install
```
### Manually building for Electron[](#manually-building-for-electron "Direct link to heading")
If you are a developer developing a native module and want to test it against Electron, you might want to rebuild the module for Electron manually. You can use `node-gyp` directly to build for Electron:
```
cd /path-to-module/
HOME=~/.electron-gyp node-gyp rebuild --target=1.2.3 --arch=x64 --dist-url=https://electronjs.org/headers
```
* `HOME=~/.electron-gyp` changes where to find development headers.
* `--target=1.2.3` is the version of Electron.
* `--dist-url=...` specifies where to download the headers.
* `--arch=x64` says the module is built for a 64-bit system.
### Manually building for a custom build of Electron[](#manually-building-for-a-custom-build-of-electron "Direct link to heading")
To compile native Node modules against a custom build of Electron that doesn't match a public release, instruct `npm` to use the version of Node you have bundled with your custom build.
```
npm rebuild --nodedir=/path/to/src/out/Default/gen/node_headers
```
Troubleshooting[](#troubleshooting "Direct link to heading")
-------------------------------------------------------------
If you installed a native module and found it was not working, you need to check the following things:
* When in doubt, run `electron-rebuild` first.
* Make sure the native module is compatible with the target platform and architecture for your Electron app.
* Make sure `win_delay_load_hook` is not set to `false` in the module's `binding.gyp`.
* After you upgrade Electron, you usually need to rebuild the modules.
### A note about `win_delay_load_hook`[](#a-note-about-win_delay_load_hook "Direct link to heading")
On Windows, by default, `node-gyp` links native modules against `node.dll`. However, in Electron 4.x and higher, the symbols needed by native modules are exported by `electron.exe`, and there is no `node.dll`. In order to load native modules on Windows, `node-gyp` installs a [delay-load hook](https://msdn.microsoft.com/en-us/library/z9h1h6ty.aspx) that triggers when the native module is loaded, and redirects the `node.dll` reference to use the loading executable instead of looking for `node.dll` in the library search path (which would turn up nothing). As such, on Electron 4.x and higher, `'win_delay_load_hook': 'true'` is required to load native modules.
If you get an error like `Module did not self-register`, or `The specified
procedure could not be found`, it may mean that the module you're trying to use did not correctly include the delay-load hook. If the module is built with node-gyp, ensure that the `win_delay_load_hook` variable is set to `true` in the `binding.gyp` file, and isn't getting overridden anywhere. If the module is built with another system, you'll need to ensure that you build with a delay-load hook installed in the main `.node` file. Your `link.exe` invocation should look like this:
```
link.exe /OUT:"foo.node" "...\node.lib" delayimp.lib /DELAYLOAD:node.exe /DLL
"my_addon.obj" "win_delay_load_hook.obj"
```
In particular, it's important that:
* you link against `node.lib` from *Electron* and not Node. If you link against the wrong `node.lib` you will get load-time errors when you require the module in Electron.
* you include the flag `/DELAYLOAD:node.exe`. If the `node.exe` link is not delayed, then the delay-load hook won't get a chance to fire and the node symbols won't be correctly resolved.
* `win_delay_load_hook.obj` is linked directly into the final DLL. If the hook is set up in a dependent DLL, it won't fire at the right time.
See [`node-gyp`](https://github.com/nodejs/node-gyp/blob/e2401e1395bef1d3c8acec268b42dc5fb71c4a38/src/win_delay_load_hook.cc) for an example delay-load hook if you're implementing your own.
Modules that rely on `prebuild`[](#modules-that-rely-on-prebuild "Direct link to heading")
-------------------------------------------------------------------------------------------
[`prebuild`](https://github.com/prebuild/prebuild) provides a way to publish native Node modules with prebuilt binaries for multiple versions of Node and Electron.
If the `prebuild`-powered module provide binaries for the usage in Electron, make sure to omit `--build-from-source` and the `npm_config_build_from_source` environment variable in order to take full advantage of the prebuilt binaries.
Modules that rely on `node-pre-gyp`[](#modules-that-rely-on-node-pre-gyp "Direct link to heading")
---------------------------------------------------------------------------------------------------
The [`node-pre-gyp` tool](https://github.com/mapbox/node-pre-gyp) provides a way to deploy native Node modules with prebuilt binaries, and many popular modules are using it.
Sometimes those modules work fine under Electron, but when there are no Electron-specific binaries available, you'll need to build from source. Because of this, it is recommended to use `electron-rebuild` for these modules.
If you are following the `npm` way of installing modules, you'll need to pass `--build-from-source` to `npm`, or set the `npm_config_build_from_source` environment variable.
electron In-App Purchases In-App Purchases
================
Preparing[](#preparing "Direct link to heading")
-------------------------------------------------
### Paid Applications Agreement[](#paid-applications-agreement "Direct link to heading")
If you haven't already, you’ll need to sign the Paid Applications Agreement and set up your banking and tax information in iTunes Connect.
[iTunes Connect Developer Help: Agreements, tax, and banking overview](https://help.apple.com/itunes-connect/developer/#/devb6df5ee51)
### Create Your In-App Purchases[](#create-your-in-app-purchases "Direct link to heading")
Then, you'll need to configure your in-app purchases in iTunes Connect, and include details such as name, pricing, and description that highlights the features and functionality of your in-app purchase.
[iTunes Connect Developer Help: Create an in-app purchase](https://help.apple.com/itunes-connect/developer/#/devae49fb316)
### Change the CFBundleIdentifier[](#change-the-cfbundleidentifier "Direct link to heading")
To test In-App Purchase in development with Electron you'll have to change the `CFBundleIdentifier` in `node_modules/electron/dist/Electron.app/Contents/Info.plist`. You have to replace `com.github.electron` by the bundle identifier of the application you created with iTunes Connect.
```
<key>CFBundleIdentifier</key>
<string>com.example.app</string>
```
Code example[](#code-example "Direct link to heading")
-------------------------------------------------------
Here is an example that shows how to use In-App Purchases in Electron. You'll have to replace the product ids by the identifiers of the products created with iTunes Connect (the identifier of `com.example.app.product1` is `product1`). Note that you have to listen to the `transactions-updated` event as soon as possible in your app.
```
// Main process
const { inAppPurchase } = require('electron')
const PRODUCT_IDS = ['id1', 'id2']
// Listen for transactions as soon as possible.
inAppPurchase.on('transactions-updated', (event, transactions) => {
if (!Array.isArray(transactions)) {
return
}
// Check each transaction.
transactions.forEach((transaction) => {
const payment = transaction.payment
switch (transaction.transactionState) {
case 'purchasing':
console.log(`Purchasing ${payment.productIdentifier}...`)
break
case 'purchased': {
console.log(`${payment.productIdentifier} purchased.`)
// Get the receipt url.
const receiptURL = inAppPurchase.getReceiptURL()
console.log(`Receipt URL: ${receiptURL}`)
// Submit the receipt file to the server and check if it is valid.
// @see https://developer.apple.com/library/content/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateRemotely.html
// ...
// If the receipt is valid, the product is purchased
// ...
// Finish the transaction.
inAppPurchase.finishTransactionByDate(transaction.transactionDate)
break
}
case 'failed':
console.log(`Failed to purchase ${payment.productIdentifier}.`)
// Finish the transaction.
inAppPurchase.finishTransactionByDate(transaction.transactionDate)
break
case 'restored':
console.log(`The purchase of ${payment.productIdentifier} has been restored.`)
break
case 'deferred':
console.log(`The purchase of ${payment.productIdentifier} has been deferred.`)
break
default:
break
}
})
})
// Check if the user is allowed to make in-app purchase.
if (!inAppPurchase.canMakePayments()) {
console.log('The user is not allowed to make in-app purchase.')
}
// Retrieve and display the product descriptions.
inAppPurchase.getProducts(PRODUCT_IDS).then(products => {
// Check the parameters.
if (!Array.isArray(products) || products.length <= 0) {
console.log('Unable to retrieve the product informations.')
return
}
// Display the name and price of each product.
products.forEach(product => {
console.log(`The price of ${product.localizedTitle} is ${product.formattedPrice}.`)
})
// Ask the user which product they want to purchase.
const selectedProduct = products[0]
const selectedQuantity = 1
// Purchase the selected product.
inAppPurchase.purchaseProduct(selectedProduct.productIdentifier, selectedQuantity).then(isProductValid => {
if (!isProductValid) {
console.log('The product is not valid.')
return
}
console.log('The payment has been added to the payment queue.')
})
})
```
electron Building your First App
Follow along the tutorial
This is **part 2** of the Electron tutorial.
1. [Prerequisites](tutorial-prerequisites)
2. **[Building your First App](tutorial-first-app)**
3. [Using Preload Scripts](tutorial-preload)
4. [Adding Features](tutorial-adding-features)
5. [Packaging Your Application](tutorial-packaging)
6. [Publishing and Updating](tutorial-publishing-updating)
Learning goals[](#learning-goals "Direct link to heading")
-----------------------------------------------------------
In this part of the tutorial, you will learn how to set up your Electron project and write a minimal starter application. By the end of this section, you should be able to run a working Electron app in development mode from your terminal.
Setting up your project[](#setting-up-your-project "Direct link to heading")
-----------------------------------------------------------------------------
Avoid WSL
If you are on a Windows machine, please do not use [Windows Subsystem for Linux](https://docs.microsoft.com/en-us/windows/wsl/about#what-is-wsl-2) (WSL) when following this tutorial as you will run into issues when trying to execute the application.
### Initializing your npm project[](#initializing-your-npm-project "Direct link to heading")
Electron apps are scaffolded using npm, with the package.json file as an entry point. Start by creating a folder and initializing an npm package within it with `npm init`.
* npm
* Yarn
```
mkdir my-electron-app && cd my-electron-app
npm init
```
```
mkdir my-electron-app && cd my-electron-app
yarn init
```
This command will prompt you to configure some fields in your package.json. There are a few rules to follow for the purposes of this tutorial:
* *entry point* should be `main.js` (you will be creating that file soon).
* *author*, *license*, and *description* can be any value, but will be necessary for [packaging](tutorial-packaging) later on.
Then, install Electron into your app's **devDependencies**, which is the list of external development-only package dependencies not required in production.
Why is Electron a devDependency?
This may seem counter-intuitive since your production code is running Electron APIs. However, packaged apps will come bundled with the Electron binary, eliminating the need to specify it as a production dependency.
* npm
* Yarn
```
npm install electron --save-dev
```
```
yarn add electron --dev
```
Your package.json file should look something like this after initializing your package and installing Electron. You should also now have a `node_modules` folder containing the Electron executable, as well as a `package-lock.json` lockfile that specifies the exact dependency versions to install.
package.json
```
{
"name": "my-electron-app",
"version": "1.0.0",
"description": "Hello World!",
"main": "main.js",
"author": "Jane Doe",
"license": "MIT",
"devDependencies": {
"electron": "19.0.0"
}
}
```
Advanced Electron installation steps
If installing Electron directly fails, please refer to our [Advanced Installation](installation) documentation for instructions on download mirrors, proxies, and troubleshooting steps.
### Adding a .gitignore[](#adding-a-gitignore "Direct link to heading")
The [`.gitignore`](https://git-scm.com/docs/gitignore) file specifies which files and directories to avoid tracking with Git. You should place a copy of [GitHub's Node.js gitignore template](https://github.com/github/gitignore/blob/main/Node.gitignore) into your project's root folder to avoid committing your project's `node_modules` folder.
Running an Electron app[](#running-an-electron-app "Direct link to heading")
-----------------------------------------------------------------------------
Further reading
Read [Electron's process model](process-model) documentation to better understand how Electron's multiple processes work together.
The [`main`](https://docs.npmjs.com/cli/v7/configuring-npm/package-json#main) script you defined in package.json is the entry point of any Electron application. This script controls the **main process**, which runs in a Node.js environment and is responsible for controlling your app's lifecycle, displaying native interfaces, performing privileged operations, and managing renderer processes (more on that later).
Before creating your first Electron app, you will first use a trivial script to ensure your main process entry point is configured correctly. Create a `main.js` file in the root folder of your project with a single line of code:
main.js
```
console.log(`Hello from Electron 👋`)
```
Because Electron's main process is a Node.js runtime, you can execute arbitrary Node.js code with the `electron` command (you can even use it as a [REPL](repl)). To execute this script, add `electron .` to the `start` command in the [`scripts`](https://docs.npmjs.com/cli/v7/using-npm/scripts) field of your package.json. This command will tell the Electron executable to look for the main script in the current directory and run it in dev mode.
package.json
```
{
"name": "my-electron-app",
"version": "1.0.0",
"description": "Hello World!",
"main": "main.js",
"author": "Jane Doe",
"license": "MIT",
"scripts": {
"start": "electron ."
},
"devDependencies": {
"electron": "^19.0.0"
}
}
```
* npm
* Yarn
```
npm run start
```
```
yarn run start
```
Your terminal should print out `Hello from Electron 👋`. Congratulations, you have executed your first line of code in Electron! Next, you will learn how to create user interfaces with HTML and load that into a native window.
Loading a web page into a BrowserWindow[](#loading-a-web-page-into-a-browserwindow "Direct link to heading")
-------------------------------------------------------------------------------------------------------------
In Electron, each window displays a web page that can be loaded either from a local HTML file or a remote web address. For this example, you will be loading in a local file. Start by creating a barebones web page in an `index.html` file in the root folder of your project:
index.html
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta
http-equiv="Content-Security-Policy"
content="default-src 'self'; script-src 'self'"
/>
<meta
http-equiv="X-Content-Security-Policy"
content="default-src 'self'; script-src 'self'"
/>
<title>Hello from Electron renderer!</title>
</head>
<body>
<h1>Hello from Electron renderer!</h1>
<p>👋</p>
</body>
</html>
```
Now that you have a web page, you can load it into an Electron [BrowserWindow](../api/browser-window). Replace the contents your `main.js` file with the following code. We will explain each highlighted block separately.
main.js
```
const { app, BrowserWindow } = require('electron')
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
})
win.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
})
```
### Importing modules[](#importing-modules "Direct link to heading")
main.js (Line 1)
```
const { app, BrowserWindow } = require('electron')
```
In the first line, we are importing two Electron modules with CommonJS module syntax:
* [app](../api/app), which controls your application's event lifecycle.
* [BrowserWindow](../api/browser-window), which creates and manages app windows.
Capitalization conventions
You might have noticed the capitalization difference between the **a**pp and **B**rowser**W**indow modules. Electron follows typical JavaScript conventions here, where PascalCase modules are instantiable class constructors (e.g. BrowserWindow, Tray, Notification) whereas camelCase modules are not instantiable (e.g. app, ipcRenderer, webContents).
ES Modules in Electron
[ECMAScript modules](https://nodejs.org/api/esm.html) (i.e. using `import` to load a module) are currently not directly supported in Electron. You can find more information about the state of ESM in Electron in [electron/electron#21457](https://github.com/electron/electron/issues/21457).
### Writing a reusable function to instantiate windows[](#writing-a-reusable-function-to-instantiate-windows "Direct link to heading")
The `createWindow()` function loads your web page into a new BrowserWindow instance:
main.js (Lines 3-10)
```
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
})
win.loadFile('index.html')
}
```
### Calling your function when the app is ready[](#calling-your-function-when-the-app-is-ready "Direct link to heading")
main.js (Lines 12-14)
```
app.whenReady().then(() => {
createWindow()
})
```
Many of Electron's core modules are Node.js [event emitters](https://nodejs.org/api/events.html#events) that adhere to Node's asynchronous event-driven architecture. The app module is one of these emitters.
In Electron, BrowserWindows can only be created after the app module's [`ready`](../api/app#event-ready) event is fired. You can wait for this event by using the [`app.whenReady()`](../api/app#appwhenready) API and calling `createWindow()` once its promise is fulfilled.
info
You typically listen to Node.js events by using an emitter's `.on` function.
```
+ app.on('ready').then(() => {
- app.whenReady().then(() => {
createWindow()
})
```
However, Electron exposes `app.whenReady()` as a helper specifically for the `ready` event to avoid subtle pitfalls with directly listening to that event in particular. See [electron/electron#21972](https://github.com/electron/electron/pull/21972) for details.
At this point, running your Electron application's `start` command should successfully open a window that displays your web page!
Each web page your app displays in a window will run in a separate process called a **renderer** process (or simply *renderer* for short). Renderer processes have access to the same JavaScript APIs and tooling you use for typical front-end web development, such as using [webpack](https://webpack.js.org) to bundle and minify your code or [React](https://reactjs.org) to build your user interfaces.
Managing your app's window lifecycle[](#managing-your-apps-window-lifecycle "Direct link to heading")
------------------------------------------------------------------------------------------------------
Application windows behave differently on each operating system. Rather than enforce these conventions by default, Electron gives you the choice to implement them in your app code if you wish to follow them. You can implement basic window conventions by listening for events emitted by the app and BrowserWindow modules.
Process-specific control flow
Checking against Node's [`process.platform`](https://nodejs.org/api/process.html#process_process_platform) variable can help you to run code conditionally on certain platforms. Note that there are only three possible platforms that Electron can run in: `win32` (Windows), `linux` (Linux), and `darwin` (macOS).
### Quit the app when all windows are closed (Windows & Linux)[](#quit-the-app-when-all-windows-are-closed-windows--linux "Direct link to heading")
On Windows and Linux, closing all windows will generally quit an application entirely. To implement this pattern in your Electron app, listen for the app module's [`window-all-closed`](../api/app#event-window-all-closed) event, and call [`app.quit()`](../api/app#appquit) to exit your app if the user is not on macOS.
```
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') app.quit()
})
```
### Open a window if none are open (macOS)[](#open-a-window-if-none-are-open-macos "Direct link to heading")
In contrast, macOS apps generally continue running even without any windows open. Activating the app when no windows are available should open a new one.
To implement this feature, listen for the app module's [`activate`](../api/app#event-activate-macos) event, and call your existing `createWindow()` method if no BrowserWindows are open.
Because windows cannot be created before the `ready` event, you should only listen for `activate` events after your app is initialized. Do this by only listening for activate events inside your existing `whenReady()` callback.
```
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
```
Final starter code[](#final-starter-code "Direct link to heading")
-------------------------------------------------------------------
[docs/fiddles/tutorial-first-app (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/tutorial-first-app)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/tutorial-first-app)
* main.js
* index.html
```
const { app, BrowserWindow } = require('electron');
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
});
win.loadFile('index.html');
};
app.whenReady().then(() => {
createWindow();
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow();
}
});
});
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit();
}
});
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<meta
http-equiv="Content-Security-Policy"
content="default-src 'self'; script-src 'self'"
/>
<meta
http-equiv="X-Content-Security-Policy"
content="default-src 'self'; script-src 'self'"
/>
<title>Hello from Electron renderer!</title>
</head>
<body>
<h1>Hello from Electron renderer!</h1>
<p>👋</p>
<p id="info"></p>
</body>
<script src="./renderer.js"></script>
</html>
```
Optional: Debugging from VS Code[](#optional-debugging-from-vs-code "Direct link to heading")
----------------------------------------------------------------------------------------------
If you want to debug your application using VS Code, you need to attach VS Code to both the main and renderer processes. Here is a sample configuration for you to run. Create a launch.json configuration in a new `.vscode` folder in your project:
.vscode/launch.json
```
{
"version": "0.2.0",
"compounds": [
{
"name": "Main + renderer",
"configurations": ["Main", "Renderer"],
"stopAll": true
}
],
"configurations": [
{
"name": "Renderer",
"port": 9222,
"request": "attach",
"type": "pwa-chrome",
"webRoot": "${workspaceFolder}"
},
{
"name": "Main",
"type": "pwa-node",
"request": "launch",
"cwd": "${workspaceFolder}",
"runtimeExecutable": "${workspaceFolder}/node_modules/.bin/electron",
"windows": {
"runtimeExecutable": "${workspaceFolder}/node_modules/.bin/electron.cmd"
},
"args": [".", "--remote-debugging-port=9222"],
"outputCapture": "std",
"console": "integratedTerminal"
}
]
}
```
The "Main + renderer" option will appear when you select "Run and Debug" from the sidebar, allowing you to set breakpoints and inspect all the variables among other things in both the main and renderer processes.
What we have done in the `launch.json` file is to create 3 configurations:
* `Main` is used to start the main process and also expose port 9222 for remote debugging (`--remote-debugging-port=9222`). This is the port that we will use to attach the debugger for the `Renderer`. Because the main process is a Node.js process, the type is set to `pwa-node` (`pwa-` is the prefix that tells VS Code to use the latest JavaScript debugger).
* `Renderer` is used to debug the renderer process. Because the main process is the one that creates the process, we have to "attach" to it (`"request": "attach"`) instead of creating a new one. The renderer process is a web one, so the debugger we have to use is `pwa-chrome`.
* `Main + renderer` is a [compound task](https://code.visualstudio.com/Docs/editor/tasks#_compound-tasks) that executes the previous ones simultaneously.
caution
Because we are attaching to a process in `Renderer`, it is possible that the first lines of your code will be skipped as the debugger will not have had enough time to connect before they are being executed. You can work around this by refreshing the page or setting a timeout before executing the code in development mode.
Further reading
If you want to dig deeper in the debugging area, the following guides provide more information:
* [Application Debugging](application-debugging)
* [DevTools Extensions](devtools-extension)
Summary[](#summary "Direct link to heading")
---------------------------------------------
Electron applications are set up using npm packages. The Electron executable should be installed in your project's `devDependencies` and can be run in development mode using a script in your package.json file.
The executable runs the JavaScript entry point found in the `main` property of your package.json. This file controls Electron's **main process**, which runs an instance of Node.js and is responsible for your app's lifecycle, displaying native interfaces, performing privileged operations, and managing renderer processes.
**Renderer processes** (or renderers for short) are responsible for display graphical content. You can load a web page into a renderer by pointing it to either a web address or a local HTML file. Renderers behave very similarly to regular web pages and have access to the same web APIs.
In the next section of the tutorial, we will be learning how to augment the renderer process with privileged APIs and how to communicate between processes.
| programming_docs |
electron Process Model Process Model
=============
Electron inherits its multi-process architecture from Chromium, which makes the framework architecturally very similar to a modern web browser. This guide will expand on the concepts applied in the [Tutorial](tutorial-prerequisites).
Why not a single process?[](#why-not-a-single-process "Direct link to heading")
--------------------------------------------------------------------------------
Web browsers are incredibly complicated applications. Aside from their primary ability to display web content, they have many secondary responsibilities, such as managing multiple windows (or tabs) and loading third-party extensions.
In the earlier days, browsers usually used a single process for all of this functionality. Although this pattern meant less overhead for each tab you had open, it also meant that one website crashing or hanging would affect the entire browser.
The multi-process model[](#the-multi-process-model "Direct link to heading")
-----------------------------------------------------------------------------
To solve this problem, the Chrome team decided that each tab would render in its own process, limiting the harm that buggy or malicious code on a web page could cause to the app as a whole. A single browser process then controls these processes, as well as the application lifecycle as a whole. This diagram below from the [Chrome Comic](https://www.google.com/googlebooks/chrome/) visualizes this model:
Electron applications are structured very similarly. As an app developer, you control two types of processes: [main](#the-main-process) and [renderer](#the-renderer-process). These are analogous to Chrome's own browser and renderer processes outlined above.
The main process[](#the-main-process "Direct link to heading")
---------------------------------------------------------------
Each Electron app has a single main process, which acts as the application's entry point. The main process runs in a Node.js environment, meaning it has the ability to `require` modules and use all of Node.js APIs.
### Window management[](#window-management "Direct link to heading")
The main process' primary purpose is to create and manage application windows with the [`BrowserWindow`](../api/browser-window) module.
Each instance of the `BrowserWindow` class creates an application window that loads a web page in a separate renderer process. You can interact with this web content from the main process using the window's [`webContents`](../api/web-contents) object.
main.js
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ width: 800, height: 1500 })
win.loadURL('https://github.com')
const contents = win.webContents
console.log(contents)
```
> Note: A renderer process is also created for [web embeds](web-embeds) such as the `BrowserView` module. The `webContents` object is also accessible for embedded web content.
>
>
Because the `BrowserWindow` module is an [`EventEmitter`](https://nodejs.org/api/events.html#events_class_eventemitter), you can also add handlers for various user events (for example, minimizing or maximizing your window).
When a `BrowserWindow` instance is destroyed, its corresponding renderer process gets terminated as well.
### Application lifecycle[](#application-lifecycle "Direct link to heading")
The main process also controls your application's lifecycle through Electron's [`app`](../api/app) module. This module provides a large set of events and methods that you can use to add custom application behaviour (for instance, programatically quitting your application, modifying the application dock, or showing an About panel).
As a practical example, the app shown in the [quick start guide](quick-start#manage-your-windows-lifecycle) uses `app` APIs to create a more native application window experience.
main.js
```
// quitting the app when no windows are open on non-macOS platforms
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') app.quit()
})
```
### Native APIs[](#native-apis "Direct link to heading")
To extend Electron's features beyond being a Chromium wrapper for web contents, the main process also adds custom APIs to interact with the user's operating system. Electron exposes various modules that control native desktop functionality, such as menus, dialogs, and tray icons.
For a full list of Electron's main process modules, check out our API documentation.
The renderer process[](#the-renderer-process "Direct link to heading")
-----------------------------------------------------------------------
Each Electron app spawns a separate renderer process for each open `BrowserWindow` (and each web embed). As its name implies, a renderer is responsible for *rendering* web content. For all intents and purposes, code ran in renderer processes should behave according to web standards (insofar as Chromium does, at least).
Therefore, all user interfaces and app functionality within a single browser window should be written with the same tools and paradigms that you use on the web.
Although explaining every web spec is out of scope for this guide, the bare minimum to understand is:
* An HTML file is your entry point for the renderer process.
* UI styling is added through Cascading Style Sheets (CSS).
* Executable JavaScript code can be added through `<script>` elements.
Moreover, this also means that the renderer has no direct access to `require` or other Node.js APIs. In order to directly include NPM modules in the renderer, you must use the same bundler toolchains (for example, `webpack` or `parcel`) that you use on the web.
danger
Renderer processes can be spawned with a full Node.js environment for ease of development. Historically, this used to be the default, but this feature was disabled for security reasons.
At this point, you might be wondering how your renderer process user interfaces can interact with Node.js and Electron's native desktop functionality if these features are only accessible from the main process. In fact, there is no direct way to import Electron's content scripts.
Preload scripts[](#preload-scripts "Direct link to heading")
-------------------------------------------------------------
Preload scripts contain code that executes in a renderer process before its web content begins loading. These scripts run within the renderer context, but are granted more privileges by having access to Node.js APIs.
A preload script can be attached to the main process in the `BrowserWindow` constructor's `webPreferences` option.
main.js
```
const { BrowserWindow } = require('electron')
//...
const win = new BrowserWindow({
webPreferences: {
preload: 'path/to/preload.js',
},
})
//...
```
Because the preload script shares a global [`Window`](https://developer.mozilla.org/en-US/docs/Web/API/Window) interface with the renderers and can access Node.js APIs, it serves to enhance your renderer by exposing arbitrary APIs in the `window` global that your web contents can then consume.
Although preload scripts share a `window` global with the renderer they're attached to, you cannot directly attach any variables from the preload script to `window` because of the [`contextIsolation`](context-isolation) default.
preload.js
```
window.myAPI = {
desktop: true,
}
```
renderer.js
```
console.log(window.myAPI)
// => undefined
```
Context Isolation means that preload scripts are isolated from the renderer's main world to avoid leaking any privileged APIs into your web content's code.
Instead, use the [`contextBridge`](../api/context-bridge) module to accomplish this securely:
preload.js
```
const { contextBridge } = require('electron')
contextBridge.exposeInMainWorld('myAPI', {
desktop: true,
})
```
renderer.js
```
console.log(window.myAPI)
// => { desktop: true }
```
This feature is incredibly useful for two main purposes:
* By exposing [`ipcRenderer`](../api/ipc-renderer) helpers to the renderer, you can use inter-process communication (IPC) to trigger main process tasks from the renderer (and vice-versa).
* If you're developing an Electron wrapper for an existing web app hosted on a remote URL, you can add custom properties onto the renderer's `window` global that can be used for desktop-only logic on the web client's side.
electron Updating Applications There are several ways to provide automatic updates to your Electron application. The easiest and officially supported one is taking advantage of the built-in [Squirrel](https://github.com/Squirrel) framework and Electron's [autoUpdater](../api/auto-updater) module.
Using update.electronjs.org[](#using-updateelectronjsorg "Direct link to heading")
-----------------------------------------------------------------------------------
The Electron team maintains [update.electronjs.org](https://github.com/electron/update.electronjs.org), a free and open-source webservice that Electron apps can use to self-update. The service is designed for Electron apps that meet the following criteria:
* App runs on macOS or Windows
* App has a public GitHub repository
* Builds are published to [GitHub Releases](https://help.github.com/articles/creating-releases/)
* Builds are [code-signed](code-signing)
The easiest way to use this service is by installing [update-electron-app](https://github.com/electron/update-electron-app), a Node.js module preconfigured for use with update.electronjs.org.
Install the module using your Node.js package manager of choice:
* npm
* Yarn
```
npm install update-electron-app
```
```
yarn add update-electron-app
```
Then, invoke the updater from your app's main process file:
main.js
```
require('update-electron-app')()
```
By default, this module will check for updates at app startup, then every ten minutes. When an update is found, it will automatically be downloaded in the background. When the download completes, a dialog is displayed allowing the user to restart the app.
If you need to customize your configuration, you can [pass options to update-electron-app](https://github.com/electron/update-electron-app) or [use the update service directly](https://github.com/electron/update.electronjs.org).
Using other update services[](#using-other-update-services "Direct link to heading")
-------------------------------------------------------------------------------------
If you're developing a private Electron application, or if you're not publishing releases to GitHub Releases, it may be necessary to run your own update server.
### Step 1: Deploying an update server[](#step-1-deploying-an-update-server "Direct link to heading")
Depending on your needs, you can choose from one of these:
* [Hazel](https://github.com/vercel/hazel) – Update server for private or open-source apps which can be deployed for free on [Vercel](https://vercel.com). It pulls from [GitHub Releases](https://help.github.com/articles/creating-releases/) and leverages the power of GitHub's CDN.
* [Nuts](https://github.com/GitbookIO/nuts) – Also uses [GitHub Releases](https://help.github.com/articles/creating-releases/), but caches app updates on disk and supports private repositories.
* [electron-release-server](https://github.com/ArekSredzki/electron-release-server) – Provides a dashboard for handling releases and does not require releases to originate on GitHub.
* [Nucleus](https://github.com/atlassian/nucleus) – A complete update server for Electron apps maintained by Atlassian. Supports multiple applications and channels; uses a static file store to minify server cost.
Once you've deployed your update server, you can instrument your app code to receive and apply the updates with Electron's [autoUpdater] module.
### Step 2: Receiving updates in your app[](#step-2-receiving-updates-in-your-app "Direct link to heading")
First, import the required modules in your main process code. The following code might vary for different server software, but it works like described when using [Hazel](https://github.com/vercel/hazel).
Check your execution environment!
Please ensure that the code below will only be executed in your packaged app, and not in development. You can use the [app.isPackaged](../api/app#appispackaged-readonly) API to check the environment.
main.js
```
const { app, autoUpdater, dialog } = require('electron')
```
Next, construct the URL of the update server feed and tell [autoUpdater](../api/auto-updater) about it:
main.js
```
const server = 'https://your-deployment-url.com'
const url = `${server}/update/${process.platform}/${app.getVersion()}`
autoUpdater.setFeedURL({ url })
```
As the final step, check for updates. The example below will check every minute:
main.js
```
setInterval(() => {
autoUpdater.checkForUpdates()
}, 60000)
```
Once your application is [packaged](application-distribution), it will receive an update for each new [GitHub Release](https://help.github.com/articles/creating-releases/) that you publish.
### Step 3: Notifying users when updates are available[](#step-3-notifying-users-when-updates-are-available "Direct link to heading")
Now that you've configured the basic update mechanism for your application, you need to ensure that the user will get notified when there's an update. This can be achieved using the [autoUpdater API events](../api/auto-updater#events):
main.js
```
autoUpdater.on('update-downloaded', (event, releaseNotes, releaseName) => {
const dialogOpts = {
type: 'info',
buttons: ['Restart', 'Later'],
title: 'Application Update',
message: process.platform === 'win32' ? releaseNotes : releaseName,
detail:
'A new version has been downloaded. Restart the application to apply the updates.',
}
dialog.showMessageBox(dialogOpts).then((returnValue) => {
if (returnValue.response === 0) autoUpdater.quitAndInstall()
})
})
```
Also make sure that errors are [being handled](../api/auto-updater#event-error). Here's an example for logging them to `stderr`:
main.js
```
autoUpdater.on('error', (message) => {
console.error('There was a problem updating the application')
console.error(message)
})
```
Handling updates manually
Because the requests made by autoUpdate aren't under your direct control, you may find situations that are difficult to handle (such as if the update server is behind authentication). The `url` field supports the `file://` protocol, which means that with some effort, you can sidestep the server-communication aspect of the process by loading your update from a local directory. [Here's an example of how this could work](https://github.com/electron/electron/issues/5020#issuecomment-477636990).
electron Process Sandboxing Process Sandboxing
==================
One key security feature in Chromium is that processes can be executed within a sandbox. The sandbox limits the harm that malicious code can cause by limiting access to most system resources — sandboxed processes can only freely use CPU cycles and memory. In order to perform operations requiring additional privilege, sandboxed processes use dedicated communication channels to delegate tasks to more privileged processes.
In Chromium, sandboxing is applied to most processes other than the main process. This includes renderer processes, as well as utility processes such as the audio service, the GPU service and the network service.
See Chromium's [Sandbox design document](https://chromium.googlesource.com/chromium/src/+/main/docs/design/sandbox.md) for more information.
Electron's sandboxing policies[](#electrons-sandboxing-policies "Direct link to heading")
------------------------------------------------------------------------------------------
Electron comes with a mixed sandbox environment, meaning sandboxed processes can run alongside privileged ones. By default, renderer processes are not sandboxed, but utility processes are. Note that as in Chromium, the main (browser) process is privileged and cannot be sandboxed.
Historically, this mixed sandbox approach was established because having Node.js available in the renderer is an extremely powerful tool for app developers. Unfortunately, this feature is also an equally massive security vulnerability.
Theoretically, unsandboxed renderers are not a problem for desktop applications that only display trusted code, but they make Electron less secure than Chromium for displaying untrusted web content. However, even purportedly trusted code may be dangerous — there are countless attack vectors that malicious actors can use, from cross-site scripting to content injection to man-in-the-middle attacks on remotely loaded websites, just to name a few. For this reason, we recommend enabling renderer sandboxing for the vast majority of cases under an abundance of caution.
Note that there is an active discussion in the issue tracker to enable renderer sandboxing by default. See [#28466](https://github.com/electron/electron/issues/28466)) for details.
Sandbox behaviour in Electron[](#sandbox-behaviour-in-electron "Direct link to heading")
-----------------------------------------------------------------------------------------
Sandboxed processes in Electron behave *mostly* in the same way as Chromium's do, but Electron has a few additional concepts to consider because it interfaces with Node.js.
### Renderer processes[](#renderer-processes "Direct link to heading")
When renderer processes in Electron are sandboxed, they behave in the same way as a regular Chrome renderer would. A sandboxed renderer won't have a Node.js environment initialized.
Therefore, when the sandbox is enabled, renderer processes can only perform privileged tasks (such as interacting with the filesystem, making changes to the system, or spawning subprocesses) by delegating these tasks to the main process via inter-process communication (IPC).
### Preload scripts[](#preload-scripts "Direct link to heading")
In order to allow renderer processes to communicate with the main process, preload scripts attached to sandboxed renderers will still have a polyfilled subset of Node.js APIs available. A `require` function similar to Node's `require` module is exposed, but can only import a subset of Electron and Node's built-in modules:
* `electron` (only renderer process modules)
* [`events`](https://nodejs.org/api/events.html)
* [`timers`](https://nodejs.org/api/timers.html)
* [`url`](https://nodejs.org/api/url.html)
In addition, the preload script also polyfills certain Node.js primitives as globals:
* [`Buffer`](https://nodejs.org/api/Buffer.html)
* [`process`](../api/process)
* [`clearImmediate`](https://nodejs.org/api/timers.html#timers_clearimmediate_immediate)
* [`setImmediate`](https://nodejs.org/api/timers.html#timers_setimmediate_callback_args)
Because the `require` function is a polyfill with limited functionality, you will not be able to use [CommonJS modules](https://nodejs.org/api/modules.html#modules_modules_commonjs_modules) to separate your preload script into multiple files. If you need to split your preload code, use a bundler such as [webpack](https://webpack.js.org/) or [Parcel](https://parceljs.org/).
Note that because the environment presented to the `preload` script is substantially more privileged than that of a sandboxed renderer, it is still possible to leak privileged APIs to untrusted code running in the renderer process unless [`contextIsolation`](context-isolation) is enabled.
Configuring the sandbox[](#configuring-the-sandbox "Direct link to heading")
-----------------------------------------------------------------------------
### Enabling the sandbox for a single process[](#enabling-the-sandbox-for-a-single-process "Direct link to heading")
In Electron, renderer sandboxing can be enabled on a per-process basis with the `sandbox: true` preference in the [`BrowserWindow`](../api/browser-window) constructor.
```
// main.js
app.whenReady().then(() => {
const win = new BrowserWindow({
webPreferences: {
sandbox: true
}
})
win.loadURL('https://google.com')
})
```
### Enabling the sandbox globally[](#enabling-the-sandbox-globally "Direct link to heading")
If you want to force sandboxing for all renderers, you can also use the [`app.enableSandbox`](../api/app#appenablesandbox) API. Note that this API has to be called before the app's `ready` event.
```
// main.js
app.enableSandbox()
app.whenReady().then(() => {
// no need to pass `sandbox: true` since `app.enableSandbox()` was called.
const win = new BrowserWindow()
win.loadURL('https://google.com')
})
```
### Disabling Chromium's sandbox (testing only)[](#disabling-chromiums-sandbox-testing-only "Direct link to heading")
You can also disable Chromium's sandbox entirely with the [`--no-sandbox`](../api/command-line-switches#--no-sandbox) CLI flag, which will disable the sandbox for all processes (including utility processes). We highly recommend that you only use this flag for testing purposes, and **never** in production.
Note that the `sandbox: true` option will still disable the renderer's Node.js environment.
A note on rendering untrusted content[](#a-note-on-rendering-untrusted-content "Direct link to heading")
---------------------------------------------------------------------------------------------------------
Rendering untrusted content in Electron is still somewhat uncharted territory, though some apps are finding success (e.g. [Beaker Browser](https://github.com/beakerbrowser/beaker)). Our goal is to get as close to Chrome as we can in terms of the security of sandboxed content, but ultimately we will always be behind due to a few fundamental issues:
1. We do not have the dedicated resources or expertise that Chromium has to apply to the security of its product. We do our best to make use of what we have, to inherit everything we can from Chromium, and to respond quickly to security issues, but Electron cannot be as secure as Chromium without the resources that Chromium is able to dedicate.
2. Some security features in Chrome (such as Safe Browsing and Certificate Transparency) require a centralized authority and dedicated servers, both of which run counter to the goals of the Electron project. As such, we disable those features in Electron, at the cost of the associated security they would otherwise bring.
3. There is only one Chromium, whereas there are many thousands of apps built on Electron, all of which behave slightly differently. Accounting for those differences can yield a huge possibility space, and make it challenging to ensure the security of the platform in unusual use cases.
4. We can't push security updates to users directly, so we rely on app vendors to upgrade the version of Electron underlying their app in order for security updates to reach users.
While we make our best effort to backport Chromium security fixes to older versions of Electron, we do not make a guarantee that every fix will be backported. Your best chance at staying secure is to be on the latest stable version of Electron.
| programming_docs |
electron Context Isolation Context Isolation
=================
What is it?[](#what-is-it "Direct link to heading")
----------------------------------------------------
Context Isolation is a feature that ensures that both your `preload` scripts and Electron's internal logic run in a separate context to the website you load in a [`webContents`](../api/web-contents). This is important for security purposes as it helps prevent the website from accessing Electron internals or the powerful APIs your preload script has access to.
This means that the `window` object that your preload script has access to is actually a **different** object than the website would have access to. For example, if you set `window.hello = 'wave'` in your preload script and context isolation is enabled, `window.hello` will be undefined if the website tries to access it.
Context isolation has been enabled by default since Electron 12, and it is a recommended security setting for *all applications*.
Migration[](#migration "Direct link to heading")
-------------------------------------------------
> Without context isolation, I used to provide APIs from my preload script using `window.X = apiObject`. Now what?
>
>
### Before: context isolation disabled[](#before-context-isolation-disabled "Direct link to heading")
Exposing APIs from your preload script to a loaded website in the renderer process is a common use-case. With context isolation disabled, your preload script would share a common global `window` object with the renderer. You could then attach arbitrary properties to a preload script:
preload.js
```
// preload with contextIsolation disabled
window.myAPI = {
doAThing: () => {}
}
```
The `doAThing()` function could then be used directly in the renderer process:
renderer.js
```
// use the exposed API in the renderer
window.myAPI.doAThing()
```
### After: context isolation enabled[](#after-context-isolation-enabled "Direct link to heading")
There is a dedicated module in Electron to help you do this in a painless way. The [`contextBridge`](../api/context-bridge) module can be used to **safely** expose APIs from your preload script's isolated context to the context the website is running in. The API will also be accessible from the website on `window.myAPI` just like it was before.
preload.js
```
// preload with contextIsolation enabled
const { contextBridge } = require('electron')
contextBridge.exposeInMainWorld('myAPI', {
doAThing: () => {}
})
```
renderer.js
```
// use the exposed API in the renderer
window.myAPI.doAThing()
```
Please read the `contextBridge` documentation linked above to fully understand its limitations. For instance, you can't send custom prototypes or symbols over the bridge.
Security considerations[](#security-considerations "Direct link to heading")
-----------------------------------------------------------------------------
Just enabling `contextIsolation` and using `contextBridge` does not automatically mean that everything you do is safe. For instance, this code is **unsafe**.
preload.js
```
// ❌ Bad code
contextBridge.exposeInMainWorld('myAPI', {
send: ipcRenderer.send
})
```
It directly exposes a powerful API without any kind of argument filtering. This would allow any website to send arbitrary IPC messages, which you do not want to be possible. The correct way to expose IPC-based APIs would instead be to provide one method per IPC message.
preload.js
```
// ✅ Good code
contextBridge.exposeInMainWorld('myAPI', {
loadPreferences: () => ipcRenderer.invoke('load-prefs')
})
```
Usage with TypeScript[](#usage-with-typescript "Direct link to heading")
-------------------------------------------------------------------------
If you're building your Electron app with TypeScript, you'll want to add types to your APIs exposed over the context bridge. The renderer's `window` object won't have the correct typings unless you extend the types with a [declaration file](https://www.typescriptlang.org/docs/handbook/declaration-files/introduction.html).
For example, given this `preload.ts` script:
preload.ts
```
contextBridge.exposeInMainWorld('electronAPI', {
loadPreferences: () => ipcRenderer.invoke('load-prefs')
})
```
You can create a `renderer.d.ts` declaration file and globally augment the `Window` interface:
renderer.d.ts
```
export interface IElectronAPI {
loadPreferences: () => Promise<void>,
}
declare global {
interface Window {
electronAPI: IElectronAPI
}
}
```
Doing so will ensure that the TypeScript compiler will know about the `electronAPI` property on your global `window` object when writing scripts in your renderer process:
renderer.ts
```
window.electronAPI.loadPreferences()
```
electron Electron Fuses Electron Fuses
==============
> Package time feature toggles
>
>
What are fuses?[](#what-are-fuses "Direct link to heading")
------------------------------------------------------------
For a subset of Electron functionality it makes sense to disable certain features for an entire application. For example, 99% of apps don't make use of `ELECTRON_RUN_AS_NODE`, these applications want to be able to ship a binary that is incapable of using that feature. We also don't want Electron consumers building Electron from source as that is both a massive technical challenge and has a high cost of both time and money.
Fuses are the solution to this problem, at a high level they are "magic bits" in the Electron binary that can be flipped when packaging your Electron app to enable / disable certain features / restrictions. Because they are flipped at package time before you code sign your app the OS becomes responsible for ensuring those bits aren't flipped back via OS level code signing validation (Gatekeeper / App Locker).
How do I flip the fuses?[](#how-do-i-flip-the-fuses "Direct link to heading")
------------------------------------------------------------------------------
### The easy way[](#the-easy-way "Direct link to heading")
We've made a handy module, [`@electron/fuses`](https://npmjs.com/package/@electron/fuses), to make flipping these fuses easy. Check out the README of that module for more details on usage and potential error cases.
```
require('@electron/fuses').flipFuses(
// Path to electron
require('electron'),
// Fuses to flip
{
runAsNode: false
}
)
```
### The hard way[](#the-hard-way "Direct link to heading")
#### Quick Glossary[](#quick-glossary "Direct link to heading")
* **Fuse Wire**: A sequence of bytes in the Electron binary used to control the fuses
* **Sentinel**: A static known sequence of bytes you can use to locate the fuse wire
* **Fuse Schema**: The format / allowed values for the fuse wire
Manually flipping fuses requires editing the Electron binary and modifying the fuse wire to be the sequence of bytes that represent the state of the fuses you want.
Somewhere in the Electron binary there will be a sequence of bytes that look like this:
```
| ...binary | sentinel_bytes | fuse_version | fuse_wire_length | fuse_wire | ...binary |
```
* `sentinel_bytes` is always this exact string `dL7pKGdnNz796PbbjQWNKmHXBZaB9tsX`
* `fuse_version` is a single byte whose unsigned integer value represents the version of the fuse schema
* `fuse_wire_length` is a single byte whose unsigned integer value represents the number of fuses in the following fuse wire
* `fuse_wire` is a sequence of N bytes, each byte represents a single fuse and its state.
+ "0" (0x30) indicates the fuse is disabled
+ "1" (0x31) indicates the fuse is enabled
+ "r" (0x72) indicates the fuse has been removed and changing the byte to either 1 or 0 will have no effect.
To flip a fuse you find its position in the fuse wire and change it to "0" or "1" depending on the state you'd like.
You can view the current schema [here](https://github.com/electron/electron/blob/main/build/fuses/fuses.json5).
electron Offscreen Rendering Offscreen Rendering
===================
Overview[](#overview "Direct link to heading")
-----------------------------------------------
Offscreen rendering lets you obtain the content of a `BrowserWindow` in a bitmap, so it can be rendered anywhere, for example, on texture in a 3D scene. The offscreen rendering in Electron uses a similar approach to that of the [Chromium Embedded Framework](https://bitbucket.org/chromiumembedded/cef) project.
*Notes*:
* There are two rendering modes that can be used (see the section below) and only the dirty area is passed to the `paint` event to be more efficient.
* You can stop/continue the rendering as well as set the frame rate.
* The maximum frame rate is 240 because greater values bring only performance losses with no benefits.
* When nothing is happening on a webpage, no frames are generated.
* An offscreen window is always created as a [Frameless Window](window-customization)..
### Rendering Modes[](#rendering-modes "Direct link to heading")
#### GPU accelerated[](#gpu-accelerated "Direct link to heading")
GPU accelerated rendering means that the GPU is used for composition. Because of that, the frame has to be copied from the GPU which requires more resources, thus this mode is slower than the Software output device. The benefit of this mode is that WebGL and 3D CSS animations are supported.
#### Software output device[](#software-output-device "Direct link to heading")
This mode uses a software output device for rendering in the CPU, so the frame generation is much faster. As a result, this mode is preferred over the GPU accelerated one.
To enable this mode, GPU acceleration has to be disabled by calling the [`app.disableHardwareAcceleration()`](../api/app#appdisablehardwareacceleration) API.
Example[](#example "Direct link to heading")
---------------------------------------------
[docs/fiddles/features/offscreen-rendering (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/offscreen-rendering)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/offscreen-rendering)
* main.js
```
const { app, BrowserWindow } = require('electron')
const fs = require('fs')
const path = require('path')
app.disableHardwareAcceleration()
let win
app.whenReady().then(() => {
win = new BrowserWindow({ webPreferences: { offscreen: true } })
win.loadURL('https://github.com')
win.webContents.on('paint', (event, dirty, image) => {
fs.writeFileSync('ex.png', image.toPNG())
})
win.webContents.setFrameRate(60)
console.log(`The screenshot has been successfully saved to ${path.join(process.cwd(), 'ex.png')}`)
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
After launching the Electron application, navigate to your application's working folder, where you'll find the rendered image.
electron Packaging Your Application
Follow along the tutorial
This is **part 5** of the Electron tutorial.
1. [Prerequisites](tutorial-prerequisites)
2. [Building your First App](tutorial-first-app)
3. [Using Preload Scripts](tutorial-preload)
4. [Adding Features](tutorial-adding-features)
5. **[Packaging Your Application](tutorial-packaging)**
6. [Publishing and Updating](tutorial-publishing-updating)
Learning goals[](#learning-goals "Direct link to heading")
-----------------------------------------------------------
In this part of the tutorial, we'll be going over the basics of packaging and distributing your app with [Electron Forge](https://www.electronforge.io).
Using Electron Forge[](#using-electron-forge "Direct link to heading")
-----------------------------------------------------------------------
Electron does not have any tooling for packaging and distribution bundled into its core modules. Once you have a working Electron app in dev mode, you need to use additional tooling to create a packaged app you can distribute to your users (also known as a **distributable**). Distributables can be either installers (e.g. MSI on Windows) or portable executable files (e.g. `.app` on macOS).
Electron Forge is an all-in-one tool that handles the packaging and distribution of Electron apps. Under the hood, it combines a lot of existing Electron tools (e.g. [`electron-packager`](https://github.com/electron/electron-packager), [`@electron/osx-sign`](https://github.com/electron/osx-sign), [`electron-winstaller`](https://github.com/electron/windows-installer), etc.) into a single interface so you do not have to worry about wiring them all together.
### Importing your project into Forge[](#importing-your-project-into-forge "Direct link to heading")
You can install Electron Forge's CLI in your project's `devDependencies` and import your existing project with a handy conversion script.
* npm
* Yarn
```
npm install --save-dev @electron-forge/cli
npx electron-forge import
```
```
yarn add --dev @electron-forge/cli
npx electron-forge import
```
Once the conversion script is done, Forge should have added a few scripts to your `package.json` file.
package.json
```
//...
"scripts": {
"start": "electron-forge start",
"package": "electron-forge package",
"make": "electron-forge make"
},
//...
```
CLI documentation
For more information on `make` and other Forge APIs, check out the [Electron Forge CLI documentation](https://www.electronforge.io/cli#commands).
You should also notice that your package.json now has a few more packages installed under your `devDependencies`, and contains an added `config.forge` field with an array of makers configured. **Makers** are Forge plugins that create distributables from your source code. You should see multiple makers in the pre-populated configuration, one for each target platform.
### Creating a distributable[](#creating-a-distributable "Direct link to heading")
To create a distributable, use your project's new `make` script, which runs the `electron-forge make` command.
* npm
* Yarn
```
npm run make
```
```
yarn run make
```
This `make` command contains two steps:
1. It will first run `electron-forge package` under the hood, which bundles your app code together with the Electron binary. The packaged code is generated into a folder.
2. It will then use this packaged app folder to create a separate distributable for each configured maker.
After the script runs, you should see an `out` folder containing both the distributable and a folder containing the packaged application code.
macOS output example
```
out/
├── out/make/zip/darwin/x64/my-electron-app-darwin-x64-1.0.0.zip
├── ...
└── out/my-electron-app-darwin-x64/my-electron-app.app/Contents/MacOS/my-electron-app
```
The distributable in the `out/make` folder should be ready to launch! You have now created your first bundled Electron application.
Distributable formats
Electron Forge can be configured to create distributables in different OS-specific formats (e.g. DMG, deb, MSI, etc.). See Forge's [Makers](https://www.electronforge.io/config/makers) documentation for all configuration options.
Packaging without Electron Forge
If you want to manually package your code, or if you're just interested understanding the mechanics behind packaging an Electron app, check out the full [Application Packaging](application-distribution) documentation.
Important: signing your code[](#important-signing-your-code "Direct link to heading")
--------------------------------------------------------------------------------------
In order to distribute desktop applications to end users, we *highly recommended* for you to **code sign** your Electron app. Code signing is an important part of shipping desktop applications, and is mandatory for the auto-update step in the final part of the tutorial.
Code signing is a security technology that you use to certify that a desktop app was created by a known source. Windows and macOS have their own OS-specific code signing systems that will make it difficult for users to download or launch unsigned applications.
If you already have code signing certificates for Windows and macOS, you can set your credentials in your Forge configuration. Otherwise, please refer to the full [Code Signing](code-signing) documentation to learn how to purchase a certificate and for more information on the desktop app code signing process.
On macOS, code signing is done at the app packaging level. On Windows, distributable installers are signed instead.
* macOS
* Windows
package.json
```
{
//...
"config": {
"forge": {
//...
"packagerConfig": {
"osxSign": {
"identity": "Developer ID Application: Felix Rieseberg (LT94ZKYDCJ)",
"hardened-runtime": true,
"entitlements": "entitlements.plist",
"entitlements-inherit": "entitlements.plist",
"signature-flags": "library"
},
"osxNotarize": {
"appleId": "[email protected]",
"appleIdPassword": "this-is-a-secret"
}
}
//...
}
}
//...
}
```
package.json
```
{
//...
"config": {
"forge": {
//...
"makers": [
{
"name": "@electron-forge/maker-squirrel",
"config": {
"certificateFile": "./cert.pfx",
"certificatePassword": "this-is-a-secret"
}
}
]
//...
}
}
//...
}
```
Summary[](#summary "Direct link to heading")
---------------------------------------------
Electron applications need to be packaged to be distributed to users. In this tutorial, you imported your app into Electron Forge and configured it to package your app and generate installers.
In order for your application to be trusted by the user's system, you need to digitally certify that the distributable is authentic and untampered by code signing it. Your app can be signed through Forge once you configure it to use your code signing certificate information.
electron Examples Overview Examples Overview
=================
In this section, we have collected a set of guides for common features that you may want to implement in your Electron application. Each guide contains a practical example in a minimal, self-contained example app. The easiest way to run these examples is by downloading [Electron Fiddle](https://www.electronjs.org/fiddle).
Once Fiddle is installed, you can press on the "Open in Fiddle" button that you will find below code samples like the following one:
[docs/fiddles/quick-start (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/quick-start)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/quick-start)
* main.js
* preload.js
* index.html
```
const { app, BrowserWindow } = require('electron')
const path = require('path')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
win.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
```
```
window.addEventListener('DOMContentLoaded', () => {
const replaceText = (selector, text) => {
const element = document.getElementById(selector)
if (element) element.innerText = text
}
for (const type of ['chrome', 'node', 'electron']) {
replaceText(`${type}-version`, process.versions[type])
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>
We are using Node.js <span id="node-version"></span>,
Chromium <span id="chrome-version"></span>,
and Electron <span id="electron-version"></span>.
</p>
</body>
</html>
```
How to...?[](#how-to "Direct link to heading")
-----------------------------------------------
You can find the full list of "How to?" in the sidebar. If there is something that you would like to do that is not documented, please join our [Discord server](https://discord.com/invite/electronjs) and let us know!
| programming_docs |
electron Window Customization Window Customization
====================
The `BrowserWindow` module is the foundation of your Electron application, and it exposes many APIs that can change the look and behavior of your browser windows. In this tutorial, we will be going over the various use-cases for window customization on macOS, Windows, and Linux.
Create frameless windows[](#create-frameless-windows "Direct link to heading")
-------------------------------------------------------------------------------
A frameless window is a window that has no [chrome](https://developer.mozilla.org/en-US/docs/Glossary/Chrome). Not to be confused with the Google Chrome browser, window *chrome* refers to the parts of the window (e.g. toolbars, controls) that are not a part of the web page.
To create a frameless window, you need to set `frame` to `false` in the `BrowserWindow` constructor.
main.js
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ frame: false })
```
Apply custom title bar styles *macOS* *Windows*[](#apply-custom-title-bar-styles-macos-windows "Direct link to heading")
-------------------------------------------------------------------------------------------------------------------------
Title bar styles allow you to hide most of a BrowserWindow's chrome while keeping the system's native window controls intact and can be configured with the `titleBarStyle` option in the `BrowserWindow` constructor.
Applying the `hidden` title bar style results in a hidden title bar and a full-size content window.
main.js
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ titleBarStyle: 'hidden' })
```
### Control the traffic lights *macOS*[](#control-the-traffic-lights-macos "Direct link to heading")
On macOS, applying the `hidden` title bar style will still expose the standard window controls (“traffic lights”) in the top left.
#### Customize the look of your traffic lights *macOS*[](#customize-the-look-of-your-traffic-lights-macos "Direct link to heading")
The `customButtonsOnHover` title bar style will hide the traffic lights until you hover over them. This is useful if you want to create custom traffic lights in your HTML but still use the native UI to control the window.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ titleBarStyle: 'customButtonsOnHover' })
```
#### Customize the traffic light position *macOS*[](#customize-the-traffic-light-position-macos "Direct link to heading")
To modify the position of the traffic light window controls, there are two configuration options available.
Applying `hiddenInset` title bar style will shift the vertical inset of the traffic lights by a fixed amount.
main.js
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ titleBarStyle: 'hiddenInset' })
```
If you need more granular control over the positioning of the traffic lights, you can pass a set of coordinates to the `trafficLightPosition` option in the `BrowserWindow` constructor.
main.js
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({
titleBarStyle: 'hidden',
trafficLightPosition: { x: 10, y: 10 }
})
```
#### Show and hide the traffic lights programmatically *macOS*[](#show-and-hide-the-traffic-lights-programmatically-macos "Direct link to heading")
You can also show and hide the traffic lights programmatically from the main process. The `win.setWindowButtonVisibility` forces traffic lights to be show or hidden depending on the value of its boolean parameter.
main.js
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
// hides the traffic lights
win.setWindowButtonVisibility(false)
```
> Note: Given the number of APIs available, there are many ways of achieving this. For instance, combining `frame: false` with `win.setWindowButtonVisibility(true)` will yield the same layout outcome as setting `titleBarStyle: 'hidden'`.
>
>
Window Controls Overlay *macOS* *Windows*[](#window-controls-overlay-macos-windows "Direct link to heading")
-------------------------------------------------------------------------------------------------------------
The [Window Controls Overlay API](https://github.com/WICG/window-controls-overlay/blob/main/explainer.md) is a web standard that gives web apps the ability to customize their title bar region when installed on desktop. Electron exposes this API through the `BrowserWindow` constructor option `titleBarOverlay`.
This option only works whenever a custom `titlebarStyle` is applied on macOS or Windows. When `titleBarOverlay` is enabled, the window controls become exposed in their default position, and DOM elements cannot use the area underneath this region.
The `titleBarOverlay` option accepts two different value formats.
Specifying `true` on either platform will result in an overlay region with default system colors:
main.js
```
// on macOS or Windows
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({
titleBarStyle: 'hidden',
titleBarOverlay: true
})
```
On Windows, you can also specify additional parameters. The color of the overlay and its symbols can be specified by setting `titleBarOverlay` to an object and using the `color` and `symbolColor` properties respectively. The height of the overlay can also be specified with the `height` property.
If a color option is not specified, the color will default to its system color for the window control buttons. Similarly, if the height option is not specified it will default to the default height:
main.js
```
// on Windows
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({
titleBarStyle: 'hidden',
titleBarOverlay: {
color: '#2f3241',
symbolColor: '#74b1be',
height: 60
}
})
```
> Note: Once your title bar overlay is enabled from the main process, you can access the overlay's color and dimension values from a renderer using a set of readonly [JavaScript APIs](https://github.com/WICG/window-controls-overlay/blob/main/explainer.md#javascript-apis) and [CSS Environment Variables](https://github.com/WICG/window-controls-overlay/blob/main/explainer.md#css-environment-variables).
>
>
### Limitations[](#limitations "Direct link to heading")
* Transparent colors are currently not supported. Progress updates for this feature can be found in PR [#33567](https://github.com/electron/electron/issues/33567).
Create transparent windows[](#create-transparent-windows "Direct link to heading")
-----------------------------------------------------------------------------------
By setting the `transparent` option to `true`, you can make a fully transparent window.
main.js
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ transparent: true })
```
### Limitations[](#limitations-1 "Direct link to heading")
* You cannot click through the transparent area. See [#1335](https://github.com/electron/electron/issues/1335) for details.
* Transparent windows are not resizable. Setting `resizable` to `true` may make a transparent window stop working on some platforms.
* The CSS [`blur()`](https://developer.mozilla.org/en-US/docs/Web/CSS/filter-function/blur()) filter only applies to the window's web contents, so there is no way to apply blur effect to the content below the window (i.e. other applications open on the user's system).
* The window will not be transparent when DevTools is opened.
* On *Windows*:
+ Transparent windows will not work when DWM is disabled.
+ Transparent windows can not be maximized using the Windows system menu or by double clicking the title bar. The reasoning behind this can be seen on PR [#28207](https://github.com/electron/electron/pull/28207).
* On *macOS*:
+ The native window shadow will not be shown on a transparent window.
Create click-through windows[](#create-click-through-windows "Direct link to heading")
---------------------------------------------------------------------------------------
To create a click-through window, i.e. making the window ignore all mouse events, you can call the [win.setIgnoreMouseEvents(ignore)](../api/browser-window#winsetignoremouseeventsignore-options) API:
main.js
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.setIgnoreMouseEvents(true)
```
### Forward mouse events *macOS* *Windows*[](#forward-mouse-events-macos-windows "Direct link to heading")
Ignoring mouse messages makes the web contents oblivious to mouse movement, meaning that mouse movement events will not be emitted. On Windows and macOS, an optional parameter can be used to forward mouse move messages to the web page, allowing events such as `mouseleave` to be emitted:
main.js
```
const { BrowserWindow, ipcMain } = require('electron')
const path = require('path')
const win = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
ipcMain.on('set-ignore-mouse-events', (event, ...args) => {
const win = BrowserWindow.fromWebContents(event.sender)
win.setIgnoreMouseEvents(...args)
})
```
preload.js
```
window.addEventListener('DOMContentLoaded', () => {
const el = document.getElementById('clickThroughElement')
el.addEventListener('mouseenter', () => {
ipcRenderer.send('set-ignore-mouse-events', true, { forward: true })
})
el.addEventListener('mouseleave', () => {
ipcRenderer.send('set-ignore-mouse-events', false)
})
})
```
This makes the web page click-through when over the `#clickThroughElement` element, and returns to normal outside it.
Set custom draggable region[](#set-custom-draggable-region "Direct link to heading")
-------------------------------------------------------------------------------------
By default, the frameless window is non-draggable. Apps need to specify `-webkit-app-region: drag` in CSS to tell Electron which regions are draggable (like the OS's standard titlebar), and apps can also use `-webkit-app-region: no-drag` to exclude the non-draggable area from the draggable region. Note that only rectangular shapes are currently supported.
To make the whole window draggable, you can add `-webkit-app-region: drag` as `body`'s style:
styles.css
```
body {
-webkit-app-region: drag;
}
```
And note that if you have made the whole window draggable, you must also mark buttons as non-draggable, otherwise it would be impossible for users to click on them:
styles.css
```
button {
-webkit-app-region: no-drag;
}
```
If you're only setting a custom titlebar as draggable, you also need to make all buttons in titlebar non-draggable.
### Tip: disable text selection[](#tip-disable-text-selection "Direct link to heading")
When creating a draggable region, the dragging behavior may conflict with text selection. For example, when you drag the titlebar, you may accidentally select its text contents. To prevent this, you need to disable text selection within a draggable area like this:
```
.titlebar {
-webkit-user-select: none;
-webkit-app-region: drag;
}
```
### Tip: disable context menus[](#tip-disable-context-menus "Direct link to heading")
On some platforms, the draggable area will be treated as a non-client frame, so when you right click on it, a system menu will pop up. To make the context menu behave correctly on all platforms, you should never use a custom context menu on draggable areas.
electron Code Signing Code signing is a security technology that you use to certify that an app was created by you. You should sign your application so it does not trigger any operating system security checks.
On macOS, the system can detect any change to the app, whether the change is introduced accidentally or by malicious code.
On Windows, the system assigns a trust level to your code signing certificate which if you don't have, or if your trust level is low, will cause security dialogs to appear when users start using your application. Trust level builds over time so it's better to start code signing as early as possible.
While it is possible to distribute unsigned apps, it is not recommended. Both Windows and macOS will, by default, prevent either the download or the execution of unsigned applications. Starting with macOS Catalina (version 10.15), users have to go through multiple manual steps to open unsigned applications.
As you can see, users get two options: Move the app straight to the trash or cancel running it. You don't want your users to see that dialog.
If you are building an Electron app that you intend to package and distribute, it should be code signed.
Signing & notarizing macOS builds[](#signing--notarizing-macos-builds "Direct link to heading")
------------------------------------------------------------------------------------------------
Properly preparing macOS applications for release requires two steps. First, the app needs to be code signed. Then, the app needs to be uploaded to Apple for a process called **notarization**, where automated systems will further verify that your app isn't doing anything to endanger its users.
To start the process, ensure that you fulfill the requirements for signing and notarizing your app:
1. Enroll in the [Apple Developer Program](https://developer.apple.com/programs/) (requires an annual fee)
2. Download and install [Xcode](https://developer.apple.com/xcode) - this requires a computer running macOS
3. Generate, download, and install [signing certificates](https://github.com/electron/electron-osx-sign/wiki/1.-Getting-Started#certificates)
Electron's ecosystem favors configuration and freedom, so there are multiple ways to get your application signed and notarized.
### Using Electron Forge[](#using-electron-forge "Direct link to heading")
If you're using Electron's favorite build tool, getting your application signed and notarized requires a few additions to your configuration. [Forge](https://electronforge.io) is a collection of the official Electron tools, using [`electron-packager`](https://github.com/electron/electron-packager), [`electron-osx-sign`](https://github.com/electron-userland/electron-osx-sign), and [`electron-notarize`](https://github.com/electron/electron-notarize) under the hood.
Let's take a look at an example `package.json` configuration with all required fields. Not all of them are required: the tools will be clever enough to automatically find a suitable `identity`, for instance, but we recommend that you are explicit.
package.json
```
{
"name": "my-app",
"version": "0.0.1",
"config": {
"forge": {
"packagerConfig": {
"osxSign": {
"identity": "Developer ID Application: Felix Rieseberg (LT94ZKYDCJ)",
"hardened-runtime": true,
"entitlements": "entitlements.plist",
"entitlements-inherit": "entitlements.plist",
"signature-flags": "library"
},
"osxNotarize": {
"appleId": "[email protected]",
"appleIdPassword": "my-apple-id-password"
}
}
}
}
}
```
The `entitlements.plist` file referenced here needs the following macOS-specific entitlements to assure the Apple security mechanisms that your app is doing these things without meaning any harm:
entitlements.plist
```
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>com.apple.security.cs.allow-jit</key>
<true/>
<key>com.apple.security.cs.debugger</key>
<true/>
</dict>
</plist>
```
Note that up until Electron 12, the `com.apple.security.cs.allow-unsigned-executable-memory` entitlement was required as well. However, it should not be used anymore if it can be avoided.
To see all of this in action, check out Electron Fiddle's source code, [especially its `electron-forge` configuration file](https://github.com/electron/fiddle/blob/master/forge.config.js).
If you plan to access the microphone or camera within your app using Electron's APIs, you'll also need to add the following entitlements:
entitlements.plist
```
<key>com.apple.security.device.audio-input</key>
<true/>
<key>com.apple.security.device.camera</key>
<true/>
```
If these are not present in your app's entitlements when you invoke, for example:
main.js
```
const { systemPreferences } = require('electron')
const microphone = systemPreferences.askForMediaAccess('microphone')
```
Your app may crash. See the Resource Access section in [Hardened Runtime](https://developer.apple.com/documentation/security/hardened_runtime) for more information and entitlements you may need.
### Using Electron Builder[](#using-electron-builder "Direct link to heading")
Electron Builder comes with a custom solution for signing your application. You can find [its documentation here](https://www.electron.build/code-signing).
### Using Electron Packager[](#using-electron-packager "Direct link to heading")
If you're not using an integrated build pipeline like Forge or Builder, you are likely using [`electron-packager`](https://github.com/electron/electron-packager), which includes [`electron-osx-sign`](https://github.com/electron-userland/electron-osx-sign) and [`electron-notarize`](https://github.com/electron/electron-notarize).
If you're using Packager's API, you can pass [in configuration that both signs and notarizes your application](https://electron.github.io/electron-packager/main/interfaces/electronpackager.options.html).
```
const packager = require('electron-packager')
packager({
dir: '/path/to/my/app',
osxSign: {
identity: 'Developer ID Application: Felix Rieseberg (LT94ZKYDCJ)',
'hardened-runtime': true,
entitlements: 'entitlements.plist',
'entitlements-inherit': 'entitlements.plist',
'signature-flags': 'library'
},
osxNotarize: {
appleId: '[email protected]',
appleIdPassword: 'my-apple-id-password'
}
})
```
The `entitlements.plist` file referenced here needs the following macOS-specific entitlements to assure the Apple security mechanisms that your app is doing these things without meaning any harm:
entitlements.plist
```
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>com.apple.security.cs.allow-jit</key>
<true/>
<key>com.apple.security.cs.debugger</key>
<true/>
</dict>
</plist>
```
Up until Electron 12, the `com.apple.security.cs.allow-unsigned-executable-memory` entitlement was required as well. However, it should not be used anymore if it can be avoided.
### Signing Mac App Store applications[](#signing-mac-app-store-applications "Direct link to heading")
See the [Mac App Store Guide](mac-app-store-submission-guide).
Signing Windows builds[](#signing-windows-builds "Direct link to heading")
---------------------------------------------------------------------------
Before signing Windows builds, you must do the following:
1. Get a Windows Authenticode code signing certificate (requires an annual fee)
2. Install Visual Studio to get the signing utility (the free [Community Edition](https://visualstudio.microsoft.com/vs/community/) is enough)
You can get a code signing certificate from a lot of resellers. Prices vary, so it may be worth your time to shop around. Popular resellers include:
* [digicert](https://www.digicert.com/code-signing/microsoft-authenticode.htm)
* [Sectigo](https://sectigo.com/ssl-certificates-tls/code-signing)
* Amongst others, please shop around to find one that suits your needs! 😄
Keep your certificate password private
Your certificate password should be a **secret**. Do not share it publicly or commit it to your source code.
### Using Electron Forge[](#using-electron-forge-1 "Direct link to heading")
Once you have a code signing certificate file (`.pfx`), you can sign [Squirrel.Windows](https://www.electronforge.io/config/makers/squirrel.windows) and [MSI](https://www.electronforge.io/config/makers/wix-msi) installers in Electron Forge with the `certificateFile` and `certificatePassword` fields in their respective configuration objects.
For example, if you keep your Forge config in your `package.json` file and are creating a Squirrel.Windows installer:
package.json
```
{
"name": "my-app",
"version": "0.0.1",
//...
"config": {
"forge": {
"packagerConfig": {},
"makers": [
{
"name": "@electron-forge/maker-squirrel",
"config": {
"certificateFile": "./cert.pfx",
"certificatePassword": "this-is-a-secret"
}
}
]
}
}
//...
}
```
### Using electron-winstaller (Squirrel.Windows)[](#using-electron-winstaller-squirrelwindows "Direct link to heading")
[`electron-winstaller`](https://github.com/electron/windows-installer) is a package that can generate Squirrel.Windows installers for your Electron app. This is the tool used under the hood by Electron Forge's [Squirrel.Windows Maker](https://www.electronforge.io/config/makers/squirrel.windows). If you're not using Electron Forge and want to use `electron-winstaller` directly, use the `certificateFile` and `certificatePassword` configuration options when creating your installer.
```
const electronInstaller = require('electron-winstaller')
// NB: Use this syntax within an async function, Node does not have support for
// top-level await as of Node 12.
try {
await electronInstaller.createWindowsInstaller({
appDirectory: '/tmp/build/my-app-64',
outputDirectory: '/tmp/build/installer64',
authors: 'My App Inc.',
exe: 'myapp.exe',
certificateFile: './cert.pfx',
certificatePassword: 'this-is-a-secret',
})
console.log('It worked!')
} catch (e) {
console.log(`No dice: ${e.message}`)
}
```
For full configuration options, check out the [`electron-winstaller`](https://github.com/electron/windows-installer) repository!
### Using electron-wix-msi (WiX MSI)[](#using-electron-wix-msi-wix-msi "Direct link to heading")
[`electron-wix-msi`](https://github.com/felixrieseberg/electron-wix-msi) is a package that can generate MSI installers for your Electron app. This is the tool used under the hood by Electron Forge's [MSI Maker](https://www.electronforge.io/config/makers/wix-msi).
If you're not using Electron Forge and want to use `electron-wix-msi` directly, use the `certificateFile` and `certificatePassword` configuration options or pass in parameters directly to [SignTool.exe](https://docs.microsoft.com/en-us/dotnet/framework/tools/signtool-exe) with the `signWithParams` option.
```
import { MSICreator } from 'electron-wix-msi'
// Step 1: Instantiate the MSICreator
const msiCreator = new MSICreator({
appDirectory: '/path/to/built/app',
description: 'My amazing Kitten simulator',
exe: 'kittens',
name: 'Kittens',
manufacturer: 'Kitten Technologies',
version: '1.1.2',
outputDirectory: '/path/to/output/folder',
certificateFile: './cert.pfx',
certificatePassword: 'this-is-a-secret',
})
// Step 2: Create a .wxs template file
const supportBinaries = await msiCreator.create()
// 🆕 Step 2a: optionally sign support binaries if you
// sign you binaries as part of of your packaging script
supportBinaries.forEach(async (binary) => {
// Binaries are the new stub executable and optionally
// the Squirrel auto updater.
await signFile(binary)
})
// Step 3: Compile the template to a .msi file
await msiCreator.compile()
```
For full configuration options, check out the [`electron-wix-msi`](https://github.com/felixrieseberg/electron-wix-msi) repository!
### Using Electron Builder[](#using-electron-builder-1 "Direct link to heading")
Electron Builder comes with a custom solution for signing your application. You can find [its documentation here](https://www.electron.build/code-signing).
### Signing Windows Store applications[](#signing-windows-store-applications "Direct link to heading")
See the [Windows Store Guide](windows-store-guide).
| programming_docs |
electron Using Preload Scripts
Follow along the tutorial
This is **part 3** of the Electron tutorial.
1. [Prerequisites](tutorial-prerequisites)
2. [Building your First App](tutorial-first-app)
3. **[Using Preload Scripts](tutorial-preload)**
4. [Adding Features](tutorial-adding-features)
5. [Packaging Your Application](tutorial-packaging)
6. [Publishing and Updating](tutorial-publishing-updating)
Learning goals[](#learning-goals "Direct link to heading")
-----------------------------------------------------------
In this part of the tutorial, you will learn what a preload script is and how to use one to securely expose privileged APIs into the renderer process. You will also learn how to communicate between main and renderer processes with Electron's inter-process communication (IPC) modules.
What is a preload script?[](#what-is-a-preload-script "Direct link to heading")
--------------------------------------------------------------------------------
Electron's main process is a Node.js environment that has full operating system access. On top of [Electron modules](../api/app), you can also access [Node.js built-ins](https://nodejs.org/dist/latest/docs/api/), as well as any packages installed via npm. On the other hand, renderer processes run web pages and do not run Node.js by default for security reasons.
To bridge Electron's different process types together, we will need to use a special script called a **preload**.
Augmenting the renderer with a preload script[](#augmenting-the-renderer-with-a-preload-script "Direct link to heading")
-------------------------------------------------------------------------------------------------------------------------
A BrowserWindow's preload script runs in a context that has access to both the HTML DOM and a Node.js environment. Preload scripts are injected before a web page loads in the renderer, similar to a Chrome extension's [content scripts](https://developer.chrome.com/docs/extensions/mv3/content_scripts/). To add features to your renderer that require privileged access, you can define [global](https://developer.mozilla.org/en-US/docs/Glossary/Global_object) objects through the [contextBridge](../api/context-bridge) API.
To demonstrate this concept, you will create a preload script that exposes your app's versions of Chrome, Node, and Electron into the renderer.
Add a new `preload.js` script that exposes selected properties of Electron's `process.versions` object to the renderer process in a `versions` global variable.
preload.js
```
const { contextBridge } = require('electron')
contextBridge.exposeInMainWorld('versions', {
node: () => process.versions.node,
chrome: () => process.versions.chrome,
electron: () => process.versions.electron,
// we can also expose variables, not just functions
})
```
To attach this script to your renderer process, pass its path to the `webPreferences.preload` option in the BrowserWindow constructor:
main.js
```
const { app, BrowserWindow } = require('electron')
const path = require('path')
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js'),
},
})
win.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
})
```
info
There are two Node.js concepts that are used here:
* The [`__dirname`](https://nodejs.org/api/modules.html#modules_dirname) string points to the path of the currently executing script (in this case, your project's root folder).
* The [`path.join`](https://nodejs.org/api/path.html#path_path_join_paths) API joins multiple path segments together, creating a combined path string that works across all platforms.
At this point, the renderer has access to the `versions` global, so let's display that information in the window. This variable can be accessed via `window.versions` or simply `versions`. Create a `renderer.js` script that uses the [`document.getElementById`](https://developer.mozilla.org/en-US/docs/Web/API/Document/getElementById) DOM API to replace the displayed text for the HTML element with `info` as its `id` property.
renderer.js
```
const information = document.getElementById('info')
information.innerText = `This app is using Chrome (v${versions.chrome()}), Node.js (v${versions.node()}), and Electron (v${versions.electron()})`
```
Then, modify your `index.html` by adding a new element with `info` as its `id` property, and attach your `renderer.js` script:
index.html
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<meta
http-equiv="Content-Security-Policy"
content="default-src 'self'; script-src 'self'"
/>
<meta
http-equiv="X-Content-Security-Policy"
content="default-src 'self'; script-src 'self'"
/>
<title>Hello from Electron renderer!</title>
</head>
<body>
<h1>Hello from Electron renderer!</h1>
<p>👋</p>
<p id="info"></p>
</body>
<script src="./renderer.js"></script>
</html>
```
After following the above steps, your app should look something like this:
And the code should look like this:
[docs/fiddles/tutorial-preload (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/tutorial-preload)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/tutorial-preload)
* main.js
* preload.js
* index.html
* renderer.js
```
const { app, BrowserWindow } = require('electron');
const path = require('path');
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js'),
},
});
win.loadFile('index.html');
};
app.whenReady().then(() => {
createWindow();
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow();
}
});
});
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit();
}
});
```
```
const { contextBridge } = require('electron');
contextBridge.exposeInMainWorld('versions', {
node: () => process.versions.node,
chrome: () => process.versions.chrome,
electron: () => process.versions.electron,
});
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<meta
http-equiv="Content-Security-Policy"
content="default-src 'self'; script-src 'self'"
/>
<meta
http-equiv="X-Content-Security-Policy"
content="default-src 'self'; script-src 'self'"
/>
<title>Hello from Electron renderer!</title>
</head>
<body>
<h1>Hello from Electron renderer!</h1>
<p>👋</p>
<p id="info"></p>
</body>
<script src="./renderer.js"></script>
</html>
```
```
const information = document.getElementById('info');
information.innerText = `This app is using Chrome (v${versions.chrome()}), Node.js (v${versions.node()}), and Electron (v${versions.electron()})`;
```
Communicating between processes[](#communicating-between-processes "Direct link to heading")
---------------------------------------------------------------------------------------------
As we have mentioned above, Electron's main and renderer process have distinct responsibilities and are not interchangeable. This means it is not possible to access the Node.js APIs directly from the renderer process, nor the HTML Document Object Model (DOM) from the main process.
The solution for this problem is to use Electron's `ipcMain` and `ipcRenderer` modules for inter-process communication (IPC). To send a message from your web page to the main process, you can set up a main process handler with `ipcMain.handle` and then expose a function that calls `ipcRenderer.invoke` to trigger the handler in your preload script.
To illustrate, we will add a global function to the renderer called `ping()` that will return a string from the main process.
First, set up the `invoke` call in your preload script:
preload.js
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('versions', {
node: () => process.versions.node,
chrome: () => process.versions.chrome,
electron: () => process.versions.electron,
ping: () => ipcRenderer.invoke('ping'),
// we can also expose variables, not just functions
})
```
IPC security
Notice how we wrap the `ipcRenderer.invoke('ping')` call in a helper function rather than expose the `ipcRenderer` module directly via context bridge. You **never** want to directly expose the entire `ipcRenderer` module via preload. This would give your renderer the ability to send arbitrary IPC messages to the main process, which becomes a powerful attack vector for malicious code.
Then, set up your `handle` listener in the main process. We do this *before* loading the HTML file so that the handler is guaranteed to be ready before you send out the `invoke` call from the renderer.
main.js
```
const { ipcMain } = require('electron')
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js'),
},
})
ipcMain.handle('ping', () => 'pong')
win.loadFile('index.html')
}
```
Once you have the sender and receiver set up, you can now send messages from the renderer to the main process through the `'ping'` channel you just defined.
renderer.js
```
const func = async () => {
const response = await window.versions.ping()
console.log(response) // prints out 'pong'
}
func()
```
info
For more in-depth explanations on using the `ipcRenderer` and `ipcMain` modules, check out the full [Inter-Process Communication](ipc) guide.
Summary[](#summary "Direct link to heading")
---------------------------------------------
A preload script contains code that runs before your web page is loaded into the browser window. It has access to both DOM APIs and Node.js environment, and is often used to expose privileged APIs to the renderer via the `contextBridge` API.
Because the main and renderer processes have very different responsibilities, Electron apps often use the preload script to set up inter-process communication (IPC) interfaces to pass arbitrary messages between the two kinds of processes.
In the next part of the tutorial, we will be showing you resources on adding more functionality to your app, then teaching you distributing your app to users.
electron Quick Start Quick Start
===========
This guide will step you through the process of creating a barebones Hello World app in Electron, similar to [`electron/electron-quick-start`](https://github.com/electron/electron-quick-start).
By the end of this tutorial, your app will open a browser window that displays a web page with information about which Chromium, Node.js, and Electron versions are running.
Prerequisites[](#prerequisites "Direct link to heading")
---------------------------------------------------------
To use Electron, you need to install [Node.js](https://nodejs.org/en/download/). We recommend that you use the latest `LTS` version available.
> Please install Node.js using pre-built installers for your platform. You may encounter incompatibility issues with different development tools otherwise.
>
>
To check that Node.js was installed correctly, type the following commands in your terminal client:
```
node -v
npm -v
```
The commands should print the versions of Node.js and npm accordingly.
**Note:** Since Electron embeds Node.js into its binary, the version of Node.js running your code is unrelated to the version running on your system.
Create your application[](#create-your-application "Direct link to heading")
-----------------------------------------------------------------------------
### Scaffold the project[](#scaffold-the-project "Direct link to heading")
Electron apps follow the same general structure as other Node.js projects. Start by creating a folder and initializing an npm package.
* npm
* Yarn
```
mkdir my-electron-app && cd my-electron-app
npm init
```
```
mkdir my-electron-app && cd my-electron-app
yarn init
```
The interactive `init` command will prompt you to set some fields in your config. There are a few rules to follow for the purposes of this tutorial:
* `entry point` should be `main.js`.
* `author` and `description` can be any value, but are necessary for [app packaging](#package-and-distribute-your-application).
Your `package.json` file should look something like this:
```
{
"name": "my-electron-app",
"version": "1.0.0",
"description": "Hello World!",
"main": "main.js",
"author": "Jane Doe",
"license": "MIT"
}
```
Then, install the `electron` package into your app's `devDependencies`.
* npm
* Yarn
```
npm install --save-dev electron
```
```
yarn add --dev electron
```
> Note: If you're encountering any issues with installing Electron, please refer to the [Advanced Installation](installation) guide.
>
>
Finally, you want to be able to execute Electron. In the [`scripts`](https://docs.npmjs.com/cli/v7/using-npm/scripts) field of your `package.json` config, add a `start` command like so:
```
{
"scripts": {
"start": "electron ."
}
}
```
This `start` command will let you open your app in development mode.
* npm
* Yarn
```
npm start
```
```
yarn start
# couldn't auto-convert command
```
> Note: This script tells Electron to run on your project's root folder. At this stage, your app will immediately throw an error telling you that it cannot find an app to run.
>
>
### Run the main process[](#run-the-main-process "Direct link to heading")
The entry point of any Electron application is its `main` script. This script controls the **main process**, which runs in a full Node.js environment and is responsible for controlling your app's lifecycle, displaying native interfaces, performing privileged operations, and managing renderer processes (more on that later).
During execution, Electron will look for this script in the [`main`](https://docs.npmjs.com/cli/v7/configuring-npm/package-json#main) field of the app's `package.json` config, which you should have configured during the [app scaffolding](#scaffold-the-project) step.
To initialize the `main` script, create an empty file named `main.js` in the root folder of your project.
> Note: If you run the `start` script again at this point, your app will no longer throw any errors! However, it won't do anything yet because we haven't added any code into `main.js`.
>
>
### Create a web page[](#create-a-web-page "Direct link to heading")
Before we can create a window for our application, we need to create the content that will be loaded into it. In Electron, each window displays web contents that can be loaded from either a local HTML file or a remote URL.
For this tutorial, you will be doing the former. Create an `index.html` file in the root folder of your project:
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Hello World!</title>
</head>
<body>
<h1>Hello World!</h1>
We are using Node.js <span id="node-version"></span>,
Chromium <span id="chrome-version"></span>,
and Electron <span id="electron-version"></span>.
</body>
</html>
```
> Note: Looking at this HTML document, you can observe that the version numbers are missing from the body text. We'll manually insert them later using JavaScript.
>
>
### Opening your web page in a browser window[](#opening-your-web-page-in-a-browser-window "Direct link to heading")
Now that you have a web page, load it into an application window. To do so, you'll need two Electron modules:
* The [`app`](../api/app) module, which controls your application's event lifecycle.
* The [`BrowserWindow`](../api/browser-window) module, which creates and manages application windows.
Because the main process runs Node.js, you can import these as [CommonJS](https://nodejs.org/docs/latest/api/modules.html#modules_modules_commonjs_modules) modules at the top of your file:
```
const { app, BrowserWindow } = require('electron')
```
Then, add a `createWindow()` function that loads `index.html` into a new `BrowserWindow` instance.
```
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600
})
win.loadFile('index.html')
}
```
Next, call this `createWindow()` function to open your window.
In Electron, browser windows can only be created after the `app` module's [`ready`](../api/app#event-ready) event is fired. You can wait for this event by using the [`app.whenReady()`](../api/app#appwhenready) API. Call `createWindow()` after `whenReady()` resolves its Promise.
```
app.whenReady().then(() => {
createWindow()
})
```
> Note: At this point, your Electron application should successfully open a window that displays your web page!
>
>
### Manage your window's lifecycle[](#manage-your-windows-lifecycle "Direct link to heading")
Although you can now open a browser window, you'll need some additional boilerplate code to make it feel more native to each platform. Application windows behave differently on each OS, and Electron puts the responsibility on developers to implement these conventions in their app.
In general, you can use the `process` global's [`platform`](https://nodejs.org/api/process.html#process_process_platform) attribute to run code specifically for certain operating systems.
#### Quit the app when all windows are closed (Windows & Linux)[](#quit-the-app-when-all-windows-are-closed-windows--linux "Direct link to heading")
On Windows and Linux, exiting all windows generally quits an application entirely.
To implement this, listen for the `app` module's [`'window-all-closed'`](../api/app#event-window-all-closed) event, and call [`app.quit()`](../api/app#appquit) if the user is not on macOS (`darwin`).
```
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') app.quit()
})
```
#### Open a window if none are open (macOS)[](#open-a-window-if-none-are-open-macos "Direct link to heading")
Whereas Linux and Windows apps quit when they have no windows open, macOS apps generally continue running even without any windows open, and activating the app when no windows are available should open a new one.
To implement this feature, listen for the `app` module's [`activate`](../api/app#event-activate-macos) event, and call your existing `createWindow()` method if no browser windows are open.
Because windows cannot be created before the `ready` event, you should only listen for `activate` events after your app is initialized. Do this by attaching your event listener from within your existing `whenReady()` callback.
```
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
```
> Note: At this point, your window controls should be fully functional!
>
>
### Access Node.js from the renderer with a preload script[](#access-nodejs-from-the-renderer-with-a-preload-script "Direct link to heading")
Now, the last thing to do is print out the version numbers for Electron and its dependencies onto your web page.
Accessing this information is trivial to do in the main process through Node's global `process` object. However, you can't just edit the DOM from the main process because it has no access to the renderer's `document` context. They're in entirely different processes!
> Note: If you need a more in-depth look at Electron processes, see the [Process Model](process-model) document.
>
>
This is where attaching a **preload** script to your renderer comes in handy. A preload script runs before the renderer process is loaded, and has access to both renderer globals (e.g. `window` and `document`) and a Node.js environment.
Create a new script named `preload.js` as such:
```
window.addEventListener('DOMContentLoaded', () => {
const replaceText = (selector, text) => {
const element = document.getElementById(selector)
if (element) element.innerText = text
}
for (const dependency of ['chrome', 'node', 'electron']) {
replaceText(`${dependency}-version`, process.versions[dependency])
}
})
```
The above code accesses the Node.js `process.versions` object and runs a basic `replaceText` helper function to insert the version numbers into the HTML document.
To attach this script to your renderer process, pass in the path to your preload script to the `webPreferences.preload` option in your existing `BrowserWindow` constructor.
```
// include the Node.js 'path' module at the top of your file
const path = require('path')
// modify your existing createWindow() function
const createWindow = () => {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
win.loadFile('index.html')
}
// ...
```
There are two Node.js concepts that are used here:
* The [`__dirname`](https://nodejs.org/api/modules.html#modules_dirname) string points to the path of the currently executing script (in this case, your project's root folder).
* The [`path.join`](https://nodejs.org/api/path.html#path_path_join_paths) API joins multiple path segments together, creating a combined path string that works across all platforms.
We use a path relative to the currently executing JavaScript file so that your relative path will work in both development and packaged mode.
### Bonus: Add functionality to your web contents[](#bonus-add-functionality-to-your-web-contents "Direct link to heading")
At this point, you might be wondering how to add more functionality to your application.
For any interactions with your web contents, you want to add scripts to your renderer process. Because the renderer runs in a normal web environment, you can add a `<script>` tag right before your `index.html` file's closing `</body>` tag to include any arbitrary scripts you want:
```
<script src="./renderer.js"></script>
```
The code contained in `renderer.js` can then use the same JavaScript APIs and tooling you use for typical front-end development, such as using [`webpack`](https://webpack.js.org) to bundle and minify your code or [React](https://reactjs.org) to manage your user interfaces.
### Recap[](#recap "Direct link to heading")
After following the above steps, you should have a fully functional Electron application that looks like this:
The full code is available below:
```
// main.js
// Modules to control application life and create native browser window
const { app, BrowserWindow } = require('electron')
const path = require('path')
const createWindow = () => {
// Create the browser window.
const mainWindow = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
// and load the index.html of the app.
mainWindow.loadFile('index.html')
// Open the DevTools.
// mainWindow.webContents.openDevTools()
}
// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
// On macOS it's common to re-create a window in the app when the
// dock icon is clicked and there are no other windows open.
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
// Quit when all windows are closed, except on macOS. There, it's common
// for applications and their menu bar to stay active until the user quits
// explicitly with Cmd + Q.
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') app.quit()
})
// In this file you can include the rest of your app's specific main process
// code. You can also put them in separate files and require them here.
```
```
// preload.js
// All the Node.js APIs are available in the preload process.
// It has the same sandbox as a Chrome extension.
window.addEventListener('DOMContentLoaded', () => {
const replaceText = (selector, text) => {
const element = document.getElementById(selector)
if (element) element.innerText = text
}
for (const dependency of ['chrome', 'node', 'electron']) {
replaceText(`${dependency}-version`, process.versions[dependency])
}
})
```
```
<!--index.html-->
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Hello World!</title>
</head>
<body>
<h1>Hello World!</h1>
We are using Node.js <span id="node-version"></span>,
Chromium <span id="chrome-version"></span>,
and Electron <span id="electron-version"></span>.
<!-- You can also require other files to run in this process -->
<script src="./renderer.js"></script>
</body>
</html>
```
[docs/fiddles/quick-start (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/quick-start)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/quick-start)
* main.js
* preload.js
* index.html
```
const { app, BrowserWindow } = require('electron')
const path = require('path')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
win.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
})
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
```
```
window.addEventListener('DOMContentLoaded', () => {
const replaceText = (selector, text) => {
const element = document.getElementById(selector)
if (element) element.innerText = text
}
for (const type of ['chrome', 'node', 'electron']) {
replaceText(`${type}-version`, process.versions[type])
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>
We are using Node.js <span id="node-version"></span>,
Chromium <span id="chrome-version"></span>,
and Electron <span id="electron-version"></span>.
</p>
</body>
</html>
```
To summarize all the steps we've done:
* We bootstrapped a Node.js application and added Electron as a dependency.
* We created a `main.js` script that runs our main process, which controls our app and runs in a Node.js environment. In this script, we used Electron's `app` and `BrowserWindow` modules to create a browser window that displays web content in a separate process (the renderer).
* In order to access certain Node.js functionality in the renderer, we attached a preload script to our `BrowserWindow` constructor.
Package and distribute your application[](#package-and-distribute-your-application "Direct link to heading")
-------------------------------------------------------------------------------------------------------------
The fastest way to distribute your newly created app is using [Electron Forge](https://www.electronforge.io).
1. Add Electron Forge as a development dependency of your app, and use its `import` command to set up Forge's scaffolding:
* npm
* Yarn
```
npm install --save-dev @electron-forge/cli
npx electron-forge import
✔ Checking your system
✔ Initializing Git Repository
✔ Writing modified package.json file
✔ Installing dependencies
✔ Writing modified package.json file
✔ Fixing .gitignore
We have ATTEMPTED to convert your app to be in a format that electron-forge understands.
Thanks for using "electron-forge"!!!
```
```
yarn add --dev @electron-forge/cli
npx electron-forge import
✔ Checking your system
✔ Initializing Git Repository
✔ Writing modified package.json file
✔ Installing dependencies
✔ Writing modified package.json file
✔ Fixing .gitignore
We have ATTEMPTED to convert your app to be in a format that electron-forge understands.
Thanks for using "electron-forge"!!!
```
2. Create a distributable using Forge's `make` command:
* npm
* Yarn
```
npm run make
> [email protected] make /my-electron-app
> electron-forge make
✔ Checking your system
✔ Resolving Forge Config
We need to package your application before we can make it
✔ Preparing to Package Application for arch: x64
✔ Preparing native dependencies
✔ Packaging Application
Making for the following targets: zip
✔ Making for target: zip - On platform: darwin - For arch: x64
```
```
yarn run make
> [email protected] make /my-electron-app
> electron-forge make
✔ Checking your system
✔ Resolving Forge Config
We need to package your application before we can make it
✔ Preparing to Package Application for arch: x64
✔ Preparing native dependencies
✔ Packaging Application
Making for the following targets: zip
✔ Making for target: zip - On platform: darwin - For arch: x64
```
Electron Forge creates the `out` folder where your package will be located:
```
// Example for macOS
out/
├── out/make/zip/darwin/x64/my-electron-app-darwin-x64-1.0.0.zip
├── ...
└── out/my-electron-app-darwin-x64/my-electron-app.app/Contents/MacOS/my-electron-app
```
| programming_docs |
electron Automated Testing Automated Testing
=================
Test automation is an efficient way of validating that your application code works as intended. While Electron doesn't actively maintain its own testing solution, this guide will go over a couple ways you can run end-to-end automated tests on your Electron app.
Using the WebDriver interface[](#using-the-webdriver-interface "Direct link to heading")
-----------------------------------------------------------------------------------------
From [ChromeDriver - WebDriver for Chrome](https://sites.google.com/chromium.org/driver/):
> WebDriver is an open source tool for automated testing of web apps across many browsers. It provides capabilities for navigating to web pages, user input, JavaScript execution, and more. ChromeDriver is a standalone server which implements WebDriver's wire protocol for Chromium. It is being developed by members of the Chromium and WebDriver teams.
>
>
There are a few ways that you can set up testing using WebDriver.
### With WebdriverIO[](#with-webdriverio "Direct link to heading")
[WebdriverIO](https://webdriver.io/) (WDIO) is a test automation framework that provides a Node.js package for testing with WebDriver. Its ecosystem also includes various plugins (e.g. reporter and services) that can help you put together your test setup.
#### Install the testrunner[](#install-the-testrunner "Direct link to heading")
First you need to run the WebdriverIO starter toolkit in your project root directory:
* npm
* Yarn
```
npx wdio . --yes
```
```
npx wdio . --yes
```
This installs all necessary packages for you and generates a `wdio.conf.js` configuration file.
#### Connect WDIO to your Electron app[](#connect-wdio-to-your-electron-app "Direct link to heading")
Update the capabilities in your configuration file to point to your Electron app binary:
wdio.conf.js
```
export.config = {
// ...
capabilities: [{
browserName: 'chrome',
'goog:chromeOptions': {
binary: '/path/to/your/electron/binary', // Path to your Electron binary.
args: [/* cli arguments */] // Optional, perhaps 'app=' + /path/to/your/app/
}
}]
// ...
}
```
#### Run your tests[](#run-your-tests "Direct link to heading")
To run your tests:
```
$ npx wdio run wdio.conf.js
```
### With Selenium[](#with-selenium "Direct link to heading")
[Selenium](https://www.selenium.dev/) is a web automation framework that exposes bindings to WebDriver APIs in many languages. Their Node.js bindings are available under the `selenium-webdriver` package on NPM.
#### Run a ChromeDriver server[](#run-a-chromedriver-server "Direct link to heading")
In order to use Selenium with Electron, you need to download the `electron-chromedriver` binary, and run it:
* npm
* Yarn
```
npm install --save-dev electron-chromedriver
./node_modules/.bin/chromedriver
Starting ChromeDriver (v2.10.291558) on port 9515
Only local connections are allowed.
```
```
yarn add --dev electron-chromedriver
./node_modules/.bin/chromedriver
Starting ChromeDriver (v2.10.291558) on port 9515
Only local connections are allowed.
```
Remember the port number `9515`, which will be used later.
#### Connect Selenium to ChromeDriver[](#connect-selenium-to-chromedriver "Direct link to heading")
Next, install Selenium into your project:
* npm
* Yarn
```
npm install --save-dev selenium-webdriver
```
```
yarn add --dev selenium-webdriver
```
Usage of `selenium-webdriver` with Electron is the same as with normal websites, except that you have to manually specify how to connect ChromeDriver and where to find the binary of your Electron app:
test.js
```
const webdriver = require('selenium-webdriver')
const driver = new webdriver.Builder()
// The "9515" is the port opened by ChromeDriver.
.usingServer('http://localhost:9515')
.withCapabilities({
'goog:chromeOptions': {
// Here is the path to your Electron binary.
binary: '/Path-to-Your-App.app/Contents/MacOS/Electron'
}
})
.forBrowser('chrome') // note: use .forBrowser('electron') for selenium-webdriver <= 3.6.0
.build()
driver.get('http://www.google.com')
driver.findElement(webdriver.By.name('q')).sendKeys('webdriver')
driver.findElement(webdriver.By.name('btnG')).click()
driver.wait(() => {
return driver.getTitle().then((title) => {
return title === 'webdriver - Google Search'
})
}, 1000)
driver.quit()
```
Using Playwright[](#using-playwright "Direct link to heading")
---------------------------------------------------------------
[Microsoft Playwright](https://playwright.dev) is an end-to-end testing framework built using browser-specific remote debugging protocols, similar to the [Puppeteer](https://github.com/puppeteer/puppeteer) headless Node.js API but geared towards end-to-end testing. Playwright has experimental Electron support via Electron's support for the [Chrome DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/) (CDP).
### Install dependencies[](#install-dependencies "Direct link to heading")
You can install Playwright through your preferred Node.js package manager. The Playwright team recommends using the `PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD` environment variable to avoid unnecessary browser downloads when testing an Electron app.
* npm
* Yarn
```
PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1 npm install --save-dev playwright
```
```
PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1 yarn add --dev playwright
```
Playwright also comes with its own test runner, Playwright Test, which is built for end-to-end testing. You can also install it as a dev dependency in your project:
* npm
* Yarn
```
npm install --save-dev @playwright/test
```
```
yarn add --dev @playwright/test
```
Dependencies
This tutorial was written `[email protected]` and `@playwright/[email protected]`. Check out [Playwright's releases](https://github.com/microsoft/playwright/releases) page to learn about changes that might affect the code below.
Using third-party test runners
If you're interested in using an alternative test runner (e.g. Jest or Mocha), check out Playwright's [Third-Party Test Runner](https://playwright.dev/docs/test-runners/) guide.
### Write your tests[](#write-your-tests "Direct link to heading")
Playwright launches your app in development mode through the `_electron.launch` API. To point this API to your Electron app, you can pass the path to your main process entry point (here, it is `main.js`).
```
const { _electron: electron } = require('playwright')
const { test } = require('@playwright/test')
test('launch app', async () => {
const electronApp = await electron.launch({ args: ['main.js'] })
// close app
await electronApp.close()
})
```
After that, you will access to an instance of Playwright's `ElectronApp` class. This is a powerful class that has access to main process modules for example:
```
const { _electron: electron } = require('playwright')
const { test } = require('@playwright/test')
test('get isPackaged', async () => {
const electronApp = await electron.launch({ args: ['main.js'] })
const isPackaged = await electronApp.evaluate(async ({ app }) => {
// This runs in Electron's main process, parameter here is always
// the result of the require('electron') in the main app script.
return app.isPackaged
})
console.log(isPackaged) // false (because we're in development mode)
// close app
await electronApp.close()
})
```
It can also create individual [Page](https://playwright.dev/docs/api/class-page) objects from Electron BrowserWindow instances. For example, to grab the first BrowserWindow and save a screenshot:
```
const { _electron: electron } = require('playwright')
const { test } = require('@playwright/test')
test('save screenshot', async () => {
const electronApp = await electron.launch({ args: ['main.js'] })
const window = await electronApp.firstWindow()
await window.screenshot({ path: 'intro.png' })
// close app
await electronApp.close()
})
```
Putting all this together using the PlayWright Test runner, let's create a `example.spec.js` test file with a single test and assertion:
example.spec.js
```
const { _electron: electron } = require('playwright')
const { test, expect } = require('@playwright/test')
test('example test', async () => {
const electronApp = await electron.launch({ args: ['.'] })
const isPackaged = await electronApp.evaluate(async ({ app }) => {
// This runs in Electron's main process, parameter here is always
// the result of the require('electron') in the main app script.
return app.isPackaged;
});
expect(isPackaged).toBe(false);
// Wait for the first BrowserWindow to open
// and return its Page object
const window = await electronApp.firstWindow()
await window.screenshot({ path: 'intro.png' })
// close app
await electronApp.close()
});
```
Then, run Playwright Test using `npx playwright test`. You should see the test pass in your console, and have an `intro.png` screenshot on your filesystem.
```
☁ $ npx playwright test
Running 1 test using 1 worker
✓ example.spec.js:4:1 › example test (1s)
```
info
Playwright Test will automatically run any files matching the `.*(test|spec)\.(js|ts|mjs)` regex. You can customize this match in the [Playwright Test configuration options](https://playwright.dev/docs/api/class-testconfig#test-config-test-match).
Further reading
Check out Playwright's documentation for the full [Electron](https://playwright.dev/docs/api/class-electron/) and [ElectronApplication](https://playwright.dev/docs/api/class-electronapplication) class APIs.
Using a custom test driver[](#using-a-custom-test-driver "Direct link to heading")
-----------------------------------------------------------------------------------
It's also possible to write your own custom driver using Node.js' built-in IPC-over-STDIO. Custom test drivers require you to write additional app code, but have lower overhead and let you expose custom methods to your test suite.
To create a custom driver, we'll use Node.js' [`child_process`](https://nodejs.org/api/child_process.html) API. The test suite will spawn the Electron process, then establish a simple messaging protocol:
testDriver.js
```
const childProcess = require('child_process')
const electronPath = require('electron')
// spawn the process
const env = { /* ... */ }
const stdio = ['inherit', 'inherit', 'inherit', 'ipc']
const appProcess = childProcess.spawn(electronPath, ['./app'], { stdio, env })
// listen for IPC messages from the app
appProcess.on('message', (msg) => {
// ...
})
// send an IPC message to the app
appProcess.send({ my: 'message' })
```
From within the Electron app, you can listen for messages and send replies using the Node.js [`process`](https://nodejs.org/api/process.html) API:
main.js
```
// listen for messages from the test suite
process.on('message', (msg) => {
// ...
})
// send a message to the test suite
process.send({ my: 'message' })
```
We can now communicate from the test suite to the Electron app using the `appProcess` object.
For convenience, you may want to wrap `appProcess` in a driver object that provides more high-level functions. Here is an example of how you can do this. Let's start by creating a `TestDriver` class:
testDriver.js
```
class TestDriver {
constructor ({ path, args, env }) {
this.rpcCalls = []
// start child process
env.APP_TEST_DRIVER = 1 // let the app know it should listen for messages
this.process = childProcess.spawn(path, args, { stdio: ['inherit', 'inherit', 'inherit', 'ipc'], env })
// handle rpc responses
this.process.on('message', (message) => {
// pop the handler
const rpcCall = this.rpcCalls[message.msgId]
if (!rpcCall) return
this.rpcCalls[message.msgId] = null
// reject/resolve
if (message.reject) rpcCall.reject(message.reject)
else rpcCall.resolve(message.resolve)
})
// wait for ready
this.isReady = this.rpc('isReady').catch((err) => {
console.error('Application failed to start', err)
this.stop()
process.exit(1)
})
}
// simple RPC call
// to use: driver.rpc('method', 1, 2, 3).then(...)
async rpc (cmd, ...args) {
// send rpc request
const msgId = this.rpcCalls.length
this.process.send({ msgId, cmd, args })
return new Promise((resolve, reject) => this.rpcCalls.push({ resolve, reject }))
}
stop () {
this.process.kill()
}
}
module.exports = { TestDriver };
```
In your app code, can then write a simple handler to receive RPC calls:
main.js
```
const METHODS = {
isReady () {
// do any setup needed
return true
}
// define your RPC-able methods here
}
const onMessage = async ({ msgId, cmd, args }) => {
let method = METHODS[cmd]
if (!method) method = () => new Error('Invalid method: ' + cmd)
try {
const resolve = await method(...args)
process.send({ msgId, resolve })
} catch (err) {
const reject = {
message: err.message,
stack: err.stack,
name: err.name
}
process.send({ msgId, reject })
}
}
if (process.env.APP_TEST_DRIVER) {
process.on('message', onMessage)
}
```
Then, in your test suite, you can use your `TestDriver` class with the test automation framework of your choosing. The following example uses [`ava`](https://www.npmjs.com/package/ava), but other popular choices like Jest or Mocha would work as well:
test.js
```
const test = require('ava')
const electronPath = require('electron')
const { TestDriver } = require('./testDriver')
const app = new TestDriver({
path: electronPath,
args: ['./app'],
env: {
NODE_ENV: 'test'
}
})
test.before(async t => {
await app.isReady
})
test.after.always('cleanup', async t => {
await app.stop()
})
```
electron Testing on Headless CI Systems (Travis CI, Jenkins) Testing on Headless CI Systems (Travis CI, Jenkins)
===================================================
Being based on Chromium, Electron requires a display driver to function. If Chromium can't find a display driver, Electron will fail to launch - and therefore not executing any of your tests, regardless of how you are running them. Testing Electron-based apps on Travis, CircleCI, Jenkins or similar Systems requires therefore a little bit of configuration. In essence, we need to use a virtual display driver.
Configuring the Virtual Display Server[](#configuring-the-virtual-display-server "Direct link to heading")
-----------------------------------------------------------------------------------------------------------
First, install [Xvfb](https://en.wikipedia.org/wiki/Xvfb). It's a virtual framebuffer, implementing the X11 display server protocol - it performs all graphical operations in memory without showing any screen output, which is exactly what we need.
Then, create a virtual Xvfb screen and export an environment variable called DISPLAY that points to it. Chromium in Electron will automatically look for `$DISPLAY`, so no further configuration of your app is required. This step can be automated with Anaïs Betts' [xvfb-maybe](https://github.com/anaisbetts/xvfb-maybe): Prepend your test commands with `xvfb-maybe` and the little tool will automatically configure Xvfb, if required by the current system. On Windows or macOS, it will do nothing.
```
## On Windows or macOS, this invokes electron-mocha
## On Linux, if we are in a headless environment, this will be equivalent
## to xvfb-run electron-mocha ./test/*.js
xvfb-maybe electron-mocha ./test/*.js
```
### Travis CI[](#travis-ci "Direct link to heading")
On Travis, your `.travis.yml` should look roughly like this:
```
addons:
apt:
packages:
- xvfb
install:
- export DISPLAY=':99.0'
- Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 &
```
### Jenkins[](#jenkins "Direct link to heading")
For Jenkins, a [Xvfb plugin is available](https://wiki.jenkins-ci.org/display/JENKINS/Xvfb+Plugin).
### CircleCI[](#circleci "Direct link to heading")
CircleCI is awesome and has Xvfb and `$DISPLAY` already set up, so no further configuration is required.
### AppVeyor[](#appveyor "Direct link to heading")
AppVeyor runs on Windows, supporting Selenium, Chromium, Electron and similar tools out of the box - no configuration is required.
electron Advanced Installation Instructions Advanced Installation Instructions
==================================
To install prebuilt Electron binaries, use [`npm`](https://docs.npmjs.com). The preferred method is to install Electron as a development dependency in your app:
```
npm install electron --save-dev
```
See the [Electron versioning doc](electron-versioning) for info on how to manage Electron versions in your apps.
Running Electron ad-hoc[](#running-electron-ad-hoc "Direct link to heading")
-----------------------------------------------------------------------------
If you're in a pinch and would prefer to not use `npm install` in your local project, you can also run Electron ad-hoc using the [`npx`](https://docs.npmjs.com/cli/v7/commands/npx) command runner bundled with `npm`:
```
npx electron .
```
The above command will run the current working directory with Electron. Note that any dependencies in your app will not be installed.
Customization[](#customization "Direct link to heading")
---------------------------------------------------------
If you want to change the architecture that is downloaded (e.g., `ia32` on an `x64` machine), you can use the `--arch` flag with npm install or set the `npm_config_arch` environment variable:
```
npm install --arch=ia32 electron
```
In addition to changing the architecture, you can also specify the platform (e.g., `win32`, `linux`, etc.) using the `--platform` flag:
```
npm install --platform=win32 electron
```
Proxies[](#proxies "Direct link to heading")
---------------------------------------------
If you need to use an HTTP proxy, you need to set the `ELECTRON_GET_USE_PROXY` variable to any value, plus additional environment variables depending on your host system's Node version:
* [Node 10 and above](https://github.com/gajus/global-agent/blob/v2.1.5/README.md#environment-variables)
* [Before Node 10](https://github.com/np-maintain/global-tunnel/blob/v2.7.1/README.md#auto-config)
Custom Mirrors and Caches[](#custom-mirrors-and-caches "Direct link to heading")
---------------------------------------------------------------------------------
During installation, the `electron` module will call out to [`@electron/get`](https://github.com/electron/get) to download prebuilt binaries of Electron for your platform. It will do so by contacting GitHub's release download page (`https://github.com/electron/electron/releases/tag/v$VERSION`, where `$VERSION` is the exact version of Electron).
If you are unable to access GitHub or you need to provide a custom build, you can do so by either providing a mirror or an existing cache directory.
#### Mirror[](#mirror "Direct link to heading")
You can use environment variables to override the base URL, the path at which to look for Electron binaries, and the binary filename. The URL used by `@electron/get` is composed as follows:
```
url = ELECTRON_MIRROR + ELECTRON_CUSTOM_DIR + '/' + ELECTRON_CUSTOM_FILENAME
```
For instance, to use the China CDN mirror:
```
ELECTRON_MIRROR="https://npmmirror.com/mirrors/electron/"
```
By default, `ELECTRON_CUSTOM_DIR` is set to `v$VERSION`. To change the format, use the `{{ version }}` placeholder. For example, `version-{{ version }}` resolves to `version-5.0.0`, `{{ version }}` resolves to `5.0.0`, and `v{{ version }}` is equivalent to the default. As a more concrete example, to use the China non-CDN mirror:
```
ELECTRON_MIRROR="https://npmmirror.com/mirrors/electron/"
ELECTRON_CUSTOM_DIR="{{ version }}"
```
The above configuration will download from URLs such as `https://npmmirror.com/mirrors/electron/8.0.0/electron-v8.0.0-linux-x64.zip`.
If your mirror serves artifacts with different checksums to the official Electron release you may have to set `electron_use_remote_checksums=1` to force Electron to use the remote `SHASUMS256.txt` file to verify the checksum instead of the embedded checksums.
#### Cache[](#cache "Direct link to heading")
Alternatively, you can override the local cache. `@electron/get` will cache downloaded binaries in a local directory to not stress your network. You can use that cache folder to provide custom builds of Electron or to avoid making contact with the network at all.
* Linux: `$XDG_CACHE_HOME` or `~/.cache/electron/`
* macOS: `~/Library/Caches/electron/`
* Windows: `$LOCALAPPDATA/electron/Cache` or `~/AppData/Local/electron/Cache/`
On environments that have been using older versions of Electron, you might find the cache also in `~/.electron`.
You can also override the local cache location by providing a `electron_config_cache` environment variable.
The cache contains the version's official zip file as well as a checksum, and is stored as `[checksum]/[filename]`. A typical cache might look like this:
```
├── a91b089b5dc5b1279966511344b805ec84869b6cd60af44f800b363bba25b915
│ └── electron-v15.3.1-darwin-x64.zip
```
Skip binary download[](#skip-binary-download "Direct link to heading")
-----------------------------------------------------------------------
Under the hood, Electron's JavaScript API binds to a binary that contains its implementations. Because this binary is crucial to the function of any Electron app, it is downloaded by default in the `postinstall` step every time you install `electron` from the npm registry.
However, if you want to install your project's dependencies but don't need to use Electron functionality, you can set the `ELECTRON_SKIP_BINARY_DOWNLOAD` environment variable to prevent the binary from being downloaded. For instance, this feature can be useful in continuous integration environments when running unit tests that mock out the `electron` module.
* npm
* Yarn
```
ELECTRON_SKIP_BINARY_DOWNLOAD=1 npm install
```
```
ELECTRON_SKIP_BINARY_DOWNLOAD=1 yarn install
```
Troubleshooting[](#troubleshooting "Direct link to heading")
-------------------------------------------------------------
When running `npm install electron`, some users occasionally encounter installation errors.
In almost all cases, these errors are the result of network problems and not actual issues with the `electron` npm package. Errors like `ELIFECYCLE`, `EAI_AGAIN`, `ECONNRESET`, and `ETIMEDOUT` are all indications of such network problems. The best resolution is to try switching networks, or wait a bit and try installing again.
You can also attempt to download Electron directly from [electron/electron/releases](https://github.com/electron/electron/releases) if installing via `npm` is failing.
If installation fails with an `EACCESS` error you may need to [fix your npm permissions](https://docs.npmjs.com/getting-started/fixing-npm-permissions).
If the above error persists, the [unsafe-perm](https://docs.npmjs.com/misc/config#unsafe-perm) flag may need to be set to true:
```
sudo npm install electron --unsafe-perm=true
```
On slower networks, it may be advisable to use the `--verbose` flag in order to show download progress:
```
npm install --verbose electron
```
If you need to force a re-download of the asset and the SHASUM file set the `force_no_cache` environment variable to `true`.
| programming_docs |
electron Adding Features
Follow along the tutorial
This is **part 4** of the Electron tutorial.
1. [Prerequisites](tutorial-prerequisites)
2. [Building your First App](tutorial-first-app)
3. [Using Preload Scripts](tutorial-preload)
4. **[Adding Features](tutorial-adding-features)**
5. [Packaging Your Application](tutorial-packaging)
6. [Publishing and Updating](tutorial-publishing-updating)
Adding application complexity[](#adding-application-complexity "Direct link to heading")
-----------------------------------------------------------------------------------------
If you have been following along, you should have a functional Electron application with a static user interface. From this starting point, you can generally progress in developing your app in two broad directions:
1. Adding complexity to your renderer process' web app code
2. Deeper integrations with the operating system and Node.js
It is important to understand the distinction between these two broad concepts. For the first point, Electron-specific resources are not necessary. Building a pretty to-do list in Electron is just pointing your Electron BrowserWindow to a pretty to-do list web app. Ultimately, you are building your renderer's UI using the same tools (HTML, CSS, JavaScript) that you would on the web. Therefore, Electron's docs will not go in-depth on how to use standard web tools.
On the other hand, Electron also provides a rich set of tools that allow you to integrate with the desktop environment, from creating tray icons to adding global shortcuts to displaying native menus. It also gives you all the power of a Node.js environment in the main process. This set of capabilities separates Electron applications from running a website in a browser tab, and are the focus of Electron's documentation.
How-to examples[](#how-to-examples "Direct link to heading")
-------------------------------------------------------------
Electron's documentation has many tutorials to help you with more advanced topics and deeper operating system integrations. To get started, check out the [How-To Examples](examples) doc.
Let us know if something is missing!
If you can't find what you are looking for, please let us know on [GitHub](https://github.com/electron/electronjs.org-new/issues/new) or in our [Discord server](https://discord.com/invite/APGC3k5yaH)!
What's next?[](#whats-next "Direct link to heading")
-----------------------------------------------------
For the rest of the tutorial, we will be shifting away from application code and giving you a look at how you can get your app from your developer machine into end users' hands.
electron Windows Store Guide Windows Store Guide
===================
With Windows 10, the good old win32 executable got a new sibling: The Universal Windows Platform. The new `.appx` format does not only enable a number of new powerful APIs like Cortana or Push Notifications, but through the Windows Store, also simplifies installation and updating.
Microsoft [developed a tool that compiles Electron apps as `.appx` packages](https://github.com/catalystcode/electron-windows-store), enabling developers to use some of the goodies found in the new application model. This guide explains how to use it - and what the capabilities and limitations of an Electron AppX package are.
Background and Requirements[](#background-and-requirements "Direct link to heading")
-------------------------------------------------------------------------------------
Windows 10 "Anniversary Update" is able to run win32 `.exe` binaries by launching them together with a virtualized filesystem and registry. Both are created during compilation by running app and installer inside a Windows Container, allowing Windows to identify exactly which modifications to the operating system are done during installation. Pairing the executable with a virtual filesystem and a virtual registry allows Windows to enable one-click installation and uninstallation.
In addition, the exe is launched inside the appx model - meaning that it can use many of the APIs available to the Universal Windows Platform. To gain even more capabilities, an Electron app can pair up with an invisible UWP background task launched together with the `exe` - sort of launched as a sidekick to run tasks in the background, receive push notifications, or to communicate with other UWP applications.
To compile any existing Electron app, ensure that you have the following requirements:
* Windows 10 with Anniversary Update (released August 2nd, 2016)
* The Windows 10 SDK, [downloadable here](https://developer.microsoft.com/en-us/windows/downloads/windows-10-sdk)
* At least Node 4 (to check, run `node -v`)
Then, go and install the `electron-windows-store` CLI:
```
npm install -g electron-windows-store
```
Step 1: Package Your Electron Application[](#step-1-package-your-electron-application "Direct link to heading")
----------------------------------------------------------------------------------------------------------------
Package the application using [electron-packager](https://github.com/electron/electron-packager) (or a similar tool). Make sure to remove `node_modules` that you don't need in your final application, since any module you don't actually need will increase your application's size.
The output should look roughly like this:
```
├── Ghost.exe
├── LICENSE
├── content_resources_200_percent.pak
├── content_shell.pak
├── d3dcompiler_47.dll
├── ffmpeg.dll
├── icudtl.dat
├── libEGL.dll
├── libGLESv2.dll
├── locales
│ ├── am.pak
│ ├── ar.pak
│ ├── [...]
├── node.dll
├── resources
│ └── app.asar
├── v8_context_snapshot.bin
├── squirrel.exe
└── ui_resources_200_percent.pak
```
Step 2: Running electron-windows-store[](#step-2-running-electron-windows-store "Direct link to heading")
----------------------------------------------------------------------------------------------------------
From an elevated PowerShell (run it "as Administrator"), run `electron-windows-store` with the required parameters, passing both the input and output directories, the app's name and version, and confirmation that `node_modules` should be flattened.
```
electron-windows-store `
--input-directory C:\myelectronapp `
--output-directory C:\output\myelectronapp `
--package-version 1.0.0.0 `
--package-name myelectronapp
```
Once executed, the tool goes to work: It accepts your Electron app as an input, flattening the `node_modules`. Then, it archives your application as `app.zip`. Using an installer and a Windows Container, the tool creates an "expanded" AppX package - including the Windows Application Manifest (`AppXManifest.xml`) as well as the virtual file system and the virtual registry inside your output folder.
Once the expanded AppX files are created, the tool uses the Windows App Packager (`MakeAppx.exe`) to create a single-file AppX package from those files on disk. Finally, the tool can be used to create a trusted certificate on your computer to sign the new AppX package. With the signed AppX package, the CLI can also automatically install the package on your machine.
Step 3: Using the AppX Package[](#step-3-using-the-appx-package "Direct link to heading")
------------------------------------------------------------------------------------------
In order to run your package, your users will need Windows 10 with the so-called "Anniversary Update" - details on how to update Windows can be found [here](https://blogs.windows.com/windowsexperience/2016/08/02/how-to-get-the-windows-10-anniversary-update).
In opposition to traditional UWP apps, packaged apps currently need to undergo a manual verification process, for which you can apply [here](https://developer.microsoft.com/en-us/windows/projects/campaigns/desktop-bridge). In the meantime, all users will be able to install your package by double-clicking it, so a submission to the store might not be necessary if you're looking for an easier installation method. In managed environments (usually enterprises), the `Add-AppxPackage` [PowerShell Cmdlet can be used to install it in an automated fashion](https://technet.microsoft.com/en-us/library/hh856048.aspx).
Another important limitation is that the compiled AppX package still contains a win32 executable - and will therefore not run on Xbox, HoloLens, or Phones.
Optional: Add UWP Features using a BackgroundTask[](#optional-add-uwp-features-using-a-backgroundtask "Direct link to heading")
--------------------------------------------------------------------------------------------------------------------------------
You can pair your Electron app up with an invisible UWP background task that gets to make full use of Windows 10 features - like push notifications, Cortana integration, or live tiles.
To check out how an Electron app that uses a background task to send toast notifications and live tiles, [check out the Microsoft-provided sample](https://github.com/felixrieseberg/electron-uwp-background).
Optional: Convert using Container Virtualization[](#optional-convert-using-container-virtualization "Direct link to heading")
------------------------------------------------------------------------------------------------------------------------------
To generate the AppX package, the `electron-windows-store` CLI uses a template that should work for most Electron apps. However, if you are using a custom installer, or should you experience any trouble with the generated package, you can attempt to create a package using compilation with a Windows Container - in that mode, the CLI will install and run your application in blank Windows Container to determine what modifications your application is exactly doing to the operating system.
Before running the CLI for the first time, you will have to setup the "Windows Desktop App Converter". This will take a few minutes, but don't worry - you only have to do this once. Download and Desktop App Converter from [here](https://docs.microsoft.com/en-us/windows/uwp/porting/desktop-to-uwp-run-desktop-app-converter). You will receive two files: `DesktopAppConverter.zip` and `BaseImage-14316.wim`.
1. Unzip `DesktopAppConverter.zip`. From an elevated PowerShell (opened with "run as Administrator", ensure that your systems execution policy allows us to run everything we intend to run by calling `Set-ExecutionPolicy bypass`.
2. Then, run the installation of the Desktop App Converter, passing in the location of the Windows base Image (downloaded as `BaseImage-14316.wim`), by calling `.\DesktopAppConverter.ps1 -Setup -BaseImage .\BaseImage-14316.wim`.
3. If running the above command prompts you for a reboot, please restart your machine and run the above command again after a successful restart.
Once installation succeeded, you can move on to compiling your Electron app.
electron MessagePorts in Electron MessagePorts in Electron
========================
[`MessagePort`](https://developer.mozilla.org/en-US/docs/Web/API/MessagePort)s are a web feature that allow passing messages between different contexts. It's like `window.postMessage`, but on different channels. The goal of this document is to describe how Electron extends the Channel Messaging model, and to give some examples of how you might use MessagePorts in your app.
Here is a very brief example of what a MessagePort is and how it works:
renderer.js (Renderer Process)
```
// MessagePorts are created in pairs. A connected pair of message ports is
// called a channel.
const channel = new MessageChannel()
// The only difference between port1 and port2 is in how you use them. Messages
// sent to port1 will be received by port2 and vice-versa.
const port1 = channel.port1
const port2 = channel.port2
// It's OK to send a message on the channel before the other end has registered
// a listener. Messages will be queued until a listener is registered.
port2.postMessage({ answer: 42 })
// Here we send the other end of the channel, port1, to the main process. It's
// also possible to send MessagePorts to other frames, or to Web Workers, etc.
ipcRenderer.postMessage('port', null, [port1])
```
main.js (Main Process)
```
// In the main process, we receive the port.
ipcMain.on('port', (event) => {
// When we receive a MessagePort in the main process, it becomes a
// MessagePortMain.
const port = event.ports[0]
// MessagePortMain uses the Node.js-style events API, rather than the
// web-style events API. So .on('message', ...) instead of .onmessage = ...
port.on('message', (event) => {
// data is { answer: 42 }
const data = event.data
})
// MessagePortMain queues messages until the .start() method has been called.
port.start()
})
```
The [Channel Messaging API](https://developer.mozilla.org/en-US/docs/Web/API/Channel_Messaging_API) documentation is a great way to learn more about how MessagePorts work.
MessagePorts in the main process[](#messageports-in-the-main-process "Direct link to heading")
-----------------------------------------------------------------------------------------------
In the renderer, the `MessagePort` class behaves exactly as it does on the web. The main process is not a web page, though—it has no Blink integration—and so it does not have the `MessagePort` or `MessageChannel` classes. In order to handle and interact with MessagePorts in the main process, Electron adds two new classes: [`MessagePortMain`](../api/message-port-main) and [`MessageChannelMain`](../api/message-channel-main). These behave similarly to the analogous classes in the renderer.
`MessagePort` objects can be created in either the renderer or the main process, and passed back and forth using the [`ipcRenderer.postMessage`](../api/ipc-renderer#ipcrendererpostmessagechannel-message-transfer) and [`WebContents.postMessage`](../api/web-contents#contentspostmessagechannel-message-transfer) methods. Note that the usual IPC methods like `send` and `invoke` cannot be used to transfer `MessagePort`s, only the `postMessage` methods can transfer `MessagePort`s.
By passing `MessagePort`s via the main process, you can connect two pages that might not otherwise be able to communicate (e.g. due to same-origin restrictions).
Extension: `close` event[](#extension-close-event "Direct link to heading")
----------------------------------------------------------------------------
Electron adds one feature to `MessagePort` that isn't present on the web, in order to make MessagePorts more useful. That is the `close` event, which is emitted when the other end of the channel is closed. Ports can also be implicitly closed by being garbage-collected.
In the renderer, you can listen for the `close` event either by assigning to `port.onclose` or by calling `port.addEventListener('close', ...)`. In the main process, you can listen for the `close` event by calling `port.on('close',
...)`.
Example use cases[](#example-use-cases "Direct link to heading")
-----------------------------------------------------------------
### Setting up a MessageChannel between two renderers[](#setting-up-a-messagechannel-between-two-renderers "Direct link to heading")
In this example, the main process sets up a MessageChannel, then sends each port to a different renderer. This allows renderers to send messages to each other without needing to use the main process as an in-between.
main.js (Main Process)
```
const { BrowserWindow, app, MessageChannelMain } = require('electron')
app.whenReady().then(async () => {
// create the windows.
const mainWindow = new BrowserWindow({
show: false,
webPreferences: {
contextIsolation: false,
preload: 'preloadMain.js'
}
})
const secondaryWindow = BrowserWindow({
show: false,
webPreferences: {
contextIsolation: false,
preload: 'preloadSecondary.js'
}
})
// set up the channel.
const { port1, port2 } = new MessageChannelMain()
// once the webContents are ready, send a port to each webContents with postMessage.
mainWindow.once('ready-to-show', () => {
mainWindow.webContents.postMessage('port', null, [port1])
})
secondaryWindow.once('ready-to-show', () => {
secondaryWindow.webContents.postMessage('port', null, [port2])
})
})
```
Then, in your preload scripts you receive the port through IPC and set up the listeners.
preloadMain.js and preloadSecondary.js (Preload scripts)
```
const { ipcRenderer } = require('electron')
ipcRenderer.on('port', e => {
// port received, make it globally available.
window.electronMessagePort = e.ports[0]
window.electronMessagePort.onmessage = messageEvent => {
// handle message
}
})
```
In this example messagePort is bound to the `window` object directly. It is better to use `contextIsolation` and set up specific contextBridge calls for each of your expected messages, but for the simplicity of this example we don't. You can find an example of context isolation further down this page at [Communicating directly between the main process and the main world of a context-isolated page](#communicating-directly-between-the-main-process-and-the-main-world-of-a-context-isolated-page)
That means window.messagePort is globally available and you can call `postMessage` on it from anywhere in your app to send a message to the other renderer.
renderer.js (Renderer Process)
```
// elsewhere in your code to send a message to the other renderers message handler
window.electronMessagePort.postmessage('ping')
```
### Worker process[](#worker-process "Direct link to heading")
In this example, your app has a worker process implemented as a hidden window. You want the app page to be able to communicate directly with the worker process, without the performance overhead of relaying via the main process.
main.js (Main Process)
```
const { BrowserWindow, app, ipcMain, MessageChannelMain } = require('electron')
app.whenReady().then(async () => {
// The worker process is a hidden BrowserWindow, so that it will have access
// to a full Blink context (including e.g. <canvas>, audio, fetch(), etc.)
const worker = new BrowserWindow({
show: false,
webPreferences: { nodeIntegration: true }
})
await worker.loadFile('worker.html')
// The main window will send work to the worker process and receive results
// over a MessagePort.
const mainWindow = new BrowserWindow({
webPreferences: { nodeIntegration: true }
})
mainWindow.loadFile('app.html')
// We can't use ipcMain.handle() here, because the reply needs to transfer a
// MessagePort.
ipcMain.on('request-worker-channel', (event) => {
// For security reasons, let's make sure only the frames we expect can
// access the worker.
if (event.senderFrame === mainWindow.webContents.mainFrame) {
// Create a new channel ...
const { port1, port2 } = new MessageChannelMain()
// ... send one end to the worker ...
worker.webContents.postMessage('new-client', null, [port1])
// ... and the other end to the main window.
event.senderFrame.postMessage('provide-worker-channel', null, [port2])
// Now the main window and the worker can communicate with each other
// without going through the main process!
}
})
})
```
worker.html
```
<script>
const { ipcRenderer } = require('electron')
const doWork = (input) => {
// Something cpu-intensive.
return input * 2
}
// We might get multiple clients, for instance if there are multiple windows,
// or if the main window reloads.
ipcRenderer.on('new-client', (event) => {
const [ port ] = event.ports
port.onmessage = (event) => {
// The event data can be any serializable object (and the event could even
// carry other MessagePorts with it!)
const result = doWork(event.data)
port.postMessage(result)
}
})
</script>
```
app.html
```
<script>
const { ipcRenderer } = require('electron')
// We request that the main process sends us a channel we can use to
// communicate with the worker.
ipcRenderer.send('request-worker-channel')
ipcRenderer.once('provide-worker-channel', (event) => {
// Once we receive the reply, we can take the port...
const [ port ] = event.ports
// ... register a handler to receive results ...
port.onmessage = (event) => {
console.log('received result:', event.data)
}
// ... and start sending it work!
port.postMessage(21)
})
</script>
```
### Reply streams[](#reply-streams "Direct link to heading")
Electron's built-in IPC methods only support two modes: fire-and-forget (e.g. `send`), or request-response (e.g. `invoke`). Using MessageChannels, you can implement a "response stream", where a single request responds with a stream of data.
renderer.js (Renderer Process)
```
const makeStreamingRequest = (element, callback) => {
// MessageChannels are lightweight--it's cheap to create a new one for each
// request.
const { port1, port2 } = new MessageChannel()
// We send one end of the port to the main process ...
ipcRenderer.postMessage(
'give-me-a-stream',
{ element, count: 10 },
[port2]
)
// ... and we hang on to the other end. The main process will send messages
// to its end of the port, and close it when it's finished.
port1.onmessage = (event) => {
callback(event.data)
}
port1.onclose = () => {
console.log('stream ended')
}
}
makeStreamingRequest(42, (data) => {
console.log('got response data:', event.data)
})
// We will see "got response data: 42" 10 times.
```
main.js (Main Process)
```
ipcMain.on('give-me-a-stream', (event, msg) => {
// The renderer has sent us a MessagePort that it wants us to send our
// response over.
const [replyPort] = event.ports
// Here we send the messages synchronously, but we could just as easily store
// the port somewhere and send messages asynchronously.
for (let i = 0; i < msg.count; i++) {
replyPort.postMessage(msg.element)
}
// We close the port when we're done to indicate to the other end that we
// won't be sending any more messages. This isn't strictly necessary--if we
// didn't explicitly close the port, it would eventually be garbage
// collected, which would also trigger the 'close' event in the renderer.
replyPort.close()
})
```
### Communicating directly between the main process and the main world of a context-isolated page[](#communicating-directly-between-the-main-process-and-the-main-world-of-a-context-isolated-page "Direct link to heading")
When [context isolation](context-isolation) is enabled, IPC messages from the main process to the renderer are delivered to the isolated world, rather than to the main world. Sometimes you want to deliver messages to the main world directly, without having to step through the isolated world.
main.js (Main Process)
```
const { BrowserWindow, app, MessageChannelMain } = require('electron')
const path = require('path')
app.whenReady().then(async () => {
// Create a BrowserWindow with contextIsolation enabled.
const bw = new BrowserWindow({
webPreferences: {
contextIsolation: true,
preload: path.join(__dirname, 'preload.js')
}
})
bw.loadURL('index.html')
// We'll be sending one end of this channel to the main world of the
// context-isolated page.
const { port1, port2 } = new MessageChannelMain()
// It's OK to send a message on the channel before the other end has
// registered a listener. Messages will be queued until a listener is
// registered.
port2.postMessage({ test: 21 })
// We can also receive messages from the main world of the renderer.
port2.on('message', (event) => {
console.log('from renderer main world:', event.data)
})
port2.start()
// The preload script will receive this IPC message and transfer the port
// over to the main world.
bw.webContents.postMessage('main-world-port', null, [port1])
})
```
preload.js (Preload Script)
```
const { ipcRenderer } = require('electron')
// We need to wait until the main world is ready to receive the message before
// sending the port. We create this promise in the preload so it's guaranteed
// to register the onload listener before the load event is fired.
const windowLoaded = new Promise(resolve => {
window.onload = resolve
})
ipcRenderer.on('main-world-port', async (event) => {
await windowLoaded
// We use regular window.postMessage to transfer the port from the isolated
// world to the main world.
window.postMessage('main-world-port', '*', event.ports)
})
```
index.html
```
<script>
window.onmessage = (event) => {
// event.source === window means the message is coming from the preload
// script, as opposed to from an <iframe> or other source.
if (event.source === window && event.data === 'main-world-port') {
const [ port ] = event.ports
// Once we have the port, we can communicate directly with the main
// process.
port.onmessage = (event) => {
console.log('from main process:', event.data)
port.postMessage(event.data * 2)
}
}
}
</script>
```
| programming_docs |
electron Keyboard Shortcuts Keyboard Shortcuts
==================
Overview[](#overview "Direct link to heading")
-----------------------------------------------
This feature allows you to configure local and global keyboard shortcuts for your Electron application.
Example[](#example "Direct link to heading")
---------------------------------------------
### Local Shortcuts[](#local-shortcuts "Direct link to heading")
Local keyboard shortcuts are triggered only when the application is focused. To configure a local keyboard shortcut, you need to specify an [`accelerator`](../api/accelerator) property when creating a [MenuItem](../api/menu-item) within the [Menu](../api/menu) module.
Starting with a working application from the [Quick Start Guide](quick-start), update the `main.js` file with the following lines:
[docs/fiddles/features/keyboard-shortcuts/local (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/keyboard-shortcuts/local)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/keyboard-shortcuts/local)
* main.js
* index.html
```
const { app, BrowserWindow, Menu, MenuItem } = require('electron')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600,
})
win.loadFile('index.html')
}
const menu = new Menu()
menu.append(new MenuItem({
label: 'Electron',
submenu: [{
role: 'help',
accelerator: process.platform === 'darwin' ? 'Alt+Cmd+I' : 'Alt+Shift+I',
click: () => { console.log('Electron rocks!') }
}]
}))
Menu.setApplicationMenu(menu)
app.whenReady().then(createWindow)
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>Hit Alt+Shift+I on Windows, or Opt+Cmd+I on mac to see a message printed to the console.</p>
</body>
</html>
```
> NOTE: In the code above, you can see that the accelerator differs based on the user's operating system. For MacOS, it is `Alt+Cmd+I`, whereas for Linux and Windows, it is `Alt+Shift+I`.
>
>
After launching the Electron application, you should see the application menu along with the local shortcut you just defined:
If you click `Help` or press the defined accelerator and then open the terminal that you ran your Electron application from, you will see the message that was generated after triggering the `click` event: "Electron rocks!".
### Global Shortcuts[](#global-shortcuts "Direct link to heading")
To configure a global keyboard shortcut, you need to use the [globalShortcut](../api/global-shortcut) module to detect keyboard events even when the application does not have keyboard focus.
Starting with a working application from the [Quick Start Guide](quick-start), update the `main.js` file with the following lines:
[docs/fiddles/features/keyboard-shortcuts/global (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/keyboard-shortcuts/global)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/keyboard-shortcuts/global)
* main.js
* index.html
```
const { app, BrowserWindow, globalShortcut } = require('electron')
function createWindow () {
const win = new BrowserWindow({
width: 800,
height: 600,
})
win.loadFile('index.html')
}
app.whenReady().then(() => {
globalShortcut.register('Alt+CommandOrControl+I', () => {
console.log('Electron loves global shortcuts!')
})
}).then(createWindow)
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if (BrowserWindow.getAllWindows().length === 0) {
createWindow()
}
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>Hit Alt+Ctrl+I on Windows or Opt+Cmd+I on Mac to see a message printed to the console.</p>
</body>
</html>
```
> NOTE: In the code above, the `CommandOrControl` combination uses `Command` on macOS and `Control` on Windows/Linux.
>
>
After launching the Electron application, if you press the defined key combination then open the terminal that you ran your Electron application from, you will see that Electron loves global shortcuts!
### Shortcuts within a BrowserWindow[](#shortcuts-within-a-browserwindow "Direct link to heading")
#### Using web APIs[](#using-web-apis "Direct link to heading")
If you want to handle keyboard shortcuts within a [BrowserWindow](../api/browser-window), you can listen for the `keyup` and `keydown` [DOM events](https://developer.mozilla.org/en-US/docs/Web/Events) inside the renderer process using the [addEventListener() API](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener).
[docs/fiddles/features/keyboard-shortcuts/web-apis (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/keyboard-shortcuts/web-apis)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/keyboard-shortcuts/web-apis)
* main.js
* index.html
* renderer.js
```
// Modules to control application life and create native browser window
const {app, BrowserWindow} = require('electron')
const path = require('path')
function createWindow () {
// Create the browser window.
const mainWindow = new BrowserWindow({
width: 800,
height: 600,
})
// and load the index.html of the app.
mainWindow.loadFile('index.html')
}
// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.whenReady().then(() => {
createWindow()
app.on('activate', function () {
// On macOS it's common to re-create a window in the app when the
// dock icon is clicked and there are no other windows open.
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
// Quit when all windows are closed, except on macOS. There, it's common
// for applications and their menu bar to stay active until the user quits
// explicitly with Cmd + Q.
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<meta http-equiv="X-Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Hello World!</title>
</head>
<body>
<h1>Hello World!</h1>
<p>Hit any key with this window focused to see it captured here.</p>
<div><span>Last Key Pressed: </span><span id="last-keypress"></span></div>
<script src="./renderer.js"></script>
</body>
</html>
```
```
function handleKeyPress (event) {
// You can put code here to handle the keypress.
document.getElementById("last-keypress").innerText = event.key
console.log(`You pressed ${event.key}`)
}
window.addEventListener('keyup', handleKeyPress, true)
```
> Note: the third parameter `true` indicates that the listener will always receive key presses before other listeners so they can't have `stopPropagation()` called on them.
>
>
#### Intercepting events in the main process[](#intercepting-events-in-the-main-process "Direct link to heading")
The [`before-input-event`](../api/web-contents#event-before-input-event) event is emitted before dispatching `keydown` and `keyup` events in the page. It can be used to catch and handle custom shortcuts that are not visible in the menu.
Starting with a working application from the [Quick Start Guide](quick-start), update the `main.js` file with the following lines:
[docs/fiddles/features/keyboard-shortcuts/interception-from-main (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/features/keyboard-shortcuts/interception-from-main)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/features/keyboard-shortcuts/interception-from-main)
* main.js
* index.html
```
const { app, BrowserWindow } = require('electron')
app.whenReady().then(() => {
const win = new BrowserWindow({ width: 800, height: 600 })
win.loadFile('index.html')
win.webContents.on('before-input-event', (event, input) => {
if (input.control && input.key.toLowerCase() === 'i') {
console.log('Pressed Control+I')
event.preventDefault()
}
})
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World!</title>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
</head>
<body>
<h1>Hello World!</h1>
<p>Hit Ctrl+I to see a message printed to the console.</p>
</body>
</html>
```
After launching the Electron application, if you open the terminal that you ran your Electron application from and press `Ctrl+I` key combination, you will see that this key combination was successfully intercepted.
#### Using third-party libraries[](#using-third-party-libraries "Direct link to heading")
If you don't want to do manual shortcut parsing, there are libraries that do advanced key detection, such as [mousetrap](https://github.com/ccampbell/mousetrap). Below are examples of usage of the `mousetrap` running in the Renderer process:
```
Mousetrap.bind('4', () => { console.log('4') })
Mousetrap.bind('?', () => { console.log('show shortcuts!') })
Mousetrap.bind('esc', () => { console.log('escape') }, 'keyup')
// combinations
Mousetrap.bind('command+shift+k', () => { console.log('command shift k') })
// map multiple combinations to the same callback
Mousetrap.bind(['command+k', 'ctrl+k'], () => {
console.log('command k or control k')
// return false to prevent default behavior and stop event from bubbling
return false
})
// gmail style sequences
Mousetrap.bind('g i', () => { console.log('go to inbox') })
Mousetrap.bind('* a', () => { console.log('select all') })
// konami code!
Mousetrap.bind('up up down down left right left right b a enter', () => {
console.log('konami code')
})
```
electron Windows on ARM Windows on ARM
==============
If your app runs with Electron 6.0.8 or later, you can now build it for Windows 10 on Arm. This considerably improves performance, but requires recompilation of any native modules used in your app. It may also require small fixups to your build and packaging scripts.
Running a basic app[](#running-a-basic-app "Direct link to heading")
---------------------------------------------------------------------
If your app doesn't use any native modules, then it's really easy to create an Arm version of your app.
1. Make sure that your app's `node_modules` directory is empty.
2. Using a *Command Prompt*, run `set npm_config_arch=arm64` before running `npm install`/`yarn install` as usual.
3. [If you have Electron installed as a development dependency](quick-start#prerequisites), npm will download and unpack the arm64 version. You can then package and distribute your app as normal.
General considerations[](#general-considerations "Direct link to heading")
---------------------------------------------------------------------------
### Architecture-specific code[](#architecture-specific-code "Direct link to heading")
Lots of Windows-specific code contains if... else logic that selects between either the x64 or x86 architectures.
```
if (process.arch === 'x64') {
// Do 64-bit thing...
} else {
// Do 32-bit thing...
}
```
If you want to target arm64, logic like this will typically select the wrong architecture, so carefully check your application and build scripts for conditions like this. In custom build and packaging scripts, you should always check the value of `npm_config_arch` in the environment, rather than relying on the current process arch.
### Native modules[](#native-modules "Direct link to heading")
If you use native modules, you must make sure that they compile against v142 of the MSVC compiler (provided in Visual Studio 2017). You must also check that any pre-built `.dll` or `.lib` files provided or referenced by the native module are available for Windows on Arm.
### Testing your app[](#testing-your-app "Direct link to heading")
To test your app, use a Windows on Arm device running Windows 10 (version 1903 or later). Make sure that you copy your application over to the target device - Chromium's sandbox will not work correctly when loading your application assets from a network location.
Development prerequisites[](#development-prerequisites "Direct link to heading")
---------------------------------------------------------------------------------
### Node.js/node-gyp[](#nodejsnode-gyp "Direct link to heading")
[Node.js v12.9.0 or later is recommended.](https://nodejs.org/en/) If updating to a new version of Node is undesirable, you can instead [update npm's copy of node-gyp manually](https://github.com/nodejs/node-gyp/wiki/Updating-npm's-bundled-node-gyp) to version 5.0.2 or later, which contains the required changes to compile native modules for Arm.
### Visual Studio 2017[](#visual-studio-2017 "Direct link to heading")
Visual Studio 2017 (any edition) is required for cross-compiling native modules. You can download Visual Studio Community 2017 via Microsoft's [Visual Studio Dev Essentials program](https://visualstudio.microsoft.com/dev-essentials/). After installation, you can add the Arm-specific components by running the following from a *Command Prompt*:
```
vs_installer.exe ^
--add Microsoft.VisualStudio.Workload.NativeDesktop ^
--add Microsoft.VisualStudio.Component.VC.ATLMFC ^
--add Microsoft.VisualStudio.Component.VC.Tools.ARM64 ^
--add Microsoft.VisualStudio.Component.VC.MFC.ARM64 ^
--includeRecommended
```
#### Creating a cross-compilation command prompt[](#creating-a-cross-compilation-command-prompt "Direct link to heading")
Setting `npm_config_arch=arm64` in the environment creates the correct arm64 `.obj` files, but the standard *Developer Command Prompt for VS 2017* will use the x64 linker. To fix this:
1. Duplicate the *x64\_x86 Cross Tools Command Prompt for VS 2017* shortcut (e.g. by locating it in the start menu, right clicking, selecting *Open File Location*, copying and pasting) to somewhere convenient.
2. Right click the new shortcut and choose *Properties*.
3. Change the *Target* field to read `vcvarsamd64_arm64.bat` at the end instead of `vcvarsamd64_x86.bat`.
If done successfully, the command prompt should print something similar to this on startup:
```
**********************************************************************
** Visual Studio 2017 Developer Command Prompt v15.9.15
** Copyright (c) 2017 Microsoft Corporation
**********************************************************************
[vcvarsall.bat] Environment initialized for: 'x64_arm64'
```
If you want to develop your application directly on a Windows on Arm device, substitute `vcvarsx86_arm64.bat` in *Target* so that cross-compilation can happen with the device's x86 emulation.
### Linking against the correct `node.lib`[](#linking-against-the-correct-nodelib "Direct link to heading")
By default, `node-gyp` unpacks Electron's node headers and downloads the x86 and x64 versions of `node.lib` into `%APPDATA%\..\Local\node-gyp\Cache`, but it does not download the arm64 version ([a fix for this is in development](https://github.com/nodejs/node-gyp/pull/1875).) To fix this:
1. Download the arm64 `node.lib` from <https://electronjs.org/headers/v6.0.9/win-arm64/node.lib>
2. Move it to `%APPDATA%\..\Local\node-gyp\Cache\6.0.9\arm64\node.lib`
Substitute `6.0.9` for the version you're using.
Cross-compiling native modules[](#cross-compiling-native-modules "Direct link to heading")
-------------------------------------------------------------------------------------------
After completing all of the above, open your cross-compilation command prompt and run `set npm_config_arch=arm64`. Then use `npm install` to build your project as normal. As with cross-compiling x86 modules, you may need to remove `node_modules` to force recompilation of native modules if they were previously compiled for another architecture.
Debugging native modules[](#debugging-native-modules "Direct link to heading")
-------------------------------------------------------------------------------
Debugging native modules can be done with Visual Studio 2017 (running on your development machine) and corresponding [Visual Studio Remote Debugger](https://docs.microsoft.com/en-us/visualstudio/debugger/remote-debugging-cpp?view=vs-2019) running on the target device. To debug:
1. Launch your app `.exe` on the target device via the *Command Prompt* (passing `--inspect-brk` to pause it before any native modules are loaded).
2. Launch Visual Studio 2017 on your development machine.
3. Connect to the target device by selecting *Debug > Attach to Process...* and enter the device's IP address and the port number displayed by the Visual Studio Remote Debugger tool.
4. Click *Refresh* and select the [appropriate Electron process to attach](../development/debugging-on-windows).
5. You may need to make sure that any symbols for native modules in your app are loaded correctly. To configure this, head to *Debug > Options...* in Visual Studio 2017, and add the folders containing your `.pdb` symbols under *Debugging > Symbols*.
6. Once attached, set any appropriate breakpoints and resume JavaScript execution using Chrome's [remote tools for Node](debugging-main-process).
Getting additional help[](#getting-additional-help "Direct link to heading")
-----------------------------------------------------------------------------
If you encounter a problem with this documentation, or if your app works when compiled for x86 but not for arm64, please [file an issue](../development/issues) with "Windows on Arm" in the title.
electron Boilerplates and CLIs Boilerplates and CLIs
=====================
Electron development is unopinionated - there is no "one true way" to develop, build, package, or release an Electron application. Additional features for Electron, both for build- and run-time, can usually be found on [npm](https://www.npmjs.com/search?q=electron) in individual packages, allowing developers to build both the app and build pipeline they need.
That level of modularity and extendability ensures that all developers working with Electron, both big and small in team-size, are never restricted in what they can or cannot do at any time during their development lifecycle. However, for many developers, one of the community-driven boilerplates or command line tools might make it dramatically easier to compile, package, and release an app.
Boilerplate vs CLI[](#boilerplate-vs-cli "Direct link to heading")
-------------------------------------------------------------------
A boilerplate is only a starting point - a canvas, so to speak - from which you build your application. They usually come in the form of a repository you can clone and customize to your heart's content.
A command line tool on the other hand continues to support you throughout the development and release. They are more helpful and supportive but enforce guidelines on how your code should be structured and built. *Especially for beginners, using a command line tool is likely to be helpful*.
electron-forge[](#electron-forge "Direct link to heading")
-----------------------------------------------------------
A "complete tool for building modern Electron applications". Electron Forge unifies the existing (and well maintained) build tools for Electron development into a cohesive package so that anyone can jump right in to Electron development.
Forge comes with [a ready-to-use template](https://electronforge.io/templates) using Webpack as a bundler. It includes an example typescript configuration and provides two configuration files to enable easy customization. It uses the same core modules used by the greater Electron community (like [`electron-packager`](https://github.com/electron/electron-packager)) – changes made by Electron maintainers (like Slack) benefit Forge's users, too.
You can find more information and documentation on [electronforge.io](https://electronforge.io/).
electron-builder[](#electron-builder "Direct link to heading")
---------------------------------------------------------------
A "complete solution to package and build a ready-for-distribution Electron app" that focuses on an integrated experience. [`electron-builder`](https://github.com/electron-userland/electron-builder) adds one single dependency focused on simplicity and manages all further requirements internally.
`electron-builder` replaces features and modules used by the Electron maintainers (such as the auto-updater) with custom ones. They are generally tighter integrated but will have less in common with popular Electron apps like Atom, Visual Studio Code, or Slack.
You can find more information and documentation in [the repository](https://github.com/electron-userland/electron-builder).
electron-react-boilerplate[](#electron-react-boilerplate "Direct link to heading")
-----------------------------------------------------------------------------------
If you don't want any tools but only a solid boilerplate to build from, CT Lin's [`electron-react-boilerplate`](https://github.com/chentsulin/electron-react-boilerplate) might be worth a look. It's quite popular in the community and uses `electron-builder` internally.
Other Tools and Boilerplates[](#other-tools-and-boilerplates "Direct link to heading")
---------------------------------------------------------------------------------------
The ["Awesome Electron" list](https://github.com/sindresorhus/awesome-electron#boilerplates) contains more tools and boilerplates to choose from. If you find the length of the list intimidating, don't forget that adding tools as you go along is a valid approach, too.
| programming_docs |
electron SpellChecker SpellChecker
============
Electron has built-in support for Chromium's spellchecker since Electron 8. On Windows and Linux this is powered by Hunspell dictionaries, and on macOS it makes use of the native spellchecker APIs.
How to enable the spellchecker?[](#how-to-enable-the-spellchecker "Direct link to heading")
--------------------------------------------------------------------------------------------
For Electron 9 and higher the spellchecker is enabled by default. For Electron 8 you need to enable it in `webPreferences`.
```
const myWindow = new BrowserWindow({
webPreferences: {
spellcheck: true
}
})
```
How to set the languages the spellchecker uses?[](#how-to-set-the-languages-the-spellchecker-uses "Direct link to heading")
----------------------------------------------------------------------------------------------------------------------------
On macOS as we use the native APIs there is no way to set the language that the spellchecker uses. By default on macOS the native spellchecker will automatically detect the language being used for you.
For Windows and Linux there are a few Electron APIs you should use to set the languages for the spellchecker.
```
// Sets the spellchecker to check English US and French
myWindow.session.setSpellCheckerLanguages(['en-US', 'fr'])
// An array of all available language codes
const possibleLanguages = myWindow.session.availableSpellCheckerLanguages
```
By default the spellchecker will enable the language matching the current OS locale.
How do I put the results of the spellchecker in my context menu?[](#how-do-i-put-the-results-of-the-spellchecker-in-my-context-menu "Direct link to heading")
--------------------------------------------------------------------------------------------------------------------------------------------------------------
All the required information to generate a context menu is provided in the [`context-menu`](../api/web-contents#event-context-menu) event on each `webContents` instance. A small example of how to make a context menu with this information is provided below.
```
const { Menu, MenuItem } = require('electron')
myWindow.webContents.on('context-menu', (event, params) => {
const menu = new Menu()
// Add each spelling suggestion
for (const suggestion of params.dictionarySuggestions) {
menu.append(new MenuItem({
label: suggestion,
click: () => mainWindow.webContents.replaceMisspelling(suggestion)
}))
}
// Allow users to add the misspelled word to the dictionary
if (params.misspelledWord) {
menu.append(
new MenuItem({
label: 'Add to dictionary',
click: () => mainWindow.webContents.session.addWordToSpellCheckerDictionary(params.misspelledWord)
})
)
}
menu.popup()
})
```
Does the spellchecker use any Google services?[](#does-the-spellchecker-use-any-google-services "Direct link to heading")
--------------------------------------------------------------------------------------------------------------------------
Although the spellchecker itself does not send any typings, words or user input to Google services the hunspell dictionary files are downloaded from a Google CDN by default. If you want to avoid this you can provide an alternative URL to download the dictionaries from.
```
myWindow.session.setSpellCheckerDictionaryDownloadURL('https://example.com/dictionaries/')
```
Check out the docs for [`session.setSpellCheckerDictionaryDownloadURL`](../api/session#sessetspellcheckerdictionarydownloadurlurl) for more information on where to get the dictionary files from and how you need to host them.
electron Inter-Process Communication Inter-Process Communication
===========================
Inter-process communication (IPC) is a key part of building feature-rich desktop applications in Electron. Because the main and renderer processes have different responsibilities in Electron's process model, IPC is the only way to perform many common tasks, such as calling a native API from your UI or triggering changes in your web contents from native menus.
IPC channels[](#ipc-channels "Direct link to heading")
-------------------------------------------------------
In Electron, processes communicate by passing messages through developer-defined "channels" with the [`ipcMain`](../api/ipc-main) and [`ipcRenderer`](../api/ipc-renderer) modules. These channels are **arbitrary** (you can name them anything you want) and **bidirectional** (you can use the same channel name for both modules).
In this guide, we'll be going over some fundamental IPC patterns with concrete examples that you can use as a reference for your app code.
Understanding context-isolated processes[](#understanding-context-isolated-processes "Direct link to heading")
---------------------------------------------------------------------------------------------------------------
Before proceeding to implementation details, you should be familiar with the idea of using a [preload script](process-model#preload-scripts) to import Node.js and Electron modules in a context-isolated renderer process.
* For a full overview of Electron's process model, you can read the [process model docs](process-model).
* For a primer into exposing APIs from your preload script using the `contextBridge` module, check out the [context isolation tutorial](context-isolation).
Pattern 1: Renderer to main (one-way)[](#pattern-1-renderer-to-main-one-way "Direct link to heading")
------------------------------------------------------------------------------------------------------
To fire a one-way IPC message from a renderer process to the main process, you can use the [`ipcRenderer.send`](../api/ipc-renderer) API to send a message that is then received by the [`ipcMain.on`](../api/ipc-main) API.
You usually use this pattern to call a main process API from your web contents. We'll demonstrate this pattern by creating a simple app that can programmatically change its window title.
For this demo, you'll need to add code to your main process, your renderer process, and a preload script. The full code is below, but we'll be explaining each file individually in the following sections.
[docs/fiddles/ipc/pattern-1 (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/ipc/pattern-1)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/ipc/pattern-1)
* main.js
* preload.js
* index.html
* renderer.js
```
const {app, BrowserWindow, ipcMain} = require('electron')
const path = require('path')
function createWindow () {
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
ipcMain.on('set-title', (event, title) => {
const webContents = event.sender
const win = BrowserWindow.fromWebContents(webContents)
win.setTitle(title)
})
mainWindow.loadFile('index.html')
}
app.whenReady().then(() => {
createWindow()
app.on('activate', function () {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
```
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electronAPI', {
setTitle: (title) => ipcRenderer.send('set-title', title)
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Hello World!</title>
</head>
<body>
Title: <input id="title"/>
<button id="btn" type="button">Set</button>
<script src="./renderer.js"></script>
</body>
</html>
```
```
const setButton = document.getElementById('btn')
const titleInput = document.getElementById('title')
setButton.addEventListener('click', () => {
const title = titleInput.value
window.electronAPI.setTitle(title)
});
```
### 1. Listen for events with `ipcMain.on`[](#1-listen-for-events-with-ipcmainon "Direct link to heading")
In the main process, set an IPC listener on the `set-title` channel with the `ipcMain.on` API:
main.js (Main Process)
```
const {app, BrowserWindow, ipcMain} = require('electron')
const path = require('path')
//...
function handleSetTitle (event, title) {
const webContents = event.sender
const win = BrowserWindow.fromWebContents(webContents)
win.setTitle(title)
}
function createWindow () {
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
mainWindow.loadFile('index.html')
}
app.whenReady().then(() => {
ipcMain.on('set-title', handleSetTitle)
createWindow()
}
//...
```
The above `handleSetTitle` callback has two parameters: an [IpcMainEvent](../api/structures/ipc-main-event) structure and a `title` string. Whenever a message comes through the `set-title` channel, this function will find the BrowserWindow instance attached to the message sender and use the `win.setTitle` API on it.
info
Make sure you're loading the `index.html` and `preload.js` entry points for the following steps!
### 2. Expose `ipcRenderer.send` via preload[](#2-expose-ipcrenderersend-via-preload "Direct link to heading")
To send messages to the listener created above, you can use the `ipcRenderer.send` API. By default, the renderer process has no Node.js or Electron module access. As an app developer, you need to choose which APIs to expose from your preload script using the `contextBridge` API.
In your preload script, add the following code, which will expose a global `window.electronAPI` variable to your renderer process.
preload.js (Preload Script)
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electronAPI', {
setTitle: (title) => ipcRenderer.send('set-title', title)
})
```
At this point, you'll be able to use the `window.electronAPI.setTitle()` function in the renderer process.
Security warning
We don't directly expose the whole `ipcRenderer.send` API for [security reasons](context-isolation#security-considerations). Make sure to limit the renderer's access to Electron APIs as much as possible.
### 3. Build the renderer process UI[](#3-build-the-renderer-process-ui "Direct link to heading")
In our BrowserWindow's loaded HTML file, add a basic user interface consisting of a text input and a button:
index.html
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Hello World!</title>
</head>
<body>
Title: <input id="title"/>
<button id="btn" type="button">Set</button>
<script src="./renderer.js"></script>
</body>
</html>
```
To make these elements interactive, we'll be adding a few lines of code in the imported `renderer.js` file that leverages the `window.electronAPI` functionality exposed from the preload script:
renderer.js (Renderer Process)
```
const setButton = document.getElementById('btn')
const titleInput = document.getElementById('title')
setButton.addEventListener('click', () => {
const title = titleInput.value
window.electronAPI.setTitle(title)
});
```
At this point, your demo should be fully functional. Try using the input field and see what happens to your BrowserWindow title!
Pattern 2: Renderer to main (two-way)[](#pattern-2-renderer-to-main-two-way "Direct link to heading")
------------------------------------------------------------------------------------------------------
A common application for two-way IPC is calling a main process module from your renderer process code and waiting for a result. This can be done by using [`ipcRenderer.invoke`](../api/ipc-renderer#ipcrendererinvokechannel-args) paired with [`ipcMain.handle`](../api/ipc-main#ipcmainhandlechannel-listener).
In the following example, we'll be opening a native file dialog from the renderer process and returning the selected file's path.
For this demo, you'll need to add code to your main process, your renderer process, and a preload script. The full code is below, but we'll be explaining each file individually in the following sections.
[docs/fiddles/ipc/pattern-2 (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/ipc/pattern-2)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/ipc/pattern-2)
* main.js
* preload.js
* index.html
* renderer.js
```
const {app, BrowserWindow, ipcMain, dialog} = require('electron')
const path = require('path')
async function handleFileOpen() {
const { canceled, filePaths } = await dialog.showOpenDialog()
if (canceled) {
return
} else {
return filePaths[0]
}
}
function createWindow () {
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
mainWindow.loadFile('index.html')
}
app.whenReady().then(() => {
ipcMain.handle('dialog:openFile', handleFileOpen)
createWindow()
app.on('activate', function () {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
```
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electronAPI',{
openFile: () => ipcRenderer.invoke('dialog:openFile')
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Dialog</title>
</head>
<body>
<button type="button" id="btn">Open a File</button>
File path: <strong id="filePath"></strong>
<script src='./renderer.js'></script>
</body>
</html>
```
```
const btn = document.getElementById('btn')
const filePathElement = document.getElementById('filePath')
btn.addEventListener('click', async () => {
const filePath = await window.electronAPI.openFile()
filePathElement.innerText = filePath
})
```
### 1. Listen for events with `ipcMain.handle`[](#1-listen-for-events-with-ipcmainhandle "Direct link to heading")
In the main process, we'll be creating a `handleFileOpen()` function that calls `dialog.showOpenDialog` and returns the value of the file path selected by the user. This function is used as a callback whenever an `ipcRender.invoke` message is sent through the `dialog:openFile` channel from the renderer process. The return value is then returned as a Promise to the original `invoke` call.
A word on error handling
Errors thrown through `handle` in the main process are not transparent as they are serialized and only the `message` property from the original error is provided to the renderer process. Please refer to [#24427](https://github.com/electron/electron/issues/24427) for details.
main.js (Main Process)
```
const { BrowserWindow, dialog, ipcMain } = require('electron')
const path = require('path')
//...
async function handleFileOpen() {
const { canceled, filePaths } = await dialog.showOpenDialog()
if (canceled) {
return
} else {
return filePaths[0]
}
}
function createWindow () {
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
mainWindow.loadFile('index.html')
}
app.whenReady(() => {
ipcMain.handle('dialog:openFile', handleFileOpen)
createWindow()
})
//...
```
on channel names
The `dialog:` prefix on the IPC channel name has no effect on the code. It only serves as a namespace that helps with code readability.
info
Make sure you're loading the `index.html` and `preload.js` entry points for the following steps!
### 2. Expose `ipcRenderer.invoke` via preload[](#2-expose-ipcrendererinvoke-via-preload "Direct link to heading")
In the preload script, we expose a one-line `openFile` function that calls and returns the value of `ipcRenderer.invoke('dialog:openFile')`. We'll be using this API in the next step to call the native dialog from our renderer's user interface.
preload.js (Preload Script)
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electronAPI', {
openFile: () => ipcRenderer.invoke('dialog:openFile')
})
```
Security warning
We don't directly expose the whole `ipcRenderer.invoke` API for [security reasons](context-isolation#security-considerations). Make sure to limit the renderer's access to Electron APIs as much as possible.
### 3. Build the renderer process UI[](#3-build-the-renderer-process-ui-1 "Direct link to heading")
Finally, let's build the HTML file that we load into our BrowserWindow.
index.html
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Dialog</title>
</head>
<body>
<button type="button" id="btn">Open a File</button>
File path: <strong id="filePath"></strong>
<script src='./renderer.js'></script>
</body>
</html>
```
The UI consists of a single `#btn` button element that will be used to trigger our preload API, and a `#filePath` element that will be used to display the path of the selected file. Making these pieces work will take a few lines of code in the renderer process script:
renderer.js (Renderer Process)
```
const btn = document.getElementById('btn')
const filePathElement = document.getElementById('filePath')
btn.addEventListener('click', async () => {
const filePath = await window.electronAPI.openFile()
filePathElement.innerText = filePath
})
```
In the above snippet, we listen for clicks on the `#btn` button, and call our `window.electronAPI.openFile()` API to activate the native Open File dialog. We then display the selected file path in the `#filePath` element.
### Note: legacy approaches[](#note-legacy-approaches "Direct link to heading")
The `ipcRenderer.invoke` API was added in Electron 7 as a developer-friendly way to tackle two-way IPC from the renderer process. However, there exist a couple alternative approaches to this IPC pattern.
Avoid legacy approaches if possible
We recommend using `ipcRenderer.invoke` whenever possible. The following two-way renderer-to-main patterns are documented for historical purposes.
info
For the following examples, we're calling `ipcRenderer` directly from the preload script to keep the code samples small.
#### Using `ipcRenderer.send`[](#using-ipcrenderersend "Direct link to heading")
The `ipcRenderer.send` API that we used for single-way communication can also be leveraged to perform two-way communication. This was the recommended way for asynchronous two-way communication via IPC prior to Electron 7.
preload.js (Preload Script)
```
// You can also put expose this code to the renderer
// process with the `contextBridge` API
const { ipcRenderer } = require('electron')
ipcRenderer.on('asynchronous-reply', (_event, arg) => {
console.log(arg) // prints "pong" in the DevTools console
})
ipcRenderer.send('asynchronous-message', 'ping')
```
main.js (Main Process)
```
ipcMain.on('asynchronous-message', (event, arg) => {
console.log(arg) // prints "ping" in the Node console
// works like `send`, but returning a message back
// to the renderer that sent the original message
event.reply('asynchronous-reply', 'pong')
})
```
There are a couple downsides to this approach:
* You need to set up a second `ipcRenderer.on` listener to handle the response in the renderer process. With `invoke`, you get the response value returned as a Promise to the original API call.
* There's no obvious way to pair the `asynchronous-reply` message to the original `asynchronous-message` one. If you have very frequent messages going back and forth through these channels, you would need to add additional app code to track each call and response individually.
#### Using `ipcRenderer.sendSync`[](#using-ipcrenderersendsync "Direct link to heading")
The `ipcRenderer.sendSync` API sends a message to the main process and waits *synchronously* for a response.
main.js (Main Process)
```
const { ipcMain } = require('electron')
ipcMain.on('synchronous-message', (event, arg) => {
console.log(arg) // prints "ping" in the Node console
event.returnValue = 'pong'
})
```
preload.js (Preload Script)
```
// You can also put expose this code to the renderer
// process with the `contextBridge` API
const { ipcRenderer } = require('electron')
const result = ipcRenderer.sendSync('synchronous-message', 'ping')
console.log(result) // prints "pong" in the DevTools console
```
The structure of this code is very similar to the `invoke` model, but we recommend **avoiding this API** for performance reasons. Its synchronous nature means that it'll block the renderer process until a reply is received.
Pattern 3: Main to renderer[](#pattern-3-main-to-renderer "Direct link to heading")
------------------------------------------------------------------------------------
When sending a message from the main process to a renderer process, you need to specify which renderer is receiving the message. Messages need to be sent to a renderer process via its [`WebContents`](../api/web-contents) instance. This WebContents instance contains a [`send`](../api/web-contents#contentssendchannel-args) method that can be used in the same way as `ipcRenderer.send`.
To demonstrate this pattern, we'll be building a number counter controlled by the native operating system menu.
For this demo, you'll need to add code to your main process, your renderer process, and a preload script. The full code is below, but we'll be explaining each file individually in the following sections.
[docs/fiddles/ipc/pattern-3 (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/ipc/pattern-3)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/ipc/pattern-3)
* main.js
* preload.js
* index.html
* renderer.js
```
const {app, BrowserWindow, Menu, ipcMain} = require('electron')
const path = require('path')
function createWindow () {
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
const menu = Menu.buildFromTemplate([
{
label: app.name,
submenu: [
{
click: () => mainWindow.webContents.send('update-counter', 1),
label: 'Increment',
},
{
click: () => mainWindow.webContents.send('update-counter', -1),
label: 'Decrement',
}
]
}
])
Menu.setApplicationMenu(menu)
mainWindow.loadFile('index.html')
// Open the DevTools.
mainWindow.webContents.openDevTools()
}
app.whenReady().then(() => {
ipcMain.on('counter-value', (_event, value) => {
console.log(value) // will print value to Node console
})
createWindow()
app.on('activate', function () {
if (BrowserWindow.getAllWindows().length === 0) createWindow()
})
})
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') app.quit()
})
```
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electronAPI', {
handleCounter: (callback) => ipcRenderer.on('update-counter', callback)
})
```
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Menu Counter</title>
</head>
<body>
Current value: <strong id="counter">0</strong>
<script src="./renderer.js"></script>
</body>
</html>
```
```
const counter = document.getElementById('counter')
window.electronAPI.handleCounter((event, value) => {
const oldValue = Number(counter.innerText)
const newValue = oldValue + value
counter.innerText = newValue
event.sender.send('counter-value', newValue)
})
```
### 1. Send messages with the `webContents` module[](#1-send-messages-with-the-webcontents-module "Direct link to heading")
For this demo, we'll need to first build a custom menu in the main process using Electron's `Menu` module that uses the `webContents.send` API to send an IPC message from the main process to the target renderer.
main.js (Main Process)
```
const {app, BrowserWindow, Menu, ipcMain} = require('electron')
const path = require('path')
function createWindow () {
const mainWindow = new BrowserWindow({
webPreferences: {
preload: path.join(__dirname, 'preload.js')
}
})
const menu = Menu.buildFromTemplate([
{
label: app.name,
submenu: [
{
click: () => mainWindow.webContents.send('update-counter', 1),
label: 'Increment',
},
{
click: () => mainWindow.webContents.send('update-counter', -1),
label: 'Decrement',
}
]
}
])
Menu.setApplicationMenu(menu)
mainWindow.loadFile('index.html')
}
//...
```
For the purposes of the tutorial, it's important to note that the `click` handler sends a message (either `1` or `-1`) to the renderer process through the `update-counter` channel.
```
click: () => mainWindow.webContents.send('update-counter', -1)
```
info
Make sure you're loading the `index.html` and `preload.js` entry points for the following steps!
### 2. Expose `ipcRenderer.on` via preload[](#2-expose-ipcrendereron-via-preload "Direct link to heading")
Like in the previous renderer-to-main example, we use the `contextBridge` and `ipcRenderer` modules in the preload script to expose IPC functionality to the renderer process:
preload.js (Preload Script)
```
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld('electronAPI', {
onUpdateCounter: (callback) => ipcRenderer.on('update-counter', callback)
})
```
After loading the preload script, your renderer process should have access to the `window.electronAPI.onUpdateCounter()` listener function.
Security warning
We don't directly expose the whole `ipcRenderer.on` API for [security reasons](context-isolation#security-considerations). Make sure to limit the renderer's access to Electron APIs as much as possible.
info
In the case of this minimal example, you can call `ipcRenderer.on` directly in the preload script rather than exposing it over the context bridge.
preload.js (Preload Script)
```
const { ipcRenderer } = require('electron')
window.addEventListener('DOMContentLoaded', () => {
const counter = document.getElementById('counter')
ipcRenderer.on('update-counter', (_event, value) => {
const oldValue = Number(counter.innerText)
const newValue = oldValue + value
counter.innerText = newValue
})
})
```
However, this approach has limited flexibility compared to exposing your preload APIs over the context bridge, since your listener can't directly interact with your renderer code.
### 3. Build the renderer process UI[](#3-build-the-renderer-process-ui-2 "Direct link to heading")
To tie it all together, we'll create an interface in the loaded HTML file that contains a `#counter` element that we'll use to display the values:
index.html
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<!-- https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
<title>Menu Counter</title>
</head>
<body>
Current value: <strong id="counter">0</strong>
<script src="./renderer.js"></script>
</body>
</html>
```
Finally, to make the values update in the HTML document, we'll add a few lines of DOM manipulation so that the value of the `#counter` element is updated whenever we fire an `update-counter` event.
renderer.js (Renderer Process)
```
const counter = document.getElementById('counter')
window.electronAPI.onUpdateCounter((_event, value) => {
const oldValue = Number(counter.innerText)
const newValue = oldValue + value
counter.innerText = newValue
})
```
In the above code, we're passing in a callback to the `window.electronAPI.onUpdateCounter` function exposed from our preload script. The second `value` parameter corresponds to the `1` or `-1` we were passing in from the `webContents.send` call from the native menu.
### Optional: returning a reply[](#optional-returning-a-reply "Direct link to heading")
There's no equivalent for `ipcRenderer.invoke` for main-to-renderer IPC. Instead, you can send a reply back to the main process from within the `ipcRenderer.on` callback.
We can demonstrate this with slight modifications to the code from the previous example. In the renderer process, use the `event` parameter to send a reply back to the main process through the `counter-value` channel.
renderer.js (Renderer Process)
```
const counter = document.getElementById('counter')
window.electronAPI.onUpdateCounter((event, value) => {
const oldValue = Number(counter.innerText)
const newValue = oldValue + value
counter.innerText = newValue
event.sender.send('counter-value', newValue)
})
```
In the main process, listen for `counter-value` events and handle them appropriately.
main.js (Main Process)
```
//...
ipcMain.on('counter-value', (_event, value) => {
console.log(value) // will print value to Node console
})
//...
```
Pattern 4: Renderer to renderer[](#pattern-4-renderer-to-renderer "Direct link to heading")
--------------------------------------------------------------------------------------------
There's no direct way to send messages between renderer processes in Electron using the `ipcMain` and `ipcRenderer` modules. To achieve this, you have two options:
* Use the main process as a message broker between renderers. This would involve sending a message from one renderer to the main process, which would forward the message to the other renderer.
* Pass a [MessagePort](message-ports) from the main process to both renderers. This will allow direct communication between renderers after the initial setup.
Object serialization[](#object-serialization "Direct link to heading")
-----------------------------------------------------------------------
Electron's IPC implementation uses the HTML standard [Structured Clone Algorithm](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm) to serialize objects passed between processes, meaning that only certain types of objects can be passed through IPC channels.
In particular, DOM objects (e.g. `Element`, `Location` and `DOMMatrix`), Node.js objects backed by C++ classes (e.g. `process.env`, some members of `Stream`), and Electron objects backed by C++ classes (e.g. `WebContents`, `BrowserWindow` and `WebFrame`) are not serializable with Structured Clone.
| programming_docs |
electron Publishing and Updating
Follow along the tutorial
This is **part 6** of the Electron tutorial.
1. [Prerequisites](tutorial-prerequisites)
2. [Building your First App](tutorial-first-app)
3. [Using Preload Scripts](tutorial-preload)
4. [Adding Features](tutorial-adding-features)
5. [Packaging Your Application](tutorial-packaging)
6. **[Publishing and Updating](tutorial-publishing-updating)**
Learning goals[](#learning-goals "Direct link to heading")
-----------------------------------------------------------
If you've been following along, this is the last step of the tutorial! In this part, you will publish your app to GitHub releases and integrate automatic updates into your app code.
Using update.electronjs.org[](#using-updateelectronjsorg "Direct link to heading")
-----------------------------------------------------------------------------------
The Electron maintainers provide a free auto-updating service for open-source apps at <https://update.electronjs.org.> Its requirements are:
* Your app runs on macOS or Windows
* Your app has a public GitHub repository
* Builds are published to [GitHub releases](https://docs.github.com/en/repositories/releasing-projects-on-github/managing-releases-in-a-repository)
* Builds are [code signed](code-signing)
At this point, we'll assume that you have already pushed all your code to a public GitHub repository.
Alternative update services
If you're using an alternate repository host (e.g. GitLab or Bitbucket) or if you need to keep your code repository private, please refer to our [step-by-step guide](updates) on hosting your own Electron update server.
Publishing a GitHub release[](#publishing-a-github-release "Direct link to heading")
-------------------------------------------------------------------------------------
Electron Forge has [Publisher](https://www.electronforge.io/config/publishers) plugins that can automate the distribution of your packaged application to various sources. In this tutorial, we will be using the GitHub Publisher, which will allow us to publish our code to GitHub releases.
### Generating a personal access token[](#generating-a-personal-access-token "Direct link to heading")
Forge cannot publish to any repository on GitHub without permission. You need to pass in an authenticated token that gives Forge access to your GitHub releases. The easiest way to do this is to [create a new personal access token (PAT)](https://github.com/settings/tokens/new) with the `public_repo` scope, which gives write access to your public repositories. **Make sure to keep this token a secret.**
### Setting up the GitHub Publisher[](#setting-up-the-github-publisher "Direct link to heading")
#### Installing the module[](#installing-the-module "Direct link to heading")
Forge's [GitHub Publisher](https://www.electronforge.io/config/publishers/github) is a plugin that needs to be installed in your project's `devDependencies`:
* npm
* Yarn
```
npm install --save-dev @electron-forge/publisher-github
```
```
yarn add --dev @electron-forge/publisher-github
```
#### Configuring the publisher in Forge[](#configuring-the-publisher-in-forge "Direct link to heading")
Once you have it installed, you need to set it up in your Forge configuration. A full list of options is documented in the Forge's [`PublisherGitHubConfig`](https://js.electronforge.io/publisher/github/interfaces/publishergithubconfig) API docs.
package.json
```
{
//...
"config": {
"forge": {
"publishers": [
{
"name": "@electron-forge/publisher-github",
"config": {
"repository": {
"owner": "github-user-name",
"name": "github-repo-name"
},
"prerelease": false,
"draft": true
}
}
]
}
}
//...
}
```
Drafting releases before publishing
Notice that you have configured Forge to publish your release as a draft. This will allow you to see the release with its generated artifacts without actually publishing it to your end users. You can manually publish your releases via GitHub after writing release notes and double-checking that your distributables work.
#### Setting up your authentication token[](#setting-up-your-authentication-token "Direct link to heading")
You also need to make the Publisher aware of your authentication token. By default, it will use the value stored in the `GITHUB_TOKEN` environment variable.
### Running the publish command[](#running-the-publish-command "Direct link to heading")
Add Forge's [publish command](https://www.electronforge.io/cli#publish) to your npm scripts.
package.json
```
//...
"scripts": {
"start": "electron-forge start",
"package": "electron-forge package",
"make": "electron-forge make",
"publish": "electron-forge publish"
},
//...
```
This command will run your configured makers and publish the output distributables to a new GitHub release.
* npm
* Yarn
```
npm run publish
```
```
yarn run publish
```
By default, this will only publish a single distributable for your host operating system and architecture. You can publish for different architectures by passing in the `--arch` flag to your Forge commands.
The name of this release will correspond to the `version` field in your project's package.json file.
Tagging releases
Optionally, you can also [tag your releases in Git][git-tag] so that your release is associated with a labeled point in your code history. npm comes with a handy [`npm version`](https://docs.npmjs.com/cli/v8/commands/npm-version) command that can handle the version bumping and tagging for you.
#### Bonus: Publishing in GitHub Actions[](#bonus-publishing-in-github-actions "Direct link to heading")
Publishing locally can be painful, especially because you can only create distributables for your host operating system (i.e. you can't publish a Window `.exe` file from macOS).
A solution for this would be to publish your app via automation workflows such as [GitHub Actions](https://github.com/features/actions), which can run tasks in the cloud on Ubuntu, macOS, and Windows. This is the exact approach taken by [Electron Fiddle](https://electronjs.org/fiddle). You can refer to Fiddle's [Build and Release pipeline](https://github.com/electron/fiddle/blob/master/.github/workflows/build.yaml) and [Forge configuration](https://github.com/electron/fiddle/blob/master/forge.config.js) for more details.
Instrumenting your updater code[](#instrumenting-your-updater-code "Direct link to heading")
---------------------------------------------------------------------------------------------
Now that we have a functional release system via GitHub releases, we now need to tell our Electron app to download an update whenever a new release is out. Electron apps do this via the [autoUpdater](../api/auto-updater) module, which reads from an update server feed to check if a new version is available for download.
The update.electronjs.org service provides an updater-compatible feed. For example, Electron Fiddle v0.28.0 will check the endpoint at <https://update.electronjs.org/electron/fiddle/darwin/v0.28.0> to see if a newer GitHub release is available.
After your release is published to GitHub, the update.electronjs.org service should work for your application. The only step left is to configure the feed with the autoUpdater module.
To make this process easier, the Electron team maintains the [`update-electron-app`](https://github.com/electron/update-electron-app) module, which sets up the autoUpdater boilerplate for update.electronjs.org in one function call — no configuration required. This module will search for the update.electronjs.org feed that matches your project's package.json `"repository"` field.
First, install the module as a runtime dependency.
* npm
* Yarn
```
npm install update-electron-app
```
```
yarn add update-electron-app
```
Then, import the module and call it immediately in the main process.
main.js
```
require('update-electron-app')()
```
And that is all it takes! Once your application is packaged, it will update itself for each new GitHub release that you publish.
Summary[](#summary "Direct link to heading")
---------------------------------------------
In this tutorial, we configured Electron Forge's GitHub Publisher to upload your app's distributables to GitHub releases. Since distributables cannot always be generated between platforms, we recommend setting up your building and publishing flow in a Continuous Integration pipeline if you do not have access to machines.
Electron applications can self-update by pointing the autoUpdater module to an update server feed. update.electronjs.org is a free update server provided by Electron for open-source applications published on GitHub releases. Configuring your Electron app to use this service is as easy as installing and importing the `update-electron-app` module.
If your application is not eligible for update.electronjs.org, you should instead deploy your own update server and configure the autoUpdater module yourself.
🌟 You're done!
From here, you have officially completed our tutorial to Electron. Feel free to explore the rest of our docs and happy developing! If you have questions, please stop by our community [Discord server](https://discord.com/invite/APGC3k5yaH).
electron Desktop Launcher Actions Desktop Launcher Actions
========================
Overview[](#overview "Direct link to heading")
-----------------------------------------------
On many Linux environments, you can add custom entries to the system launcher by modifying the `.desktop` file. For Canonical's Unity documentation, see [Adding Shortcuts to a Launcher](https://help.ubuntu.com/community/UnityLaunchersAndDesktopFiles#Adding_shortcuts_to_a_launcher). For details on a more generic implementation, see the [freedesktop.org Specification](https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html).
> NOTE: The screenshot above is an example of launcher shortcuts in Audacious audio player
>
>
To create a shortcut, you need to provide `Name` and `Exec` properties for the entry you want to add to the shortcut menu. Unity will execute the command defined in the `Exec` field after the user clicked the shortcut menu item. An example of the `.desktop` file may look as follows:
```
Actions=PlayPause;Next;Previous
[Desktop Action PlayPause]
Name=Play-Pause
Exec=audacious -t
OnlyShowIn=Unity;
[Desktop Action Next]
Name=Next
Exec=audacious -f
OnlyShowIn=Unity;
[Desktop Action Previous]
Name=Previous
Exec=audacious -r
OnlyShowIn=Unity;
```
The preferred way for Unity to instruct your application on what to do is using parameters. You can find them in your application in the global variable `process.argv`.
electron Goma Goma
====
> Goma is a distributed compiler service for open-source projects such as Chromium and Android.
>
>
Electron has a deployment of a custom Goma Backend that we make available to all Electron Maintainers. See the [Access](#access) section below for details on authentication. There is also a `cache-only` Goma endpoint that will be used by default if you do not have credentials. Requests to the cache-only Goma will not hit our cluster, but will read from our cache and should result in significantly faster build times.
Enabling Goma[](#enabling-goma "Direct link to heading")
---------------------------------------------------------
Currently the only supported way to use Goma is to use our [Build Tools](https://github.com/electron/build-tools). Goma configuration is automatically included when you set up `build-tools`.
If you are a maintainer and have access to our cluster, please ensure that you run `e init` with `--goma=cluster` in order to configure `build-tools` to use the Goma cluster. If you have an existing config, you can just set `"goma": "cluster"` in your config file.
Building with Goma[](#building-with-goma "Direct link to heading")
-------------------------------------------------------------------
When you are using Goma you can run `ninja` with a substantially higher `j` value than would normally be supported by your machine.
Please do not set a value higher than **200**. We monitor Goma system usage, and users found to be abusing it with unreasonable concurrency will be de-activated.
```
ninja -C out/Testing electron -j 200
```
If you're using `build-tools`, appropriate `-j` values will automatically be used for you.
Monitoring Goma[](#monitoring-goma "Direct link to heading")
-------------------------------------------------------------
If you access <http://localhost:8088> on your local machine you can monitor compile jobs as they flow through the goma system.
Access[](#access "Direct link to heading")
-------------------------------------------
For security and cost reasons, access to Electron's Goma cluster is currently restricted to Electron Maintainers. If you want access please head to `#access-requests` in Slack and ping `@goma-squad` to ask for access. Please be aware that being a maintainer does not *automatically* grant access and access is determined on a case by case basis.
Uptime / Support[](#uptime--support "Direct link to heading")
--------------------------------------------------------------
We have automated monitoring of our Goma cluster and cache at <https://status.notgoma.com>
We do not provide support for usage of Goma and any issues raised asking for help / having issues will *probably* be closed without much reason, we do not have the capacity to handle that kind of support.
electron Using clang-tidy on C++ Code Using clang-tidy on C++ Code
============================
[`clang-tidy`](https://clang.llvm.org/extra/clang-tidy/) is a tool to automatically check C/C++/Objective-C code for style violations, programming errors, and best practices.
Electron's `clang-tidy` integration is provided as a linter script which can be run with `npm run lint:clang-tidy`. While `clang-tidy` checks your on-disk files, you need to have built Electron so that it knows which compiler flags were used. There is one required option for the script `--output-dir`, which tells the script which build directory to pull the compilation information from. A typical usage would be: `npm run lint:clang-tidy --out-dir ../out/Testing`
With no filenames provided, all C/C++/Objective-C files will be checked. You can provide a list of files to be checked by passing the filenames after the options: `npm run lint:clang-tidy --out-dir ../out/Testing shell/browser/api/electron_api_app.cc`
While `clang-tidy` has a [long list](https://clang.llvm.org/extra/clang-tidy/checks/list.html) of possible checks, in Electron only a few are enabled by default. At the moment Electron doesn't have a `.clang-tidy` config, so `clang-tidy` will find the one from Chromium at `src/.clang-tidy` and use the checks which Chromium has enabled. You can change which checks are run by using the `--checks=` option. This is passed straight through to `clang-tidy`, so see its documentation for full details. Wildcards can be used, and checks can be disabled by prefixing a `-`. By default any checks listed are added to those in `.clang-tidy`, so if you'd like to limit the checks to specific ones you should first exclude all checks then add back what you want, like `--checks=-*,performance*`.
Running `clang-tidy` is rather slow - internally it compiles each file and then runs the checks so it will always be some factor slower than compilation. While you can use parallel runs to speed it up using the `--jobs|-j` option, `clang-tidy` also uses a lot of memory during its checks, so it can easily run into out-of-memory errors. As such the default number of jobs is one.
electron Setting Up Symbol Server in Debugger Setting Up Symbol Server in Debugger
====================================
Debug symbols allow you to have better debugging sessions. They have information about the functions contained in executables and dynamic libraries and provide you with information to get clean call stacks. A Symbol Server allows the debugger to load the correct symbols, binaries and sources automatically without forcing users to download large debugging files. The server functions like [Microsoft's symbol server](https://support.microsoft.com/kb/311503) so the documentation there can be useful.
Note that because released Electron builds are heavily optimized, debugging is not always easy. The debugger will not be able to show you the content of all variables and the execution path can seem strange because of inlining, tail calls, and other compiler optimizations. The only workaround is to build an unoptimized local build.
The official symbol server URL for Electron is <https://symbols.electronjs.org.> You cannot visit this URL directly, you must add it to the symbol path of your debugging tool. In the examples below, a local cache directory is used to avoid repeatedly fetching the PDB from the server. Replace `c:\code\symbols` with an appropriate cache directory on your machine.
Using the Symbol Server in Windbg[](#using-the-symbol-server-in-windbg "Direct link to heading")
-------------------------------------------------------------------------------------------------
The Windbg symbol path is configured with a string value delimited with asterisk characters. To use only the Electron symbol server, add the following entry to your symbol path (**Note:** you can replace `c:\code\symbols` with any writable directory on your computer, if you'd prefer a different location for downloaded symbols):
```
SRV*c:\code\symbols\*https://symbols.electronjs.org
```
Set this string as `_NT_SYMBOL_PATH` in the environment, using the Windbg menus, or by typing the `.sympath` command. If you would like to get symbols from Microsoft's symbol server as well, you should list that first:
```
SRV*c:\code\symbols\*https://msdl.microsoft.com/download/symbols;SRV*c:\code\symbols\*https://symbols.electronjs.org
```
Using the symbol server in Visual Studio[](#using-the-symbol-server-in-visual-studio "Direct link to heading")
---------------------------------------------------------------------------------------------------------------
Troubleshooting: Symbols will not load[](#troubleshooting-symbols-will-not-load "Direct link to heading")
----------------------------------------------------------------------------------------------------------
Type the following commands in Windbg to print why symbols are not loading:
```
> !sym noisy
> .reload /f electron.exe
```
electron Creating a New Electron Browser Module Creating a New Electron Browser Module
======================================
Welcome to the Electron API guide! If you are unfamiliar with creating a new Electron API module within the [`browser`](https://github.com/electron/electron/tree/main/shell/browser) directory, this guide serves as a checklist for some of the necessary steps that you will need to implement.
This is not a comprehensive end-all guide to creating an Electron Browser API, rather an outline documenting some of the more unintuitive steps.
Add your files to Electron's project configuration[](#add-your-files-to-electrons-project-configuration "Direct link to heading")
----------------------------------------------------------------------------------------------------------------------------------
Electron uses [GN](https://gn.googlesource.com/gn) as a meta build system to generate files for its compiler, [Ninja](https://ninja-build.org/). This means that in order to tell Electron to compile your code, we have to add your API's code and header file names into [`filenames.gni`](https://github.com/electron/electron/blob/main/filenames.gni).
You will need to append your API file names alphabetically into the appropriate files like so:
filenames.gni
```
lib_sources = [
"path/to/api/api_name.cc",
"path/to/api/api_name.h",
]
lib_sources_mac = [
"path/to/api/api_name_mac.h",
"path/to/api/api_name_mac.mm",
]
lib_sources_win = [
"path/to/api/api_name_win.cc",
"path/to/api/api_name_win.h",
]
lib_sources_linux = [
"path/to/api/api_name_linux.cc",
"path/to/api/api_name_linux.h",
]
```
Note that the Windows, macOS and Linux array additions are optional and should only be added if your API has specific platform implementations.
Create API documentation[](#create-api-documentation "Direct link to heading")
-------------------------------------------------------------------------------
Type definitions are generated by Electron using [`@electron/docs-parser`](https://github.com/electron/docs-parser) and [`@electron/typescript-definitions`](https://github.com/electron/typescript-definitions). This step is necessary to ensure consistency across Electron's API documentation. This means that for your API type definition to appear in the `electron.d.ts` file, we must create a `.md` file. Examples can be found in [this folder](https://github.com/electron/electron/tree/main/docs/api).
Set up `ObjectTemplateBuilder` and `Wrappable`[](#set-up-objecttemplatebuilder-and-wrappable "Direct link to heading")
-----------------------------------------------------------------------------------------------------------------------
Electron constructs its modules using [`object_template_builder`](https://www.electronjs.org/blog/from-native-to-js#mateobjecttemplatebuilder).
[`wrappable`](https://chromium.googlesource.com/chromium/src/+/refs/heads/main/gin/wrappable.h) is a base class for C++ objects that have corresponding v8 wrapper objects.
Here is a basic example of code that you may need to add, in order to incorporate `object_template_builder` and `wrappable` into your API. For further reference, you can find more implementations [here](https://github.com/electron/electron/tree/main/shell/browser/api).
In your `api_name.h` file:
api\_name.h
```
#ifndef ELECTRON_SHELL_BROWSER_API_ELECTRON_API_{API_NAME}_H_
#define ELECTRON_SHELL_BROWSER_API_ELECTRON_API_{API_NAME}_H_
#include "gin/handle.h"
#include "gin/wrappable.h"
namespace electron {
namespace api {
class ApiName : public gin::Wrappable<ApiName> {
public:
static gin::Handle<ApiName> Create(v8::Isolate* isolate);
// gin::Wrappable
static gin::WrapperInfo kWrapperInfo;
gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
v8::Isolate* isolate) override;
const char* GetTypeName() override;
} // namespace api
} // namespace electron
```
In your `api_name.cc` file:
api\_name.cc
```
#include "shell/browser/api/electron_api_safe_storage.h"
#include "shell/browser/browser.h"
#include "shell/common/gin_converters/base_converter.h"
#include "shell/common/gin_converters/callback_converter.h"
#include "shell/common/gin_helper/dictionary.h"
#include "shell/common/gin_helper/object_template_builder.h"
#include "shell/common/node_includes.h"
#include "shell/common/platform_util.h"
namespace electron {
namespace api {
gin::WrapperInfo ApiName::kWrapperInfo = {gin::kEmbedderNativeGin};
gin::ObjectTemplateBuilder ApiName::GetObjectTemplateBuilder(
v8::Isolate* isolate) {
return gin::ObjectTemplateBuilder(isolate)
.SetMethod("methodName", &ApiName::methodName);
}
const char* ApiName::GetTypeName() {
return "ApiName";
}
// static
gin::Handle<ApiName> ApiName::Create(v8::Isolate* isolate) {
return gin::CreateHandle(isolate, new ApiName());
}
} // namespace api
} // namespace electron
namespace {
void Initialize(v8::Local<v8::Object> exports,
v8::Local<v8::Value> unused,
v8::Local<v8::Context> context,
void* priv) {
v8::Isolate* isolate = context->GetIsolate();
gin_helper::Dictionary dict(isolate, exports);
dict.Set("apiName", electron::api::ApiName::Create(isolate));
}
} // namespace
```
Link your Electron API with Node[](#link-your-electron-api-with-node "Direct link to heading")
-----------------------------------------------------------------------------------------------
In the [`typings/internal-ambient.d.ts`](https://github.com/electron/electron/blob/main/typings/internal-ambient.d.ts) file, we need to append a new property onto the `Process` interface like so:
typings/internal-ambient.d.ts
```
interface Process {
_linkedBinding(name: 'electron_browser_{api_name}', Electron.ApiName);
}
```
At the very bottom of your `api_name.cc` file:
api\_name.cc
```
NODE_LINKED_MODULE_CONTEXT_AWARE(electron_browser_{api_name},Initialize)
```
In your [`shell/common/node_bindings.cc`](https://github.com/electron/electron/blob/main/shell/common/node_bindings.cc) file, add your node binding name to Electron's built-in modules.
shell/common/node\_bindings.cc
```
#define ELECTRON_BUILTIN_MODULES(V) \
V(electron_browser_{api_name})
```
> Note: More technical details on how Node links with Electron can be found on [our blog](https://www.electronjs.org/blog/electron-internals-using-node-as-a-library#link-node-with-electron).
>
>
Expose your API to TypeScript[](#expose-your-api-to-typescript "Direct link to heading")
-----------------------------------------------------------------------------------------
### Export your API as a module[](#export-your-api-as-a-module "Direct link to heading")
We will need to create a new TypeScript file in the path that follows:
`"lib/browser/api/{electron_browser_{api_name}}.ts"`
An example of the contents of this file can be found [here](https://github.com/electron/electron/blob/main/lib/browser/api/native-image.ts).
### Expose your module to TypeScript[](#expose-your-module-to-typescript "Direct link to heading")
Add your module to the module list found at `"lib/browser/api/module-list.ts"` like so:
lib/browser/api/module-list.ts
```
export const browserModuleList: ElectronInternal.ModuleEntry[] = [
{ name: 'apiName', loader: () => require('./api-name') },
];
```
| programming_docs |
electron Build Instructions Build Instructions
==================
Follow the guidelines below for building **Electron itself**, for the purposes of creating custom Electron binaries. For bundling and distributing your app code with the prebuilt Electron binaries, see the [application distribution](../tutorial/application-distribution) guide.
Platform prerequisites[](#platform-prerequisites "Direct link to heading")
---------------------------------------------------------------------------
Check the build prerequisites for your platform before proceeding
* [macOS](build-instructions-macos#prerequisites)
* [Linux](build-instructions-linux#prerequisites)
* [Windows](build-instructions-windows#prerequisites)
Build Tools[](#build-tools "Direct link to heading")
-----------------------------------------------------
[Electron's Build Tools](https://github.com/electron/build-tools) automate much of the setup for compiling Electron from source with different configurations and build targets. If you wish to set up the environment manually, the instructions are listed below.
Electron uses [GN](https://gn.googlesource.com/gn) for project generation and [ninja](https://ninja-build.org/) for building. Project configurations can be found in the `.gn` and `.gni` files.
GN Files[](#gn-files "Direct link to heading")
-----------------------------------------------
The following `gn` files contain the main rules for building Electron:
* `BUILD.gn` defines how Electron itself is built and includes the default configurations for linking with Chromium.
* `build/args/{testing,release,all}.gn` contain the default build arguments for building Electron.
GN prerequisites[](#gn-prerequisites "Direct link to heading")
---------------------------------------------------------------
You'll need to install [`depot_tools`](https://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/depot_tools_tutorial.html#_setting_up), the toolset used for fetching Chromium and its dependencies.
Also, on Windows, you'll need to set the environment variable `DEPOT_TOOLS_WIN_TOOLCHAIN=0`. To do so, open `Control Panel` → `System and
Security` → `System` → `Advanced system settings` and add a system variable `DEPOT_TOOLS_WIN_TOOLCHAIN` with value `0`. This tells `depot_tools` to use your locally installed version of Visual Studio (by default, `depot_tools` will try to download a Google-internal version that only Googlers have access to).
### Setting up the git cache[](#setting-up-the-git-cache "Direct link to heading")
If you plan on checking out Electron more than once (for example, to have multiple parallel directories checked out to different branches), using the git cache will speed up subsequent calls to `gclient`. To do this, set a `GIT_CACHE_PATH` environment variable:
```
$ export GIT_CACHE_PATH="${HOME}/.git_cache"
$ mkdir -p "${GIT_CACHE_PATH}"
# This will use about 16G.
```
Getting the code[](#getting-the-code "Direct link to heading")
---------------------------------------------------------------
```
$ mkdir electron && cd electron
$ gclient config --name "src/electron" --unmanaged https://github.com/electron/electron
$ gclient sync --with_branch_heads --with_tags
# This will take a while, go get a coffee.
```
> Instead of `https://github.com/electron/electron`, you can use your own fork here (something like `https://github.com/<username>/electron`).
>
>
### A note on pulling/pushing[](#a-note-on-pullingpushing "Direct link to heading")
If you intend to `git pull` or `git push` from the official `electron` repository in the future, you now need to update the respective folder's origin URLs.
```
$ cd src/electron
$ git remote remove origin
$ git remote add origin https://github.com/electron/electron
$ git checkout main
$ git branch --set-upstream-to=origin/main
$ cd -
```
📝 `gclient` works by checking a file called `DEPS` inside the `src/electron` folder for dependencies (like Chromium or Node.js). Running `gclient sync -f` ensures that all dependencies required to build Electron match that file.
So, in order to pull, you'd run the following commands:
```
$ cd src/electron
$ git pull
$ gclient sync -f
```
Building[](#building "Direct link to heading")
-----------------------------------------------
**Set the environment variable for chromium build tools**
On Linux & MacOS
```
$ cd src
$ export CHROMIUM_BUILDTOOLS_PATH=`pwd`/buildtools
```
On Windows:
```
$ cd src
$ set CHROMIUM_BUILDTOOLS_PATH=%cd%\buildtools
```
**To generate Testing build config of Electron:**
```
$ gn gen out/Testing --args="import(\"//electron/build/args/testing.gn\")"
```
**To generate Release build config of Electron:**
```
$ gn gen out/Release --args="import(\"//electron/build/args/release.gn\")"
```
**Note:** This will generate a `out/Testing` or `out/Release` build directory under `src/` with the testing or release build depending upon the configuration passed above. You can replace `Testing|Release` with another names, but it should be a subdirectory of `out`.
Also you shouldn't have to run `gn gen` again—if you want to change the build arguments, you can run `gn args out/Testing` to bring up an editor. To see the list of available build configuration options, run `gn args out/Testing --list`.
**To build, run `ninja` with the `electron` target:** Note: This will also take a while and probably heat up your lap.
For the testing configuration:
```
$ ninja -C out/Testing electron
```
For the release configuration:
```
$ ninja -C out/Release electron
```
This will build all of what was previously 'libchromiumcontent' (i.e. the `content/` directory of `chromium` and its dependencies, incl. WebKit and V8), so it will take a while.
The built executable will be under `./out/Testing`:
```
$ ./out/Testing/Electron.app/Contents/MacOS/Electron
# or, on Windows
$ ./out/Testing/electron.exe
# or, on Linux
$ ./out/Testing/electron
```
### Packaging[](#packaging "Direct link to heading")
On linux, first strip the debugging and symbol information:
```
$ electron/script/strip-binaries.py -d out/Release
```
To package the electron build as a distributable zip file:
```
$ ninja -C out/Release electron:electron_dist_zip
```
### Cross-compiling[](#cross-compiling "Direct link to heading")
To compile for a platform that isn't the same as the one you're building on, set the `target_cpu` and `target_os` GN arguments. For example, to compile an x86 target from an x64 host, specify `target_cpu = "x86"` in `gn args`.
```
$ gn gen out/Testing-x86 --args='... target_cpu = "x86"'
```
Not all combinations of source and target CPU/OS are supported by Chromium.
| Host | Target | Status |
| --- | --- | --- |
| Windows x64 | Windows arm64 | Experimental |
| Windows x64 | Windows x86 | Automatically tested |
| Linux x64 | Linux x86 | Automatically tested |
If you test other combinations and find them to work, please update this document :)
See the GN reference for allowable values of [`target_os`](https://gn.googlesource.com/gn/+/main/docs/reference.md#built_in-predefined-variables-target_os_the-desired-operating-system-for-the-build-possible-values) and [`target_cpu`](https://gn.googlesource.com/gn/+/main/docs/reference.md#built_in-predefined-variables-target_cpu_the-desired-cpu-architecture-for-the-build-possible-values).
#### Windows on Arm (experimental)[](#windows-on-arm-experimental "Direct link to heading")
To cross-compile for Windows on Arm, [follow Chromium's guide](https://chromium.googlesource.com/chromium/src/+/refs/heads/main/docs/windows_build_instructions.md#Visual-Studio) to get the necessary dependencies, SDK and libraries, then build with `ELECTRON_BUILDING_WOA=1` in your environment before running `gclient sync`.
```
set ELECTRON_BUILDING_WOA=1
gclient sync -f --with_branch_heads --with_tags
```
Or (if using PowerShell):
```
$env:ELECTRON_BUILDING_WOA=1
gclient sync -f --with_branch_heads --with_tags
```
Next, run `gn gen` as above with `target_cpu="arm64"`.
Tests[](#tests "Direct link to heading")
-----------------------------------------
To run the tests, you'll first need to build the test modules against the same version of Node.js that was built as part of the build process. To generate build headers for the modules to compile against, run the following under `src/` directory.
```
$ ninja -C out/Testing third_party/electron_node:headers
```
You can now [run the tests](testing#unit-tests).
If you're debugging something, it can be helpful to pass some extra flags to the Electron binary:
```
$ npm run test -- \
--enable-logging -g 'BrowserWindow module'
```
Sharing the git cache between multiple machines[](#sharing-the-git-cache-between-multiple-machines "Direct link to heading")
-----------------------------------------------------------------------------------------------------------------------------
It is possible to share the gclient git cache with other machines by exporting it as SMB share on linux, but only one process/machine can be using the cache at a time. The locks created by git-cache script will try to prevent this, but it may not work perfectly in a network.
On Windows, SMBv2 has a directory cache that will cause problems with the git cache script, so it is necessary to disable it by setting the registry key
```
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Lanmanworkstation\Parameters\DirectoryCacheLifetime
```
to 0. More information: <https://stackoverflow.com/a/9935126>
This can be set quickly in powershell (ran as administrator):
```
New-ItemProperty -Path "HKLM:\System\CurrentControlSet\Services\Lanmanworkstation\Parameters" -Name DirectoryCacheLifetime -Value 0 -PropertyType DWORD -Force
```
Troubleshooting[](#troubleshooting "Direct link to heading")
-------------------------------------------------------------
### gclient sync complains about rebase[](#gclient-sync-complains-about-rebase "Direct link to heading")
If `gclient sync` is interrupted the git tree may be left in a bad state, leading to a cryptic message when running `gclient sync` in the future:
```
2> Conflict while rebasing this branch.
2> Fix the conflict and run gclient again.
2> See man git-rebase for details.
```
If there are no git conflicts or rebases in `src/electron`, you may need to abort a `git am` in `src`:
```
$ cd ../
$ git am --abort
$ cd electron
$ gclient sync -f
```
### I'm being asked for a username/password for chromium-internal.googlesource.com[](#im-being-asked-for-a-usernamepassword-for-chromium-internalgooglesourcecom "Direct link to heading")
If you see a prompt for `Username for 'https://chrome-internal.googlesource.com':` when running `gclient sync` on Windows, it's probably because the `DEPOT_TOOLS_WIN_TOOLCHAIN` environment variable is not set to 0. Open `Control Panel` → `System and Security` → `System` → `Advanced system settings` and add a system variable `DEPOT_TOOLS_WIN_TOOLCHAIN` with value `0`. This tells `depot_tools` to use your locally installed version of Visual Studio (by default, `depot_tools` will try to download a Google-internal version that only Googlers have access to).
electron Updating an Appveyor Azure Image Updating an Appveyor Azure Image
================================
Electron CI on Windows uses AppVeyor, which in turn uses Azure VM images to run. Occasionally, these VM images need to be updated due to changes in Chromium requirements. In order to update you will need [PowerShell](https://docs.microsoft.com/en-us/powershell/scripting/install/installing-powershell?view=powershell-6) and the [Azure PowerShell module](https://docs.microsoft.com/en-us/powershell/azure/install-az-ps?view=azps-1.8.0&viewFallbackFrom=azurermps-6.13.0).
Occasionally we need to update these images owing to changes in Chromium or other miscellaneous build requirement changes.
Example Use Case:
```
* We need `VS15.9` and we have `VS15.7` installed; this would require us to update an Azure image.
```
1. Identify the image you wish to modify.
* In [appveyor.yml](https://github.com/electron/electron/blob/main/appveyor.yml), the image is identified by the property *image*.
+ The names used correspond to the *"images"* defined for a build cloud, eg the [libcc-20 cloud](https://windows-ci.electronjs.org/build-clouds/8).
* Find the image you wish to modify in the build cloud and make note of the **VHD Blob Path** for that image, which is the value for that corresponding key.
+ You will need this URI path to copy into a new image.
* You will also need the storage account name which is labeled in AppVeyor as the **Disk Storage Account Name**
2. Get the Azure storage account key
* Log into Azure using credentials stored in LastPass (under Azure Enterprise) and then find the storage account corresponding to the name found in AppVeyor.
+ Example, for `appveyorlibccbuilds` **Disk Storage Account Name** you'd look for `appveyorlibccbuilds` in the list of storage accounts @ Home < Storage Accounts
- Click into it and look for `Access Keys`, and then you can use any of the keys present in the list.
3. Get the full virtual machine image URI from Azure
* Navigate to Home < Storage Accounts < `$ACCT_NAME` < Blobs < Images
+ In the following list, look for the VHD path name you got from Appveyor and then click on it.
- Copy the whole URL from the top of the subsequent window.
4. Copy the image using the [Copy Master Image PowerShell script](https://github.com/appveyor/ci/blob/master/scripts/enterprise/copy-master-image-azure.ps1).
* It is essential to copy the VM because if you spin up a VM against an image that image cannot at the same time be used by AppVeyor.
* Use the storage account name, key, and URI obtained from Azure to run this script.
+ See Step 3 for URI & when prompted, press enter to use same storage account as destination.
+ Use default destination container name `(images)`
+ Also, when naming the copy, use a name that indicates what the new image will contain (if that has changed) and date stamp.
- Ex. `libcc-20core-vs2017-15.9-2019-04-15.vhd`
* Go into Azure and get the URI for the newly created image as described in a previous step
5. Spin up a new VM using the [Create Master VM from VHD PowerShell](https://github.com/appveyor/ci/blob/master/scripts/enterprise/create_master_vm_from_vhd.ps1).
* From PowerShell, execute `ps1` file with `./create_master_vm_from_vhd.ps1`
* You will need the credential information available in the AppVeyor build cloud definition.
+ This includes:
- Client ID
- Client Secret
- Tenant ID
- Subscription ID
- Resource Group
- Virtual Network
* You will also need to specify
+ Master VM name - just a unique name to identify the temporary VM
+ Master VM size - use `Standard_F32s_v2`
+ Master VHD URI - use URI obtained @ end of previous step
+ Location use `East US`
6. Log back into Azure and find the VM you just created in Home < Virtual Machines < `$YOUR_NEW_VM`
* You can download a RDP (Remote Desktop) file to access the VM.
7. Using Microsoft Remote Desktop, click `Connect` to connect to the VM.
* Credentials for logging into the VM are found in LastPass under the `AppVeyor Enterprise master VM` credentials.
8. Modify the VM as required.
9. Shut down the VM and then delete it in Azure.
10. Add the new image to the Appveyor Cloud settings or modify an existing image to point to the new VHD.
electron Coding Style Coding Style
============
These are the style guidelines for coding in Electron.
You can run `npm run lint` to show any style issues detected by `cpplint` and `eslint`.
General Code[](#general-code "Direct link to heading")
-------------------------------------------------------
* End files with a newline.
* Place requires in the following order:
+ Built in Node Modules (such as `path`)
+ Built in Electron Modules (such as `ipc`, `app`)
+ Local Modules (using relative paths)
* Place class properties in the following order:
+ Class methods and properties (methods starting with a `@`)
+ Instance methods and properties
* Avoid platform-dependent code:
+ Use `path.join()` to concatenate filenames.
+ Use `os.tmpdir()` rather than `/tmp` when you need to reference the temporary directory.
* Using a plain `return` when returning explicitly at the end of a function.
+ Not `return null`, `return undefined`, `null` or `undefined`
C++ and Python[](#c-and-python "Direct link to heading")
---------------------------------------------------------
For C++ and Python, we follow Chromium's [Coding Style](https://chromium.googlesource.com/chromium/src/+/refs/heads/main/styleguide/styleguide.md). There is also a script `script/cpplint.py` to check whether all files conform.
The Python version we are using now is Python 3.9.
The C++ code uses a lot of Chromium's abstractions and types, so it's recommended to get acquainted with them. A good place to start is Chromium's [Important Abstractions and Data Structures](https://www.chromium.org/developers/coding-style/important-abstractions-and-data-structures) document. The document mentions some special types, scoped types (that automatically release their memory when going out of scope), logging mechanisms etc.
Documentation[](#documentation "Direct link to heading")
---------------------------------------------------------
* Write [remark](https://github.com/remarkjs/remark) markdown style.
You can run `npm run lint-docs` to ensure that your documentation changes are formatted correctly.
JavaScript[](#javascript "Direct link to heading")
---------------------------------------------------
* Write [standard](https://www.npmjs.com/package/standard) JavaScript style.
* File names should be concatenated with `-` instead of `_`, e.g. `file-name.js` rather than `file_name.js`, because in [github/atom](https://github.com/github/atom) module names are usually in the `module-name` form. This rule only applies to `.js` files.
* Use newer ES6/ES2015 syntax where appropriate
+ [`const`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/const) for requires and other constants. If the value is a primitive, use uppercase naming (eg `const NUMBER_OF_RETRIES = 5`).
+ [`let`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let) for defining variables
+ [Arrow functions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions) instead of `function () { }`
+ [Template literals](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals) instead of string concatenation using `+`
Naming Things[](#naming-things "Direct link to heading")
---------------------------------------------------------
Electron APIs uses the same capitalization scheme as Node.js:
* When the module itself is a class like `BrowserWindow`, use `PascalCase`.
* When the module is a set of APIs, like `globalShortcut`, use `camelCase`.
* When the API is a property of object, and it is complex enough to be in a separate chapter like `win.webContents`, use `mixedCase`.
* For other non-module APIs, use natural titles, like `<webview> Tag` or `Process Object`.
When creating a new API, it is preferred to use getters and setters instead of jQuery's one-function style. For example, `.getText()` and `.setText(text)` are preferred to `.text([text])`. There is a [discussion](https://github.com/electron/electron/issues/46) on this.
electron Electron Debugging Electron Debugging
==================
There are many different approaches to debugging issues and bugs in Electron, many of which are platform specific.
Some of the more common approaches are outlined below.
Generic Debugging[](#generic-debugging "Direct link to heading")
-----------------------------------------------------------------
Chromium contains logging macros which can aid debugging by printing information to console in C++ and Objective-C++.
You might use this to print out variable values, function names, and line numbers, amonst other things.
Some examples:
```
LOG(INFO) << "bitmap.width(): " << bitmap.width();
LOG(INFO, bitmap.width() > 10) << "bitmap.width() is greater than 10!";
```
There are also different levels of logging severity: `INFO`, `WARN`, and `ERROR`.
See [logging.h](https://chromium.googlesource.com/chromium/src/base/+/refs/heads/main/logging.h) in Chromium's source tree for more information and examples.
Printing Stacktraces[](#printing-stacktraces "Direct link to heading")
-----------------------------------------------------------------------
Chromium contains a helper to print stack traces to console without interrrupting the program.
```
#include "base/debug/stack_trace.h"
...
base::debug::StackTrace().Print();
```
This will allow you to observe call chains and identify potential issue areas.
Breakpoint Debugging[](#breakpoint-debugging "Direct link to heading")
-----------------------------------------------------------------------
> Note that this will increase the size of the build significantly, taking up around 50G of disk space
>
>
Write the following file to `electron/.git/info/exclude/debug.gn`
```
import("//electron/build/args/testing.gn")
is_debug = true
symbol_level = 2
forbid_non_component_debug_builds = false
```
Then execute:
```
$ gn gen out/Debug --args="import(\"//electron/.git/info/exclude/debug.gn\") $GN_EXTRA_ARGS"
$ ninja -C out/Debug electron
```
Now you can use `LLDB` for breakpoint debugging.
Platform-Specific Debugging[](#platform-specific-debugging "Direct link to heading")
-------------------------------------------------------------------------------------
* [macOS Debugging](debugging-on-macos)
+ [Debugging with Xcode](debugging-with-xcode)
* [Windows Debugging](debugging-on-windows)
Debugging with the Symbol Server[](#debugging-with-the-symbol-server "Direct link to heading")
-----------------------------------------------------------------------------------------------
Debug symbols allow you to have better debugging sessions. They have information about the functions contained in executables and dynamic libraries and provide you with information to get clean call stacks. A Symbol Server allows the debugger to load the correct symbols, binaries and sources automatically without forcing users to download large debugging files.
For more information about how to set up a symbol server for Electron, see [debugging with a symbol server](debugging-with-symbol-server).
| programming_docs |
electron Chromium Development Chromium Development
====================
> A collection of resources for learning about Chromium and tracking its development.
>
>
See also [V8 Development](v8-development)
Contributing to Chromium[](#contributing-to-chromium "Direct link to heading")
-------------------------------------------------------------------------------
* [Checking Out and Building](https://chromium.googlesource.com/chromium/src/+/main/docs/#checking-out-and-building)
+ [Windows](https://chromium.googlesource.com/chromium/src/+/main/docs/windows_build_instructions.md)
+ [macOS](https://chromium.googlesource.com/chromium/src/+/main/docs/mac_build_instructions.md)
+ [Linux](https://chromium.googlesource.com/chromium/src/+/main/docs/linux/build_instructions.md)
* [Contributing](https://chromium.googlesource.com/chromium/src/+/refs/heads/main/docs/contributing.md) - This document outlines the process of getting a code change merged to the Chromium source tree.
+ Assumes a working Chromium checkout and build.
Resources for Chromium Development[](#resources-for-chromium-development "Direct link to heading")
---------------------------------------------------------------------------------------------------
### Code Resources[](#code-resources "Direct link to heading")
* [Code Search](https://cs.chromium.org/) - Indexed and searchable source code for Chromium and associated projects.
* [Source Code](https://cs.chromium.org/chromium/src/) - The source code for Chromium itself.
* [Chromium Review](https://chromium-review.googlesource.com) - The searchable code host which facilitates code reviews for Chromium and related projects.
### Informational Resources[](#informational-resources "Direct link to heading")
* [Chromium Dash](https://chromiumdash.appspot.com/home) - Chromium Dash ties together multiple data sources in order to present a consolidated view of what's going on in Chromium and Chrome, plus related projects like V8, WebRTC & Skia.
+ [Schedule](https://chromiumdash.appspot.com/schedule) - Review upcoming Chromium release schedule.
+ [Branches](https://chromiumdash.appspot.com/branches) - Look up which branch corresponds to which milestone.
+ [Releases](https://chromiumdash.appspot.com/releases) - See what version of Chromium is shipping to each release channel and look up changes between each version.
+ [Commits](https://chromiumdash.appspot.com/commits) - See and search for commits to the Chromium source tree by commit SHA or committer username.
* [Discussion Groups](https://www.chromium.org/developers/discussion-groups) - Subscribe to the following groups to get project updates and discuss the Chromium projects, and to get help in developing for Chromium-based browsers.
* [Chromium Slack](https://www.chromium.org/developers/slack) - a virtual meeting place where Chromium ecosystem developers can foster community and coordinate work.
Social Links[](#social-links "Direct link to heading")
-------------------------------------------------------
* [Blog](https://blog.chromium.org) - News and developments from Chromium.
* [@ChromiumDev](https://twitter.com/ChromiumDev) - Twitter account containing news & guidance for developers from the Google Chrome Developer Relations team.
* [@googlechrome](https://twitter.com/googlechrome) - Official Twitter account for the Google Chrome browser.
electron Debugging on macOS Debugging on macOS
==================
If you experience crashes or issues in Electron that you believe are not caused by your JavaScript application, but instead by Electron itself, debugging can be a little bit tricky especially for developers not used to native/C++ debugging. However, using `lldb` and the Electron source code, you can enable step-through debugging with breakpoints inside Electron's source code. You can also use [XCode for debugging](debugging-with-xcode) if you prefer a graphical interface.
Requirements[](#requirements "Direct link to heading")
-------------------------------------------------------
* **A testing build of Electron**: The easiest way is usually to build it from source, which you can do by following the instructions in the [build instructions](build-instructions-macos). While you can attach to and debug Electron as you can download it directly, you will find that it is heavily optimized, making debugging substantially more difficult. In this case the debugger will not be able to show you the content of all variables and the execution path can seem strange because of inlining, tail calls, and other compiler optimizations.
* **Xcode**: In addition to Xcode, you should also install the Xcode command line tools. They include [LLDB](https://lldb.llvm.org/), the default debugger in Xcode on macOS. It supports debugging C, Objective-C and C++ on the desktop and iOS devices and simulator.
* **.lldbinit**: Create or edit `~/.lldbinit` to allow Chromium code to be properly source-mapped.
```
# e.g: ['~/electron/src/tools/lldb']
script sys.path[:0] = ['<...path/to/electron/src/tools/lldb>']
script import lldbinit
```
Attaching to and Debugging Electron[](#attaching-to-and-debugging-electron "Direct link to heading")
-----------------------------------------------------------------------------------------------------
To start a debugging session, open up Terminal and start `lldb`, passing a non-release build of Electron as a parameter.
```
$ lldb ./out/Testing/Electron.app
(lldb) target create "./out/Testing/Electron.app"
Current executable set to './out/Testing/Electron.app' (x86_64).
```
### Setting Breakpoints[](#setting-breakpoints "Direct link to heading")
LLDB is a powerful tool and supports multiple strategies for code inspection. For this basic introduction, let's assume that you're calling a command from JavaScript that isn't behaving correctly - so you'd like to break on that command's C++ counterpart inside the Electron source.
Relevant code files can be found in `./shell/`.
Let's assume that you want to debug `app.setName()`, which is defined in `browser.cc` as `Browser::SetName()`. Set the breakpoint using the `breakpoint` command, specifying file and line to break on:
```
(lldb) breakpoint set --file browser.cc --line 117
Breakpoint 1: where = Electron Framework`atom::Browser::SetName(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) + 20 at browser.cc:118, address = 0x000000000015fdb4
```
Then, start Electron:
```
(lldb) run
```
The app will immediately be paused, since Electron sets the app's name on launch:
```
(lldb) run
Process 25244 launched: '/Users/fr/Code/electron/out/Testing/Electron.app/Contents/MacOS/Electron' (x86_64)
Process 25244 stopped
* thread #1: tid = 0x839a4c, 0x0000000100162db4 Electron Framework`atom::Browser::SetName(this=0x0000000108b14f20, name="Electron") + 20 at browser.cc:118, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
frame #0: 0x0000000100162db4 Electron Framework`atom::Browser::SetName(this=0x0000000108b14f20, name="Electron") + 20 at browser.cc:118
115 }
116
117 void Browser::SetName(const std::string& name) {
-> 118 name_override_ = name;
119 }
120
121 int Browser::GetBadgeCount() {
(lldb)
```
To show the arguments and local variables for the current frame, run `frame variable` (or `fr v`), which will show you that the app is currently setting the name to "Electron".
```
(lldb) frame variable
(atom::Browser *) this = 0x0000000108b14f20
(const string &) name = "Electron": {
[...]
}
```
To do a source level single step in the currently selected thread, execute `step` (or `s`). This would take you into `name_override_.empty()`. To proceed and do a step over, run `next` (or `n`).
```
(lldb) step
Process 25244 stopped
* thread #1: tid = 0x839a4c, 0x0000000100162dcc Electron Framework`atom::Browser::SetName(this=0x0000000108b14f20, name="Electron") + 44 at browser.cc:119, queue = 'com.apple.main-thread', stop reason = step in
frame #0: 0x0000000100162dcc Electron Framework`atom::Browser::SetName(this=0x0000000108b14f20, name="Electron") + 44 at browser.cc:119
116
117 void Browser::SetName(const std::string& name) {
118 name_override_ = name;
-> 119 }
120
121 int Browser::GetBadgeCount() {
122 return badge_count_;
```
**NOTE:** If you don't see source code when you think you should, you may not have added the `~/.lldbinit` file above.
To finish debugging at this point, run `process continue`. You can also continue until a certain line is hit in this thread (`thread until 100`). This command will run the thread in the current frame till it reaches line 100 in this frame or stops if it leaves the current frame.
Now, if you open up Electron's developer tools and call `setName`, you will once again hit the breakpoint.
### Further Reading[](#further-reading "Direct link to heading")
LLDB is a powerful tool with a great documentation. To learn more about it, consider Apple's debugging documentation, for instance the [LLDB Command Structure Reference](https://developer.apple.com/library/mac/documentation/IDEs/Conceptual/gdb_to_lldb_transition_guide/document/lldb-basics.html#//apple_ref/doc/uid/TP40012917-CH2-SW2) or the introduction to [Using LLDB as a Standalone Debugger](https://developer.apple.com/library/mac/documentation/IDEs/Conceptual/gdb_to_lldb_transition_guide/document/lldb-terminal-workflow-tutorial.html).
You can also check out LLDB's fantastic [manual and tutorial](https://lldb.llvm.org/tutorial.html), which will explain more complex debugging scenarios.
electron Build Instructions (macOS) Build Instructions (macOS)
==========================
Follow the guidelines below for building **Electron itself** on macOS, for the purposes of creating custom Electron binaries. For bundling and distributing your app code with the prebuilt Electron binaries, see the [application distribution](../tutorial/application-distribution) guide.
Prerequisites[](#prerequisites "Direct link to heading")
---------------------------------------------------------
* macOS >= 11.6.0
* [Xcode](https://developer.apple.com/technologies/tools/). The exact version needed depends on what branch you are building, but the latest version of Xcode is generally a good bet for building `main`.
* [node.js](https://nodejs.org) (external)
* Python >= 3.7
Building Electron[](#building-electron "Direct link to heading")
-----------------------------------------------------------------
See [Build Instructions: GN](build-instructions-gn).
electron Issues In Electron Issues In Electron
==================
* [How to Contribute to Issues](#how-to-contribute-to-issues)
* [Asking for General Help](#asking-for-general-help)
* [Submitting a Bug Report](#submitting-a-bug-report)
* [Triaging a Bug Report](#triaging-a-bug-report)
* [Resolving a Bug Report](#resolving-a-bug-report)
How to Contribute to Issues[](#how-to-contribute-to-issues "Direct link to heading")
-------------------------------------------------------------------------------------
For any issue, there are fundamentally three ways an individual can contribute:
1. By opening the issue for discussion: If you believe that you have found a new bug in Electron, you should report it by creating a new issue in the [`electron/electron` issue tracker](https://github.com/electron/electron/issues).
2. By helping to triage the issue: You can do this either by providing assistive details (a reproducible test case that demonstrates a bug) or by providing suggestions to address the issue.
3. By helping to resolve the issue: This can be done by demonstrating that the issue is not a bug or is fixed; but more often, by opening a pull request that changes the source in `electron/electron` in a concrete and reviewable manner.
Asking for General Help[](#asking-for-general-help "Direct link to heading")
-----------------------------------------------------------------------------
[The Electron website](https://electronjs.org/community) has a list of resources for getting programming help, reporting security issues, contributing, and more. Please use the issue tracker for bugs only!
Submitting a Bug Report[](#submitting-a-bug-report "Direct link to heading")
-----------------------------------------------------------------------------
To submit a bug report:
When opening a new issue in the [`electron/electron` issue tracker](https://github.com/electron/electron/issues/new/choose), users will be presented with a template that should be filled in.
If you believe that you have found a bug in Electron, please fill out the template to the best of your ability.
The two most important pieces of information needed to evaluate the report are a description of the bug and a simple test case to recreate it. It is easier to fix a bug if it can be reproduced.
See [How to create a Minimal, Complete, and Verifiable example](https://stackoverflow.com/help/mcve).
Triaging a Bug Report[](#triaging-a-bug-report "Direct link to heading")
-------------------------------------------------------------------------
It's common for open issues to involve discussion. Some contributors may have differing opinions, including whether the behavior is a bug or feature. This discussion is part of the process and should be kept focused, helpful, and professional.
Terse responses that provide neither additional context nor supporting detail are not helpful or professional. To many, such responses are annoying and unfriendly.
Contributors are encouraged to solve issues collaboratively and help one another make progress. If you encounter an issue that you feel is invalid, or which contains incorrect information, explain *why* you feel that way with additional supporting context, and be willing to be convinced that you may be wrong. By doing so, we can often reach the correct outcome faster.
Resolving a Bug Report[](#resolving-a-bug-report "Direct link to heading")
---------------------------------------------------------------------------
Most issues are resolved by opening a pull request. The process for opening and reviewing a pull request is similar to that of opening and triaging issues, but carries with it a necessary review and approval workflow that ensures that the proposed changes meet the minimal quality and functional guidelines of the Electron project.
electron Build Instructions (Windows) Build Instructions (Windows)
============================
Follow the guidelines below for building **Electron itself** on Windows, for the purposes of creating custom Electron binaries. For bundling and distributing your app code with the prebuilt Electron binaries, see the [application distribution](../tutorial/application-distribution) guide.
Prerequisites[](#prerequisites "Direct link to heading")
---------------------------------------------------------
* Windows 10 / Server 2012 R2 or higher
* Visual Studio 2017 15.7.2 or higher - [download VS 2019 Community Edition for free](https://www.visualstudio.com/vs/)
+ See [the Chromium build documentation](https://chromium.googlesource.com/chromium/src/+/main/docs/windows_build_instructions.md#visual-studio) for more details on which Visual Studio components are required.
+ If your Visual Studio is installed in a directory other than the default, you'll need to set a few environment variables to point the toolchains to your installation path.
- `vs2019_install = DRIVE:\path\to\Microsoft Visual Studio\2019\Community`, replacing `2019` and `Community` with your installed versions and replacing `DRIVE:` with the drive that Visual Studio is on. Often, this will be `C:`.
- `WINDOWSSDKDIR = DRIVE:\path\to\Windows Kits\10`, replacing `DRIVE:` with the drive that Windows Kits is on. Often, this will be `C:`.
* [Node.js](https://nodejs.org/download/)
* [Git](https://git-scm.com)
* Debugging Tools for Windows of Windows SDK 10.0.15063.468 if you plan on creating a full distribution since `symstore.exe` is used for creating a symbol store from `.pdb` files.
+ Different versions of the SDK can be installed side by side. To install the SDK, open Visual Studio Installer, select `Modify` → `Individual Components`, scroll down and select the appropriate Windows SDK to install. Another option would be to look at the [Windows SDK and emulator archive](https://developer.microsoft.com/en-us/windows/downloads/sdk-archive) and download the standalone version of the SDK respectively.
+ The SDK Debugging Tools must also be installed. If the Windows 10 SDK was installed via the Visual Studio installer, then they can be installed by going to: `Control Panel` → `Programs` → `Programs and Features` → Select the "Windows Software Development Kit" → `Change` → `Change` → Check "Debugging Tools For Windows" → `Change`. Or, you can download the standalone SDK installer and use it to install the Debugging Tools.
If you don't currently have a Windows installation, [dev.microsoftedge.com](https://developer.microsoft.com/en-us/microsoft-edge/tools/vms/) has timebombed versions of Windows that you can use to build Electron.
Building Electron is done entirely with command-line scripts and cannot be done with Visual Studio. You can develop Electron with any editor but support for building with Visual Studio will come in the future.
**Note:** Even though Visual Studio is not used for building, it's still **required** because we need the build toolchains it provides.
Exclude source tree from Windows Security[](#exclude-source-tree-from-windows-security "Direct link to heading")
-----------------------------------------------------------------------------------------------------------------
Windows Security doesn't like one of the files in the Chromium source code (see <https://crbug.com/441184>), so it will constantly delete it, causing `gclient sync` issues. You can exclude the source tree from being monitored by Windows Security by [following these instructions](https://support.microsoft.com/en-us/windows/add-an-exclusion-to-windows-security-811816c0-4dfd-af4a-47e4-c301afe13b26).
Building[](#building "Direct link to heading")
-----------------------------------------------
See [Build Instructions: GN](build-instructions-gn)
32bit Build[](#32bit-build "Direct link to heading")
-----------------------------------------------------
To build for the 32bit target, you need to pass `target_cpu = "x86"` as a GN arg. You can build the 32bit target alongside the 64bit target by using a different output directory for GN, e.g. `out/Release-x86`, with different arguments.
```
$ gn gen out/Release-x86 --args="import(\"//electron/build/args/release.gn\") target_cpu=\"x86\""
```
The other building steps are exactly the same.
Visual Studio project[](#visual-studio-project "Direct link to heading")
-------------------------------------------------------------------------
To generate a Visual Studio project, you can pass the `--ide=vs2017` parameter to `gn gen`:
```
$ gn gen out/Testing --ide=vs2017
```
Troubleshooting[](#troubleshooting "Direct link to heading")
-------------------------------------------------------------
### Command xxxx not found[](#command-xxxx-not-found "Direct link to heading")
If you encountered an error like `Command xxxx not found`, you may try to use the `VS2015 Command Prompt` console to execute the build scripts.
### Fatal internal compiler error: C1001[](#fatal-internal-compiler-error-c1001 "Direct link to heading")
Make sure you have the latest Visual Studio update installed.
### LNK1181: cannot open input file 'kernel32.lib'[](#lnk1181-cannot-open-input-file-kernel32lib "Direct link to heading")
Try reinstalling 32bit Node.js.
### Error: ENOENT, stat 'C:\Users\USERNAME\AppData\Roaming\npm'[](#error-enoent-stat-cusersusernameappdataroamingnpm "Direct link to heading")
Creating that directory [should fix the problem](https://stackoverflow.com/a/25095327/102704):
```
$ mkdir ~\AppData\Roaming\npm
```
### node-gyp is not recognized as an internal or external command[](#node-gyp-is-not-recognized-as-an-internal-or-external-command "Direct link to heading")
You may get this error if you are using Git Bash for building, you should use PowerShell or VS2015 Command Prompt instead.
### cannot create directory at '...': Filename too long[](#cannot-create-directory-at--filename-too-long "Direct link to heading")
node.js has some [extremely long pathnames](https://github.com/electron/node/tree/electron/deps/npm/node_modules/libnpx/node_modules/yargs/node_modules/read-pkg-up/node_modules/read-pkg/node_modules/load-json-file/node_modules/parse-json/node_modules/error-ex/node_modules/is-arrayish), and by default git on windows doesn't handle long pathnames correctly (even though windows supports them). This should fix it:
```
$ git config --system core.longpaths true
```
### error: use of undeclared identifier 'DefaultDelegateCheckMode'[](#error-use-of-undeclared-identifier-defaultdelegatecheckmode "Direct link to heading")
This can happen during build, when Debugging Tools for Windows has been installed with Windows Driver Kit. Uninstall Windows Driver Kit and install Debugging Tools with steps described above.
### ImportError: No module named win32file[](#importerror-no-module-named-win32file "Direct link to heading")
Make sure you have installed `pywin32` with `pip install pywin32`.
### Build Scripts Hang Until Keypress[](#build-scripts-hang-until-keypress "Direct link to heading")
This bug is a "feature" of Windows' command prompt. It happens when clicking inside the prompt window with `QuickEdit` enabled and is intended to allow selecting and copying output text easily. Since each accidental click will pause the build process, you might want to disable this feature in the command prompt properties.
| programming_docs |
electron Pull Requests Pull Requests
=============
* [Setting up your local environment](#setting-up-your-local-environment)
+ [Step 1: Fork](#step-1-fork)
+ [Step 2: Build](#step-2-build)
+ [Step 3: Branch](#step-3-branch)
* [Making Changes](#making-changes)
+ [Step 4: Code](#step-4-code)
+ [Step 5: Commit](#step-5-commit)
- [Commit message guidelines](#commit-message-guidelines)
+ [Step 6: Rebase](#step-6-rebase)
+ [Step 7: Test](#step-7-test)
+ [Step 8: Push](#step-8-push)
+ [Step 9: Opening the Pull Request](#step-9-opening-the-pull-request)
+ [Step 10: Discuss and Update](#step-10-discuss-and-update)
- [Approval and Request Changes Workflow](#approval-and-request-changes-workflow)
+ [Step 11: Landing](#step-11-landing)
+ [Continuous Integration Testing](#continuous-integration-testing)
Setting up your local environment[](#setting-up-your-local-environment "Direct link to heading")
-------------------------------------------------------------------------------------------------
### Step 1: Fork[](#step-1-fork "Direct link to heading")
Fork the project [on GitHub](https://github.com/electron/electron) and clone your fork locally.
```
$ git clone [email protected]:username/electron.git
$ cd electron
$ git remote add upstream https://github.com/electron/electron.git
$ git fetch upstream
```
### Step 2: Build[](#step-2-build "Direct link to heading")
Build steps and dependencies differ slightly depending on your operating system. See these detailed guides on building Electron locally:
* [Building on macOS](build-instructions-macos)
* [Building on Linux](build-instructions-linux)
* [Building on Windows](build-instructions-windows)
Once you've built the project locally, you're ready to start making changes!
### Step 3: Branch[](#step-3-branch "Direct link to heading")
To keep your development environment organized, create local branches to hold your work. These should be branched directly off of the `main` branch.
```
$ git checkout -b my-branch -t upstream/main
```
Making Changes[](#making-changes "Direct link to heading")
-----------------------------------------------------------
### Step 4: Code[](#step-4-code "Direct link to heading")
Most pull requests opened against the `electron/electron` repository include changes to either the C/C++ code in the `shell/` folder, the JavaScript code in the `lib/` folder, the documentation in `docs/api/` or tests in the `spec/` folder.
Please be sure to run `npm run lint` from time to time on any code changes to ensure that they follow the project's code style.
See [coding style](coding-style) for more information about best practice when modifying code in different parts of the project.
### Step 5: Commit[](#step-5-commit "Direct link to heading")
It is recommended to keep your changes grouped logically within individual commits. Many contributors find it easier to review changes that are split across multiple commits. There is no limit to the number of commits in a pull request.
```
$ git add my/changed/files
$ git commit
```
Note that multiple commits get squashed when they are landed.
#### Commit message guidelines[](#commit-message-guidelines "Direct link to heading")
A good commit message should describe what changed and why. The Electron project uses [semantic commit messages](https://conventionalcommits.org/) to streamline the release process.
Before a pull request can be merged, it **must** have a pull request title with a semantic prefix.
Examples of commit messages with semantic prefixes:
* `fix: don't overwrite prevent_default if default wasn't prevented`
* `feat: add app.isPackaged() method`
* `docs: app.isDefaultProtocolClient is now available on Linux`
Common prefixes:
* fix: A bug fix
* feat: A new feature
* docs: Documentation changes
* test: Adding missing tests or correcting existing tests
* build: Changes that affect the build system
* ci: Changes to our CI configuration files and scripts
* perf: A code change that improves performance
* refactor: A code change that neither fixes a bug nor adds a feature
* style: Changes that do not affect the meaning of the code (linting)
Other things to keep in mind when writing a commit message:
1. The first line should:
* contain a short description of the change (preferably 50 characters or less, and no more than 72 characters)
* be entirely in lowercase with the exception of proper nouns, acronyms, and the words that refer to code, like function/variable names
2. Keep the second line blank.
3. Wrap all other lines at 72 columns.
#### Breaking Changes[](#breaking-changes "Direct link to heading")
A commit that has the text `BREAKING CHANGE:` at the beginning of its optional body or footer section introduces a breaking API change (correlating with Major in semantic versioning). A breaking change can be part of commits of any type. e.g., a `fix:`, `feat:` & `chore:` types would all be valid, in addition to any other type.
See [conventionalcommits.org](https://conventionalcommits.org) for more details.
### Step 6: Rebase[](#step-6-rebase "Direct link to heading")
Once you have committed your changes, it is a good idea to use `git rebase` (not `git merge`) to synchronize your work with the main repository.
```
$ git fetch upstream
$ git rebase upstream/main
```
This ensures that your working branch has the latest changes from `electron/electron` main.
### Step 7: Test[](#step-7-test "Direct link to heading")
Bug fixes and features should always come with tests. A [testing guide](testing) has been provided to make the process easier. Looking at other tests to see how they should be structured can also help.
Before submitting your changes in a pull request, always run the full test suite. To run the tests:
```
$ npm run test
```
Make sure the linter does not report any issues and that all tests pass. Please do not submit patches that fail either check.
If you are updating tests and want to run a single spec to check it:
```
$ npm run test -match=menu
```
The above would only run spec modules matching `menu`, which is useful for anyone who's working on tests that would otherwise be at the very end of the testing cycle.
### Step 8: Push[](#step-8-push "Direct link to heading")
Once your commits are ready to go -- with passing tests and linting -- begin the process of opening a pull request by pushing your working branch to your fork on GitHub.
```
$ git push origin my-branch
```
### Step 9: Opening the Pull Request[](#step-9-opening-the-pull-request "Direct link to heading")
From within GitHub, opening a new pull request will present you with a template that should be filled out. It can be found [here](https://github.com/electron/electron/blob/main/.github/PULL_REQUEST_TEMPLATE.md).
If you do not adequately complete this template, your PR may be delayed in being merged as maintainers seek more information or clarify ambiguities.
### Step 10: Discuss and update[](#step-10-discuss-and-update "Direct link to heading")
You will probably get feedback or requests for changes to your pull request. This is a big part of the submission process so don't be discouraged! Some contributors may sign off on the pull request right away. Others may have detailed comments or feedback. This is a necessary part of the process in order to evaluate whether the changes are correct and necessary.
To make changes to an existing pull request, make the changes to your local branch, add a new commit with those changes, and push those to your fork. GitHub will automatically update the pull request.
```
$ git add my/changed/files
$ git commit
$ git push origin my-branch
```
There are a number of more advanced mechanisms for managing commits using `git rebase` that can be used, but are beyond the scope of this guide.
Feel free to post a comment in the pull request to ping reviewers if you are awaiting an answer on something. If you encounter words or acronyms that seem unfamiliar, refer to this [glossary](https://sites.google.com/a/chromium.org/dev/glossary).
#### Approval and Request Changes Workflow[](#approval-and-request-changes-workflow "Direct link to heading")
All pull requests require approval from a [Code Owner](https://github.com/electron/electron/blob/main/.github/CODEOWNERS) of the area you modified in order to land. Whenever a maintainer reviews a pull request they may request changes. These may be small, such as fixing a typo, or may involve substantive changes. Such requests are intended to be helpful, but at times may come across as abrupt or unhelpful, especially if they do not include concrete suggestions on *how* to change them.
Try not to be discouraged. If you feel that a review is unfair, say so or seek the input of another project contributor. Often such comments are the result of a reviewer having taken insufficient time to review and are not ill-intended. Such difficulties can often be resolved with a bit of patience. That said, reviewers should be expected to provide helpful feedback.
### Step 11: Landing[](#step-11-landing "Direct link to heading")
In order to land, a pull request needs to be reviewed and approved by at least one Electron Code Owner and pass CI. After that, if there are no objections from other contributors, the pull request can be merged.
Congratulations and thanks for your contribution!
### Continuous Integration Testing[](#continuous-integration-testing "Direct link to heading")
Every pull request is tested on the Continuous Integration (CI) system to confirm that it works on Electron's supported platforms.
Ideally, the pull request will pass ("be green") on all of CI's platforms. This means that all tests pass and there are no linting errors. However, it is not uncommon for the CI infrastructure itself to fail on specific platforms or for so-called "flaky" tests to fail ("be red"). Each CI failure must be manually inspected to determine the cause.
CI starts automatically when you open a pull request, but only core maintainers can restart a CI run. If you believe CI is giving a false negative, ask a maintainer to restart the tests.
electron V8 Development V8 Development
==============
> A collection of resources for learning and using V8
>
>
* [V8 Tracing](https://v8.dev/docs/trace)
* [V8 Profiler](https://v8.dev/docs/profile) - Profiler combinations which are useful for profiling: `--prof`, `--trace-ic`, `--trace-opt`, `--trace-deopt`, `--print-bytecode`, `--print-opt-code`
* [V8 Interpreter Design](https://docs.google.com/document/d/11T2CRex9hXxoJwbYqVQ32yIPMh0uouUZLdyrtmMoL44/edit?ts=56f27d9d#heading=h.6jz9dj3bnr8t)
* [Optimizing compiler](https://v8.dev/docs/turbofan)
* [V8 GDB Debugging](https://v8.dev/docs/gdb-jit)
See also [Chromium Development](chromium-development)
electron Debugging with XCode Debugging with XCode[](#debugging-with-xcode "Direct link to heading")
-----------------------------------------------------------------------
### Generate xcode project for debugging sources (cannot build code from xcode)[](#generate-xcode-project-for-debugging-sources-cannot-build-code-from-xcode "Direct link to heading")
Run `gn gen` with the --ide=xcode argument.
```
$ gn gen out/Testing --ide=xcode
```
This will generate the electron.ninja.xcworkspace. You will have to open this workspace to set breakpoints and inspect.
See `gn help gen` for more information on generating IDE projects with GN.
### Debugging and breakpoints[](#debugging-and-breakpoints "Direct link to heading")
Launch Electron app after build. You can now open the xcode workspace created above and attach to the Electron process through the Debug > Attach To Process > Electron debug menu. [Note: If you want to debug the renderer process, you need to attach to the Electron Helper as well.]
You can now set breakpoints in any of the indexed files. However, you will not be able to set breakpoints directly in the Chromium source. To set break points in the Chromium source, you can choose Debug > Breakpoints > Create Symbolic Breakpoint and set any function name as the symbol. This will set the breakpoint for all functions with that name, from all the classes if there are more than one. You can also do this step of setting break points prior to attaching the debugger, however, actual breakpoints for symbolic breakpoint functions may not show up until the debugger is attached to the app.
electron Patches in Electron Patches in Electron
===================
Electron is built on two major upstream projects: Chromium and Node.js. Each of these projects has several of their own dependencies, too. We try our best to use these dependencies exactly as they are but sometimes we can't achieve our goals without patching those upstream dependencies to fit our use cases.
Patch justification[](#patch-justification "Direct link to heading")
---------------------------------------------------------------------
Every patch in Electron is a maintenance burden. When upstream code changes, patches can break—sometimes without even a patch conflict or a compilation error. It's an ongoing effort to keep our patch set up-to-date and effective. So we strive to keep our patch count at a minimum. To that end, every patch must describe its reason for existence in its commit message. That reason must be one of the following:
1. The patch is temporary, and is intended to be (or has been) committed upstream or otherwise eventually removed. Include a link to an upstream PR or code review if available, or a procedure for verifying whether the patch is still needed at a later date.
2. The patch allows the code to compile in the Electron environment, but cannot be upstreamed because it's Electron-specific (e.g. patching out references to Chrome's `Profile`). Include reasoning about why the change cannot be implemented without a patch (e.g. by subclassing or copying the code).
3. The patch makes Electron-specific changes in functionality which are fundamentally incompatible with upstream.
In general, all the upstream projects we work with are friendly folks and are often happy to accept refactorings that allow the code in question to be compatible with both Electron and the upstream project. (See e.g. [this](https://chromium-review.googlesource.com/c/chromium/src/+/1637040) change in Chromium, which allowed us to remove a patch that did the same thing, or [this](https://github.com/nodejs/node/pull/22110) change in Node, which was a no-op for Node but fixed a bug in Electron.) **We should aim to upstream changes whenever we can, and avoid indefinite-lifetime patches**.
Patch system[](#patch-system "Direct link to heading")
-------------------------------------------------------
If you find yourself in the unfortunate position of having to make a change which can only be made through patching an upstream project, you'll need to know how to manage patches in Electron.
All patches to upstream projects in Electron are contained in the `patches/` directory. Each subdirectory of `patches/` contains several patch files, along with a `.patches` file which lists the order in which the patches should be applied. Think of these files as making up a series of git commits that are applied on top of the upstream project after we check it out.
```
patches
├── config.json <-- this describes which patchset directory is applied to what project
├── chromium
│ ├── .patches
│ ├── accelerator.patch
│ ├── add_contentgpuclient_precreatemessageloop_callback.patch
│ ⋮
├── node
│ ├── .patches
│ ├── add_openssl_is_boringssl_guard_to_oaep_hash_check.patch
│ ├── build_add_gn_build_files.patch
│ ⋮
⋮
```
To help manage these patch sets, we provide two tools: `git-import-patches` and `git-export-patches`. `git-import-patches` imports a set of patch files into a git repository by applying each patch in the correct order and creating a commit for each one. `git-export-patches` does the reverse; it exports a series of git commits in a repository into a set of files in a directory and an accompanying `.patches` file.
> Side note: the reason we use a `.patches` file to maintain the order of applied patches, rather than prepending a number like `001-` to each file, is because it reduces conflicts related to patch ordering. It prevents the situation where two PRs both add a patch at the end of the series with the same numbering and end up both getting merged resulting in a duplicate identifier, and it also reduces churn when a patch is added or deleted in the middle of the series.
>
>
### Usage[](#usage "Direct link to heading")
#### Adding a new patch[](#adding-a-new-patch "Direct link to heading")
```
$ cd src/third_party/electron_node
$ vim some/code/file.cc
$ git commit
$ ../../electron/script/git-export-patches -o ../../electron/patches/node
```
> **NOTE**: `git-export-patches` ignores any uncommitted files, so you must create a commit if you want your changes to be exported. The subject line of the commit message will be used to derive the patch file name, and the body of the commit message should include the reason for the patch's existence.
>
>
Re-exporting patches will sometimes cause shasums in unrelated patches to change. This is generally harmless and can be ignored (but go ahead and add those changes to your PR, it'll stop them from showing up for other people).
#### Editing an existing patch[](#editing-an-existing-patch "Direct link to heading")
```
$ cd src/v8
$ vim some/code/file.cc
$ git log
# Find the commit sha of the patch you want to edit.
$ git commit --fixup [COMMIT_SHA]
$ git rebase --autosquash -i [COMMIT_SHA]^
$ ../electron/script/git-export-patches -o ../electron/patches/v8
```
#### Removing a patch[](#removing-a-patch "Direct link to heading")
```
$ vim src/electron/patches/node/.patches
# Delete the line with the name of the patch you want to remove
$ cd src/third_party/electron_node
$ git reset --hard refs/patches/upstream-head
$ ../../electron/script/git-import-patches ../../electron/patches/node
$ ../../electron/script/git-export-patches -o ../../electron/patches/node
```
Note that `git-import-patches` will mark the commit that was `HEAD` when it was run as `refs/patches/upstream-head`. This lets you keep track of which commits are from Electron patches (those that come after `refs/patches/upstream-head`) and which commits are in upstream (those before `refs/patches/upstream-head`).
#### Resolving conflicts[](#resolving-conflicts "Direct link to heading")
When updating an upstream dependency, patches may fail to apply cleanly. Often, the conflict can be resolved automatically by git with a 3-way merge. You can instruct `git-import-patches` to use the 3-way merge algorithm by passing the `-3` argument:
```
$ cd src/third_party/electron_node
# If the patch application failed midway through, you can reset it with:
$ git am --abort
# And then retry with 3-way merge:
$ ../../electron/script/git-import-patches -3 ../../electron/patches/node
```
If `git-import-patches -3` encounters a merge conflict that it can't resolve automatically, it will pause and allow you to resolve the conflict manually. Once you have resolved the conflict, `git add` the resolved files and continue to apply the rest of the patches by running `git am --continue`.
electron Debugging on Windows Debugging on Windows
====================
If you experience crashes or issues in Electron that you believe are not caused by your JavaScript application, but instead by Electron itself, debugging can be a little bit tricky, especially for developers not used to native/C++ debugging. However, using Visual Studio, Electron's hosted Symbol Server, and the Electron source code, you can enable step-through debugging with breakpoints inside Electron's source code.
**See also**: There's a wealth of information on debugging Chromium, much of which also applies to Electron, on the Chromium developers site: [Debugging Chromium on Windows](https://www.chromium.org/developers/how-tos/debugging-on-windows).
Requirements[](#requirements "Direct link to heading")
-------------------------------------------------------
* **A debug build of Electron**: The easiest way is usually building it yourself, using the tools and prerequisites listed in the [build instructions for Windows](build-instructions-windows). While you can attach to and debug Electron as you can download it directly, you will find that it is heavily optimized, making debugging substantially more difficult: The debugger will not be able to show you the content of all variables and the execution path can seem strange because of inlining, tail calls, and other compiler optimizations.
* **Visual Studio with C++ Tools**: The free community editions of Visual Studio 2013 and Visual Studio 2015 both work. Once installed, [configure Visual Studio to use Electron's Symbol server](debugging-with-symbol-server). It will enable Visual Studio to gain a better understanding of what happens inside Electron, making it easier to present variables in a human-readable format.
* **ProcMon**: The [free SysInternals tool](https://technet.microsoft.com/en-us/sysinternals/processmonitor.aspx) allows you to inspect a processes parameters, file handles, and registry operations.
Attaching to and Debugging Electron[](#attaching-to-and-debugging-electron "Direct link to heading")
-----------------------------------------------------------------------------------------------------
To start a debugging session, open up PowerShell/CMD and execute your debug build of Electron, using the application to open as a parameter.
```
$ ./out/Testing/electron.exe ~/my-electron-app/
```
### Setting Breakpoints[](#setting-breakpoints "Direct link to heading")
Then, open up Visual Studio. Electron is not built with Visual Studio and hence does not contain a project file - you can however open up the source code files "As File", meaning that Visual Studio will open them up by themselves. You can still set breakpoints - Visual Studio will automatically figure out that the source code matches the code running in the attached process and break accordingly.
Relevant code files can be found in `./shell/`.
### Attaching[](#attaching "Direct link to heading")
You can attach the Visual Studio debugger to a running process on a local or remote computer. After the process is running, click Debug / Attach to Process (or press `CTRL+ALT+P`) to open the "Attach to Process" dialog box. You can use this capability to debug apps that are running on a local or remote computer, debug multiple processes simultaneously.
If Electron is running under a different user account, select the `Show processes from all users` check box. Notice that depending on how many BrowserWindows your app opened, you will see multiple processes. A typical one-window app will result in Visual Studio presenting you with two `Electron.exe` entries - one for the main process and one for the renderer process. Since the list only gives you names, there's currently no reliable way of figuring out which is which.
### Which Process Should I Attach to?[](#which-process-should-i-attach-to "Direct link to heading")
Code executed within the main process (that is, code found in or eventually run by your main JavaScript file) will run inside the main process, while other code will execute inside its respective renderer process.
You can be attached to multiple programs when you are debugging, but only one program is active in the debugger at any time. You can set the active program in the `Debug Location` toolbar or the `Processes window`.
Using ProcMon to Observe a Process[](#using-procmon-to-observe-a-process "Direct link to heading")
---------------------------------------------------------------------------------------------------
While Visual Studio is fantastic for inspecting specific code paths, ProcMon's strength is really in observing everything your application is doing with the operating system - it captures File, Registry, Network, Process, and Profiling details of processes. It attempts to log **all** events occurring and can be quite overwhelming, but if you seek to understand what and how your application is doing to the operating system, it can be a valuable resource.
For an introduction to ProcMon's basic and advanced debugging features, go check out [this video tutorial](https://channel9.msdn.com/shows/defrag-tools/defrag-tools-4-process-monitor) provided by Microsoft.
Using WinDbg[](#using-windbg "Direct link to heading")
-------------------------------------------------------
It's possible to debug crashes and issues in the Renderer process with [WinDbg](https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/getting-started-with-windbg).
To attach to a debug a process with WinDbg:
1. Add `--renderer-startup-dialog` as a command line flag to Electron.
2. Launch the app you are intending to debug.
3. A dialog box will appear with a pid: “Renderer starting with pid: 1234”.
4. Launch WinDbg and choose “File > Attach to process” in the application menu.
5. Enter in pid from the dialog box in Step 3.
6. See that the debugger will be in a paused state, and that there is a command line in the app to enter text into.
7. Type “g” into the above command line to start the debuggee.
8. Press the enter key to continue the program.
9. Go back to the dialog box and press “ok”.
| programming_docs |
electron Testing Testing
=======
We aim to keep the code coverage of Electron high. We ask that all pull request not only pass all existing tests, but ideally also add new tests to cover changed code and new scenarios. Ensuring that we capture as many code paths and use cases of Electron as possible ensures that we all ship apps with fewer bugs.
This repository comes with linting rules for both JavaScript and C++ – as well as unit and integration tests. To learn more about Electron's coding style, please see the <coding-style> document.
Linting[](#linting "Direct link to heading")
---------------------------------------------
To ensure that your changes are in compliance with the Electron coding style, run `npm run lint`, which will run a variety of linting checks against your changes depending on which areas of the code they touch.
Many of these checks are included as precommit hooks, so it's likely you error would be caught at commit time.
Unit Tests[](#unit-tests "Direct link to heading")
---------------------------------------------------
If you are not using [build-tools](https://github.com/electron/build-tools), ensure that the name you have configured for your local build of Electron is one of `Testing`, `Release`, `Default`, or you have set `process.env.ELECTRON_OUT_DIR`. Without these set, Electron will fail to perform some pre-testing steps.
To run all unit tests, run `npm run test`. The unit tests are an Electron app (surprise!) that can be found in the `spec` folder. Note that it has its own `package.json` and that its dependencies are therefore not defined in the top-level `package.json`.
To run only tests in a specific process, run `npm run test --runners=PROCESS` where `PROCESS` is one of `main` or `remote`.
To run only specific tests matching a pattern, run `npm run test --
-g=PATTERN`, replacing the `PATTERN` with a regex that matches the tests you would like to run. As an example: If you want to run only IPC tests, you would run `npm run test -- -g ipc`.
Node.js Smoke Tests[](#nodejs-smoke-tests "Direct link to heading")
--------------------------------------------------------------------
If you've made changes that might affect the way Node.js is embedded into Electron, we have a test runner that runs all of the tests from Node.js, using Electron's custom fork of Node.js.
To run all of the Node.js tests:
```
$ node script/node-spec-runner.js
```
To run a single Node.js test:
```
$ node script/node-spec-runner.js parallel/test-crypto-keygen
```
where the argument passed to the runner is the path to the test in the Node.js source tree.
### Testing on Windows 10 devices[](#testing-on-windows-10-devices "Direct link to heading")
#### Extra steps to run the unit test:[](#extra-steps-to-run-the-unit-test "Direct link to heading")
1. Visual Studio 2019 must be installed.
2. Node headers have to be compiled for your configuration.
```
ninja -C out\Testing third_party\electron_node:headers
```
3. The electron.lib has to be copied as node.lib.
```
cd out\Testing
mkdir gen\node_headers\Release
copy electron.lib gen\node_headers\Release\node.lib
```
#### Missing fonts[](#missing-fonts "Direct link to heading")
[Some Windows 10 devices](https://docs.microsoft.com/en-us/typography/fonts/windows_10_font_list) do not ship with the Meiryo font installed, which may cause a font fallback test to fail. To install Meiryo:
1. Push the Windows key and search for *Manage optional features*.
2. Click *Add a feature*.
3. Select *Japanese Supplemental Fonts* and click *Install*.
#### Pixel measurements[](#pixel-measurements "Direct link to heading")
Some tests which rely on precise pixel measurements may not work correctly on devices with Hi-DPI screen settings due to floating point precision errors. To run these tests correctly, make sure the device is set to 100% scaling.
To configure display scaling:
1. Push the Windows key and search for *Display settings*.
2. Under *Scale and layout*, make sure that the device is set to 100%.
electron Source Code Directory Structure Source Code Directory Structure
===============================
The source code of Electron is separated into a few parts, mostly following Chromium on the separation conventions.
You may need to become familiar with [Chromium's multi-process architecture](https://dev.chromium.org/developers/design-documents/multi-process-architecture) to understand the source code better.
Structure of Source Code[](#structure-of-source-code "Direct link to heading")
-------------------------------------------------------------------------------
```
Electron
├── build/ - Build configuration files needed to build with GN.
├── buildflags/ - Determines the set of features that can be conditionally built.
├── chromium_src/ - Source code copied from Chromium that isn't part of the content layer.
├── default_app/ - A default app run when Electron is started without
| providing a consumer app.
├── docs/ - Electron's documentation.
| ├── api/ - Documentation for Electron's externally-facing modules and APIs.
| ├── development/ - Documentation to aid in developing for and with Electron.
| ├── fiddles/ - A set of code snippets one can run in Electron Fiddle.
| ├── images/ - Images used in documentation.
| └── tutorial/ - Tutorial documents for various aspects of Electron.
├── lib/ - JavaScript/TypeScript source code.
| ├── browser/ - Main process initialization code.
| | ├── api/ - API implementation for main process modules.
| | └── remote/ - Code related to the remote module as it is
| | used in the main process.
| ├── common/ - Relating to logic needed by both main and renderer processes.
| | └── api/ - API implementation for modules that can be used in
| | both the main and renderer processes
| ├── isolated_renderer/ - Handles creation of isolated renderer processes when
| | contextIsolation is enabled.
| ├── renderer/ - Renderer process initialization code.
| | ├── api/ - API implementation for renderer process modules.
| | ├── extension/ - Code related to use of Chrome Extensions
| | | in Electron's renderer process.
| | ├── remote/ - Logic that handles use of the remote module in
| | | the main process.
| | └── web-view/ - Logic that handles the use of webviews in the
| | renderer process.
| ├── sandboxed_renderer/ - Logic that handles creation of sandboxed renderer
| | | processes.
| | └── api/ - API implementation for sandboxed renderer processes.
| └── worker/ - Logic that handles proper functionality of Node.js
| environments in Web Workers.
├── patches/ - Patches applied on top of Electron's core dependencies
| | in order to handle differences between our use cases and
| | default functionality.
| ├── boringssl/ - Patches applied to Google's fork of OpenSSL, BoringSSL.
| ├── chromium/ - Patches applied to Chromium.
| ├── node/ - Patches applied on top of Node.js.
| └── v8/ - Patches applied on top of Google's V8 engine.
├── shell/ - C++ source code.
| ├── app/ - System entry code.
| ├── browser/ - The frontend including the main window, UI, and all of the
| | | main process things. This talks to the renderer to manage web
| | | pages.
| | ├── ui/ - Implementation of UI stuff for different platforms.
| | | ├── cocoa/ - Cocoa specific source code.
| | | ├── win/ - Windows GUI specific source code.
| | | └── x/ - X11 specific source code.
| | ├── api/ - The implementation of the main process APIs.
| | ├── net/ - Network related code.
| | ├── mac/ - Mac specific Objective-C source code.
| | └── resources/ - Icons, platform-dependent files, etc.
| ├── renderer/ - Code that runs in renderer process.
| | └── api/ - The implementation of renderer process APIs.
| └── common/ - Code that used by both the main and renderer processes,
| | including some utility functions and code to integrate node's
| | message loop into Chromium's message loop.
| └── api/ - The implementation of common APIs, and foundations of
| Electron's built-in modules.
├── spec/ - Components of Electron's test suite run in the renderer process.
├── spec-main/ - Components of Electron's test suite run in the main process.
└── BUILD.gn - Building rules of Electron.
```
Structure of Other Directories[](#structure-of-other-directories "Direct link to heading")
-------------------------------------------------------------------------------------------
* **.circleci** - Config file for CI with CircleCI.
* **.github** - GitHub-specific config files including issues templates and CODEOWNERS.
* **dist** - Temporary directory created by `script/create-dist.py` script when creating a distribution.
* **node\_modules** - Third party node modules used for building.
* **npm** - Logic for installation of Electron via npm.
* **out** - Temporary output directory of `ninja`.
* **script** - Scripts used for development purpose like building, packaging, testing, etc.
```
script/ - The set of all scripts Electron runs for a variety of purposes.
├── codesign/ - Fakes codesigning for Electron apps; used for testing.
├── lib/ - Miscellaneous python utility scripts.
└── release/ - Scripts run during Electron's release process.
├── notes/ - Generates release notes for new Electron versions.
└── uploaders/ - Uploads various release-related files during release.
```
* **typings** - TypeScript typings for Electron's internal code.
electron Build Instructions (Linux) Build Instructions (Linux)
==========================
Follow the guidelines below for building **Electron itself** on Linux, for the purposes of creating custom Electron binaries. For bundling and distributing your app code with the prebuilt Electron binaries, see the [application distribution](../tutorial/application-distribution) guide.
Prerequisites[](#prerequisites "Direct link to heading")
---------------------------------------------------------
* At least 25GB disk space and 8GB RAM.
* Python >= 3.7.
* Node.js. There are various ways to install Node. You can download source code from [nodejs.org](https://nodejs.org) and compile it. Doing so permits installing Node on your own home directory as a standard user. Or try repositories such as [NodeSource](https://nodesource.com/blog/nodejs-v012-iojs-and-the-nodesource-linux-repositories).
* [clang](https://clang.llvm.org/get_started.html) 3.4 or later.
* Development headers of GTK 3 and libnotify.
On Ubuntu >= 20.04, install the following libraries:
```
$ sudo apt-get install build-essential clang libdbus-1-dev libgtk-3-dev \
libnotify-dev libasound2-dev libcap-dev \
libcups2-dev libxtst-dev \
libxss1 libnss3-dev gcc-multilib g++-multilib curl \
gperf bison python3-dbusmock openjdk-8-jre
```
On Ubuntu < 20.04, install the following libraries:
```
$ sudo apt-get install build-essential clang libdbus-1-dev libgtk-3-dev \
libnotify-dev libgnome-keyring-dev \
libasound2-dev libcap-dev libcups2-dev libxtst-dev \
libxss1 libnss3-dev gcc-multilib g++-multilib curl \
gperf bison python-dbusmock openjdk-8-jre
```
On RHEL / CentOS, install the following libraries:
```
$ sudo yum install clang dbus-devel gtk3-devel libnotify-devel \
libgnome-keyring-devel xorg-x11-server-utils libcap-devel \
cups-devel libXtst-devel alsa-lib-devel libXrandr-devel \
nss-devel python-dbusmock openjdk-8-jre
```
On Fedora, install the following libraries:
```
$ sudo dnf install clang dbus-devel gtk3-devel libnotify-devel \
libgnome-keyring-devel xorg-x11-server-utils libcap-devel \
cups-devel libXtst-devel alsa-lib-devel libXrandr-devel \
nss-devel python-dbusmock openjdk-8-jre
```
On Arch Linux / Manjaro, install the following libraries:
```
$ sudo pacman -Syu base-devel clang libdbus gtk2 libnotify \
libgnome-keyring alsa-lib libcap libcups libxtst \
libxss nss gcc-multilib curl gperf bison \
python2 python-dbusmock jdk8-openjdk
```
Other distributions may offer similar packages for installation via package managers such as pacman. Or one can compile from source code.
### Cross compilation[](#cross-compilation "Direct link to heading")
If you want to build for an `arm` target you should also install the following dependencies:
```
$ sudo apt-get install libc6-dev-armhf-cross linux-libc-dev-armhf-cross \
g++-arm-linux-gnueabihf
```
Similarly for `arm64`, install the following:
```
$ sudo apt-get install libc6-dev-arm64-cross linux-libc-dev-arm64-cross \
g++-aarch64-linux-gnu
```
And to cross-compile for `arm` or targets, you should pass the `target_cpu` parameter to `gn gen`:
```
$ gn gen out/Testing --args='import(...) target_cpu="arm"'
```
Building[](#building "Direct link to heading")
-----------------------------------------------
See [Build Instructions: GN](build-instructions-gn)
Troubleshooting[](#troubleshooting "Direct link to heading")
-------------------------------------------------------------
### Error While Loading Shared Libraries: libtinfo.so.5[](#error-while-loading-shared-libraries-libtinfoso5 "Direct link to heading")
Prebuilt `clang` will try to link to `libtinfo.so.5`. Depending on the host architecture, symlink to appropriate `libncurses`:
```
$ sudo ln -s /usr/lib/libncurses.so.5 /usr/lib/libtinfo.so.5
```
Advanced topics[](#advanced-topics "Direct link to heading")
-------------------------------------------------------------
The default building configuration is targeted for major desktop Linux distributions. To build for a specific distribution or device, the following information may help you.
### Using system `clang` instead of downloaded `clang` binaries[](#using-system-clang-instead-of-downloaded-clang-binaries "Direct link to heading")
By default Electron is built with prebuilt [`clang`](https://clang.llvm.org/get_started.html) binaries provided by the Chromium project. If for some reason you want to build with the `clang` installed in your system, you can specify the `clang_base_path` argument in the GN args.
For example if you installed `clang` under `/usr/local/bin/clang`:
```
$ gn gen out/Testing --args='import("//electron/build/args/testing.gn") clang_base_path = "/usr/local/bin"'
```
### Using compilers other than `clang`[](#using-compilers-other-than-clang "Direct link to heading")
Building Electron with compilers other than `clang` is not supported.
electron powerSaveBlocker powerSaveBlocker
================
> Block the system from entering low-power (sleep) mode.
>
>
Process: [Main](../glossary#main-process)
For example:
```
const { powerSaveBlocker } = require('electron')
const id = powerSaveBlocker.start('prevent-display-sleep')
console.log(powerSaveBlocker.isStarted(id))
powerSaveBlocker.stop(id)
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `powerSaveBlocker` module has the following methods:
###
`powerSaveBlocker.start(type)`[](#powersaveblockerstarttype "Direct link to heading")
* `type` string - Power save blocker type.
+ `prevent-app-suspension` - Prevent the application from being suspended. Keeps system active but allows screen to be turned off. Example use cases: downloading a file or playing audio.
+ `prevent-display-sleep` - Prevent the display from going to sleep. Keeps system and screen active. Example use case: playing video.
Returns `Integer` - The blocker ID that is assigned to this power blocker.
Starts preventing the system from entering lower-power mode. Returns an integer identifying the power save blocker.
**Note:** `prevent-display-sleep` has higher precedence over `prevent-app-suspension`. Only the highest precedence type takes effect. In other words, `prevent-display-sleep` always takes precedence over `prevent-app-suspension`.
For example, an API calling A requests for `prevent-app-suspension`, and another calling B requests for `prevent-display-sleep`. `prevent-display-sleep` will be used until B stops its request. After that, `prevent-app-suspension` is used.
###
`powerSaveBlocker.stop(id)`[](#powersaveblockerstopid "Direct link to heading")
* `id` Integer - The power save blocker id returned by `powerSaveBlocker.start`.
Stops the specified power save blocker.
###
`powerSaveBlocker.isStarted(id)`[](#powersaveblockerisstartedid "Direct link to heading")
* `id` Integer - The power save blocker id returned by `powerSaveBlocker.start`.
Returns `boolean` - Whether the corresponding `powerSaveBlocker` has started.
electron Class: TouchBarSlider Class: TouchBarSlider[](#class-touchbarslider "Direct link to heading")
------------------------------------------------------------------------
> Create a slider in the touch bar for native macOS applications
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarSlider(options)`[](#new-touchbarslideroptions "Direct link to heading")
* `options` Object
+ `label` string (optional) - Label text.
+ `value` Integer (optional) - Selected value.
+ `minValue` Integer (optional) - Minimum value.
+ `maxValue` Integer (optional) - Maximum value.
+ `change` Function (optional) - Function to call when the slider is changed.
- `newValue` number - The value that the user selected on the Slider.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBarSlider`:
####
`touchBarSlider.label`[](#touchbarsliderlabel "Direct link to heading")
A `string` representing the slider's current text. Changing this value immediately updates the slider in the touch bar.
####
`touchBarSlider.value`[](#touchbarslidervalue "Direct link to heading")
A `number` representing the slider's current value. Changing this value immediately updates the slider in the touch bar.
####
`touchBarSlider.minValue`[](#touchbarsliderminvalue "Direct link to heading")
A `number` representing the slider's current minimum value. Changing this value immediately updates the slider in the touch bar.
####
`touchBarSlider.maxValue`[](#touchbarslidermaxvalue "Direct link to heading")
A `number` representing the slider's current maximum value. Changing this value immediately updates the slider in the touch bar.
electron Class: IncomingMessage Class: IncomingMessage[](#class-incomingmessage "Direct link to heading")
--------------------------------------------------------------------------
> Handle responses to HTTP/HTTPS requests.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
`IncomingMessage` implements the [Readable Stream](https://nodejs.org/api/stream.html#stream_readable_streams) interface and is therefore an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter).
### Instance Events[](#instance-events "Direct link to heading")
#### Event: 'data'[](#event-data "Direct link to heading")
Returns:
* `chunk` Buffer - A chunk of response body's data.
The `data` event is the usual method of transferring response data into applicative code.
#### Event: 'end'[](#event-end "Direct link to heading")
Indicates that response body has ended. Must be placed before 'data' event.
#### Event: 'aborted'[](#event-aborted "Direct link to heading")
Emitted when a request has been canceled during an ongoing HTTP transaction.
#### Event: 'error'[](#event-error "Direct link to heading")
Returns:
`error` Error - Typically holds an error string identifying failure root cause.
Emitted when an error was encountered while streaming response data events. For instance, if the server closes the underlying while the response is still streaming, an `error` event will be emitted on the response object and a `close` event will subsequently follow on the request object.
### Instance Properties[](#instance-properties "Direct link to heading")
An `IncomingMessage` instance has the following readable properties:
####
`response.statusCode`[](#responsestatuscode "Direct link to heading")
An `Integer` indicating the HTTP response status code.
####
`response.statusMessage`[](#responsestatusmessage "Direct link to heading")
A `string` representing the HTTP status message.
####
`response.headers`[](#responseheaders "Direct link to heading")
A `Record<string, string | string[]>` representing the HTTP response headers. The `headers` object is formatted as follows:
* All header names are lowercased.
* Duplicates of `age`, `authorization`, `content-length`, `content-type`, `etag`, `expires`, `from`, `host`, `if-modified-since`, `if-unmodified-since`, `last-modified`, `location`, `max-forwards`, `proxy-authorization`, `referer`, `retry-after`, `server`, or `user-agent` are discarded.
* `set-cookie` is always an array. Duplicates are added to the array.
* For duplicate `cookie` headers, the values are joined together with '; '.
* For all other headers, the values are joined together with ', '.
####
`response.httpVersion`[](#responsehttpversion "Direct link to heading")
A `string` indicating the HTTP protocol version number. Typical values are '1.0' or '1.1'. Additionally `httpVersionMajor` and `httpVersionMinor` are two Integer-valued readable properties that return respectively the HTTP major and minor version numbers.
####
`response.httpVersionMajor`[](#responsehttpversionmajor "Direct link to heading")
An `Integer` indicating the HTTP protocol major version number.
####
`response.httpVersionMinor`[](#responsehttpversionminor "Direct link to heading")
An `Integer` indicating the HTTP protocol minor version number.
####
`response.rawHeaders`[](#responserawheaders "Direct link to heading")
A `string[]` containing the raw HTTP response headers exactly as they were received. The keys and values are in the same list. It is not a list of tuples. So, the even-numbered offsets are key values, and the odd-numbered offsets are the associated values. Header names are not lowercased, and duplicates are not merged.
```
// Prints something like:
//
// [ 'user-agent',
// 'this is invalid because there can be only one',
// 'User-Agent',
// 'curl/7.22.0',
// 'Host',
// '127.0.0.1:8000',
// 'ACCEPT',
// '*/*' ]
console.log(request.rawHeaders)
```
| programming_docs |
electron Class: TouchBarScrubber Class: TouchBarScrubber[](#class-touchbarscrubber "Direct link to heading")
----------------------------------------------------------------------------
> Create a scrubber (a scrollable selector)
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarScrubber(options)`[](#new-touchbarscrubberoptions "Direct link to heading")
* `options` Object
+ `items` [ScrubberItem[]](structures/scrubber-item) - An array of items to place in this scrubber.
+ `select` Function (optional) - Called when the user taps an item that was not the last tapped item.
- `selectedIndex` Integer - The index of the item the user selected.
+ `highlight` Function (optional) - Called when the user taps any item.
- `highlightedIndex` Integer - The index of the item the user touched.
+ `selectedStyle` string (optional) - Selected item style. Can be `background`, `outline` or `none`. Defaults to `none`.
+ `overlayStyle` string (optional) - Selected overlay item style. Can be `background`, `outline` or `none`. Defaults to `none`.
+ `showArrowButtons` boolean (optional) - Whether to show arrow buttons. Defaults to `false` and is only shown if `items` is non-empty.
+ `mode` string (optional) - Can be `fixed` or `free`. The default is `free`.
+ `continuous` boolean (optional) - Defaults to `true`.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBarScrubber`:
####
`touchBarScrubber.items`[](#touchbarscrubberitems "Direct link to heading")
A `ScrubberItem[]` array representing the items in this scrubber. Updating this value immediately updates the control in the touch bar. Updating deep properties inside this array **does not update the touch bar**.
####
`touchBarScrubber.selectedStyle`[](#touchbarscrubberselectedstyle "Direct link to heading")
A `string` representing the style that selected items in the scrubber should have. Updating this value immediately updates the control in the touch bar. Possible values:
* `background` - Maps to `[NSScrubberSelectionStyle roundedBackgroundStyle]`.
* `outline` - Maps to `[NSScrubberSelectionStyle outlineOverlayStyle]`.
* `none` - Removes all styles.
####
`touchBarScrubber.overlayStyle`[](#touchbarscrubberoverlaystyle "Direct link to heading")
A `string` representing the style that selected items in the scrubber should have. This style is overlayed on top of the scrubber item instead of being placed behind it. Updating this value immediately updates the control in the touch bar. Possible values:
* `background` - Maps to `[NSScrubberSelectionStyle roundedBackgroundStyle]`.
* `outline` - Maps to `[NSScrubberSelectionStyle outlineOverlayStyle]`.
* `none` - Removes all styles.
####
`touchBarScrubber.showArrowButtons`[](#touchbarscrubbershowarrowbuttons "Direct link to heading")
A `boolean` representing whether to show the left / right selection arrows in this scrubber. Updating this value immediately updates the control in the touch bar.
####
`touchBarScrubber.mode`[](#touchbarscrubbermode "Direct link to heading")
A `string` representing the mode of this scrubber. Updating this value immediately updates the control in the touch bar. Possible values:
* `fixed` - Maps to `NSScrubberModeFixed`.
* `free` - Maps to `NSScrubberModeFree`.
####
`touchBarScrubber.continuous`[](#touchbarscrubbercontinuous "Direct link to heading")
A `boolean` representing whether this scrubber is continuous or not. Updating this value immediately updates the control in the touch bar.
electron net net
===
> Issue HTTP/HTTPS requests using Chromium's native networking library
>
>
Process: [Main](../glossary#main-process)
The `net` module is a client-side API for issuing HTTP(S) requests. It is similar to the [HTTP](https://nodejs.org/api/http.html) and [HTTPS](https://nodejs.org/api/https.html) modules of Node.js but uses Chromium's native networking library instead of the Node.js implementation, offering better support for web proxies. It also supports checking network status.
The following is a non-exhaustive list of why you may consider using the `net` module instead of the native Node.js modules:
* Automatic management of system proxy configuration, support of the wpad protocol and proxy pac configuration files.
* Automatic tunneling of HTTPS requests.
* Support for authenticating proxies using basic, digest, NTLM, Kerberos or negotiate authentication schemes.
* Support for traffic monitoring proxies: Fiddler-like proxies used for access control and monitoring.
The API components (including classes, methods, properties and event names) are similar to those used in Node.js.
Example usage:
```
const { app } = require('electron')
app.whenReady().then(() => {
const { net } = require('electron')
const request = net.request('https://github.com')
request.on('response', (response) => {
console.log(`STATUS: ${response.statusCode}`)
console.log(`HEADERS: ${JSON.stringify(response.headers)}`)
response.on('data', (chunk) => {
console.log(`BODY: ${chunk}`)
})
response.on('end', () => {
console.log('No more data in response.')
})
})
request.end()
})
```
The `net` API can be used only after the application emits the `ready` event. Trying to use the module before the `ready` event will throw an error.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `net` module has the following methods:
###
`net.request(options)`[](#netrequestoptions "Direct link to heading")
* `options` (ClientRequestConstructorOptions | string) - The `ClientRequest` constructor options.
Returns [`ClientRequest`](client-request)
Creates a [`ClientRequest`](client-request) instance using the provided `options` which are directly forwarded to the `ClientRequest` constructor. The `net.request` method would be used to issue both secure and insecure HTTP requests according to the specified protocol scheme in the `options` object.
###
`net.isOnline()`[](#netisonline "Direct link to heading")
Returns `boolean` - Whether there is currently internet connection.
A return value of `false` is a pretty strong indicator that the user won't be able to connect to remote sites. However, a return value of `true` is inconclusive; even if some link is up, it is uncertain whether a particular connection attempt to a particular remote site will be successful.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
###
`net.online` *Readonly*[](#netonline-readonly "Direct link to heading")
A `boolean` property. Whether there is currently internet connection.
A return value of `false` is a pretty strong indicator that the user won't be able to connect to remote sites. However, a return value of `true` is inconclusive; even if some link is up, it is uncertain whether a particular connection attempt to a particular remote site will be successful.
electron process process
=======
> Extensions to process object.
>
>
Process: [Main](../glossary#main-process), [Renderer](../glossary#renderer-process)
Electron's `process` object is extended from the [Node.js `process` object](https://nodejs.org/api/process.html). It adds the following events, properties, and methods:
Sandbox[](#sandbox "Direct link to heading")
---------------------------------------------
In sandboxed renderers the `process` object contains only a subset of the APIs:
* `crash()`
* `hang()`
* `getCreationTime()`
* `getHeapStatistics()`
* `getBlinkMemoryInfo()`
* `getProcessMemoryInfo()`
* `getSystemMemoryInfo()`
* `getSystemVersion()`
* `getCPUUsage()`
* `getIOCounters()`
* `uptime()`
* `argv`
* `execPath`
* `env`
* `pid`
* `arch`
* `platform`
* `sandboxed`
* `contextIsolated`
* `type`
* `version`
* `versions`
* `mas`
* `windowsStore`
* `contextId`
Events[](#events "Direct link to heading")
-------------------------------------------
### Event: 'loaded'[](#event-loaded "Direct link to heading")
Emitted when Electron has loaded its internal initialization script and is beginning to load the web page or the main script.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
###
`process.defaultApp` *Readonly*[](#processdefaultapp-readonly "Direct link to heading")
A `boolean`. When app is started by being passed as parameter to the default app, this property is `true` in the main process, otherwise it is `undefined`.
###
`process.isMainFrame` *Readonly*[](#processismainframe-readonly "Direct link to heading")
A `boolean`, `true` when the current renderer context is the "main" renderer frame. If you want the ID of the current frame you should use `webFrame.routingId`.
###
`process.mas` *Readonly*[](#processmas-readonly "Direct link to heading")
A `boolean`. For Mac App Store build, this property is `true`, for other builds it is `undefined`.
###
`process.noAsar`[](#processnoasar "Direct link to heading")
A `boolean` that controls ASAR support inside your application. Setting this to `true` will disable the support for `asar` archives in Node's built-in modules.
###
`process.noDeprecation`[](#processnodeprecation "Direct link to heading")
A `boolean` that controls whether or not deprecation warnings are printed to `stderr`. Setting this to `true` will silence deprecation warnings. This property is used instead of the `--no-deprecation` command line flag.
###
`process.resourcesPath` *Readonly*[](#processresourcespath-readonly "Direct link to heading")
A `string` representing the path to the resources directory.
###
`process.sandboxed` *Readonly*[](#processsandboxed-readonly "Direct link to heading")
A `boolean`. When the renderer process is sandboxed, this property is `true`, otherwise it is `undefined`.
###
`process.contextIsolated` *Readonly*[](#processcontextisolated-readonly "Direct link to heading")
A `boolean` that indicates whether the current renderer context has `contextIsolation` enabled. It is `undefined` in the main process.
###
`process.throwDeprecation`[](#processthrowdeprecation "Direct link to heading")
A `boolean` that controls whether or not deprecation warnings will be thrown as exceptions. Setting this to `true` will throw errors for deprecations. This property is used instead of the `--throw-deprecation` command line flag.
###
`process.traceDeprecation`[](#processtracedeprecation "Direct link to heading")
A `boolean` that controls whether or not deprecations printed to `stderr` include their stack trace. Setting this to `true` will print stack traces for deprecations. This property is instead of the `--trace-deprecation` command line flag.
###
`process.traceProcessWarnings`[](#processtraceprocesswarnings "Direct link to heading")
A `boolean` that controls whether or not process warnings printed to `stderr` include their stack trace. Setting this to `true` will print stack traces for process warnings (including deprecations). This property is instead of the `--trace-warnings` command line flag.
###
`process.type` *Readonly*[](#processtype-readonly "Direct link to heading")
A `string` representing the current process's type, can be:
* `browser` - The main process
* `renderer` - A renderer process
* `worker` - In a web worker
###
`process.versions.chrome` *Readonly*[](#processversionschrome-readonly "Direct link to heading")
A `string` representing Chrome's version string.
###
`process.versions.electron` *Readonly*[](#processversionselectron-readonly "Direct link to heading")
A `string` representing Electron's version string.
###
`process.windowsStore` *Readonly*[](#processwindowsstore-readonly "Direct link to heading")
A `boolean`. If the app is running as a Windows Store app (appx), this property is `true`, for otherwise it is `undefined`.
###
`process.contextId` *Readonly*[](#processcontextid-readonly "Direct link to heading")
A `string` (optional) representing a globally unique ID of the current JavaScript context. Each frame has its own JavaScript context. When contextIsolation is enabled, the isolated world also has a separate JavaScript context. This property is only available in the renderer process.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `process` object has the following methods:
###
`process.crash()`[](#processcrash "Direct link to heading")
Causes the main thread of the current process crash.
###
`process.getCreationTime()`[](#processgetcreationtime "Direct link to heading")
Returns `number | null` - The number of milliseconds since epoch, or `null` if the information is unavailable
Indicates the creation time of the application. The time is represented as number of milliseconds since epoch. It returns null if it is unable to get the process creation time.
###
`process.getCPUUsage()`[](#processgetcpuusage "Direct link to heading")
Returns [CPUUsage](structures/cpu-usage)
###
`process.getIOCounters()` *Windows* *Linux*[](#processgetiocounters-windows-linux "Direct link to heading")
Returns [IOCounters](structures/io-counters)
###
`process.getHeapStatistics()`[](#processgetheapstatistics "Direct link to heading")
Returns `Object`:
* `totalHeapSize` Integer
* `totalHeapSizeExecutable` Integer
* `totalPhysicalSize` Integer
* `totalAvailableSize` Integer
* `usedHeapSize` Integer
* `heapSizeLimit` Integer
* `mallocedMemory` Integer
* `peakMallocedMemory` Integer
* `doesZapGarbage` boolean
Returns an object with V8 heap statistics. Note that all statistics are reported in Kilobytes.
###
`process.getBlinkMemoryInfo()`[](#processgetblinkmemoryinfo "Direct link to heading")
Returns `Object`:
* `allocated` Integer - Size of all allocated objects in Kilobytes.
* `total` Integer - Total allocated space in Kilobytes.
Returns an object with Blink memory information. It can be useful for debugging rendering / DOM related memory issues. Note that all values are reported in Kilobytes.
###
`process.getProcessMemoryInfo()`[](#processgetprocessmemoryinfo "Direct link to heading")
Returns `Promise<ProcessMemoryInfo>` - Resolves with a [ProcessMemoryInfo](structures/process-memory-info)
Returns an object giving memory usage statistics about the current process. Note that all statistics are reported in Kilobytes. This api should be called after app ready.
Chromium does not provide `residentSet` value for macOS. This is because macOS performs in-memory compression of pages that haven't been recently used. As a result the resident set size value is not what one would expect. `private` memory is more representative of the actual pre-compression memory usage of the process on macOS.
###
`process.getSystemMemoryInfo()`[](#processgetsystemmemoryinfo "Direct link to heading")
Returns `Object`:
* `total` Integer - The total amount of physical memory in Kilobytes available to the system.
* `free` Integer - The total amount of memory not being used by applications or disk cache.
* `swapTotal` Integer *Windows* *Linux* - The total amount of swap memory in Kilobytes available to the system.
* `swapFree` Integer *Windows* *Linux* - The free amount of swap memory in Kilobytes available to the system.
Returns an object giving memory usage statistics about the entire system. Note that all statistics are reported in Kilobytes.
###
`process.getSystemVersion()`[](#processgetsystemversion "Direct link to heading")
Returns `string` - The version of the host operating system.
Example:
```
const version = process.getSystemVersion()
console.log(version)
// On macOS -> '10.13.6'
// On Windows -> '10.0.17763'
// On Linux -> '4.15.0-45-generic'
```
**Note:** It returns the actual operating system version instead of kernel version on macOS unlike `os.release()`.
###
`process.takeHeapSnapshot(filePath)`[](#processtakeheapsnapshotfilepath "Direct link to heading")
* `filePath` string - Path to the output file.
Returns `boolean` - Indicates whether the snapshot has been created successfully.
Takes a V8 heap snapshot and saves it to `filePath`.
###
`process.hang()`[](#processhang "Direct link to heading")
Causes the main thread of the current process hang.
###
`process.setFdLimit(maxDescriptors)` *macOS* *Linux*[](#processsetfdlimitmaxdescriptors-macos-linux "Direct link to heading")
* `maxDescriptors` Integer
Sets the file descriptor soft limit to `maxDescriptors` or the OS hard limit, whichever is lower for the current process.
electron Environment Variables Environment Variables
=====================
> Control application configuration and behavior without changing code.
>
>
Certain Electron behaviors are controlled by environment variables because they are initialized earlier than the command line flags and the app's code.
POSIX shell example:
```
$ export ELECTRON_ENABLE_LOGGING=true
$ electron
```
Windows console example:
```
> set ELECTRON_ENABLE_LOGGING=true
> electron
```
Production Variables[](#production-variables "Direct link to heading")
-----------------------------------------------------------------------
The following environment variables are intended primarily for use at runtime in packaged Electron applications.
###
`NODE_OPTIONS`[](#node_options "Direct link to heading")
Electron includes support for a subset of Node's [`NODE_OPTIONS`](https://nodejs.org/api/cli.html#cli_node_options_options). The majority are supported with the exception of those which conflict with Chromium's use of BoringSSL.
Example:
```
export NODE_OPTIONS="--no-warnings --max-old-space-size=2048"
```
Unsupported options are:
```
--use-bundled-ca
--force-fips
--enable-fips
--openssl-config
--use-openssl-ca
```
`NODE_OPTIONS` are explicitly disallowed in packaged apps, except for the following:
```
--max-http-header-size
--http-parser
```
###
`GOOGLE_API_KEY`[](#google_api_key "Direct link to heading")
Geolocation support in Electron requires the use of Google Cloud Platform's geolocation webservice. To enable this feature, acquire a [Google API key](https://developers.google.com/maps/documentation/geolocation/get-api-key) and place the following code in your main process file, before opening any browser windows that will make geolocation requests:
```
process.env.GOOGLE_API_KEY = 'YOUR_KEY_HERE'
```
By default, a newly generated Google API key may not be allowed to make geolocation requests. To enable the geolocation webservice for your project, enable it through the [API library](https://console.cloud.google.com/apis/library).
N.B. You will need to add a [Billing Account](https://cloud.google.com/billing/docs/how-to/payment-methods#add_a_payment_method) to the project associated to the API key for the geolocation webservice to work.
###
`ELECTRON_NO_ASAR`[](#electron_no_asar "Direct link to heading")
Disables ASAR support. This variable is only supported in forked child processes and spawned child processes that set `ELECTRON_RUN_AS_NODE`.
###
`ELECTRON_RUN_AS_NODE`[](#electron_run_as_node "Direct link to heading")
Starts the process as a normal Node.js process.
In this mode, you will be able to pass [cli options](https://nodejs.org/api/cli.html) to Node.js as you would when running the normal Node.js executable, with the exception of the following flags:
* "--openssl-config"
* "--use-bundled-ca"
* "--use-openssl-ca",
* "--force-fips"
* "--enable-fips"
These flags are disabled owing to the fact that Electron uses BoringSSL instead of OpenSSL when building Node.js' `crypto` module, and so will not work as designed.
###
`ELECTRON_NO_ATTACH_CONSOLE` *Windows*[](#electron_no_attach_console-windows "Direct link to heading")
Don't attach to the current console session.
###
`ELECTRON_FORCE_WINDOW_MENU_BAR` *Linux*[](#electron_force_window_menu_bar-linux "Direct link to heading")
Don't use the global menu bar on Linux.
###
`ELECTRON_TRASH` *Linux*[](#electron_trash-linux "Direct link to heading")
Set the trash implementation on Linux. Default is `gio`.
Options:
* `gvfs-trash`
* `trash-cli`
* `kioclient5`
* `kioclient`
Development Variables[](#development-variables "Direct link to heading")
-------------------------------------------------------------------------
The following environment variables are intended primarily for development and debugging purposes.
###
`ELECTRON_ENABLE_LOGGING`[](#electron_enable_logging "Direct link to heading")
Prints Chromium's internal logging to the console.
Setting this variable is the same as passing `--enable-logging` on the command line. For more info, see `--enable-logging` in [command-line switches](command-line-switches#--enable-loggingfile).
###
`ELECTRON_LOG_FILE`[](#electron_log_file "Direct link to heading")
Sets the file destination for Chromium's internal logging.
Setting this variable is the same as passing `--log-file` on the command line. For more info, see `--log-file` in [command-line switches](command-line-switches#--log-filepath).
###
`ELECTRON_DEBUG_DRAG_REGIONS`[](#electron_debug_drag_regions "Direct link to heading")
Adds coloration to draggable regions on [`BrowserView`](browser-view)s on macOS - draggable regions will be colored green and non-draggable regions will be colored red to aid debugging.
###
`ELECTRON_DEBUG_NOTIFICATIONS`[](#electron_debug_notifications "Direct link to heading")
Adds extra logs to [`Notification`](notification) lifecycles on macOS to aid in debugging. Extra logging will be displayed when new Notifications are created or activated. They will also be displayed when common a tions are taken: a notification is shown, dismissed, its button is clicked, or it is replied to.
Sample output:
```
Notification created (com.github.Electron:notification:EAF7B87C-A113-43D7-8E76-F88EC9D73D44)
Notification displayed (com.github.Electron:notification:EAF7B87C-A113-43D7-8E76-F88EC9D73D44)
Notification activated (com.github.Electron:notification:EAF7B87C-A113-43D7-8E76-F88EC9D73D44)
Notification replied to (com.github.Electron:notification:EAF7B87C-A113-43D7-8E76-F88EC9D73D44)
```
###
`ELECTRON_LOG_ASAR_READS`[](#electron_log_asar_reads "Direct link to heading")
When Electron reads from an ASAR file, log the read offset and file path to the system `tmpdir`. The resulting file can be provided to the ASAR module to optimize file ordering.
###
`ELECTRON_ENABLE_STACK_DUMPING`[](#electron_enable_stack_dumping "Direct link to heading")
Prints the stack trace to the console when Electron crashes.
This environment variable will not work if the `crashReporter` is started.
###
`ELECTRON_DEFAULT_ERROR_MODE` *Windows*[](#electron_default_error_mode-windows "Direct link to heading")
Shows the Windows's crash dialog when Electron crashes.
This environment variable will not work if the `crashReporter` is started.
###
`ELECTRON_OVERRIDE_DIST_PATH`[](#electron_override_dist_path "Direct link to heading")
When running from the `electron` package, this variable tells the `electron` command to use the specified build of Electron instead of the one downloaded by `npm install`. Usage:
```
export ELECTRON_OVERRIDE_DIST_PATH=/Users/username/projects/electron/out/Testing
```
Set By Electron[](#set-by-electron "Direct link to heading")
-------------------------------------------------------------
Electron sets some variables in your environment at runtime.
###
`ORIGINAL_XDG_CURRENT_DESKTOP`[](#original_xdg_current_desktop "Direct link to heading")
This variable is set to the value of `XDG_CURRENT_DESKTOP` that your application originally launched with. Electron sometimes modifies the value of `XDG_CURRENT_DESKTOP` to affect other logic within Chromium so if you want access to the *original* value you should look up this environment variable instead.
| programming_docs |
electron Class: ServiceWorkers Class: ServiceWorkers[](#class-serviceworkers "Direct link to heading")
------------------------------------------------------------------------
> Query and receive events from a sessions active service workers.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
Instances of the `ServiceWorkers` class are accessed by using `serviceWorkers` property of a `Session`.
For example:
```
const { session } = require('electron')
// Get all service workers.
console.log(session.defaultSession.serviceWorkers.getAllRunning())
// Handle logs and get service worker info
session.defaultSession.serviceWorkers.on('console-message', (event, messageDetails) => {
console.log(
'Got service worker message',
messageDetails,
'from',
session.defaultSession.serviceWorkers.getFromVersionID(messageDetails.versionId)
)
})
```
### Instance Events[](#instance-events "Direct link to heading")
The following events are available on instances of `ServiceWorkers`:
#### Event: 'console-message'[](#event-console-message "Direct link to heading")
Returns:
* `event` Event
* `messageDetails` Object - Information about the console message
+ `message` string - The actual console message
+ `versionId` number - The version ID of the service worker that sent the log message
+ `source` string - The type of source for this message. Can be `javascript`, `xml`, `network`, `console-api`, `storage`, `rendering`, `security`, `deprecation`, `worker`, `violation`, `intervention`, `recommendation` or `other`.
+ `level` number - The log level, from 0 to 3. In order it matches `verbose`, `info`, `warning` and `error`.
+ `sourceUrl` string - The URL the message came from
+ `lineNumber` number - The line number of the source that triggered this console message
Emitted when a service worker logs something to the console.
#### Event: 'registration-completed'[](#event-registration-completed "Direct link to heading")
Returns:
* `event` Event
* `details` Object - Information about the registered service worker
+ `scope` string - The base URL that a service worker is registered for
Emitted when a service worker has been registered. Can occur after a call to [`navigator.serviceWorker.register('/sw.js')`](https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerContainer/register) successfully resolves or when a Chrome extension is loaded.
### Instance Methods[](#instance-methods "Direct link to heading")
The following methods are available on instances of `ServiceWorkers`:
####
`serviceWorkers.getAllRunning()`[](#serviceworkersgetallrunning "Direct link to heading")
Returns `Record<number, ServiceWorkerInfo>` - A [ServiceWorkerInfo](structures/service-worker-info) object where the keys are the service worker version ID and the values are the information about that service worker.
####
`serviceWorkers.getFromVersionID(versionId)`[](#serviceworkersgetfromversionidversionid "Direct link to heading")
* `versionId` number
Returns [ServiceWorkerInfo](structures/service-worker-info) - Information about this service worker
If the service worker does not exist or is not running this method will throw an exception.
electron Notification Notification
============
> Create OS desktop notifications
>
>
Process: [Main](../glossary#main-process)
Using in the renderer process[](#using-in-the-renderer-process "Direct link to heading")
-----------------------------------------------------------------------------------------
If you want to show Notifications from a renderer process you should use the [HTML5 Notification API](../tutorial/notifications)
Class: Notification[](#class-notification "Direct link to heading")
--------------------------------------------------------------------
> Create OS desktop notifications
>
>
Process: [Main](../glossary#main-process)
`Notification` is an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter).
It creates a new `Notification` with native properties as set by the `options`.
### Static Methods[](#static-methods "Direct link to heading")
The `Notification` class has the following static methods:
####
`Notification.isSupported()`[](#notificationissupported "Direct link to heading")
Returns `boolean` - Whether or not desktop notifications are supported on the current system
###
`new Notification([options])`[](#new-notificationoptions "Direct link to heading")
* `options` Object (optional)
+ `title` string (optional) - A title for the notification, which will be shown at the top of the notification window when it is shown.
+ `subtitle` string (optional) *macOS* - A subtitle for the notification, which will be displayed below the title.
+ `body` string (optional) - The body text of the notification, which will be displayed below the title or subtitle.
+ `silent` boolean (optional) - Whether or not to emit an OS notification noise when showing the notification.
+ `icon` (string | [NativeImage](native-image)) (optional) - An icon to use in the notification.
+ `hasReply` boolean (optional) *macOS* - Whether or not to add an inline reply option to the notification.
+ `timeoutType` string (optional) *Linux* *Windows* - The timeout duration of the notification. Can be 'default' or 'never'.
+ `replyPlaceholder` string (optional) *macOS* - The placeholder to write in the inline reply input field.
+ `sound` string (optional) *macOS* - The name of the sound file to play when the notification is shown.
+ `urgency` string (optional) *Linux* - The urgency level of the notification. Can be 'normal', 'critical', or 'low'.
+ `actions` [NotificationAction[]](structures/notification-action) (optional) *macOS* - Actions to add to the notification. Please read the available actions and limitations in the `NotificationAction` documentation.
+ `closeButtonText` string (optional) *macOS* - A custom title for the close button of an alert. An empty string will cause the default localized text to be used.
+ `toastXml` string (optional) *Windows* - A custom description of the Notification on Windows superseding all properties above. Provides full customization of design and behavior of the notification.
### Instance Events[](#instance-events "Direct link to heading")
Objects created with `new Notification` emit the following events:
**Note:** Some events are only available on specific operating systems and are labeled as such.
#### Event: 'show'[](#event-show "Direct link to heading")
Returns:
* `event` Event
Emitted when the notification is shown to the user, note this could be fired multiple times as a notification can be shown multiple times through the `show()` method.
#### Event: 'click'[](#event-click "Direct link to heading")
Returns:
* `event` Event
Emitted when the notification is clicked by the user.
#### Event: 'close'[](#event-close "Direct link to heading")
Returns:
* `event` Event
Emitted when the notification is closed by manual intervention from the user.
This event is not guaranteed to be emitted in all cases where the notification is closed.
#### Event: 'reply' *macOS*[](#event-reply-macos "Direct link to heading")
Returns:
* `event` Event
* `reply` string - The string the user entered into the inline reply field.
Emitted when the user clicks the "Reply" button on a notification with `hasReply: true`.
#### Event: 'action' *macOS*[](#event-action-macos "Direct link to heading")
Returns:
* `event` Event
* `index` number - The index of the action that was activated.
#### Event: 'failed' *Windows*[](#event-failed-windows "Direct link to heading")
Returns:
* `event` Event
* `error` string - The error encountered during execution of the `show()` method.
Emitted when an error is encountered while creating and showing the native notification.
### Instance Methods[](#instance-methods "Direct link to heading")
Objects created with `new Notification` have the following instance methods:
####
`notification.show()`[](#notificationshow "Direct link to heading")
Immediately shows the notification to the user, please note this means unlike the HTML5 Notification implementation, instantiating a `new Notification` does not immediately show it to the user, you need to call this method before the OS will display it.
If the notification has been shown before, this method will dismiss the previously shown notification and create a new one with identical properties.
####
`notification.close()`[](#notificationclose "Direct link to heading")
Dismisses the notification.
### Instance Properties[](#instance-properties "Direct link to heading")
####
`notification.title`[](#notificationtitle "Direct link to heading")
A `string` property representing the title of the notification.
####
`notification.subtitle`[](#notificationsubtitle "Direct link to heading")
A `string` property representing the subtitle of the notification.
####
`notification.body`[](#notificationbody "Direct link to heading")
A `string` property representing the body of the notification.
####
`notification.replyPlaceholder`[](#notificationreplyplaceholder "Direct link to heading")
A `string` property representing the reply placeholder of the notification.
####
`notification.sound`[](#notificationsound "Direct link to heading")
A `string` property representing the sound of the notification.
####
`notification.closeButtonText`[](#notificationclosebuttontext "Direct link to heading")
A `string` property representing the close button text of the notification.
####
`notification.silent`[](#notificationsilent "Direct link to heading")
A `boolean` property representing whether the notification is silent.
####
`notification.hasReply`[](#notificationhasreply "Direct link to heading")
A `boolean` property representing whether the notification has a reply action.
####
`notification.urgency` *Linux*[](#notificationurgency-linux "Direct link to heading")
A `string` property representing the urgency level of the notification. Can be 'normal', 'critical', or 'low'.
Default is 'low' - see [NotifyUrgency](https://developer.gnome.org/notification-spec/#urgency-levels) for more information.
####
`notification.timeoutType` *Linux* *Windows*[](#notificationtimeouttype-linux-windows "Direct link to heading")
A `string` property representing the type of timeout duration for the notification. Can be 'default' or 'never'.
If `timeoutType` is set to 'never', the notification never expires. It stays open until closed by the calling API or the user.
####
`notification.actions`[](#notificationactions "Direct link to heading")
A [NotificationAction[]](structures/notification-action) property representing the actions of the notification.
####
`notification.toastXml` *Windows*[](#notificationtoastxml-windows "Direct link to heading")
A `string` property representing the custom Toast XML of the notification.
### Playing Sounds[](#playing-sounds "Direct link to heading")
On macOS, you can specify the name of the sound you'd like to play when the notification is shown. Any of the default sounds (under System Preferences > Sound) can be used, in addition to custom sound files. Be sure that the sound file is copied under the app bundle (e.g., `YourApp.app/Contents/Resources`), or one of the following locations:
* `~/Library/Sounds`
* `/Library/Sounds`
* `/Network/Library/Sounds`
* `/System/Library/Sounds`
See the [`NSSound`](https://developer.apple.com/documentation/appkit/nssound) docs for more information.
electron webFrame webFrame
========
> Customize the rendering of the current web page.
>
>
Process: [Renderer](../glossary#renderer-process)
`webFrame` export of the Electron module is an instance of the `WebFrame` class representing the current frame. Sub-frames can be retrieved by certain properties and methods (e.g. `webFrame.firstChild`).
An example of zooming current page to 200%.
```
const { webFrame } = require('electron')
webFrame.setZoomFactor(2)
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `WebFrame` class has the following instance methods:
###
`webFrame.setZoomFactor(factor)`[](#webframesetzoomfactorfactor "Direct link to heading")
* `factor` Double - Zoom factor; default is 1.0.
Changes the zoom factor to the specified factor. Zoom factor is zoom percent divided by 100, so 300% = 3.0.
The factor must be greater than 0.0.
###
`webFrame.getZoomFactor()`[](#webframegetzoomfactor "Direct link to heading")
Returns `number` - The current zoom factor.
###
`webFrame.setZoomLevel(level)`[](#webframesetzoomlevellevel "Direct link to heading")
* `level` number - Zoom level.
Changes the zoom level to the specified level. The original size is 0 and each increment above or below represents zooming 20% larger or smaller to default limits of 300% and 50% of original size, respectively.
> **NOTE**: The zoom policy at the Chromium level is same-origin, meaning that the zoom level for a specific domain propagates across all instances of windows with the same domain. Differentiating the window URLs will make zoom work per-window.
>
>
###
`webFrame.getZoomLevel()`[](#webframegetzoomlevel "Direct link to heading")
Returns `number` - The current zoom level.
###
`webFrame.setVisualZoomLevelLimits(minimumLevel, maximumLevel)`[](#webframesetvisualzoomlevellimitsminimumlevel-maximumlevel "Direct link to heading")
* `minimumLevel` number
* `maximumLevel` number
Sets the maximum and minimum pinch-to-zoom level.
>
> **NOTE**: Visual zoom is disabled by default in Electron. To re-enable it, call:
>
>
>
>
> ```
> webFrame.setVisualZoomLevelLimits(1, 3)
> ```
>
>
>
> **NOTE**: Visual zoom only applies to pinch-to-zoom behavior. Cmd+/-/0 zoom shortcuts are controlled by the 'zoomIn', 'zoomOut', and 'resetZoom' MenuItem roles in the application Menu. To disable shortcuts, manually [define the Menu](menu#examples) and omit zoom roles from the definition.
>
>
###
`webFrame.setSpellCheckProvider(language, provider)`[](#webframesetspellcheckproviderlanguage-provider "Direct link to heading")
* `language` string
* `provider` Object
+ `spellCheck` Function
- `words` string[]
- `callback` Function
* `misspeltWords` string[]
Sets a provider for spell checking in input fields and text areas.
If you want to use this method you must disable the builtin spellchecker when you construct the window.
```
const mainWindow = new BrowserWindow({
webPreferences: {
spellcheck: false
}
})
```
The `provider` must be an object that has a `spellCheck` method that accepts an array of individual words for spellchecking. The `spellCheck` function runs asynchronously and calls the `callback` function with an array of misspelt words when complete.
An example of using [node-spellchecker](https://github.com/atom/node-spellchecker) as provider:
```
const { webFrame } = require('electron')
const spellChecker = require('spellchecker')
webFrame.setSpellCheckProvider('en-US', {
spellCheck (words, callback) {
setTimeout(() => {
const spellchecker = require('spellchecker')
const misspelled = words.filter(x => spellchecker.isMisspelled(x))
callback(misspelled)
}, 0)
}
})
```
###
`webFrame.insertCSS(css[, options])`[](#webframeinsertcsscss-options "Direct link to heading")
* `css` string
* `options` Object (optional)
+ `cssOrigin` string (optional) - Can be either 'user' or 'author'. Sets the [cascade origin](https://www.w3.org/TR/css3-cascade/#cascade-origin) of the inserted stylesheet. Default is 'author'.
Returns `string` - A key for the inserted CSS that can later be used to remove the CSS via `webFrame.removeInsertedCSS(key)`.
Injects CSS into the current web page and returns a unique key for the inserted stylesheet.
###
`webFrame.removeInsertedCSS(key)`[](#webframeremoveinsertedcsskey "Direct link to heading")
* `key` string
Removes the inserted CSS from the current web page. The stylesheet is identified by its key, which is returned from `webFrame.insertCSS(css)`.
###
`webFrame.insertText(text)`[](#webframeinserttexttext "Direct link to heading")
* `text` string
Inserts `text` to the focused element.
###
`webFrame.executeJavaScript(code[, userGesture, callback])`[](#webframeexecutejavascriptcode-usergesture-callback "Direct link to heading")
* `code` string
* `userGesture` boolean (optional) - Default is `false`.
* `callback` Function (optional) - Called after script has been executed. Unless the frame is suspended (e.g. showing a modal alert), execution will be synchronous and the callback will be invoked before the method returns. For compatibility with an older version of this method, the error parameter is second.
+ `result` Any
+ `error` Error
Returns `Promise<any>` - A promise that resolves with the result of the executed code or is rejected if execution throws or results in a rejected promise.
Evaluates `code` in page.
In the browser window some HTML APIs like `requestFullScreen` can only be invoked by a gesture from the user. Setting `userGesture` to `true` will remove this limitation.
###
`webFrame.executeJavaScriptInIsolatedWorld(worldId, scripts[, userGesture, callback])`[](#webframeexecutejavascriptinisolatedworldworldid-scripts-usergesture-callback "Direct link to heading")
* `worldId` Integer - The ID of the world to run the javascript in, `0` is the default main world (where content runs), `999` is the world used by Electron's `contextIsolation` feature. Accepts values in the range 1..536870911.
* `scripts` [WebSource[]](structures/web-source)
* `userGesture` boolean (optional) - Default is `false`.
* `callback` Function (optional) - Called after script has been executed. Unless the frame is suspended (e.g. showing a modal alert), execution will be synchronous and the callback will be invoked before the method returns. For compatibility with an older version of this method, the error parameter is second.
+ `result` Any
+ `error` Error
Returns `Promise<any>` - A promise that resolves with the result of the executed code or is rejected if execution could not start.
Works like `executeJavaScript` but evaluates `scripts` in an isolated context.
Note that when the execution of script fails, the returned promise will not reject and the `result` would be `undefined`. This is because Chromium does not dispatch errors of isolated worlds to foreign worlds.
###
`webFrame.setIsolatedWorldInfo(worldId, info)`[](#webframesetisolatedworldinfoworldid-info "Direct link to heading")
* `worldId` Integer - The ID of the world to run the javascript in, `0` is the default world, `999` is the world used by Electrons `contextIsolation` feature. Chrome extensions reserve the range of IDs in `[1 << 20, 1 << 29)`. You can provide any integer here.
* `info` Object
+ `securityOrigin` string (optional) - Security origin for the isolated world.
+ `csp` string (optional) - Content Security Policy for the isolated world.
+ `name` string (optional) - Name for isolated world. Useful in devtools.
Set the security origin, content security policy and name of the isolated world. Note: If the `csp` is specified, then the `securityOrigin` also has to be specified.
###
`webFrame.getResourceUsage()`[](#webframegetresourceusage "Direct link to heading")
Returns `Object`:
* `images` [MemoryUsageDetails](structures/memory-usage-details)
* `scripts` [MemoryUsageDetails](structures/memory-usage-details)
* `cssStyleSheets` [MemoryUsageDetails](structures/memory-usage-details)
* `xslStyleSheets` [MemoryUsageDetails](structures/memory-usage-details)
* `fonts` [MemoryUsageDetails](structures/memory-usage-details)
* `other` [MemoryUsageDetails](structures/memory-usage-details)
Returns an object describing usage information of Blink's internal memory caches.
```
const { webFrame } = require('electron')
console.log(webFrame.getResourceUsage())
```
This will generate:
```
{
images: {
count: 22,
size: 2549,
liveSize: 2542
},
cssStyleSheets: { /* same with "images" */ },
xslStyleSheets: { /* same with "images" */ },
fonts: { /* same with "images" */ },
other: { /* same with "images" */ }
}
```
###
`webFrame.clearCache()`[](#webframeclearcache "Direct link to heading")
Attempts to free memory that is no longer being used (like images from a previous navigation).
Note that blindly calling this method probably makes Electron slower since it will have to refill these emptied caches, you should only call it if an event in your app has occurred that makes you think your page is actually using less memory (i.e. you have navigated from a super heavy page to a mostly empty one, and intend to stay there).
###
`webFrame.getFrameForSelector(selector)`[](#webframegetframeforselectorselector "Direct link to heading")
* `selector` string - CSS selector for a frame element.
Returns `WebFrame` - The frame element in `webFrame's` document selected by `selector`, `null` would be returned if `selector` does not select a frame or if the frame is not in the current renderer process.
###
`webFrame.findFrameByName(name)`[](#webframefindframebynamename "Direct link to heading")
* `name` string
Returns `WebFrame` - A child of `webFrame` with the supplied `name`, `null` would be returned if there's no such frame or if the frame is not in the current renderer process.
###
`webFrame.findFrameByRoutingId(routingId)`[](#webframefindframebyroutingidroutingid "Direct link to heading")
* `routingId` Integer - An `Integer` representing the unique frame id in the current renderer process. Routing IDs can be retrieved from `WebFrame` instances (`webFrame.routingId`) and are also passed by frame specific `WebContents` navigation events (e.g. `did-frame-navigate`)
Returns `WebFrame` - that has the supplied `routingId`, `null` if not found.
###
`webFrame.isWordMisspelled(word)`[](#webframeiswordmisspelledword "Direct link to heading")
* `word` string - The word to be spellchecked.
Returns `boolean` - True if the word is misspelled according to the built in spellchecker, false otherwise. If no dictionary is loaded, always return false.
###
`webFrame.getWordSuggestions(word)`[](#webframegetwordsuggestionsword "Direct link to heading")
* `word` string - The misspelled word.
Returns `string[]` - A list of suggested words for a given word. If the word is spelled correctly, the result will be empty.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
###
`webFrame.top` *Readonly*[](#webframetop-readonly "Direct link to heading")
A `WebFrame | null` representing top frame in frame hierarchy to which `webFrame` belongs, the property would be `null` if top frame is not in the current renderer process.
###
`webFrame.opener` *Readonly*[](#webframeopener-readonly "Direct link to heading")
A `WebFrame | null` representing the frame which opened `webFrame`, the property would be `null` if there's no opener or opener is not in the current renderer process.
###
`webFrame.parent` *Readonly*[](#webframeparent-readonly "Direct link to heading")
A `WebFrame | null` representing parent frame of `webFrame`, the property would be `null` if `webFrame` is top or parent is not in the current renderer process.
###
`webFrame.firstChild` *Readonly*[](#webframefirstchild-readonly "Direct link to heading")
A `WebFrame | null` representing the first child frame of `webFrame`, the property would be `null` if `webFrame` has no children or if first child is not in the current renderer process.
###
`webFrame.nextSibling` *Readonly*[](#webframenextsibling-readonly "Direct link to heading")
A `WebFrame | null` representing next sibling frame, the property would be `null` if `webFrame` is the last frame in its parent or if the next sibling is not in the current renderer process.
###
`webFrame.routingId` *Readonly*[](#webframeroutingid-readonly "Direct link to heading")
An `Integer` representing the unique frame id in the current renderer process. Distinct WebFrame instances that refer to the same underlying frame will have the same `routingId`.
| programming_docs |
electron Class: TouchBarSegmentedControl Class: TouchBarSegmentedControl[](#class-touchbarsegmentedcontrol "Direct link to heading")
--------------------------------------------------------------------------------------------
> Create a segmented control (a button group) where one button has a selected state
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarSegmentedControl(options)`[](#new-touchbarsegmentedcontroloptions "Direct link to heading")
* `options` Object
+ `segmentStyle` string (optional) - Style of the segments:
- `automatic` - Default. The appearance of the segmented control is automatically determined based on the type of window in which the control is displayed and the position within the window. Maps to `NSSegmentStyleAutomatic`.
- `rounded` - The control is displayed using the rounded style. Maps to `NSSegmentStyleRounded`.
- `textured-rounded` - The control is displayed using the textured rounded style. Maps to `NSSegmentStyleTexturedRounded`.
- `round-rect` - The control is displayed using the round rect style. Maps to `NSSegmentStyleRoundRect`.
- `textured-square` - The control is displayed using the textured square style. Maps to `NSSegmentStyleTexturedSquare`.
- `capsule` - The control is displayed using the capsule style. Maps to `NSSegmentStyleCapsule`.
- `small-square` - The control is displayed using the small square style. Maps to `NSSegmentStyleSmallSquare`.
- `separated` - The segments in the control are displayed very close to each other but not touching. Maps to `NSSegmentStyleSeparated`.
+ `mode` string (optional) - The selection mode of the control:
- `single` - Default. One item selected at a time, selecting one deselects the previously selected item. Maps to `NSSegmentSwitchTrackingSelectOne`.
- `multiple` - Multiple items can be selected at a time. Maps to `NSSegmentSwitchTrackingSelectAny`.
- `buttons` - Make the segments act as buttons, each segment can be pressed and released but never marked as active. Maps to `NSSegmentSwitchTrackingMomentary`.
+ `segments` [SegmentedControlSegment[]](structures/segmented-control-segment) - An array of segments to place in this control.
+ `selectedIndex` Integer (optional) - The index of the currently selected segment, will update automatically with user interaction. When the mode is `multiple` it will be the last selected item.
+ `change` Function (optional) - Called when the user selects a new segment.
- `selectedIndex` Integer - The index of the segment the user selected.
- `isSelected` boolean - Whether as a result of user selection the segment is selected or not.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBarSegmentedControl`:
####
`touchBarSegmentedControl.segmentStyle`[](#touchbarsegmentedcontrolsegmentstyle "Direct link to heading")
A `string` representing the controls current segment style. Updating this value immediately updates the control in the touch bar.
####
`touchBarSegmentedControl.segments`[](#touchbarsegmentedcontrolsegments "Direct link to heading")
A `SegmentedControlSegment[]` array representing the segments in this control. Updating this value immediately updates the control in the touch bar. Updating deep properties inside this array **does not update the touch bar**.
####
`touchBarSegmentedControl.selectedIndex`[](#touchbarsegmentedcontrolselectedindex "Direct link to heading")
An `Integer` representing the currently selected segment. Changing this value immediately updates the control in the touch bar. User interaction with the touch bar will update this value automatically.
####
`touchBarSegmentedControl.mode`[](#touchbarsegmentedcontrolmode "Direct link to heading")
A `string` representing the current selection mode of the control. Can be `single`, `multiple` or `buttons`.
electron protocol protocol
========
> Register a custom protocol and intercept existing protocol requests.
>
>
Process: [Main](../glossary#main-process)
An example of implementing a protocol that has the same effect as the `file://` protocol:
```
const { app, protocol } = require('electron')
const path = require('path')
app.whenReady().then(() => {
protocol.registerFileProtocol('atom', (request, callback) => {
const url = request.url.substr(7)
callback({ path: path.normalize(`${__dirname}/${url}`) })
})
})
```
**Note:** All methods unless specified can only be used after the `ready` event of the `app` module gets emitted.
Using `protocol` with a custom `partition` or `session`[](#using-protocol-with-a-custom-partition-or-session "Direct link to heading")
---------------------------------------------------------------------------------------------------------------------------------------
A protocol is registered to a specific Electron [`session`](session) object. If you don't specify a session, then your `protocol` will be applied to the default session that Electron uses. However, if you define a `partition` or `session` on your `browserWindow`'s `webPreferences`, then that window will use a different session and your custom protocol will not work if you just use `electron.protocol.XXX`.
To have your custom protocol work in combination with a custom session, you need to register it to that session explicitly.
```
const { session, app, protocol } = require('electron')
const path = require('path')
app.whenReady().then(() => {
const partition = 'persist:example'
const ses = session.fromPartition(partition)
ses.protocol.registerFileProtocol('atom', (request, callback) => {
const url = request.url.substr(7)
callback({ path: path.normalize(`${__dirname}/${url}`) })
})
mainWindow = new BrowserWindow({ webPreferences: { partition } })
})
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `protocol` module has the following methods:
###
`protocol.registerSchemesAsPrivileged(customSchemes)`[](#protocolregisterschemesasprivilegedcustomschemes "Direct link to heading")
* `customSchemes` [CustomScheme[]](structures/custom-scheme)
**Note:** This method can only be used before the `ready` event of the `app` module gets emitted and can be called only once.
Registers the `scheme` as standard, secure, bypasses content security policy for resources, allows registering ServiceWorker, supports fetch API, and streaming video/audio. Specify a privilege with the value of `true` to enable the capability.
An example of registering a privileged scheme, that bypasses Content Security Policy:
```
const { protocol } = require('electron')
protocol.registerSchemesAsPrivileged([
{ scheme: 'foo', privileges: { bypassCSP: true } }
])
```
A standard scheme adheres to what RFC 3986 calls [generic URI syntax](https://tools.ietf.org/html/rfc3986#section-3). For example `http` and `https` are standard schemes, while `file` is not.
Registering a scheme as standard allows relative and absolute resources to be resolved correctly when served. Otherwise the scheme will behave like the `file` protocol, but without the ability to resolve relative URLs.
For example when you load following page with custom protocol without registering it as standard scheme, the image will not be loaded because non-standard schemes can not recognize relative URLs:
```
<body>
<img src='test.png'>
</body>
```
Registering a scheme as standard will allow access to files through the [FileSystem API](https://developer.mozilla.org/en-US/docs/Web/API/LocalFileSystem). Otherwise the renderer will throw a security error for the scheme.
By default web storage apis (localStorage, sessionStorage, webSQL, indexedDB, cookies) are disabled for non standard schemes. So in general if you want to register a custom protocol to replace the `http` protocol, you have to register it as a standard scheme.
Protocols that use streams (http and stream protocols) should set `stream: true`. The `<video>` and `<audio>` HTML elements expect protocols to buffer their responses by default. The `stream` flag configures those elements to correctly expect streaming responses.
###
`protocol.registerFileProtocol(scheme, handler)`[](#protocolregisterfileprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` (string | [ProtocolResponse](structures/protocol-response))
Returns `boolean` - Whether the protocol was successfully registered
Registers a protocol of `scheme` that will send a file as the response. The `handler` will be called with `request` and `callback` where `request` is an incoming request for the `scheme`.
To handle the `request`, the `callback` should be called with either the file's path or an object that has a `path` property, e.g. `callback(filePath)` or `callback({ path: filePath })`. The `filePath` must be an absolute path.
By default the `scheme` is treated like `http:`, which is parsed differently from protocols that follow the "generic URI syntax" like `file:`.
###
`protocol.registerBufferProtocol(scheme, handler)`[](#protocolregisterbufferprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` (Buffer | [ProtocolResponse](structures/protocol-response))
Returns `boolean` - Whether the protocol was successfully registered
Registers a protocol of `scheme` that will send a `Buffer` as a response.
The usage is the same with `registerFileProtocol`, except that the `callback` should be called with either a `Buffer` object or an object that has the `data` property.
Example:
```
protocol.registerBufferProtocol('atom', (request, callback) => {
callback({ mimeType: 'text/html', data: Buffer.from('<h5>Response</h5>') })
})
```
###
`protocol.registerStringProtocol(scheme, handler)`[](#protocolregisterstringprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` (string | [ProtocolResponse](structures/protocol-response))
Returns `boolean` - Whether the protocol was successfully registered
Registers a protocol of `scheme` that will send a `string` as a response.
The usage is the same with `registerFileProtocol`, except that the `callback` should be called with either a `string` or an object that has the `data` property.
###
`protocol.registerHttpProtocol(scheme, handler)`[](#protocolregisterhttpprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` ProtocolResponse
Returns `boolean` - Whether the protocol was successfully registered
Registers a protocol of `scheme` that will send an HTTP request as a response.
The usage is the same with `registerFileProtocol`, except that the `callback` should be called with an object that has the `url` property.
###
`protocol.registerStreamProtocol(scheme, handler)`[](#protocolregisterstreamprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` (ReadableStream | [ProtocolResponse](structures/protocol-response))
Returns `boolean` - Whether the protocol was successfully registered
Registers a protocol of `scheme` that will send a stream as a response.
The usage is the same with `registerFileProtocol`, except that the `callback` should be called with either a [`ReadableStream`](https://nodejs.org/api/stream.html#stream_class_stream_readable) object or an object that has the `data` property.
Example:
```
const { protocol } = require('electron')
const { PassThrough } = require('stream')
function createStream (text) {
const rv = new PassThrough() // PassThrough is also a Readable stream
rv.push(text)
rv.push(null)
return rv
}
protocol.registerStreamProtocol('atom', (request, callback) => {
callback({
statusCode: 200,
headers: {
'content-type': 'text/html'
},
data: createStream('<h5>Response</h5>')
})
})
```
It is possible to pass any object that implements the readable stream API (emits `data`/`end`/`error` events). For example, here's how a file could be returned:
```
protocol.registerStreamProtocol('atom', (request, callback) => {
callback(fs.createReadStream('index.html'))
})
```
###
`protocol.unregisterProtocol(scheme)`[](#protocolunregisterprotocolscheme "Direct link to heading")
* `scheme` string
Returns `boolean` - Whether the protocol was successfully unregistered
Unregisters the custom protocol of `scheme`.
###
`protocol.isProtocolRegistered(scheme)`[](#protocolisprotocolregisteredscheme "Direct link to heading")
* `scheme` string
Returns `boolean` - Whether `scheme` is already registered.
###
`protocol.interceptFileProtocol(scheme, handler)`[](#protocolinterceptfileprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` (string | [ProtocolResponse](structures/protocol-response))
Returns `boolean` - Whether the protocol was successfully intercepted
Intercepts `scheme` protocol and uses `handler` as the protocol's new handler which sends a file as a response.
###
`protocol.interceptStringProtocol(scheme, handler)`[](#protocolinterceptstringprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` (string | [ProtocolResponse](structures/protocol-response))
Returns `boolean` - Whether the protocol was successfully intercepted
Intercepts `scheme` protocol and uses `handler` as the protocol's new handler which sends a `string` as a response.
###
`protocol.interceptBufferProtocol(scheme, handler)`[](#protocolinterceptbufferprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` (Buffer | [ProtocolResponse](structures/protocol-response))
Returns `boolean` - Whether the protocol was successfully intercepted
Intercepts `scheme` protocol and uses `handler` as the protocol's new handler which sends a `Buffer` as a response.
###
`protocol.interceptHttpProtocol(scheme, handler)`[](#protocolintercepthttpprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` [ProtocolResponse](structures/protocol-response)
Returns `boolean` - Whether the protocol was successfully intercepted
Intercepts `scheme` protocol and uses `handler` as the protocol's new handler which sends a new HTTP request as a response.
###
`protocol.interceptStreamProtocol(scheme, handler)`[](#protocolinterceptstreamprotocolscheme-handler "Direct link to heading")
* `scheme` string
* `handler` Function
+ `request` [ProtocolRequest](structures/protocol-request)
+ `callback` Function
- `response` (ReadableStream | [ProtocolResponse](structures/protocol-response))
Returns `boolean` - Whether the protocol was successfully intercepted
Same as `protocol.registerStreamProtocol`, except that it replaces an existing protocol handler.
###
`protocol.uninterceptProtocol(scheme)`[](#protocoluninterceptprotocolscheme "Direct link to heading")
* `scheme` string
Returns `boolean` - Whether the protocol was successfully unintercepted
Remove the interceptor installed for `scheme` and restore its original handler.
###
`protocol.isProtocolIntercepted(scheme)`[](#protocolisprotocolinterceptedscheme "Direct link to heading")
* `scheme` string
Returns `boolean` - Whether `scheme` is already intercepted.
electron MessageChannelMain MessageChannelMain
==================
`MessageChannelMain` is the main-process-side equivalent of the DOM [`MessageChannel`](https://developer.mozilla.org/en-US/docs/Web/API/MessageChannel) object. Its singular function is to create a pair of connected [`MessagePortMain`](message-port-main) objects.
See the [Channel Messaging API](https://developer.mozilla.org/en-US/docs/Web/API/Channel_Messaging_API) documentation for more information on using channel messaging.
Class: MessageChannelMain[](#class-messagechannelmain "Direct link to heading")
--------------------------------------------------------------------------------
> Channel interface for channel messaging in the main process.
>
>
Process: [Main](../glossary#main-process)
Example:
```
// Main process
const { MessageChannelMain } = require('electron')
const { port1, port2 } = new MessageChannelMain()
w.webContents.postMessage('port', null, [port2])
port1.postMessage({ some: 'message' })
// Renderer process
const { ipcRenderer } = require('electron')
ipcRenderer.on('port', (e) => {
// e.ports is a list of ports sent along with this message
e.ports[0].on('message', (messageEvent) => {
console.log(messageEvent.data)
})
})
```
### Instance Properties[](#instance-properties "Direct link to heading")
####
`channel.port1`[](#channelport1 "Direct link to heading")
A [`MessagePortMain`](message-port-main) property.
####
`channel.port2`[](#channelport2 "Direct link to heading")
A [`MessagePortMain`](message-port-main) property.
electron shell shell
=====
> Manage files and URLs using their default applications.
>
>
Process: [Main](../glossary#main-process), [Renderer](../glossary#renderer-process) (non-sandboxed only)
The `shell` module provides functions related to desktop integration.
An example of opening a URL in the user's default browser:
```
const { shell } = require('electron')
shell.openExternal('https://github.com')
```
**Note:** While the `shell` module can be used in the renderer process, it will not function in a sandboxed renderer.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `shell` module has the following methods:
###
`shell.showItemInFolder(fullPath)`[](#shellshowiteminfolderfullpath "Direct link to heading")
* `fullPath` string
Show the given file in a file manager. If possible, select the file.
###
`shell.openPath(path)`[](#shellopenpathpath "Direct link to heading")
* `path` string
Returns `Promise<string>` - Resolves with a string containing the error message corresponding to the failure if a failure occurred, otherwise "".
Open the given file in the desktop's default manner.
###
`shell.openExternal(url[, options])`[](#shellopenexternalurl-options "Direct link to heading")
* `url` string - Max 2081 characters on windows.
* `options` Object (optional)
+ `activate` boolean (optional) *macOS* - `true` to bring the opened application to the foreground. The default is `true`.
+ `workingDirectory` string (optional) *Windows* - The working directory.
Returns `Promise<void>`
Open the given external protocol URL in the desktop's default manner. (For example, mailto: URLs in the user's default mail agent).
###
`shell.trashItem(path)`[](#shelltrashitempath "Direct link to heading")
* `path` string - path to the item to be moved to the trash.
Returns `Promise<void>` - Resolves when the operation has been completed. Rejects if there was an error while deleting the requested item.
This moves a path to the OS-specific trash location (Trash on macOS, Recycle Bin on Windows, and a desktop-environment-specific location on Linux).
###
`shell.beep()`[](#shellbeep "Direct link to heading")
Play the beep sound.
###
`shell.writeShortcutLink(shortcutPath[, operation], options)` *Windows*[](#shellwriteshortcutlinkshortcutpath-operation-options-windows "Direct link to heading")
* `shortcutPath` string
* `operation` string (optional) - Default is `create`, can be one of following:
+ `create` - Creates a new shortcut, overwriting if necessary.
+ `update` - Updates specified properties only on an existing shortcut.
+ `replace` - Overwrites an existing shortcut, fails if the shortcut doesn't exist.
* `options` [ShortcutDetails](structures/shortcut-details)
Returns `boolean` - Whether the shortcut was created successfully.
Creates or updates a shortcut link at `shortcutPath`.
###
`shell.readShortcutLink(shortcutPath)` *Windows*[](#shellreadshortcutlinkshortcutpath-windows "Direct link to heading")
* `shortcutPath` string
Returns [ShortcutDetails](structures/shortcut-details)
Resolves the shortcut link at `shortcutPath`.
An exception will be thrown when any error happens.
| programming_docs |
electron
File Object
`File` Object
==============
> Use the HTML5 `File` API to work natively with files on the filesystem.
>
>
The DOM's File interface provides abstraction around native files in order to let users work on native files directly with the HTML5 file API. Electron has added a `path` attribute to the `File` interface which exposes the file's real path on filesystem.
Example of getting a real path from a dragged-onto-the-app file:
```
<div id="holder">
Drag your file here
</div>
<script>
document.addEventListener('drop', (e) => {
e.preventDefault();
e.stopPropagation();
for (const f of e.dataTransfer.files) {
console.log('File(s) you dragged here: ', f.path)
}
});
document.addEventListener('dragover', (e) => {
e.preventDefault();
e.stopPropagation();
});
</script>
```
electron Class: Cookies Class: Cookies[](#class-cookies "Direct link to heading")
----------------------------------------------------------
> Query and modify a session's cookies.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
Instances of the `Cookies` class are accessed by using `cookies` property of a `Session`.
For example:
```
const { session } = require('electron')
// Query all cookies.
session.defaultSession.cookies.get({})
.then((cookies) => {
console.log(cookies)
}).catch((error) => {
console.log(error)
})
// Query all cookies associated with a specific url.
session.defaultSession.cookies.get({ url: 'http://www.github.com' })
.then((cookies) => {
console.log(cookies)
}).catch((error) => {
console.log(error)
})
// Set a cookie with the given cookie data;
// may overwrite equivalent cookies if they exist.
const cookie = { url: 'http://www.github.com', name: 'dummy_name', value: 'dummy' }
session.defaultSession.cookies.set(cookie)
.then(() => {
// success
}, (error) => {
console.error(error)
})
```
### Instance Events[](#instance-events "Direct link to heading")
The following events are available on instances of `Cookies`:
#### Event: 'changed'[](#event-changed "Direct link to heading")
Returns:
* `event` Event
* `cookie` [Cookie](structures/cookie) - The cookie that was changed.
* `cause` string - The cause of the change with one of the following values:
+ `explicit` - The cookie was changed directly by a consumer's action.
+ `overwrite` - The cookie was automatically removed due to an insert operation that overwrote it.
+ `expired` - The cookie was automatically removed as it expired.
+ `evicted` - The cookie was automatically evicted during garbage collection.
+ `expired-overwrite` - The cookie was overwritten with an already-expired expiration date.
* `removed` boolean - `true` if the cookie was removed, `false` otherwise.
Emitted when a cookie is changed because it was added, edited, removed, or expired.
### Instance Methods[](#instance-methods "Direct link to heading")
The following methods are available on instances of `Cookies`:
####
`cookies.get(filter)`[](#cookiesgetfilter "Direct link to heading")
* `filter` Object
+ `url` string (optional) - Retrieves cookies which are associated with `url`. Empty implies retrieving cookies of all URLs.
+ `name` string (optional) - Filters cookies by name.
+ `domain` string (optional) - Retrieves cookies whose domains match or are subdomains of `domains`.
+ `path` string (optional) - Retrieves cookies whose path matches `path`.
+ `secure` boolean (optional) - Filters cookies by their Secure property.
+ `session` boolean (optional) - Filters out session or persistent cookies.
Returns `Promise<Cookie[]>` - A promise which resolves an array of cookie objects.
Sends a request to get all cookies matching `filter`, and resolves a promise with the response.
####
`cookies.set(details)`[](#cookiessetdetails "Direct link to heading")
* `details` Object
+ `url` string - The URL to associate the cookie with. The promise will be rejected if the URL is invalid.
+ `name` string (optional) - The name of the cookie. Empty by default if omitted.
+ `value` string (optional) - The value of the cookie. Empty by default if omitted.
+ `domain` string (optional) - The domain of the cookie; this will be normalized with a preceding dot so that it's also valid for subdomains. Empty by default if omitted.
+ `path` string (optional) - The path of the cookie. Empty by default if omitted.
+ `secure` boolean (optional) - Whether the cookie should be marked as Secure. Defaults to false unless [Same Site=None](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie/SameSite#samesitenone_requires_secure) attribute is used.
+ `httpOnly` boolean (optional) - Whether the cookie should be marked as HTTP only. Defaults to false.
+ `expirationDate` Double (optional) - The expiration date of the cookie as the number of seconds since the UNIX epoch. If omitted then the cookie becomes a session cookie and will not be retained between sessions.
+ `sameSite` string (optional) - The [Same Site](https://developer.mozilla.org/en-US/docs/Web/HTTP/Cookies#SameSite_cookies) policy to apply to this cookie. Can be `unspecified`, `no_restriction`, `lax` or `strict`. Default is `lax`.
Returns `Promise<void>` - A promise which resolves when the cookie has been set
Sets a cookie with `details`.
####
`cookies.remove(url, name)`[](#cookiesremoveurl-name "Direct link to heading")
* `url` string - The URL associated with the cookie.
* `name` string - The name of cookie to remove.
Returns `Promise<void>` - A promise which resolves when the cookie has been removed
Removes the cookies matching `url` and `name`
####
`cookies.flushStore()`[](#cookiesflushstore "Direct link to heading")
Returns `Promise<void>` - A promise which resolves when the cookie store has been flushed
Writes any unwritten cookies data to disk.
electron Class: TouchBarColorPicker Class: TouchBarColorPicker[](#class-touchbarcolorpicker "Direct link to heading")
----------------------------------------------------------------------------------
> Create a color picker in the touch bar for native macOS applications
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarColorPicker(options)`[](#new-touchbarcolorpickeroptions "Direct link to heading")
* `options` Object
+ `availableColors` string[] (optional) - Array of hex color strings to appear as possible colors to select.
+ `selectedColor` string (optional) - The selected hex color in the picker, i.e `#ABCDEF`.
+ `change` Function (optional) - Function to call when a color is selected.
- `color` string - The color that the user selected from the picker.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBarColorPicker`:
####
`touchBarColorPicker.availableColors`[](#touchbarcolorpickeravailablecolors "Direct link to heading")
A `string[]` array representing the color picker's available colors to select. Changing this value immediately updates the color picker in the touch bar.
####
`touchBarColorPicker.selectedColor`[](#touchbarcolorpickerselectedcolor "Direct link to heading")
A `string` hex code representing the color picker's currently selected color. Changing this value immediately updates the color picker in the touch bar.
electron Menu Menu
====
Class: Menu[](#class-menu "Direct link to heading")
----------------------------------------------------
> Create native application menus and context menus.
>
>
Process: [Main](../glossary#main-process)
###
`new Menu()`[](#new-menu "Direct link to heading")
Creates a new menu.
### Static Methods[](#static-methods "Direct link to heading")
The `Menu` class has the following static methods:
####
`Menu.setApplicationMenu(menu)`[](#menusetapplicationmenumenu "Direct link to heading")
* `menu` Menu | null
Sets `menu` as the application menu on macOS. On Windows and Linux, the `menu` will be set as each window's top menu.
Also on Windows and Linux, you can use a `&` in the top-level item name to indicate which letter should get a generated accelerator. For example, using `&File` for the file menu would result in a generated `Alt-F` accelerator that opens the associated menu. The indicated character in the button label then gets an underline, and the `&` character is not displayed on the button label.
In order to escape the `&` character in an item name, add a proceeding `&`. For example, `&&File` would result in `&File` displayed on the button label.
Passing `null` will suppress the default menu. On Windows and Linux, this has the additional effect of removing the menu bar from the window.
**Note:** The default menu will be created automatically if the app does not set one. It contains standard items such as `File`, `Edit`, `View`, `Window` and `Help`.
####
`Menu.getApplicationMenu()`[](#menugetapplicationmenu "Direct link to heading")
Returns `Menu | null` - The application menu, if set, or `null`, if not set.
**Note:** The returned `Menu` instance doesn't support dynamic addition or removal of menu items. [Instance properties](#instance-properties) can still be dynamically modified.
####
`Menu.sendActionToFirstResponder(action)` *macOS*[](#menusendactiontofirstresponderaction-macos "Direct link to heading")
* `action` string
Sends the `action` to the first responder of application. This is used for emulating default macOS menu behaviors. Usually you would use the [`role`](menu-item#roles) property of a [`MenuItem`](menu-item).
See the [macOS Cocoa Event Handling Guide](https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/EventOverview/EventArchitecture/EventArchitecture.html#//apple_ref/doc/uid/10000060i-CH3-SW7) for more information on macOS' native actions.
####
`Menu.buildFromTemplate(template)`[](#menubuildfromtemplatetemplate "Direct link to heading")
* `template` (MenuItemConstructorOptions | MenuItem)[]
Returns `Menu`
Generally, the `template` is an array of `options` for constructing a [MenuItem](menu-item). The usage can be referenced above.
You can also attach other fields to the element of the `template` and they will become properties of the constructed menu items.
### Instance Methods[](#instance-methods "Direct link to heading")
The `menu` object has the following instance methods:
####
`menu.popup([options])`[](#menupopupoptions "Direct link to heading")
* `options` Object (optional)
+ `window` [BrowserWindow](browser-window) (optional) - Default is the focused window.
+ `x` number (optional) - Default is the current mouse cursor position. Must be declared if `y` is declared.
+ `y` number (optional) - Default is the current mouse cursor position. Must be declared if `x` is declared.
+ `positioningItem` number (optional) *macOS* - The index of the menu item to be positioned under the mouse cursor at the specified coordinates. Default is -1.
+ `callback` Function (optional) - Called when menu is closed.
Pops up this menu as a context menu in the [`BrowserWindow`](browser-window).
####
`menu.closePopup([browserWindow])`[](#menuclosepopupbrowserwindow "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional) - Default is the focused window.
Closes the context menu in the `browserWindow`.
####
`menu.append(menuItem)`[](#menuappendmenuitem "Direct link to heading")
* `menuItem` [MenuItem](menu-item)
Appends the `menuItem` to the menu.
####
`menu.getMenuItemById(id)`[](#menugetmenuitembyidid "Direct link to heading")
* `id` string
Returns `MenuItem | null` the item with the specified `id`
####
`menu.insert(pos, menuItem)`[](#menuinsertpos-menuitem "Direct link to heading")
* `pos` Integer
* `menuItem` [MenuItem](menu-item)
Inserts the `menuItem` to the `pos` position of the menu.
### Instance Events[](#instance-events "Direct link to heading")
Objects created with `new Menu` or returned by `Menu.buildFromTemplate` emit the following events:
**Note:** Some events are only available on specific operating systems and are labeled as such.
#### Event: 'menu-will-show'[](#event-menu-will-show "Direct link to heading")
Returns:
* `event` Event
Emitted when `menu.popup()` is called.
#### Event: 'menu-will-close'[](#event-menu-will-close "Direct link to heading")
Returns:
* `event` Event
Emitted when a popup is closed either manually or with `menu.closePopup()`.
### Instance Properties[](#instance-properties "Direct link to heading")
`menu` objects also have the following properties:
####
`menu.items`[](#menuitems "Direct link to heading")
A `MenuItem[]` array containing the menu's items.
Each `Menu` consists of multiple [`MenuItem`](menu-item)s and each `MenuItem` can have a submenu.
Examples[](#examples "Direct link to heading")
-----------------------------------------------
An example of creating the application menu with the simple template API:
```
const { app, Menu } = require('electron')
const isMac = process.platform === 'darwin'
const template = [
// { role: 'appMenu' }
...(isMac ? [{
label: app.name,
submenu: [
{ role: 'about' },
{ type: 'separator' },
{ role: 'services' },
{ type: 'separator' },
{ role: 'hide' },
{ role: 'hideOthers' },
{ role: 'unhide' },
{ type: 'separator' },
{ role: 'quit' }
]
}] : []),
// { role: 'fileMenu' }
{
label: 'File',
submenu: [
isMac ? { role: 'close' } : { role: 'quit' }
]
},
// { role: 'editMenu' }
{
label: 'Edit',
submenu: [
{ role: 'undo' },
{ role: 'redo' },
{ type: 'separator' },
{ role: 'cut' },
{ role: 'copy' },
{ role: 'paste' },
...(isMac ? [
{ role: 'pasteAndMatchStyle' },
{ role: 'delete' },
{ role: 'selectAll' },
{ type: 'separator' },
{
label: 'Speech',
submenu: [
{ role: 'startSpeaking' },
{ role: 'stopSpeaking' }
]
}
] : [
{ role: 'delete' },
{ type: 'separator' },
{ role: 'selectAll' }
])
]
},
// { role: 'viewMenu' }
{
label: 'View',
submenu: [
{ role: 'reload' },
{ role: 'forceReload' },
{ role: 'toggleDevTools' },
{ type: 'separator' },
{ role: 'resetZoom' },
{ role: 'zoomIn' },
{ role: 'zoomOut' },
{ type: 'separator' },
{ role: 'togglefullscreen' }
]
},
// { role: 'windowMenu' }
{
label: 'Window',
submenu: [
{ role: 'minimize' },
{ role: 'zoom' },
...(isMac ? [
{ type: 'separator' },
{ role: 'front' },
{ type: 'separator' },
{ role: 'window' }
] : [
{ role: 'close' }
])
]
},
{
role: 'help',
submenu: [
{
label: 'Learn More',
click: async () => {
const { shell } = require('electron')
await shell.openExternal('https://electronjs.org')
}
}
]
}
]
const menu = Menu.buildFromTemplate(template)
Menu.setApplicationMenu(menu)
```
### Render process[](#render-process "Direct link to heading")
To create menus initiated by the renderer process, send the required information to the main process using IPC and have the main process display the menu on behalf of the renderer.
Below is an example of showing a menu when the user right clicks the page:
```
// renderer
window.addEventListener('contextmenu', (e) => {
e.preventDefault()
ipcRenderer.send('show-context-menu')
})
ipcRenderer.on('context-menu-command', (e, command) => {
// ...
})
// main
ipcMain.on('show-context-menu', (event) => {
const template = [
{
label: 'Menu Item 1',
click: () => { event.sender.send('context-menu-command', 'menu-item-1') }
},
{ type: 'separator' },
{ label: 'Menu Item 2', type: 'checkbox', checked: true }
]
const menu = Menu.buildFromTemplate(template)
menu.popup(BrowserWindow.fromWebContents(event.sender))
})
```
Notes on macOS Application Menu[](#notes-on-macos-application-menu "Direct link to heading")
---------------------------------------------------------------------------------------------
macOS has a completely different style of application menu from Windows and Linux. Here are some notes on making your app's menu more native-like.
### Standard Menus[](#standard-menus "Direct link to heading")
On macOS there are many system-defined standard menus, like the [`Services`](https://developer.apple.com/documentation/appkit/nsapplication/1428608-servicesmenu?language=objc) and `Windows` menus. To make your menu a standard menu, you should set your menu's `role` to one of the following and Electron will recognize them and make them become standard menus:
* `window`
* `help`
* `services`
### Standard Menu Item Actions[](#standard-menu-item-actions "Direct link to heading")
macOS has provided standard actions for some menu items, like `About xxx`, `Hide xxx`, and `Hide Others`. To set the action of a menu item to a standard action, you should set the `role` attribute of the menu item.
### Main Menu's Name[](#main-menus-name "Direct link to heading")
On macOS the label of the application menu's first item is always your app's name, no matter what label you set. To change it, modify your app bundle's `Info.plist` file. See [About Information Property List Files](https://developer.apple.com/library/ios/documentation/general/Reference/InfoPlistKeyReference/Articles/AboutInformationPropertyListFiles.html) for more information.
Setting Menu for Specific Browser Window (*Linux* *Windows*)[](#setting-menu-for-specific-browser-window-linux-windows "Direct link to heading")
-------------------------------------------------------------------------------------------------------------------------------------------------
The [`setMenu` method](browser-window#winsetmenumenu-linux-windows) of browser windows can set the menu of certain browser windows.
Menu Item Position[](#menu-item-position "Direct link to heading")
-------------------------------------------------------------------
You can make use of `before`, `after`, `beforeGroupContaining`, `afterGroupContaining` and `id` to control how the item will be placed when building a menu with `Menu.buildFromTemplate`.
* `before` - Inserts this item before the item with the specified label. If the referenced item doesn't exist the item will be inserted at the end of the menu. Also implies that the menu item in question should be placed in the same “group” as the item.
* `after` - Inserts this item after the item with the specified label. If the referenced item doesn't exist the item will be inserted at the end of the menu. Also implies that the menu item in question should be placed in the same “group” as the item.
* `beforeGroupContaining` - Provides a means for a single context menu to declare the placement of their containing group before the containing group of the item with the specified label.
* `afterGroupContaining` - Provides a means for a single context menu to declare the placement of their containing group after the containing group of the item with the specified label.
By default, items will be inserted in the order they exist in the template unless one of the specified positioning keywords is used.
### Examples[](#examples-1 "Direct link to heading")
Template:
```
[
{ id: '1', label: 'one' },
{ id: '2', label: 'two' },
{ id: '3', label: 'three' },
{ id: '4', label: 'four' }
]
```
Menu:
```
- 1
- 2
- 3
- 4
```
Template:
```
[
{ id: '1', label: 'one' },
{ type: 'separator' },
{ id: '3', label: 'three', beforeGroupContaining: ['1'] },
{ id: '4', label: 'four', afterGroupContaining: ['2'] },
{ type: 'separator' },
{ id: '2', label: 'two' }
]
```
Menu:
```
- 3
- 4
- ---
- 1
- ---
- 2
```
Template:
```
[
{ id: '1', label: 'one', after: ['3'] },
{ id: '2', label: 'two', before: ['1'] },
{ id: '3', label: 'three' }
]
```
Menu:
```
- ---
- 3
- 2
- 1
```
| programming_docs |
electron desktopCapturer desktopCapturer
===============
> Access information about media sources that can be used to capture audio and video from the desktop using the [`navigator.mediaDevices.getUserMedia`](https://developer.mozilla.org/en/docs/Web/API/MediaDevices/getUserMedia) API.
>
>
Process: [Main](../glossary#main-process)
The following example shows how to capture video from a desktop window whose title is `Electron`:
```
// In the main process.
const { desktopCapturer } = require('electron')
desktopCapturer.getSources({ types: ['window', 'screen'] }).then(async sources => {
for (const source of sources) {
if (source.name === 'Electron') {
mainWindow.webContents.send('SET_SOURCE', source.id)
return
}
}
})
```
```
// In the preload script.
const { ipcRenderer } = require('electron')
ipcRenderer.on('SET_SOURCE', async (event, sourceId) => {
try {
const stream = await navigator.mediaDevices.getUserMedia({
audio: false,
video: {
mandatory: {
chromeMediaSource: 'desktop',
chromeMediaSourceId: sourceId,
minWidth: 1280,
maxWidth: 1280,
minHeight: 720,
maxHeight: 720
}
}
})
handleStream(stream)
} catch (e) {
handleError(e)
}
})
function handleStream (stream) {
const video = document.querySelector('video')
video.srcObject = stream
video.onloadedmetadata = (e) => video.play()
}
function handleError (e) {
console.log(e)
}
```
To capture video from a source provided by `desktopCapturer` the constraints passed to [`navigator.mediaDevices.getUserMedia`](https://developer.mozilla.org/en/docs/Web/API/MediaDevices/getUserMedia) must include `chromeMediaSource: 'desktop'`, and `audio: false`.
To capture both audio and video from the entire desktop the constraints passed to [`navigator.mediaDevices.getUserMedia`](https://developer.mozilla.org/en/docs/Web/API/MediaDevices/getUserMedia) must include `chromeMediaSource: 'desktop'`, for both `audio` and `video`, but should not include a `chromeMediaSourceId` constraint.
```
const constraints = {
audio: {
mandatory: {
chromeMediaSource: 'desktop'
}
},
video: {
mandatory: {
chromeMediaSource: 'desktop'
}
}
}
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `desktopCapturer` module has the following methods:
###
`desktopCapturer.getSources(options)`[](#desktopcapturergetsourcesoptions "Direct link to heading")
* `options` Object
+ `types` string[] - An array of strings that lists the types of desktop sources to be captured, available types are `screen` and `window`.
+ `thumbnailSize` [Size](structures/size) (optional) - The size that the media source thumbnail should be scaled to. Default is `150` x `150`. Set width or height to 0 when you do not need the thumbnails. This will save the processing time required for capturing the content of each window and screen.
+ `fetchWindowIcons` boolean (optional) - Set to true to enable fetching window icons. The default value is false. When false the appIcon property of the sources return null. Same if a source has the type screen.
Returns `Promise<DesktopCapturerSource[]>` - Resolves with an array of [DesktopCapturerSource](structures/desktop-capturer-source) objects, each `DesktopCapturerSource` represents a screen or an individual window that can be captured.
**Note** Capturing the screen contents requires user consent on macOS 10.15 Catalina or higher, which can detected by [`systemPreferences.getMediaAccessStatus`](system-preferences#systempreferencesgetmediaaccessstatusmediatype-windows-macos).
Caveats[](#caveats "Direct link to heading")
---------------------------------------------
`navigator.mediaDevices.getUserMedia` does not work on macOS for audio capture due to a fundamental limitation whereby apps that want to access the system's audio require a [signed kernel extension](https://developer.apple.com/library/archive/documentation/Security/Conceptual/System_Integrity_Protection_Guide/KernelExtensions/KernelExtensions.html). Chromium, and by extension Electron, does not provide this.
It is possible to circumvent this limitation by capturing system audio with another macOS app like Soundflower and passing it through a virtual audio input device. This virtual device can then be queried with `navigator.mediaDevices.getUserMedia`.
electron Class: TouchBarGroup Class: TouchBarGroup[](#class-touchbargroup "Direct link to heading")
----------------------------------------------------------------------
> Create a group in the touch bar for native macOS applications
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarGroup(options)`[](#new-touchbargroupoptions "Direct link to heading")
* `options` Object
+ `items` [TouchBar](touch-bar) - Items to display as a group.
electron MessagePortMain MessagePortMain
===============
`MessagePortMain` is the main-process-side equivalent of the DOM [`MessagePort`](https://developer.mozilla.org/en-US/docs/Web/API/MessagePort) object. It behaves similarly to the DOM version, with the exception that it uses the Node.js `EventEmitter` event system, instead of the DOM `EventTarget` system. This means you should use `port.on('message', ...)` to listen for events, instead of `port.onmessage = ...` or `port.addEventListener('message', ...)`
See the [Channel Messaging API](https://developer.mozilla.org/en-US/docs/Web/API/Channel_Messaging_API) documentation for more information on using channel messaging.
`MessagePortMain` is an [EventEmitter][event-emitter].
Class: MessagePortMain[](#class-messageportmain "Direct link to heading")
--------------------------------------------------------------------------
> Port interface for channel messaging in the main process.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
### Instance Methods[](#instance-methods "Direct link to heading")
####
`port.postMessage(message, [transfer])`[](#portpostmessagemessage-transfer "Direct link to heading")
* `message` any
* `transfer` MessagePortMain[] (optional)
Sends a message from the port, and optionally, transfers ownership of objects to other browsing contexts.
####
`port.start()`[](#portstart "Direct link to heading")
Starts the sending of messages queued on the port. Messages will be queued until this method is called.
####
`port.close()`[](#portclose "Direct link to heading")
Disconnects the port, so it is no longer active.
### Instance Events[](#instance-events "Direct link to heading")
#### Event: 'message'[](#event-message "Direct link to heading")
Returns:
* `messageEvent` Object
+ `data` any
+ `ports` MessagePortMain[]
Emitted when a MessagePortMain object receives a message.
#### Event: 'close'[](#event-close "Direct link to heading")
Emitted when the remote end of a MessagePortMain object becomes disconnected.
electron inAppPurchase inAppPurchase
=============
> In-app purchases on Mac App Store.
>
>
Process: [Main](../glossary#main-process)
Events[](#events "Direct link to heading")
-------------------------------------------
The `inAppPurchase` module emits the following events:
### Event: 'transactions-updated'[](#event-transactions-updated "Direct link to heading")
Emitted when one or more transactions have been updated.
Returns:
* `event` Event
* `transactions` Transaction[] - Array of [Transaction](structures/transaction) objects.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `inAppPurchase` module has the following methods:
###
`inAppPurchase.purchaseProduct(productID[, quantity])`[](#inapppurchasepurchaseproductproductid-quantity "Direct link to heading")
* `productID` string - The identifiers of the product to purchase. (The identifier of `com.example.app.product1` is `product1`).
* `quantity` Integer (optional) - The number of items the user wants to purchase.
Returns `Promise<boolean>` - Returns `true` if the product is valid and added to the payment queue.
You should listen for the `transactions-updated` event as soon as possible and certainly before you call `purchaseProduct`.
###
`inAppPurchase.getProducts(productIDs)`[](#inapppurchasegetproductsproductids "Direct link to heading")
* `productIDs` string[] - The identifiers of the products to get.
Returns `Promise<Product[]>` - Resolves with an array of [Product](structures/product) objects.
Retrieves the product descriptions.
###
`inAppPurchase.canMakePayments()`[](#inapppurchasecanmakepayments "Direct link to heading")
Returns `boolean` - whether a user can make a payment.
###
`inAppPurchase.restoreCompletedTransactions()`[](#inapppurchaserestorecompletedtransactions "Direct link to heading")
Restores finished transactions. This method can be called either to install purchases on additional devices, or to restore purchases for an application that the user deleted and reinstalled.
[The payment queue](https://developer.apple.com/documentation/storekit/skpaymentqueue?language=objc) delivers a new transaction for each previously completed transaction that can be restored. Each transaction includes a copy of the original transaction.
###
`inAppPurchase.getReceiptURL()`[](#inapppurchasegetreceipturl "Direct link to heading")
Returns `string` - the path to the receipt.
###
`inAppPurchase.finishAllTransactions()`[](#inapppurchasefinishalltransactions "Direct link to heading")
Completes all pending transactions.
###
`inAppPurchase.finishTransactionByDate(date)`[](#inapppurchasefinishtransactionbydatedate "Direct link to heading")
* `date` string - The ISO formatted date of the transaction to finish.
Completes the pending transactions corresponding to the date.
electron webFrameMain webFrameMain
============
> Control web pages and iframes.
>
>
Process: [Main](../glossary#main-process)
The `webFrameMain` module can be used to lookup frames across existing [`WebContents`](web-contents) instances. Navigation events are the common use case.
```
const { BrowserWindow, webFrameMain } = require('electron')
const win = new BrowserWindow({ width: 800, height: 1500 })
win.loadURL('https://twitter.com')
win.webContents.on(
'did-frame-navigate',
(event, url, httpResponseCode, httpStatusText, isMainFrame, frameProcessId, frameRoutingId) => {
const frame = webFrameMain.fromId(frameProcessId, frameRoutingId)
if (frame) {
const code = 'document.body.innerHTML = document.body.innerHTML.replaceAll("heck", "h*ck")'
frame.executeJavaScript(code)
}
}
)
```
You can also access frames of existing pages by using the `mainFrame` property of [`WebContents`](web-contents).
```
const { BrowserWindow } = require('electron')
async function main () {
const win = new BrowserWindow({ width: 800, height: 600 })
await win.loadURL('https://reddit.com')
const youtubeEmbeds = win.webContents.mainFrame.frames.filter((frame) => {
try {
const url = new URL(frame.url)
return url.host === 'www.youtube.com'
} catch {
return false
}
})
console.log(youtubeEmbeds)
}
main()
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
These methods can be accessed from the `webFrameMain` module:
###
`webFrameMain.fromId(processId, routingId)`[](#webframemainfromidprocessid-routingid "Direct link to heading")
* `processId` Integer - An `Integer` representing the internal ID of the process which owns the frame.
* `routingId` Integer - An `Integer` representing the unique frame ID in the current renderer process. Routing IDs can be retrieved from `WebFrameMain` instances (`frame.routingId`) and are also passed by frame specific `WebContents` navigation events (e.g. `did-frame-navigate`).
Returns `WebFrameMain | undefined` - A frame with the given process and routing IDs, or `undefined` if there is no WebFrameMain associated with the given IDs.
Class: WebFrameMain[](#class-webframemain "Direct link to heading")
--------------------------------------------------------------------
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
### Instance Events[](#instance-events "Direct link to heading")
#### Event: 'dom-ready'[](#event-dom-ready "Direct link to heading")
Emitted when the document is loaded.
### Instance Methods[](#instance-methods "Direct link to heading")
####
`frame.executeJavaScript(code[, userGesture])`[](#frameexecutejavascriptcode-usergesture "Direct link to heading")
* `code` string
* `userGesture` boolean (optional) - Default is `false`.
Returns `Promise<unknown>` - A promise that resolves with the result of the executed code or is rejected if execution throws or results in a rejected promise.
Evaluates `code` in page.
In the browser window some HTML APIs like `requestFullScreen` can only be invoked by a gesture from the user. Setting `userGesture` to `true` will remove this limitation.
####
`frame.reload()`[](#framereload "Direct link to heading")
Returns `boolean` - Whether the reload was initiated successfully. Only results in `false` when the frame has no history.
####
`frame.send(channel, ...args)`[](#framesendchannel-args "Direct link to heading")
* `channel` string
* `...args` any[]
Send an asynchronous message to the renderer process via `channel`, along with arguments. Arguments will be serialized with the [Structured Clone Algorithm](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm), just like [`postMessage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage), so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.
The renderer process can handle the message by listening to `channel` with the [`ipcRenderer`](ipc-renderer) module.
####
`frame.postMessage(channel, message, [transfer])`[](#framepostmessagechannel-message-transfer "Direct link to heading")
* `channel` string
* `message` any
* `transfer` MessagePortMain[] (optional)
Send a message to the renderer process, optionally transferring ownership of zero or more [`MessagePortMain`][] objects.
The transferred `MessagePortMain` objects will be available in the renderer process by accessing the `ports` property of the emitted event. When they arrive in the renderer, they will be native DOM `MessagePort` objects.
For example:
```
// Main process
const { port1, port2 } = new MessageChannelMain()
webContents.mainFrame.postMessage('port', { message: 'hello' }, [port1])
// Renderer process
ipcRenderer.on('port', (e, msg) => {
const [port] = e.ports
// ...
})
```
### Instance Properties[](#instance-properties "Direct link to heading")
####
`frame.url` *Readonly*[](#frameurl-readonly "Direct link to heading")
A `string` representing the current URL of the frame.
####
`frame.top` *Readonly*[](#frametop-readonly "Direct link to heading")
A `WebFrameMain | null` representing top frame in the frame hierarchy to which `frame` belongs.
####
`frame.parent` *Readonly*[](#frameparent-readonly "Direct link to heading")
A `WebFrameMain | null` representing parent frame of `frame`, the property would be `null` if `frame` is the top frame in the frame hierarchy.
####
`frame.frames` *Readonly*[](#frameframes-readonly "Direct link to heading")
A `WebFrameMain[]` collection containing the direct descendents of `frame`.
####
`frame.framesInSubtree` *Readonly*[](#frameframesinsubtree-readonly "Direct link to heading")
A `WebFrameMain[]` collection containing every frame in the subtree of `frame`, including itself. This can be useful when traversing through all frames.
####
`frame.frameTreeNodeId` *Readonly*[](#frameframetreenodeid-readonly "Direct link to heading")
An `Integer` representing the id of the frame's internal FrameTreeNode instance. This id is browser-global and uniquely identifies a frame that hosts content. The identifier is fixed at the creation of the frame and stays constant for the lifetime of the frame. When the frame is removed, the id is not used again.
####
`frame.name` *Readonly*[](#framename-readonly "Direct link to heading")
A `string` representing the frame name.
####
`frame.osProcessId` *Readonly*[](#frameosprocessid-readonly "Direct link to heading")
An `Integer` representing the operating system `pid` of the process which owns this frame.
####
`frame.processId` *Readonly*[](#frameprocessid-readonly "Direct link to heading")
An `Integer` representing the Chromium internal `pid` of the process which owns this frame. This is not the same as the OS process ID; to read that use `frame.osProcessId`.
####
`frame.routingId` *Readonly*[](#frameroutingid-readonly "Direct link to heading")
An `Integer` representing the unique frame id in the current renderer process. Distinct `WebFrameMain` instances that refer to the same underlying frame will have the same `routingId`.
####
`frame.visibilityState` *Readonly*[](#framevisibilitystate-readonly "Direct link to heading")
A `string` representing the [visibility state](https://developer.mozilla.org/en-US/docs/Web/API/Document/visibilityState) of the frame.
See also how the [Page Visibility API](browser-window#page-visibility) is affected by other Electron APIs.
electron clipboard clipboard
=========
> Perform copy and paste operations on the system clipboard.
>
>
Process: [Main](../glossary#main-process), [Renderer](../glossary#renderer-process)
On Linux, there is also a `selection` clipboard. To manipulate it you need to pass `selection` to each method:
```
const { clipboard } = require('electron')
clipboard.writeText('Example string', 'selection')
console.log(clipboard.readText('selection'))
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `clipboard` module has the following methods:
**Note:** Experimental APIs are marked as such and could be removed in future.
###
`clipboard.readText([type])`[](#clipboardreadtexttype "Direct link to heading")
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Returns `string` - The content in the clipboard as plain text.
```
const { clipboard } = require('electron')
clipboard.writeText('hello i am a bit of text!')
const text = clipboard.readText()
console.log(text)
// hello i am a bit of text!'
```
###
`clipboard.writeText(text[, type])`[](#clipboardwritetexttext-type "Direct link to heading")
* `text` string
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Writes the `text` into the clipboard as plain text.
```
const { clipboard } = require('electron')
const text = 'hello i am a bit of text!'
clipboard.writeText(text)
```
###
`clipboard.readHTML([type])`[](#clipboardreadhtmltype "Direct link to heading")
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Returns `string` - The content in the clipboard as markup.
```
const { clipboard } = require('electron')
clipboard.writeHTML('<b>Hi</b>')
const html = clipboard.readHTML()
console.log(html)
// <meta charset='utf-8'><b>Hi</b>
```
###
`clipboard.writeHTML(markup[, type])`[](#clipboardwritehtmlmarkup-type "Direct link to heading")
* `markup` string
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Writes `markup` to the clipboard.
```
const { clipboard } = require('electron')
clipboard.writeHTML('<b>Hi</b>')
```
###
`clipboard.readImage([type])`[](#clipboardreadimagetype "Direct link to heading")
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Returns [`NativeImage`](native-image) - The image content in the clipboard.
###
`clipboard.writeImage(image[, type])`[](#clipboardwriteimageimage-type "Direct link to heading")
* `image` [NativeImage](native-image)
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Writes `image` to the clipboard.
###
`clipboard.readRTF([type])`[](#clipboardreadrtftype "Direct link to heading")
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Returns `string` - The content in the clipboard as RTF.
```
const { clipboard } = require('electron')
clipboard.writeRTF('{\\rtf1\\ansi{\\fonttbl\\f0\\fswiss Helvetica;}\\f0\\pard\nThis is some {\\b bold} text.\\par\n}')
const rtf = clipboard.readRTF()
console.log(rtf)
// {\\rtf1\\ansi{\\fonttbl\\f0\\fswiss Helvetica;}\\f0\\pard\nThis is some {\\b bold} text.\\par\n}
```
###
`clipboard.writeRTF(text[, type])`[](#clipboardwritertftext-type "Direct link to heading")
* `text` string
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Writes the `text` into the clipboard in RTF.
```
const { clipboard } = require('electron')
const rtf = '{\\rtf1\\ansi{\\fonttbl\\f0\\fswiss Helvetica;}\\f0\\pard\nThis is some {\\b bold} text.\\par\n}'
clipboard.writeRTF(rtf)
```
###
`clipboard.readBookmark()` *macOS* *Windows*[](#clipboardreadbookmark-macos-windows "Direct link to heading")
Returns `Object`:
* `title` string
* `url` string
Returns an Object containing `title` and `url` keys representing the bookmark in the clipboard. The `title` and `url` values will be empty strings when the bookmark is unavailable. The `title` value will always be empty on Windows.
###
`clipboard.writeBookmark(title, url[, type])` *macOS* *Windows*[](#clipboardwritebookmarktitle-url-type-macos-windows "Direct link to heading")
* `title` string - Unused on Windows
* `url` string
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Writes the `title` (macOS only) and `url` into the clipboard as a bookmark.
**Note:** Most apps on Windows don't support pasting bookmarks into them so you can use `clipboard.write` to write both a bookmark and fallback text to the clipboard.
```
const { clipboard } = require('electron')
clipboard.writeBookmark({
text: 'https://electronjs.org',
bookmark: 'Electron Homepage'
})
```
###
`clipboard.readFindText()` *macOS*[](#clipboardreadfindtext-macos "Direct link to heading")
Returns `string` - The text on the find pasteboard, which is the pasteboard that holds information about the current state of the active application’s find panel.
This method uses synchronous IPC when called from the renderer process. The cached value is reread from the find pasteboard whenever the application is activated.
###
`clipboard.writeFindText(text)` *macOS*[](#clipboardwritefindtexttext-macos "Direct link to heading")
* `text` string
Writes the `text` into the find pasteboard (the pasteboard that holds information about the current state of the active application’s find panel) as plain text. This method uses synchronous IPC when called from the renderer process.
###
`clipboard.clear([type])`[](#clipboardcleartype "Direct link to heading")
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Clears the clipboard content.
###
`clipboard.availableFormats([type])`[](#clipboardavailableformatstype "Direct link to heading")
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Returns `string[]` - An array of supported formats for the clipboard `type`.
```
const { clipboard } = require('electron')
const formats = clipboard.availableFormats()
console.log(formats)
// [ 'text/plain', 'text/html' ]
```
###
`clipboard.has(format[, type])` *Experimental*[](#clipboardhasformat-type-experimental "Direct link to heading")
* `format` string
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Returns `boolean` - Whether the clipboard supports the specified `format`.
```
const { clipboard } = require('electron')
const hasFormat = clipboard.has('public/utf8-plain-text')
console.log(hasFormat)
// 'true' or 'false'
```
###
`clipboard.read(format)` *Experimental*[](#clipboardreadformat-experimental "Direct link to heading")
* `format` string
Returns `string` - Reads `format` type from the clipboard.
`format` should contain valid ASCII characters and have `/` separator. `a/c`, `a/bc` are valid formats while `/abc`, `abc/`, `a/`, `/a`, `a` are not valid.
###
`clipboard.readBuffer(format)` *Experimental*[](#clipboardreadbufferformat-experimental "Direct link to heading")
* `format` string
Returns `Buffer` - Reads `format` type from the clipboard.
```
const { clipboard } = require('electron')
const buffer = Buffer.from('this is binary', 'utf8')
clipboard.writeBuffer('public/utf8-plain-text', buffer)
const ret = clipboard.readBuffer('public/utf8-plain-text')
console.log(buffer.equals(out))
// true
```
###
`clipboard.writeBuffer(format, buffer[, type])` *Experimental*[](#clipboardwritebufferformat-buffer-type-experimental "Direct link to heading")
* `format` string
* `buffer` Buffer
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Writes the `buffer` into the clipboard as `format`.
```
const { clipboard } = require('electron')
const buffer = Buffer.from('writeBuffer', 'utf8')
clipboard.writeBuffer('public/utf8-plain-text', buffer)
```
###
`clipboard.write(data[, type])`[](#clipboardwritedata-type "Direct link to heading")
* `data` Object
+ `text` string (optional)
+ `html` string (optional)
+ `image` [NativeImage](native-image) (optional)
+ `rtf` string (optional)
+ `bookmark` string (optional) - The title of the URL at `text`.
* `type` string (optional) - Can be `selection` or `clipboard`; default is 'clipboard'. `selection` is only available on Linux.
Writes `data` to the clipboard.
```
const { clipboard } = require('electron')
clipboard.write({
text: 'test',
html: '<b>Hi</b>',
rtf: '{\\rtf1\\utf8 text}',
bookmark: 'a title'
})
console.log(clipboard.readText())
// 'test'
console.log(clipboard.readHTML())
// <meta charset='utf-8'><b>Hi</b>
console.log(clipboard.readRTF())
// '{\\rtf1\\utf8 text}'
console.log(clipboard.readBookmark())
// { title: 'a title', url: 'test' }
```
| programming_docs |
electron globalShortcut globalShortcut
==============
> Detect keyboard events when the application does not have keyboard focus.
>
>
Process: [Main](../glossary#main-process)
The `globalShortcut` module can register/unregister a global keyboard shortcut with the operating system so that you can customize the operations for various shortcuts.
**Note:** The shortcut is global; it will work even if the app does not have the keyboard focus. This module cannot be used before the `ready` event of the app module is emitted.
```
const { app, globalShortcut } = require('electron')
app.whenReady().then(() => {
// Register a 'CommandOrControl+X' shortcut listener.
const ret = globalShortcut.register('CommandOrControl+X', () => {
console.log('CommandOrControl+X is pressed')
})
if (!ret) {
console.log('registration failed')
}
// Check whether a shortcut is registered.
console.log(globalShortcut.isRegistered('CommandOrControl+X'))
})
app.on('will-quit', () => {
// Unregister a shortcut.
globalShortcut.unregister('CommandOrControl+X')
// Unregister all shortcuts.
globalShortcut.unregisterAll()
})
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `globalShortcut` module has the following methods:
###
`globalShortcut.register(accelerator, callback)`[](#globalshortcutregisteraccelerator-callback "Direct link to heading")
* `accelerator` [Accelerator](accelerator)
* `callback` Function
Returns `boolean` - Whether or not the shortcut was registered successfully.
Registers a global shortcut of `accelerator`. The `callback` is called when the registered shortcut is pressed by the user.
When the accelerator is already taken by other applications, this call will silently fail. This behavior is intended by operating systems, since they don't want applications to fight for global shortcuts.
The following accelerators will not be registered successfully on macOS 10.14 Mojave unless the app has been authorized as a [trusted accessibility client](https://developer.apple.com/library/archive/documentation/Accessibility/Conceptual/AccessibilityMacOSX/OSXAXTestingApps.html):
* "Media Play/Pause"
* "Media Next Track"
* "Media Previous Track"
* "Media Stop"
###
`globalShortcut.registerAll(accelerators, callback)`[](#globalshortcutregisterallaccelerators-callback "Direct link to heading")
* `accelerators` string[] - an array of [Accelerator](accelerator)s.
* `callback` Function
Registers a global shortcut of all `accelerator` items in `accelerators`. The `callback` is called when any of the registered shortcuts are pressed by the user.
When a given accelerator is already taken by other applications, this call will silently fail. This behavior is intended by operating systems, since they don't want applications to fight for global shortcuts.
The following accelerators will not be registered successfully on macOS 10.14 Mojave unless the app has been authorized as a [trusted accessibility client](https://developer.apple.com/library/archive/documentation/Accessibility/Conceptual/AccessibilityMacOSX/OSXAXTestingApps.html):
* "Media Play/Pause"
* "Media Next Track"
* "Media Previous Track"
* "Media Stop"
###
`globalShortcut.isRegistered(accelerator)`[](#globalshortcutisregisteredaccelerator "Direct link to heading")
* `accelerator` [Accelerator](accelerator)
Returns `boolean` - Whether this application has registered `accelerator`.
When the accelerator is already taken by other applications, this call will still return `false`. This behavior is intended by operating systems, since they don't want applications to fight for global shortcuts.
###
`globalShortcut.unregister(accelerator)`[](#globalshortcutunregisteraccelerator "Direct link to heading")
* `accelerator` [Accelerator](accelerator)
Unregisters the global shortcut of `accelerator`.
###
`globalShortcut.unregisterAll()`[](#globalshortcutunregisterall "Direct link to heading")
Unregisters all of the global shortcuts.
electron Chrome Extension Support Chrome Extension Support
========================
Electron supports a subset of the [Chrome Extensions API](https://developer.chrome.com/extensions/api_index), primarily to support DevTools extensions and Chromium-internal extensions, but it also happens to support some other extension capabilities.
> **Note:** Electron does not support arbitrary Chrome extensions from the store, and it is a **non-goal** of the Electron project to be perfectly compatible with Chrome's implementation of Extensions.
>
>
Loading extensions[](#loading-extensions "Direct link to heading")
-------------------------------------------------------------------
Electron only supports loading unpacked extensions (i.e., `.crx` files do not work). Extensions are installed per-`session`. To load an extension, call [`ses.loadExtension`](session#sesloadextensionpath-options):
```
const { session } = require('electron')
session.loadExtension('path/to/unpacked/extension').then(({ id }) => {
// ...
})
```
Loaded extensions will not be automatically remembered across exits; if you do not call `loadExtension` when the app runs, the extension will not be loaded.
Note that loading extensions is only supported in persistent sessions. Attempting to load an extension into an in-memory session will throw an error.
See the [`session`](session) documentation for more information about loading, unloading, and querying active extensions.
Supported Extensions APIs[](#supported-extensions-apis "Direct link to heading")
---------------------------------------------------------------------------------
We support the following extensions APIs, with some caveats. Other APIs may additionally be supported, but support for any APIs not listed here is provisional and may be removed.
###
`chrome.devtools.inspectedWindow`[](#chromedevtoolsinspectedwindow "Direct link to heading")
All features of this API are supported.
###
`chrome.devtools.network`[](#chromedevtoolsnetwork "Direct link to heading")
All features of this API are supported.
###
`chrome.devtools.panels`[](#chromedevtoolspanels "Direct link to heading")
All features of this API are supported.
###
`chrome.extension`[](#chromeextension "Direct link to heading")
The following properties of `chrome.extension` are supported:
* `chrome.extension.lastError`
The following methods of `chrome.extension` are supported:
* `chrome.extension.getURL`
* `chrome.extension.getBackgroundPage`
###
`chrome.runtime`[](#chromeruntime "Direct link to heading")
The following properties of `chrome.runtime` are supported:
* `chrome.runtime.lastError`
* `chrome.runtime.id`
The following methods of `chrome.runtime` are supported:
* `chrome.runtime.getBackgroundPage`
* `chrome.runtime.getManifest`
* `chrome.runtime.getPlatformInfo`
* `chrome.runtime.getURL`
* `chrome.runtime.connect`
* `chrome.runtime.sendMessage`
* `chrome.runtime.reload`
The following events of `chrome.runtime` are supported:
* `chrome.runtime.onStartup`
* `chrome.runtime.onInstalled`
* `chrome.runtime.onSuspend`
* `chrome.runtime.onSuspendCanceled`
* `chrome.runtime.onConnect`
* `chrome.runtime.onMessage`
###
`chrome.storage`[](#chromestorage "Direct link to heading")
Only `chrome.storage.local` is supported; `chrome.storage.sync` and `chrome.storage.managed` are not.
###
`chrome.tabs`[](#chrometabs "Direct link to heading")
The following methods of `chrome.tabs` are supported:
* `chrome.tabs.sendMessage`
* `chrome.tabs.reload`
* `chrome.tabs.executeScript`
* `chrome.tabs.update` (partial support)
+ supported properties: `url`, `muted`.
> **Note:** In Chrome, passing `-1` as a tab ID signifies the "currently active tab". Since Electron has no such concept, passing `-1` as a tab ID is not supported and will raise an error.
>
>
###
`chrome.management`[](#chromemanagement "Direct link to heading")
The following methods of `chrome.management` are supported:
* `chrome.management.getAll`
* `chrome.management.get`
* `chrome.management.getSelf`
* `chrome.management.getPermissionWarningsById`
* `chrome.management.getPermissionWarningsByManifest`
* `chrome.management.onEnabled`
* `chrome.management.onDisabled`
###
`chrome.webRequest`[](#chromewebrequest "Direct link to heading")
All features of this API are supported.
> **NOTE:** Electron's [`webRequest`](web-request) module takes precedence over `chrome.webRequest` if there are conflicting handlers.
>
>
electron nativeImage nativeImage
===========
> Create tray, dock, and application icons using PNG or JPG files.
>
>
Process: [Main](../glossary#main-process), [Renderer](../glossary#renderer-process)
In Electron, for the APIs that take images, you can pass either file paths or `NativeImage` instances. An empty image will be used when `null` is passed.
For example, when creating a tray or setting a window's icon, you can pass an image file path as a `string`:
```
const { BrowserWindow, Tray } = require('electron')
const appIcon = new Tray('/Users/somebody/images/icon.png')
const win = new BrowserWindow({ icon: '/Users/somebody/images/window.png' })
console.log(appIcon, win)
```
Or read the image from the clipboard, which returns a `NativeImage`:
```
const { clipboard, Tray } = require('electron')
const image = clipboard.readImage()
const appIcon = new Tray(image)
console.log(appIcon)
```
Supported Formats[](#supported-formats "Direct link to heading")
-----------------------------------------------------------------
Currently `PNG` and `JPEG` image formats are supported. `PNG` is recommended because of its support for transparency and lossless compression.
On Windows, you can also load `ICO` icons from file paths. For best visual quality, it is recommended to include at least the following sizes in the:
* Small icon
+ 16x16 (100% DPI scale)
+ 20x20 (125% DPI scale)
+ 24x24 (150% DPI scale)
+ 32x32 (200% DPI scale)
* Large icon
+ 32x32 (100% DPI scale)
+ 40x40 (125% DPI scale)
+ 48x48 (150% DPI scale)
+ 64x64 (200% DPI scale)
+ 256x256
Check the *Size requirements* section in [this article](https://msdn.microsoft.com/en-us/library/windows/desktop/dn742485(v=vs.85).aspx).
High Resolution Image[](#high-resolution-image "Direct link to heading")
-------------------------------------------------------------------------
On platforms that have high-DPI support such as Apple Retina displays, you can append `@2x` after image's base filename to mark it as a high resolution image.
For example, if `icon.png` is a normal image that has standard resolution, then `[email protected]` will be treated as a high resolution image that has double DPI density.
If you want to support displays with different DPI densities at the same time, you can put images with different sizes in the same folder and use the filename without DPI suffixes. For example:
```
images/
├── icon.png
├── [email protected]
└── [email protected]
```
```
const { Tray } = require('electron')
const appIcon = new Tray('/Users/somebody/images/icon.png')
console.log(appIcon)
```
The following suffixes for DPI are also supported:
* `@1x`
* `@1.25x`
* `@1.33x`
* `@1.4x`
* `@1.5x`
* `@1.8x`
* `@2x`
* `@2.5x`
* `@3x`
* `@4x`
* `@5x`
Template Image[](#template-image "Direct link to heading")
-----------------------------------------------------------
Template images consist of black and an alpha channel. Template images are not intended to be used as standalone images and are usually mixed with other content to create the desired final appearance.
The most common case is to use template images for a menu bar icon, so it can adapt to both light and dark menu bars.
**Note:** Template image is only supported on macOS.
To mark an image as a template image, its filename should end with the word `Template`. For example:
* `xxxTemplate.png`
* `[email protected]`
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `nativeImage` module has the following methods, all of which return an instance of the `NativeImage` class:
###
`nativeImage.createEmpty()`[](#nativeimagecreateempty "Direct link to heading")
Returns `NativeImage`
Creates an empty `NativeImage` instance.
###
`nativeImage.createThumbnailFromPath(path, maxSize)` *macOS* *Windows*[](#nativeimagecreatethumbnailfrompathpath-maxsize-macos-windows "Direct link to heading")
* `path` string - path to a file that we intend to construct a thumbnail out of.
* `maxSize` [Size](structures/size) - the maximum width and height (positive numbers) the thumbnail returned can be. The Windows implementation will ignore `maxSize.height` and scale the height according to `maxSize.width`.
Returns `Promise<NativeImage>` - fulfilled with the file's thumbnail preview image, which is a [NativeImage](native-image).
###
`nativeImage.createFromPath(path)`[](#nativeimagecreatefrompathpath "Direct link to heading")
* `path` string
Returns `NativeImage`
Creates a new `NativeImage` instance from a file located at `path`. This method returns an empty image if the `path` does not exist, cannot be read, or is not a valid image.
```
const nativeImage = require('electron').nativeImage
const image = nativeImage.createFromPath('/Users/somebody/images/icon.png')
console.log(image)
```
###
`nativeImage.createFromBitmap(buffer, options)`[](#nativeimagecreatefrombitmapbuffer-options "Direct link to heading")
* `buffer` [Buffer](https://nodejs.org/api/buffer.html#buffer_class_buffer)
* `options` Object
+ `width` Integer
+ `height` Integer
+ `scaleFactor` Double (optional) - Defaults to 1.0.
Returns `NativeImage`
Creates a new `NativeImage` instance from `buffer` that contains the raw bitmap pixel data returned by `toBitmap()`. The specific format is platform-dependent.
###
`nativeImage.createFromBuffer(buffer[, options])`[](#nativeimagecreatefrombufferbuffer-options "Direct link to heading")
* `buffer` [Buffer](https://nodejs.org/api/buffer.html#buffer_class_buffer)
* `options` Object (optional)
+ `width` Integer (optional) - Required for bitmap buffers.
+ `height` Integer (optional) - Required for bitmap buffers.
+ `scaleFactor` Double (optional) - Defaults to 1.0.
Returns `NativeImage`
Creates a new `NativeImage` instance from `buffer`. Tries to decode as PNG or JPEG first.
###
`nativeImage.createFromDataURL(dataURL)`[](#nativeimagecreatefromdataurldataurl "Direct link to heading")
* `dataURL` string
Returns `NativeImage`
Creates a new `NativeImage` instance from `dataURL`.
###
`nativeImage.createFromNamedImage(imageName[, hslShift])` *macOS*[](#nativeimagecreatefromnamedimageimagename-hslshift-macos "Direct link to heading")
* `imageName` string
* `hslShift` number[] (optional)
Returns `NativeImage`
Creates a new `NativeImage` instance from the NSImage that maps to the given image name. See [`System Icons`](https://developer.apple.com/design/human-interface-guidelines/macos/icons-and-images/system-icons/) for a list of possible values.
The `hslShift` is applied to the image with the following rules:
* `hsl_shift[0]` (hue): The absolute hue value for the image - 0 and 1 map to 0 and 360 on the hue color wheel (red).
* `hsl_shift[1]` (saturation): A saturation shift for the image, with the following key values: 0 = remove all color. 0.5 = leave unchanged. 1 = fully saturate the image.
* `hsl_shift[2]` (lightness): A lightness shift for the image, with the following key values: 0 = remove all lightness (make all pixels black). 0.5 = leave unchanged. 1 = full lightness (make all pixels white).
This means that `[-1, 0, 1]` will make the image completely white and `[-1, 1, 0]` will make the image completely black.
In some cases, the `NSImageName` doesn't match its string representation; one example of this is `NSFolderImageName`, whose string representation would actually be `NSFolder`. Therefore, you'll need to determine the correct string representation for your image before passing it in. This can be done with the following:
`echo -e '#import <Cocoa/Cocoa.h>\nint main() { NSLog(@"%@", SYSTEM_IMAGE_NAME); }' | clang -otest -x objective-c -framework Cocoa - && ./test`
where `SYSTEM_IMAGE_NAME` should be replaced with any value from [this list](https://developer.apple.com/documentation/appkit/nsimagename?language=objc).
Class: NativeImage[](#class-nativeimage "Direct link to heading")
------------------------------------------------------------------
> Natively wrap images such as tray, dock, and application icons.
>
>
Process: [Main](../glossary#main-process), [Renderer](../glossary#renderer-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
### Instance Methods[](#instance-methods "Direct link to heading")
The following methods are available on instances of the `NativeImage` class:
####
`image.toPNG([options])`[](#imagetopngoptions "Direct link to heading")
* `options` Object (optional)
+ `scaleFactor` Double (optional) - Defaults to 1.0.
Returns `Buffer` - A [Buffer](https://nodejs.org/api/buffer.html#buffer_class_buffer) that contains the image's `PNG` encoded data.
####
`image.toJPEG(quality)`[](#imagetojpegquality "Direct link to heading")
* `quality` Integer - Between 0 - 100.
Returns `Buffer` - A [Buffer](https://nodejs.org/api/buffer.html#buffer_class_buffer) that contains the image's `JPEG` encoded data.
####
`image.toBitmap([options])`[](#imagetobitmapoptions "Direct link to heading")
* `options` Object (optional)
+ `scaleFactor` Double (optional) - Defaults to 1.0.
Returns `Buffer` - A [Buffer](https://nodejs.org/api/buffer.html#buffer_class_buffer) that contains a copy of the image's raw bitmap pixel data.
####
`image.toDataURL([options])`[](#imagetodataurloptions "Direct link to heading")
* `options` Object (optional)
+ `scaleFactor` Double (optional) - Defaults to 1.0.
Returns `string` - The data URL of the image.
####
`image.getBitmap([options])`[](#imagegetbitmapoptions "Direct link to heading")
* `options` Object (optional)
+ `scaleFactor` Double (optional) - Defaults to 1.0.
Returns `Buffer` - A [Buffer](https://nodejs.org/api/buffer.html#buffer_class_buffer) that contains the image's raw bitmap pixel data.
The difference between `getBitmap()` and `toBitmap()` is that `getBitmap()` does not copy the bitmap data, so you have to use the returned Buffer immediately in current event loop tick; otherwise the data might be changed or destroyed.
####
`image.getNativeHandle()` *macOS*[](#imagegetnativehandle-macos "Direct link to heading")
Returns `Buffer` - A [Buffer](https://nodejs.org/api/buffer.html#buffer_class_buffer) that stores C pointer to underlying native handle of the image. On macOS, a pointer to `NSImage` instance would be returned.
Notice that the returned pointer is a weak pointer to the underlying native image instead of a copy, so you *must* ensure that the associated `nativeImage` instance is kept around.
####
`image.isEmpty()`[](#imageisempty "Direct link to heading")
Returns `boolean` - Whether the image is empty.
####
`image.getSize([scaleFactor])`[](#imagegetsizescalefactor "Direct link to heading")
* `scaleFactor` Double (optional) - Defaults to 1.0.
Returns [Size](structures/size).
If `scaleFactor` is passed, this will return the size corresponding to the image representation most closely matching the passed value.
####
`image.setTemplateImage(option)`[](#imagesettemplateimageoption "Direct link to heading")
* `option` boolean
Marks the image as a template image.
####
`image.isTemplateImage()`[](#imageistemplateimage "Direct link to heading")
Returns `boolean` - Whether the image is a template image.
####
`image.crop(rect)`[](#imagecroprect "Direct link to heading")
* `rect` [Rectangle](structures/rectangle) - The area of the image to crop.
Returns `NativeImage` - The cropped image.
####
`image.resize(options)`[](#imageresizeoptions "Direct link to heading")
* `options` Object
+ `width` Integer (optional) - Defaults to the image's width.
+ `height` Integer (optional) - Defaults to the image's height.
+ `quality` string (optional) - The desired quality of the resize image. Possible values are `good`, `better`, or `best`. The default is `best`. These values express a desired quality/speed tradeoff. They are translated into an algorithm-specific method that depends on the capabilities (CPU, GPU) of the underlying platform. It is possible for all three methods to be mapped to the same algorithm on a given platform.
Returns `NativeImage` - The resized image.
If only the `height` or the `width` are specified then the current aspect ratio will be preserved in the resized image.
####
`image.getAspectRatio([scaleFactor])`[](#imagegetaspectratioscalefactor "Direct link to heading")
* `scaleFactor` Double (optional) - Defaults to 1.0.
Returns `Float` - The image's aspect ratio.
If `scaleFactor` is passed, this will return the aspect ratio corresponding to the image representation most closely matching the passed value.
####
`image.getScaleFactors()`[](#imagegetscalefactors "Direct link to heading")
Returns `Float[]` - An array of all scale factors corresponding to representations for a given nativeImage.
####
`image.addRepresentation(options)`[](#imageaddrepresentationoptions "Direct link to heading")
* `options` Object
+ `scaleFactor` Double - The scale factor to add the image representation for.
+ `width` Integer (optional) - Defaults to 0. Required if a bitmap buffer is specified as `buffer`.
+ `height` Integer (optional) - Defaults to 0. Required if a bitmap buffer is specified as `buffer`.
+ `buffer` Buffer (optional) - The buffer containing the raw image data.
+ `dataURL` string (optional) - The data URL containing either a base 64 encoded PNG or JPEG image.
Add an image representation for a specific scale factor. This can be used to explicitly add different scale factor representations to an image. This can be called on empty images.
### Instance Properties[](#instance-properties "Direct link to heading")
####
`nativeImage.isMacTemplateImage` *macOS*[](#nativeimageismactemplateimage-macos "Direct link to heading")
A `boolean` property that determines whether the image is considered a [template image](https://developer.apple.com/documentation/appkit/nsimage/1520017-template).
Please note that this property only has an effect on macOS.
| programming_docs |
electron Class: TouchBarLabel Class: TouchBarLabel[](#class-touchbarlabel "Direct link to heading")
----------------------------------------------------------------------
> Create a label in the touch bar for native macOS applications
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarLabel(options)`[](#new-touchbarlabeloptions "Direct link to heading")
* `options` Object
+ `label` string (optional) - Text to display.
+ `accessibilityLabel` string (optional) - A short description of the button for use by screenreaders like VoiceOver.
+ `textColor` string (optional) - Hex color of text, i.e `#ABCDEF`.
When defining `accessibilityLabel`, ensure you have considered macOS [best practices](https://developer.apple.com/documentation/appkit/nsaccessibilitybutton/1524910-accessibilitylabel?language=objc).
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBarLabel`:
####
`touchBarLabel.label`[](#touchbarlabellabel "Direct link to heading")
A `string` representing the label's current text. Changing this value immediately updates the label in the touch bar.
####
`touchBarLabel.accessibilityLabel`[](#touchbarlabelaccessibilitylabel "Direct link to heading")
A `string` representing the description of the label to be read by a screen reader.
####
`touchBarLabel.textColor`[](#touchbarlabeltextcolor "Direct link to heading")
A `string` hex code representing the label's current text color. Changing this value immediately updates the label in the touch bar.
electron contextBridge contextBridge
=============
> Create a safe, bi-directional, synchronous bridge across isolated contexts
>
>
Process: [Renderer](../glossary#renderer-process)
An example of exposing an API to a renderer from an isolated preload script is given below:
```
// Preload (Isolated World)
const { contextBridge, ipcRenderer } = require('electron')
contextBridge.exposeInMainWorld(
'electron',
{
doThing: () => ipcRenderer.send('do-a-thing')
}
)
```
```
// Renderer (Main World)
window.electron.doThing()
```
Glossary[](#glossary "Direct link to heading")
-----------------------------------------------
### Main World[](#main-world "Direct link to heading")
The "Main World" is the JavaScript context that your main renderer code runs in. By default, the page you load in your renderer executes code in this world.
### Isolated World[](#isolated-world "Direct link to heading")
When `contextIsolation` is enabled in your `webPreferences` (this is the default behavior since Electron 12.0.0), your `preload` scripts run in an "Isolated World". You can read more about context isolation and what it affects in the [security](../tutorial/security#3-enable-context-isolation) docs.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `contextBridge` module has the following methods:
###
`contextBridge.exposeInMainWorld(apiKey, api)`[](#contextbridgeexposeinmainworldapikey-api "Direct link to heading")
* `apiKey` string - The key to inject the API onto `window` with. The API will be accessible on `window[apiKey]`.
* `api` any - Your API, more information on what this API can be and how it works is available below.
Usage[](#usage "Direct link to heading")
-----------------------------------------
### API[](#api "Direct link to heading")
The `api` provided to [`exposeInMainWorld`](#contextbridgeexposeinmainworldapikey-api) must be a `Function`, `string`, `number`, `Array`, `boolean`, or an object whose keys are strings and values are a `Function`, `string`, `number`, `Array`, `boolean`, or another nested object that meets the same conditions.
`Function` values are proxied to the other context and all other values are **copied** and **frozen**. Any data / primitives sent in the API become immutable and updates on either side of the bridge do not result in an update on the other side.
An example of a complex API is shown below:
```
const { contextBridge } = require('electron')
contextBridge.exposeInMainWorld(
'electron',
{
doThing: () => ipcRenderer.send('do-a-thing'),
myPromises: [Promise.resolve(), Promise.reject(new Error('whoops'))],
anAsyncFunction: async () => 123,
data: {
myFlags: ['a', 'b', 'c'],
bootTime: 1234
},
nestedAPI: {
evenDeeper: {
youCanDoThisAsMuchAsYouWant: {
fn: () => ({
returnData: 123
})
}
}
}
}
)
```
### API Functions[](#api-functions "Direct link to heading")
`Function` values that you bind through the `contextBridge` are proxied through Electron to ensure that contexts remain isolated. This results in some key limitations that we've outlined below.
#### Parameter / Error / Return Type support[](#parameter--error--return-type-support "Direct link to heading")
Because parameters, errors and return values are **copied** when they are sent over the bridge, there are only certain types that can be used. At a high level, if the type you want to use can be serialized and deserialized into the same object it will work. A table of type support has been included below for completeness:
| Type | Complexity | Parameter Support | Return Value Support | Limitations |
| --- | --- | --- | --- | --- |
| `string` | Simple | ✅ | ✅ | N/A |
| `number` | Simple | ✅ | ✅ | N/A |
| `boolean` | Simple | ✅ | ✅ | N/A |
| `Object` | Complex | ✅ | ✅ | Keys must be supported using only "Simple" types in this table. Values must be supported in this table. Prototype modifications are dropped. Sending custom classes will copy values but not the prototype. |
| `Array` | Complex | ✅ | ✅ | Same limitations as the `Object` type |
| `Error` | Complex | ✅ | ✅ | Errors that are thrown are also copied, this can result in the message and stack trace of the error changing slightly due to being thrown in a different context, and any custom properties on the Error object [will be lost](https://github.com/electron/electron/issues/25596) |
| `Promise` | Complex | ✅ | ✅ | N/A |
| `Function` | Complex | ✅ | ✅ | Prototype modifications are dropped. Sending classes or constructors will not work. |
| [Cloneable Types](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm) | Simple | ✅ | ✅ | See the linked document on cloneable types |
| `Element` | Complex | ✅ | ✅ | Prototype modifications are dropped. Sending custom elements will not work. |
| `Blob` | Complex | ✅ | ✅ | N/A |
| `Symbol` | N/A | ❌ | ❌ | Symbols cannot be copied across contexts so they are dropped |
If the type you care about is not in the above table, it is probably not supported.
### Exposing Node Global Symbols[](#exposing-node-global-symbols "Direct link to heading")
The `contextBridge` can be used by the preload script to give your renderer access to Node APIs. The table of supported types described above also applies to Node APIs that you expose through `contextBridge`. Please note that many Node APIs grant access to local system resources. Be very cautious about which globals and APIs you expose to untrusted remote content.
```
const { contextBridge } = require('electron')
const crypto = require('crypto')
contextBridge.exposeInMainWorld('nodeCrypto', {
sha256sum (data) {
const hash = crypto.createHash('sha256')
hash.update(data)
return hash.digest('hex')
}
})
```
electron Class: TouchBarSpacer Class: TouchBarSpacer[](#class-touchbarspacer "Direct link to heading")
------------------------------------------------------------------------
> Create a spacer between two items in the touch bar for native macOS applications
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarSpacer(options)`[](#new-touchbarspaceroptions "Direct link to heading")
* `options` Object
+ `size` string (optional) - Size of spacer, possible values are:
- `small` - Small space between items. Maps to `NSTouchBarItemIdentifierFixedSpaceSmall`. This is the default.
- `large` - Large space between items. Maps to `NSTouchBarItemIdentifierFixedSpaceLarge`.
- `flexible` - Take up all available space. Maps to `NSTouchBarItemIdentifierFlexibleSpace`.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBarSpacer`:
####
`touchBarSpacer.size`[](#touchbarspacersize "Direct link to heading")
A `string` representing the size of the spacer. Can be `small`, `large` or `flexible`.
electron dialog dialog
======
> Display native system dialogs for opening and saving files, alerting, etc.
>
>
Process: [Main](../glossary#main-process)
An example of showing a dialog to select multiple files:
```
const { dialog } = require('electron')
console.log(dialog.showOpenDialog({ properties: ['openFile', 'multiSelections'] }))
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `dialog` module has the following methods:
###
`dialog.showOpenDialogSync([browserWindow, ]options)`[](#dialogshowopendialogsyncbrowserwindow-options "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional)
* `options` Object
+ `title` string (optional)
+ `defaultPath` string (optional)
+ `buttonLabel` string (optional) - Custom label for the confirmation button, when left empty the default label will be used.
+ `filters` [FileFilter[]](structures/file-filter) (optional)
+ `properties` string[] (optional) - Contains which features the dialog should use. The following values are supported:
- `openFile` - Allow files to be selected.
- `openDirectory` - Allow directories to be selected.
- `multiSelections` - Allow multiple paths to be selected.
- `showHiddenFiles` - Show hidden files in dialog.
- `createDirectory` *macOS* - Allow creating new directories from dialog.
- `promptToCreate` *Windows* - Prompt for creation if the file path entered in the dialog does not exist. This does not actually create the file at the path but allows non-existent paths to be returned that should be created by the application.
- `noResolveAliases` *macOS* - Disable the automatic alias (symlink) path resolution. Selected aliases will now return the alias path instead of their target path.
- `treatPackageAsDirectory` *macOS* - Treat packages, such as `.app` folders, as a directory instead of a file.
- `dontAddToRecent` *Windows* - Do not add the item being opened to the recent documents list.
+ `message` string (optional) *macOS* - Message to display above input boxes.
+ `securityScopedBookmarks` boolean (optional) *macOS* *mas* - Create [security scoped bookmarks](https://developer.apple.com/library/content/documentation/Security/Conceptual/AppSandboxDesignGuide/AppSandboxInDepth/AppSandboxInDepth.html#//apple_ref/doc/uid/TP40011183-CH3-SW16) when packaged for the Mac App Store.
Returns `string[] | undefined`, the file paths chosen by the user; if the dialog is cancelled it returns `undefined`.
The `browserWindow` argument allows the dialog to attach itself to a parent window, making it modal.
The `filters` specifies an array of file types that can be displayed or selected when you want to limit the user to a specific type. For example:
```
{
filters: [
{ name: 'Images', extensions: ['jpg', 'png', 'gif'] },
{ name: 'Movies', extensions: ['mkv', 'avi', 'mp4'] },
{ name: 'Custom File Type', extensions: ['as'] },
{ name: 'All Files', extensions: ['*'] }
]
}
```
The `extensions` array should contain extensions without wildcards or dots (e.g. `'png'` is good but `'.png'` and `'*.png'` are bad). To show all files, use the `'*'` wildcard (no other wildcard is supported).
**Note:** On Windows and Linux an open dialog can not be both a file selector and a directory selector, so if you set `properties` to `['openFile', 'openDirectory']` on these platforms, a directory selector will be shown.
```
dialog.showOpenDialogSync(mainWindow, {
properties: ['openFile', 'openDirectory']
})
```
###
`dialog.showOpenDialog([browserWindow, ]options)`[](#dialogshowopendialogbrowserwindow-options "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional)
* `options` Object
+ `title` string (optional)
+ `defaultPath` string (optional)
+ `buttonLabel` string (optional) - Custom label for the confirmation button, when left empty the default label will be used.
+ `filters` [FileFilter[]](structures/file-filter) (optional)
+ `properties` string[] (optional) - Contains which features the dialog should use. The following values are supported:
- `openFile` - Allow files to be selected.
- `openDirectory` - Allow directories to be selected.
- `multiSelections` - Allow multiple paths to be selected.
- `showHiddenFiles` - Show hidden files in dialog.
- `createDirectory` *macOS* - Allow creating new directories from dialog.
- `promptToCreate` *Windows* - Prompt for creation if the file path entered in the dialog does not exist. This does not actually create the file at the path but allows non-existent paths to be returned that should be created by the application.
- `noResolveAliases` *macOS* - Disable the automatic alias (symlink) path resolution. Selected aliases will now return the alias path instead of their target path.
- `treatPackageAsDirectory` *macOS* - Treat packages, such as `.app` folders, as a directory instead of a file.
- `dontAddToRecent` *Windows* - Do not add the item being opened to the recent documents list.
+ `message` string (optional) *macOS* - Message to display above input boxes.
+ `securityScopedBookmarks` boolean (optional) *macOS* *mas* - Create [security scoped bookmarks](https://developer.apple.com/library/content/documentation/Security/Conceptual/AppSandboxDesignGuide/AppSandboxInDepth/AppSandboxInDepth.html#//apple_ref/doc/uid/TP40011183-CH3-SW16) when packaged for the Mac App Store.
Returns `Promise<Object>` - Resolve with an object containing the following:
* `canceled` boolean - whether or not the dialog was canceled.
* `filePaths` string[] - An array of file paths chosen by the user. If the dialog is cancelled this will be an empty array.
* `bookmarks` string[] (optional) *macOS* *mas* - An array matching the `filePaths` array of base64 encoded strings which contains security scoped bookmark data. `securityScopedBookmarks` must be enabled for this to be populated. (For return values, see [table here](#bookmarks-array).)
The `browserWindow` argument allows the dialog to attach itself to a parent window, making it modal.
The `filters` specifies an array of file types that can be displayed or selected when you want to limit the user to a specific type. For example:
```
{
filters: [
{ name: 'Images', extensions: ['jpg', 'png', 'gif'] },
{ name: 'Movies', extensions: ['mkv', 'avi', 'mp4'] },
{ name: 'Custom File Type', extensions: ['as'] },
{ name: 'All Files', extensions: ['*'] }
]
}
```
The `extensions` array should contain extensions without wildcards or dots (e.g. `'png'` is good but `'.png'` and `'*.png'` are bad). To show all files, use the `'*'` wildcard (no other wildcard is supported).
**Note:** On Windows and Linux an open dialog can not be both a file selector and a directory selector, so if you set `properties` to `['openFile', 'openDirectory']` on these platforms, a directory selector will be shown.
```
dialog.showOpenDialog(mainWindow, {
properties: ['openFile', 'openDirectory']
}).then(result => {
console.log(result.canceled)
console.log(result.filePaths)
}).catch(err => {
console.log(err)
})
```
###
`dialog.showSaveDialogSync([browserWindow, ]options)`[](#dialogshowsavedialogsyncbrowserwindow-options "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional)
* `options` Object
+ `title` string (optional) - The dialog title. Cannot be displayed on some *Linux* desktop environments.
+ `defaultPath` string (optional) - Absolute directory path, absolute file path, or file name to use by default.
+ `buttonLabel` string (optional) - Custom label for the confirmation button, when left empty the default label will be used.
+ `filters` [FileFilter[]](structures/file-filter) (optional)
+ `message` string (optional) *macOS* - Message to display above text fields.
+ `nameFieldLabel` string (optional) *macOS* - Custom label for the text displayed in front of the filename text field.
+ `showsTagField` boolean (optional) *macOS* - Show the tags input box, defaults to `true`.
+ `properties` string[] (optional)
- `showHiddenFiles` - Show hidden files in dialog.
- `createDirectory` *macOS* - Allow creating new directories from dialog.
- `treatPackageAsDirectory` *macOS* - Treat packages, such as `.app` folders, as a directory instead of a file.
- `showOverwriteConfirmation` *Linux* - Sets whether the user will be presented a confirmation dialog if the user types a file name that already exists.
- `dontAddToRecent` *Windows* - Do not add the item being saved to the recent documents list.
+ `securityScopedBookmarks` boolean (optional) *macOS* *mas* - Create a [security scoped bookmark](https://developer.apple.com/library/content/documentation/Security/Conceptual/AppSandboxDesignGuide/AppSandboxInDepth/AppSandboxInDepth.html#//apple_ref/doc/uid/TP40011183-CH3-SW16) when packaged for the Mac App Store. If this option is enabled and the file doesn't already exist a blank file will be created at the chosen path.
Returns `string | undefined`, the path of the file chosen by the user; if the dialog is cancelled it returns `undefined`.
The `browserWindow` argument allows the dialog to attach itself to a parent window, making it modal.
The `filters` specifies an array of file types that can be displayed, see `dialog.showOpenDialog` for an example.
###
`dialog.showSaveDialog([browserWindow, ]options)`[](#dialogshowsavedialogbrowserwindow-options "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional)
* `options` Object
+ `title` string (optional) - The dialog title. Cannot be displayed on some *Linux* desktop environments.
+ `defaultPath` string (optional) - Absolute directory path, absolute file path, or file name to use by default.
+ `buttonLabel` string (optional) - Custom label for the confirmation button, when left empty the default label will be used.
+ `filters` [FileFilter[]](structures/file-filter) (optional)
+ `message` string (optional) *macOS* - Message to display above text fields.
+ `nameFieldLabel` string (optional) *macOS* - Custom label for the text displayed in front of the filename text field.
+ `showsTagField` boolean (optional) *macOS* - Show the tags input box, defaults to `true`.
+ `properties` string[] (optional)
- `showHiddenFiles` - Show hidden files in dialog.
- `createDirectory` *macOS* - Allow creating new directories from dialog.
- `treatPackageAsDirectory` *macOS* - Treat packages, such as `.app` folders, as a directory instead of a file.
- `showOverwriteConfirmation` *Linux* - Sets whether the user will be presented a confirmation dialog if the user types a file name that already exists.
- `dontAddToRecent` *Windows* - Do not add the item being saved to the recent documents list.
+ `securityScopedBookmarks` boolean (optional) *macOS* *mas* - Create a [security scoped bookmark](https://developer.apple.com/library/content/documentation/Security/Conceptual/AppSandboxDesignGuide/AppSandboxInDepth/AppSandboxInDepth.html#//apple_ref/doc/uid/TP40011183-CH3-SW16) when packaged for the Mac App Store. If this option is enabled and the file doesn't already exist a blank file will be created at the chosen path.
Returns `Promise<Object>` - Resolve with an object containing the following:
* `canceled` boolean - whether or not the dialog was canceled.
* `filePath` string (optional) - If the dialog is canceled, this will be `undefined`.
* `bookmark` string (optional) *macOS* *mas* - Base64 encoded string which contains the security scoped bookmark data for the saved file. `securityScopedBookmarks` must be enabled for this to be present. (For return values, see [table here](#bookmarks-array).)
The `browserWindow` argument allows the dialog to attach itself to a parent window, making it modal.
The `filters` specifies an array of file types that can be displayed, see `dialog.showOpenDialog` for an example.
**Note:** On macOS, using the asynchronous version is recommended to avoid issues when expanding and collapsing the dialog.
###
`dialog.showMessageBoxSync([browserWindow, ]options)`[](#dialogshowmessageboxsyncbrowserwindow-options "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional)
* `options` Object
+ `message` string - Content of the message box.
+ `type` string (optional) - Can be `"none"`, `"info"`, `"error"`, `"question"` or `"warning"`. On Windows, `"question"` displays the same icon as `"info"`, unless you set an icon using the `"icon"` option. On macOS, both `"warning"` and `"error"` display the same warning icon.
+ `buttons` string[] (optional) - Array of texts for buttons. On Windows, an empty array will result in one button labeled "OK".
+ `defaultId` Integer (optional) - Index of the button in the buttons array which will be selected by default when the message box opens.
+ `title` string (optional) - Title of the message box, some platforms will not show it.
+ `detail` string (optional) - Extra information of the message.
+ `icon` ([NativeImage](native-image) | string) (optional)
+ `textWidth` Integer (optional) *macOS* - Custom width of the text in the message box.
+ `cancelId` Integer (optional) - The index of the button to be used to cancel the dialog, via the `Esc` key. By default this is assigned to the first button with "cancel" or "no" as the label. If no such labeled buttons exist and this option is not set, `0` will be used as the return value.
+ `noLink` boolean (optional) - On Windows Electron will try to figure out which one of the `buttons` are common buttons (like "Cancel" or "Yes"), and show the others as command links in the dialog. This can make the dialog appear in the style of modern Windows apps. If you don't like this behavior, you can set `noLink` to `true`.
+ `normalizeAccessKeys` boolean (optional) - Normalize the keyboard access keys across platforms. Default is `false`. Enabling this assumes `&` is used in the button labels for the placement of the keyboard shortcut access key and labels will be converted so they work correctly on each platform, `&` characters are removed on macOS, converted to `_` on Linux, and left untouched on Windows. For example, a button label of `Vie&w` will be converted to `Vie_w` on Linux and `View` on macOS and can be selected via `Alt-W` on Windows and Linux.
Returns `Integer` - the index of the clicked button.
Shows a message box, it will block the process until the message box is closed. It returns the index of the clicked button.
The `browserWindow` argument allows the dialog to attach itself to a parent window, making it modal. If `browserWindow` is not shown dialog will not be attached to it. In such case it will be displayed as an independent window.
###
`dialog.showMessageBox([browserWindow, ]options)`[](#dialogshowmessageboxbrowserwindow-options "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional)
* `options` Object
+ `message` string - Content of the message box.
+ `type` string (optional) - Can be `"none"`, `"info"`, `"error"`, `"question"` or `"warning"`. On Windows, `"question"` displays the same icon as `"info"`, unless you set an icon using the `"icon"` option. On macOS, both `"warning"` and `"error"` display the same warning icon.
+ `buttons` string[] (optional) - Array of texts for buttons. On Windows, an empty array will result in one button labeled "OK".
+ `defaultId` Integer (optional) - Index of the button in the buttons array which will be selected by default when the message box opens.
+ `signal` AbortSignal (optional) - Pass an instance of [AbortSignal](https://nodejs.org/api/globals.html#globals_class_abortsignal) to optionally close the message box, the message box will behave as if it was cancelled by the user. On macOS, `signal` does not work with message boxes that do not have a parent window, since those message boxes run synchronously due to platform limitations.
+ `title` string (optional) - Title of the message box, some platforms will not show it.
+ `detail` string (optional) - Extra information of the message.
+ `checkboxLabel` string (optional) - If provided, the message box will include a checkbox with the given label.
+ `checkboxChecked` boolean (optional) - Initial checked state of the checkbox. `false` by default.
+ `icon` ([NativeImage](native-image) | string) (optional)
+ `textWidth` Integer (optional) *macOS* - Custom width of the text in the message box.
+ `cancelId` Integer (optional) - The index of the button to be used to cancel the dialog, via the `Esc` key. By default this is assigned to the first button with "cancel" or "no" as the label. If no such labeled buttons exist and this option is not set, `0` will be used as the return value.
+ `noLink` boolean (optional) - On Windows Electron will try to figure out which one of the `buttons` are common buttons (like "Cancel" or "Yes"), and show the others as command links in the dialog. This can make the dialog appear in the style of modern Windows apps. If you don't like this behavior, you can set `noLink` to `true`.
+ `normalizeAccessKeys` boolean (optional) - Normalize the keyboard access keys across platforms. Default is `false`. Enabling this assumes `&` is used in the button labels for the placement of the keyboard shortcut access key and labels will be converted so they work correctly on each platform, `&` characters are removed on macOS, converted to `_` on Linux, and left untouched on Windows. For example, a button label of `Vie&w` will be converted to `Vie_w` on Linux and `View` on macOS and can be selected via `Alt-W` on Windows and Linux.
Returns `Promise<Object>` - resolves with a promise containing the following properties:
* `response` number - The index of the clicked button.
* `checkboxChecked` boolean - The checked state of the checkbox if `checkboxLabel` was set. Otherwise `false`.
Shows a message box.
The `browserWindow` argument allows the dialog to attach itself to a parent window, making it modal.
###
`dialog.showErrorBox(title, content)`[](#dialogshowerrorboxtitle-content "Direct link to heading")
* `title` string - The title to display in the error box.
* `content` string - The text content to display in the error box.
Displays a modal dialog that shows an error message.
This API can be called safely before the `ready` event the `app` module emits, it is usually used to report errors in early stage of startup. If called before the app `ready`event on Linux, the message will be emitted to stderr, and no GUI dialog will appear.
###
`dialog.showCertificateTrustDialog([browserWindow, ]options)` *macOS* *Windows*[](#dialogshowcertificatetrustdialogbrowserwindow-options-macos-windows "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional)
* `options` Object
+ `certificate` [Certificate](structures/certificate) - The certificate to trust/import.
+ `message` string - The message to display to the user.
Returns `Promise<void>` - resolves when the certificate trust dialog is shown.
On macOS, this displays a modal dialog that shows a message and certificate information, and gives the user the option of trusting/importing the certificate. If you provide a `browserWindow` argument the dialog will be attached to the parent window, making it modal.
On Windows the options are more limited, due to the Win32 APIs used:
* The `message` argument is not used, as the OS provides its own confirmation dialog.
* The `browserWindow` argument is ignored since it is not possible to make this confirmation dialog modal.
Bookmarks array[](#bookmarks-array "Direct link to heading")
-------------------------------------------------------------
`showOpenDialog`, `showOpenDialogSync`, `showSaveDialog`, and `showSaveDialogSync` will return a `bookmarks` array.
| Build Type | securityScopedBookmarks boolean | Return Type | Return Value |
| --- | --- | --- | --- |
| macOS mas | True | Success | `['LONGBOOKMARKSTRING']` |
| macOS mas | True | Error | `['']` (array of empty string) |
| macOS mas | False | NA | `[]` (empty array) |
| non mas | any | NA | `[]` (empty array) |
Sheets[](#sheets "Direct link to heading")
-------------------------------------------
On macOS, dialogs are presented as sheets attached to a window if you provide a [`BrowserWindow`](browser-window) reference in the `browserWindow` parameter, or modals if no window is provided.
You can call `BrowserWindow.getCurrentWindow().setSheetOffset(offset)` to change the offset from the window frame where sheets are attached.
| programming_docs |
electron Supported Command Line Switches Supported Command Line Switches
===============================
> Command line switches supported by Electron.
>
>
You can use [app.commandLine.appendSwitch](command-line#commandlineappendswitchswitch-value) to append them in your app's main script before the [ready](app#event-ready) event of the <app> module is emitted:
```
const { app } = require('electron')
app.commandLine.appendSwitch('remote-debugging-port', '8315')
app.commandLine.appendSwitch('host-rules', 'MAP * 127.0.0.1')
app.whenReady().then(() => {
// Your code here
})
```
Electron CLI Flags[](#electron-cli-flags "Direct link to heading")
-------------------------------------------------------------------
### --auth-server-whitelist=`url`[](#--auth-server-whitelisturl "Direct link to heading")
A comma-separated list of servers for which integrated authentication is enabled.
For example:
```
--auth-server-whitelist='*example.com, *foobar.com, *baz'
```
then any `url` ending with `example.com`, `foobar.com`, `baz` will be considered for integrated authentication. Without `*` prefix the URL has to match exactly.
### --auth-negotiate-delegate-whitelist=`url`[](#--auth-negotiate-delegate-whitelisturl "Direct link to heading")
A comma-separated list of servers for which delegation of user credentials is required. Without `*` prefix the URL has to match exactly.
### --disable-ntlm-v2[](#--disable-ntlm-v2 "Direct link to heading")
Disables NTLM v2 for posix platforms, no effect elsewhere.
### --disable-http-cache[](#--disable-http-cache "Direct link to heading")
Disables the disk cache for HTTP requests.
### --disable-http2[](#--disable-http2 "Direct link to heading")
Disable HTTP/2 and SPDY/3.1 protocols.
### --disable-renderer-backgrounding[](#--disable-renderer-backgrounding "Direct link to heading")
Prevents Chromium from lowering the priority of invisible pages' renderer processes.
This flag is global to all renderer processes, if you only want to disable throttling in one window, you can take the hack of [playing silent audio](https://github.com/atom/atom/pull/9485/files).
### --disk-cache-size=`size`[](#--disk-cache-sizesize "Direct link to heading")
Forces the maximum disk space to be used by the disk cache, in bytes.
### --enable-logging[=file][](#--enable-loggingfile "Direct link to heading")
Prints Chromium's logging to stderr (or a log file).
The `ELECTRON_ENABLE_LOGGING` environment variable has the same effect as passing `--enable-logging`.
Passing `--enable-logging` will result in logs being printed on stderr. Passing `--enable-logging=file` will result in logs being saved to the file specified by `--log-file=...`, or to `electron_debug.log` in the user-data directory if `--log-file` is not specified.
> **Note:** On Windows, logs from child processes cannot be sent to stderr. Logging to a file is the most reliable way to collect logs on Windows.
>
>
See also `--log-file`, `--log-level`, `--v`, and `--vmodule`.
### --force-fieldtrials=`trials`[](#--force-fieldtrialstrials "Direct link to heading")
Field trials to be forcefully enabled or disabled.
For example: `WebRTC-Audio-Red-For-Opus/Enabled/`
### --host-rules=`rules`[](#--host-rulesrules "Direct link to heading")
A comma-separated list of `rules` that control how hostnames are mapped.
For example:
* `MAP * 127.0.0.1` Forces all hostnames to be mapped to 127.0.0.1
* `MAP *.google.com proxy` Forces all google.com subdomains to be resolved to "proxy".
* `MAP test.com [::1]:77` Forces "test.com" to resolve to IPv6 loopback. Will also force the port of the resulting socket address to be 77.
* `MAP * baz, EXCLUDE www.google.com` Remaps everything to "baz", except for "[www.google.com"](http://www.google.com%22).
These mappings apply to the endpoint host in a net request (the TCP connect and host resolver in a direct connection, and the `CONNECT` in an HTTP proxy connection, and the endpoint host in a `SOCKS` proxy connection).
### --host-resolver-rules=`rules`[](#--host-resolver-rulesrules "Direct link to heading")
Like `--host-rules` but these `rules` only apply to the host resolver.
### --ignore-certificate-errors[](#--ignore-certificate-errors "Direct link to heading")
Ignores certificate related errors.
### --ignore-connections-limit=`domains`[](#--ignore-connections-limitdomains "Direct link to heading")
Ignore the connections limit for `domains` list separated by `,`.
### --js-flags=`flags`[](#--js-flagsflags "Direct link to heading")
Specifies the flags passed to the Node.js engine. It has to be passed when starting Electron if you want to enable the `flags` in the main process.
```
$ electron --js-flags="--harmony_proxies --harmony_collections" your-app
```
See the [Node.js documentation](https://nodejs.org/api/cli.html) or run `node --help` in your terminal for a list of available flags. Additionally, run `node --v8-options` to see a list of flags that specifically refer to Node.js's V8 JavaScript engine.
### --lang[](#--lang "Direct link to heading")
Set a custom locale.
### --log-file=`path`[](#--log-filepath "Direct link to heading")
If `--enable-logging` is specified, logs will be written to the given path. The parent directory must exist.
Setting the `ELECTRON_LOG_FILE` environment variable is equivalent to passing this flag. If both are present, the command-line switch takes precedence.
### --log-net-log=`path`[](#--log-net-logpath "Direct link to heading")
Enables net log events to be saved and writes them to `path`.
### --log-level=`N`[](#--log-leveln "Direct link to heading")
Sets the verbosity of logging when used together with `--enable-logging`. `N` should be one of [Chrome's LogSeverities](https://source.chromium.org/chromium/chromium/src/+/main:base/logging.h?q=logging::LogSeverity&ss=chromium).
Note that two complimentary logging mechanisms in Chromium -- `LOG()` and `VLOG()` -- are controlled by different switches. `--log-level` controls `LOG()` messages, while `--v` and `--vmodule` control `VLOG()` messages. So you may want to use a combination of these three switches depending on the granularity you want and what logging calls are made by the code you're trying to watch.
See [Chromium Logging source](https://source.chromium.org/chromium/chromium/src/+/main:base/logging.h) for more information on how `LOG()` and `VLOG()` interact. Loosely speaking, `VLOG()` can be thought of as sub-levels / per-module levels inside `LOG(INFO)` to control the firehose of `LOG(INFO)` data.
See also `--enable-logging`, `--log-level`, `--v`, and `--vmodule`.
### --no-proxy-server[](#--no-proxy-server "Direct link to heading")
Don't use a proxy server and always make direct connections. Overrides any other proxy server flags that are passed.
### --no-sandbox[](#--no-sandbox "Direct link to heading")
Disables the Chromium [sandbox](https://www.chromium.org/developers/design-documents/sandbox). Forces renderer process and Chromium helper processes to run un-sandboxed. Should only be used for testing.
### --proxy-bypass-list=`hosts`[](#--proxy-bypass-listhosts "Direct link to heading")
Instructs Electron to bypass the proxy server for the given semi-colon-separated list of hosts. This flag has an effect only if used in tandem with `--proxy-server`.
For example:
```
const { app } = require('electron')
app.commandLine.appendSwitch('proxy-bypass-list', '<local>;*.google.com;*foo.com;1.2.3.4:5678')
```
Will use the proxy server for all hosts except for local addresses (`localhost`, `127.0.0.1` etc.), `google.com` subdomains, hosts that contain the suffix `foo.com` and anything at `1.2.3.4:5678`.
### --proxy-pac-url=`url`[](#--proxy-pac-urlurl "Direct link to heading")
Uses the PAC script at the specified `url`.
### --proxy-server=`address:port`[](#--proxy-serveraddressport "Direct link to heading")
Use a specified proxy server, which overrides the system setting. This switch only affects requests with HTTP protocol, including HTTPS and WebSocket requests. It is also noteworthy that not all proxy servers support HTTPS and WebSocket requests. The proxy URL does not support username and password authentication [per Chromium issue](https://bugs.chromium.org/p/chromium/issues/detail?id=615947).
### --remote-debugging-port=`port`[](#--remote-debugging-portport "Direct link to heading")
Enables remote debugging over HTTP on the specified `port`.
### --v=`log_level`[](#--vlog_level "Direct link to heading")
Gives the default maximal active V-logging level; 0 is the default. Normally positive values are used for V-logging levels.
This switch only works when `--enable-logging` is also passed.
See also `--enable-logging`, `--log-level`, and `--vmodule`.
### --vmodule=`pattern`[](#--vmodulepattern "Direct link to heading")
Gives the per-module maximal V-logging levels to override the value given by `--v`. E.g. `my_module=2,foo*=3` would change the logging level for all code in source files `my_module.*` and `foo*.*`.
Any pattern containing a forward or backward slash will be tested against the whole pathname and not only the module. E.g. `*/foo/bar/*=2` would change the logging level for all code in the source files under a `foo/bar` directory.
This switch only works when `--enable-logging` is also passed.
See also `--enable-logging`, `--log-level`, and `--v`.
### --force\_high\_performance\_gpu[](#--force_high_performance_gpu "Direct link to heading")
Force using discrete GPU when there are multiple GPUs available.
### --force\_low\_power\_gpu[](#--force_low_power_gpu "Direct link to heading")
Force using integrated GPU when there are multiple GPUs available.
Node.js Flags[](#nodejs-flags "Direct link to heading")
--------------------------------------------------------
Electron supports some of the [CLI flags](https://nodejs.org/api/cli.html) supported by Node.js.
**Note:** Passing unsupported command line switches to Electron when it is not running in `ELECTRON_RUN_AS_NODE` will have no effect.
### --inspect-brk[=[host:]port][](#--inspect-brkhostport "Direct link to heading")
Activate inspector on host:port and break at start of user script. Default host:port is 127.0.0.1:9229.
Aliased to `--debug-brk=[host:]port`.
### --inspect-port=[host:]port[](#--inspect-porthostport "Direct link to heading")
Set the `host:port` to be used when the inspector is activated. Useful when activating the inspector by sending the SIGUSR1 signal. Default host is `127.0.0.1`.
Aliased to `--debug-port=[host:]port`.
### --inspect[=[host:]port][](#--inspecthostport "Direct link to heading")
Activate inspector on `host:port`. Default is `127.0.0.1:9229`.
V8 inspector integration allows tools such as Chrome DevTools and IDEs to debug and profile Electron instances. The tools attach to Electron instances via a TCP port and communicate using the [Chrome DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/).
See the [Debugging the Main Process](../tutorial/debugging-main-process) guide for more details.
Aliased to `--debug[=[host:]port`.
### --inspect-publish-uid=stderr,http[](#--inspect-publish-uidstderrhttp "Direct link to heading")
Specify ways of the inspector web socket url exposure.
By default inspector websocket url is available in stderr and under /json/list endpoint on http://host:port/json/list.
electron Opening windows from the renderer Opening windows from the renderer
=================================
There are several ways to control how windows are created from trusted or untrusted content within a renderer. Windows can be created from the renderer in two ways:
* clicking on links or submitting forms adorned with `target=_blank`
* JavaScript calling `window.open()`
For same-origin content, the new window is created within the same process, enabling the parent to access the child window directly. This can be very useful for app sub-windows that act as preference panels, or similar, as the parent can render to the sub-window directly, as if it were a `div` in the parent. This is the same behavior as in the browser.
Electron pairs this native Chrome `Window` with a BrowserWindow under the hood. You can take advantage of all the customization available when creating a BrowserWindow in the main process by using `webContents.setWindowOpenHandler()` for renderer-created windows.
BrowserWindow constructor options are set by, in increasing precedence order: parsed options from the `features` string from `window.open()`, security-related webPreferences inherited from the parent, and options given by [`webContents.setWindowOpenHandler`](web-contents#contentssetwindowopenhandlerhandler). Note that `webContents.setWindowOpenHandler` has final say and full privilege because it is invoked in the main process.
###
`window.open(url[, frameName][, features])`[](#windowopenurl-framename-features "Direct link to heading")
* `url` string
* `frameName` string (optional)
* `features` string (optional)
Returns [`Window`](https://developer.mozilla.org/en-US/docs/Web/API/Window) | null
`features` is a comma-separated key-value list, following the standard format of the browser. Electron will parse `BrowserWindowConstructorOptions` out of this list where possible, for convenience. For full control and better ergonomics, consider using `webContents.setWindowOpenHandler` to customize the BrowserWindow creation.
A subset of `WebPreferences` can be set directly, unnested, from the features string: `zoomFactor`, `nodeIntegration`, `preload`, `javascript`, `contextIsolation`, and `webviewTag`.
For example:
```
window.open('https://github.com', '_blank', 'top=500,left=200,frame=false,nodeIntegration=no')
```
**Notes:**
* Node integration will always be disabled in the opened `window` if it is disabled on the parent window.
* Context isolation will always be enabled in the opened `window` if it is enabled on the parent window.
* JavaScript will always be disabled in the opened `window` if it is disabled on the parent window.
* Non-standard features (that are not handled by Chromium or Electron) given in `features` will be passed to any registered `webContents`'s `did-create-window` event handler in the `options` argument.
* `frameName` follows the specification of `windowName` located in the [native documentation](https://developer.mozilla.org/en-US/docs/Web/API/Window/open#parameters).
* When opening `about:blank`, the child window's `WebPreferences` will be copied from the parent window, and there is no way to override it because Chromium skips browser side navigation in this case.
To customize or cancel the creation of the window, you can optionally set an override handler with `webContents.setWindowOpenHandler()` from the main process. Returning `{ action: 'deny' }` cancels the window. Returning `{
action: 'allow', overrideBrowserWindowOptions: { ... } }` will allow opening the window and setting the `BrowserWindowConstructorOptions` to be used when creating the window. Note that this is more powerful than passing options through the feature string, as the renderer has more limited privileges in deciding security preferences than the main process.
In addition to passing in `action` and `overrideBrowserWindowOptions`, `outlivesOpener` can be passed like: `{ action: 'allow', outlivesOpener: true,
overrideBrowserWindowOptions: { ... } }`. If set to `true`, the newly created window will not close when the opener window closes. The default value is `false`.
### Native `Window` example[](#native-window-example "Direct link to heading")
```
// main.js
const mainWindow = new BrowserWindow()
// In this example, only windows with the `about:blank` url will be created.
// All other urls will be blocked.
mainWindow.webContents.setWindowOpenHandler(({ url }) => {
if (url === 'about:blank') {
return {
action: 'allow',
overrideBrowserWindowOptions: {
frame: false,
fullscreenable: false,
backgroundColor: 'black',
webPreferences: {
preload: 'my-child-window-preload-script.js'
}
}
}
}
return { action: 'deny' }
})
```
```
// renderer process (mainWindow)
const childWindow = window.open('', 'modal')
childWindow.document.write('<h1>Hello</h1>')
```
electron Tray Tray
====
Class: Tray[](#class-tray "Direct link to heading")
----------------------------------------------------
> Add icons and context menus to the system's notification area.
>
>
Process: [Main](../glossary#main-process)
`Tray` is an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter).
```
const { app, Menu, Tray } = require('electron')
let tray = null
app.whenReady().then(() => {
tray = new Tray('/path/to/my/icon')
const contextMenu = Menu.buildFromTemplate([
{ label: 'Item1', type: 'radio' },
{ label: 'Item2', type: 'radio' },
{ label: 'Item3', type: 'radio', checked: true },
{ label: 'Item4', type: 'radio' }
])
tray.setToolTip('This is my application.')
tray.setContextMenu(contextMenu)
})
```
**Platform Considerations**
If you want to keep exact same behaviors on all platforms, you should not rely on the `click` event; instead, always attach a context menu to the tray icon.
**Linux**
* On Linux distributions that only have app indicator support, you have to install `libappindicator1` to make the tray icon work.
* The app indicator will be used if it is supported, otherwise `GtkStatusIcon` will be used instead.
* App indicator will only be shown when it has a context menu.
* The `click` event is ignored when using the app indicator.
* In order for changes made to individual `MenuItem`s to take effect, you have to call `setContextMenu` again. For example:
```
const { app, Menu, Tray } = require('electron')
let appIcon = null
app.whenReady().then(() => {
appIcon = new Tray('/path/to/my/icon')
const contextMenu = Menu.buildFromTemplate([
{ label: 'Item1', type: 'radio' },
{ label: 'Item2', type: 'radio' }
])
// Make a change to the context menu
contextMenu.items[1].checked = false
// Call this again for Linux because we modified the context menu
appIcon.setContextMenu(contextMenu)
})
```
**MacOS**
* Icons passed to the Tray constructor should be [Template Images](native-image#template-image).
* To make sure your icon isn't grainy on retina monitors, be sure your `@2x` image is 144dpi.
* If you are bundling your application (e.g., with webpack for development), be sure that the file names are not being mangled or hashed. The filename needs to end in Template, and the `@2x` image needs to have the same filename as the standard image, or MacOS will not magically invert your image's colors or use the high density image.
* 16x16 (72dpi) and 32x32@2x (144dpi) work well for most icons.
**Windows**
* It is recommended to use `ICO` icons to get best visual effects.
###
`new Tray(image, [guid])`[](#new-trayimage-guid "Direct link to heading")
* `image` ([NativeImage](native-image) | string)
* `guid` string (optional) *Windows* - Assigns a GUID to the tray icon. If the executable is signed and the signature contains an organization in the subject line then the GUID is permanently associated with that signature. OS level settings like the position of the tray icon in the system tray will persist even if the path to the executable changes. If the executable is not code-signed then the GUID is permanently associated with the path to the executable. Changing the path to the executable will break the creation of the tray icon and a new GUID must be used. However, it is highly recommended to use the GUID parameter only in conjunction with code-signed executable. If an App defines multiple tray icons then each icon must use a separate GUID.
Creates a new tray icon associated with the `image`.
### Instance Events[](#instance-events "Direct link to heading")
The `Tray` module emits the following events:
#### Event: 'click'[](#event-click "Direct link to heading")
Returns:
* `event` [KeyboardEvent](structures/keyboard-event)
* `bounds` [Rectangle](structures/rectangle) - The bounds of tray icon.
* `position` [Point](structures/point) - The position of the event.
Emitted when the tray icon is clicked.
#### Event: 'right-click' *macOS* *Windows*[](#event-right-click-macos-windows "Direct link to heading")
Returns:
* `event` [KeyboardEvent](structures/keyboard-event)
* `bounds` [Rectangle](structures/rectangle) - The bounds of tray icon.
Emitted when the tray icon is right clicked.
#### Event: 'double-click' *macOS* *Windows*[](#event-double-click-macos-windows "Direct link to heading")
Returns:
* `event` [KeyboardEvent](structures/keyboard-event)
* `bounds` [Rectangle](structures/rectangle) - The bounds of tray icon.
Emitted when the tray icon is double clicked.
#### Event: 'balloon-show' *Windows*[](#event-balloon-show-windows "Direct link to heading")
Emitted when the tray balloon shows.
#### Event: 'balloon-click' *Windows*[](#event-balloon-click-windows "Direct link to heading")
Emitted when the tray balloon is clicked.
#### Event: 'balloon-closed' *Windows*[](#event-balloon-closed-windows "Direct link to heading")
Emitted when the tray balloon is closed because of timeout or user manually closes it.
#### Event: 'drop' *macOS*[](#event-drop-macos "Direct link to heading")
Emitted when any dragged items are dropped on the tray icon.
#### Event: 'drop-files' *macOS*[](#event-drop-files-macos "Direct link to heading")
Returns:
* `event` Event
* `files` string[] - The paths of the dropped files.
Emitted when dragged files are dropped in the tray icon.
#### Event: 'drop-text' *macOS*[](#event-drop-text-macos "Direct link to heading")
Returns:
* `event` Event
* `text` string - the dropped text string.
Emitted when dragged text is dropped in the tray icon.
#### Event: 'drag-enter' *macOS*[](#event-drag-enter-macos "Direct link to heading")
Emitted when a drag operation enters the tray icon.
#### Event: 'drag-leave' *macOS*[](#event-drag-leave-macos "Direct link to heading")
Emitted when a drag operation exits the tray icon.
#### Event: 'drag-end' *macOS*[](#event-drag-end-macos "Direct link to heading")
Emitted when a drag operation ends on the tray or ends at another location.
#### Event: 'mouse-up' *macOS*[](#event-mouse-up-macos "Direct link to heading")
Returns:
* `event` [KeyboardEvent](structures/keyboard-event)
* `position` [Point](structures/point) - The position of the event.
Emitted when the mouse is released from clicking the tray icon.
Note: This will not be emitted if you have set a context menu for your Tray using `tray.setContextMenu`, as a result of macOS-level constraints.
#### Event: 'mouse-down' *macOS*[](#event-mouse-down-macos "Direct link to heading")
Returns:
* `event` [KeyboardEvent](structures/keyboard-event)
* `position` [Point](structures/point) - The position of the event.
Emitted when the mouse clicks the tray icon.
#### Event: 'mouse-enter' *macOS*[](#event-mouse-enter-macos "Direct link to heading")
Returns:
* `event` [KeyboardEvent](structures/keyboard-event)
* `position` [Point](structures/point) - The position of the event.
Emitted when the mouse enters the tray icon.
#### Event: 'mouse-leave' *macOS*[](#event-mouse-leave-macos "Direct link to heading")
Returns:
* `event` [KeyboardEvent](structures/keyboard-event)
* `position` [Point](structures/point) - The position of the event.
Emitted when the mouse exits the tray icon.
#### Event: 'mouse-move' *macOS* *Windows*[](#event-mouse-move-macos-windows "Direct link to heading")
Returns:
* `event` [KeyboardEvent](structures/keyboard-event)
* `position` [Point](structures/point) - The position of the event.
Emitted when the mouse moves in the tray icon.
### Instance Methods[](#instance-methods "Direct link to heading")
The `Tray` class has the following methods:
####
`tray.destroy()`[](#traydestroy "Direct link to heading")
Destroys the tray icon immediately.
####
`tray.setImage(image)`[](#traysetimageimage "Direct link to heading")
* `image` ([NativeImage](native-image) | string)
Sets the `image` associated with this tray icon.
####
`tray.setPressedImage(image)` *macOS*[](#traysetpressedimageimage-macos "Direct link to heading")
* `image` ([NativeImage](native-image) | string)
Sets the `image` associated with this tray icon when pressed on macOS.
####
`tray.setToolTip(toolTip)`[](#traysettooltiptooltip "Direct link to heading")
* `toolTip` string
Sets the hover text for this tray icon.
####
`tray.setTitle(title[, options])` *macOS*[](#traysettitletitle-options-macos "Direct link to heading")
* `title` string
* `options` Object (optional)
+ `fontType` string (optional) - The font family variant to display, can be `monospaced` or `monospacedDigit`. `monospaced` is available in macOS 10.15+ and `monospacedDigit` is available in macOS 10.11+. When left blank, the title uses the default system font.
Sets the title displayed next to the tray icon in the status bar (Support ANSI colors).
####
`tray.getTitle()` *macOS*[](#traygettitle-macos "Direct link to heading")
Returns `string` - the title displayed next to the tray icon in the status bar
####
`tray.setIgnoreDoubleClickEvents(ignore)` *macOS*[](#traysetignoredoubleclickeventsignore-macos "Direct link to heading")
* `ignore` boolean
Sets the option to ignore double click events. Ignoring these events allows you to detect every individual click of the tray icon.
This value is set to false by default.
####
`tray.getIgnoreDoubleClickEvents()` *macOS*[](#traygetignoredoubleclickevents-macos "Direct link to heading")
Returns `boolean` - Whether double click events will be ignored.
####
`tray.displayBalloon(options)` *Windows*[](#traydisplayballoonoptions-windows "Direct link to heading")
* `options` Object
+ `icon` ([NativeImage](native-image) | string) (optional) - Icon to use when `iconType` is `custom`.
+ `iconType` string (optional) - Can be `none`, `info`, `warning`, `error` or `custom`. Default is `custom`.
+ `title` string
+ `content` string
+ `largeIcon` boolean (optional) - The large version of the icon should be used. Default is `true`. Maps to [`NIIF_LARGE_ICON`](https://docs.microsoft.com/en-us/windows/win32/api/shellapi/ns-shellapi-notifyicondataa#niif_large_icon-0x00000020).
+ `noSound` boolean (optional) - Do not play the associated sound. Default is `false`. Maps to [`NIIF_NOSOUND`](https://docs.microsoft.com/en-us/windows/win32/api/shellapi/ns-shellapi-notifyicondataa#niif_nosound-0x00000010).
+ `respectQuietTime` boolean (optional) - Do not display the balloon notification if the current user is in "quiet time". Default is `false`. Maps to [`NIIF_RESPECT_QUIET_TIME`](https://docs.microsoft.com/en-us/windows/win32/api/shellapi/ns-shellapi-notifyicondataa#niif_respect_quiet_time-0x00000080).
Displays a tray balloon.
####
`tray.removeBalloon()` *Windows*[](#trayremoveballoon-windows "Direct link to heading")
Removes a tray balloon.
####
`tray.focus()` *Windows*[](#trayfocus-windows "Direct link to heading")
Returns focus to the taskbar notification area. Notification area icons should use this message when they have completed their UI operation. For example, if the icon displays a shortcut menu, but the user presses ESC to cancel it, use `tray.focus()` to return focus to the notification area.
####
`tray.popUpContextMenu([menu, position])` *macOS* *Windows*[](#traypopupcontextmenumenu-position-macos-windows "Direct link to heading")
* `menu` Menu (optional)
* `position` [Point](structures/point) (optional) - The pop up position.
Pops up the context menu of the tray icon. When `menu` is passed, the `menu` will be shown instead of the tray icon's context menu.
The `position` is only available on Windows, and it is (0, 0) by default.
####
`tray.closeContextMenu()` *macOS* *Windows*[](#trayclosecontextmenu-macos-windows "Direct link to heading")
Closes an open context menu, as set by `tray.setContextMenu()`.
####
`tray.setContextMenu(menu)`[](#traysetcontextmenumenu "Direct link to heading")
* `menu` Menu | null
Sets the context menu for this icon.
####
`tray.getBounds()` *macOS* *Windows*[](#traygetbounds-macos-windows "Direct link to heading")
Returns [Rectangle](structures/rectangle)
The `bounds` of this tray icon as `Object`.
####
`tray.isDestroyed()`[](#trayisdestroyed "Direct link to heading")
Returns `boolean` - Whether the tray icon is destroyed.
| programming_docs |
electron crashReporter crashReporter
=============
> Submit crash reports to a remote server.
>
>
Process: [Main](../glossary#main-process), [Renderer](../glossary#renderer-process)
The following is an example of setting up Electron to automatically submit crash reports to a remote server:
```
const { crashReporter } = require('electron')
crashReporter.start({ submitURL: 'https://your-domain.com/url-to-submit' })
```
For setting up a server to accept and process crash reports, you can use following projects:
* [socorro](https://github.com/mozilla/socorro)
* [mini-breakpad-server](https://github.com/electron/mini-breakpad-server)
> **Note:** Electron uses Crashpad, not Breakpad, to collect and upload crashes, but for the time being, the [upload protocol is the same](https://chromium.googlesource.com/crashpad/crashpad/+/HEAD/doc/overview_design.md#Upload-to-collection-server).
>
>
Or use a 3rd party hosted solution:
* [Backtrace](https://backtrace.io/electron/)
* [Sentry](https://docs.sentry.io/clients/electron)
* [BugSplat](https://www.bugsplat.com/docs/platforms/electron)
* [Bugsnag](https://docs.bugsnag.com/platforms/electron/)
Crash reports are stored temporarily before being uploaded in a directory underneath the app's user data directory, called 'Crashpad'. You can override this directory by calling `app.setPath('crashDumps', '/path/to/crashes')` before starting the crash reporter.
Electron uses [crashpad](https://chromium.googlesource.com/crashpad/crashpad/+/refs/heads/main/README.md) to monitor and report crashes.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `crashReporter` module has the following methods:
###
`crashReporter.start(options)`[](#crashreporterstartoptions "Direct link to heading")
* `options` Object
+ `submitURL` string (optional) - URL that crash reports will be sent to as POST. Required unless `uploadToServer` is `false`.
+ `productName` string (optional) - Defaults to `app.name`.
+ `companyName` string (optional) *Deprecated* - Deprecated alias for `{ globalExtra: { _companyName: ... } }`.
+ `uploadToServer` boolean (optional) - Whether crash reports should be sent to the server. If false, crash reports will be collected and stored in the crashes directory, but not uploaded. Default is `true`.
+ `ignoreSystemCrashHandler` boolean (optional) - If true, crashes generated in the main process will not be forwarded to the system crash handler. Default is `false`.
+ `rateLimit` boolean (optional) *macOS* *Windows* - If true, limit the number of crashes uploaded to 1/hour. Default is `false`.
+ `compress` boolean (optional) - If true, crash reports will be compressed and uploaded with `Content-Encoding: gzip`. Default is `true`.
+ `extra` Record<string, string> (optional) - Extra string key/value annotations that will be sent along with crash reports that are generated in the main process. Only string values are supported. Crashes generated in child processes will not contain these extra parameters to crash reports generated from child processes, call [`addExtraParameter`](#crashreporteraddextraparameterkey-value) from the child process.
+ `globalExtra` Record<string, string> (optional) - Extra string key/value annotations that will be sent along with any crash reports generated in any process. These annotations cannot be changed once the crash reporter has been started. If a key is present in both the global extra parameters and the process-specific extra parameters, then the global one will take precedence. By default, `productName` and the app version are included, as well as the Electron version.
This method must be called before using any other `crashReporter` APIs. Once initialized this way, the crashpad handler collects crashes from all subsequently created processes. The crash reporter cannot be disabled once started.
This method should be called as early as possible in app startup, preferably before `app.on('ready')`. If the crash reporter is not initialized at the time a renderer process is created, then that renderer process will not be monitored by the crash reporter.
**Note:** You can test out the crash reporter by generating a crash using `process.crash()`.
**Note:** If you need to send additional/updated `extra` parameters after your first call `start` you can call `addExtraParameter`.
**Note:** Parameters passed in `extra`, `globalExtra` or set with `addExtraParameter` have limits on the length of the keys and values. Key names must be at most 39 bytes long, and values must be no longer than 127 bytes. Keys with names longer than the maximum will be silently ignored. Key values longer than the maximum length will be truncated.
**Note:** This method is only available in the main process.
###
`crashReporter.getLastCrashReport()`[](#crashreportergetlastcrashreport "Direct link to heading")
Returns [CrashReport](structures/crash-report) - The date and ID of the last crash report. Only crash reports that have been uploaded will be returned; even if a crash report is present on disk it will not be returned until it is uploaded. In the case that there are no uploaded reports, `null` is returned.
**Note:** This method is only available in the main process.
###
`crashReporter.getUploadedReports()`[](#crashreportergetuploadedreports "Direct link to heading")
Returns [CrashReport[]](structures/crash-report):
Returns all uploaded crash reports. Each report contains the date and uploaded ID.
**Note:** This method is only available in the main process.
###
`crashReporter.getUploadToServer()`[](#crashreportergetuploadtoserver "Direct link to heading")
Returns `boolean` - Whether reports should be submitted to the server. Set through the `start` method or `setUploadToServer`.
**Note:** This method is only available in the main process.
###
`crashReporter.setUploadToServer(uploadToServer)`[](#crashreportersetuploadtoserveruploadtoserver "Direct link to heading")
* `uploadToServer` boolean - Whether reports should be submitted to the server.
This would normally be controlled by user preferences. This has no effect if called before `start` is called.
**Note:** This method is only available in the main process.
###
`crashReporter.addExtraParameter(key, value)`[](#crashreporteraddextraparameterkey-value "Direct link to heading")
* `key` string - Parameter key, must be no longer than 39 bytes.
* `value` string - Parameter value, must be no longer than 127 bytes.
Set an extra parameter to be sent with the crash report. The values specified here will be sent in addition to any values set via the `extra` option when `start` was called.
Parameters added in this fashion (or via the `extra` parameter to `crashReporter.start`) are specific to the calling process. Adding extra parameters in the main process will not cause those parameters to be sent along with crashes from renderer or other child processes. Similarly, adding extra parameters in a renderer process will not result in those parameters being sent with crashes that occur in other renderer processes or in the main process.
**Note:** Parameters have limits on the length of the keys and values. Key names must be no longer than 39 bytes, and values must be no longer than 20320 bytes. Keys with names longer than the maximum will be silently ignored. Key values longer than the maximum length will be truncated.
###
`crashReporter.removeExtraParameter(key)`[](#crashreporterremoveextraparameterkey "Direct link to heading")
* `key` string - Parameter key, must be no longer than 39 bytes.
Remove an extra parameter from the current set of parameters. Future crashes will not include this parameter.
###
`crashReporter.getParameters()`[](#crashreportergetparameters "Direct link to heading")
Returns `Record<string, string>` - The current 'extra' parameters of the crash reporter.
In Node child processes[](#in-node-child-processes "Direct link to heading")
-----------------------------------------------------------------------------
Since `require('electron')` is not available in Node child processes, the following APIs are available on the `process` object in Node child processes.
####
`process.crashReporter.start(options)`[](#processcrashreporterstartoptions "Direct link to heading")
See [`crashReporter.start()`](#crashreporterstartoptions).
Note that if the crash reporter is started in the main process, it will automatically monitor child processes, so it should not be started in the child process. Only use this method if the main process does not initialize the crash reporter.
####
`process.crashReporter.getParameters()`[](#processcrashreportergetparameters "Direct link to heading")
See [`crashReporter.getParameters()`](#crashreportergetparameters).
####
`process.crashReporter.addExtraParameter(key, value)`[](#processcrashreporteraddextraparameterkey-value "Direct link to heading")
See [`crashReporter.addExtraParameter(key, value)`](#crashreporteraddextraparameterkey-value).
####
`process.crashReporter.removeExtraParameter(key)`[](#processcrashreporterremoveextraparameterkey "Direct link to heading")
See [`crashReporter.removeExtraParameter(key)`](#crashreporterremoveextraparameterkey).
Crash Report Payload[](#crash-report-payload "Direct link to heading")
-----------------------------------------------------------------------
The crash reporter will send the following data to the `submitURL` as a `multipart/form-data` `POST`:
* `ver` string - The version of Electron.
* `platform` string - e.g. 'win32'.
* `process_type` string - e.g. 'renderer'.
* `guid` string - e.g. '5e1286fc-da97-479e-918b-6bfb0c3d1c72'.
* `_version` string - The version in `package.json`.
* `_productName` string - The product name in the `crashReporter` `options` object.
* `prod` string - Name of the underlying product. In this case Electron.
* `_companyName` string - The company name in the `crashReporter` `options` object.
* `upload_file_minidump` File - The crash report in the format of `minidump`.
* All level one properties of the `extra` object in the `crashReporter``options` object.
electron ipcRenderer ipcRenderer
===========
> Communicate asynchronously from a renderer process to the main process.
>
>
Process: [Renderer](../glossary#renderer-process)
The `ipcRenderer` module is an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter). It provides a few methods so you can send synchronous and asynchronous messages from the render process (web page) to the main process. You can also receive replies from the main process.
See [IPC tutorial](../tutorial/ipc) for code examples.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `ipcRenderer` module has the following method to listen for events and send messages:
###
`ipcRenderer.on(channel, listener)`[](#ipcrendereronchannel-listener "Direct link to heading")
* `channel` string
* `listener` Function
+ `event` IpcRendererEvent
+ `...args` any[]
Listens to `channel`, when a new message arrives `listener` would be called with `listener(event, args...)`.
###
`ipcRenderer.once(channel, listener)`[](#ipcrendereroncechannel-listener "Direct link to heading")
* `channel` string
* `listener` Function
+ `event` IpcRendererEvent
+ `...args` any[]
Adds a one time `listener` function for the event. This `listener` is invoked only the next time a message is sent to `channel`, after which it is removed.
###
`ipcRenderer.removeListener(channel, listener)`[](#ipcrendererremovelistenerchannel-listener "Direct link to heading")
* `channel` string
* `listener` Function
+ `...args` any[]
Removes the specified `listener` from the listener array for the specified `channel`.
###
`ipcRenderer.removeAllListeners(channel)`[](#ipcrendererremovealllistenerschannel "Direct link to heading")
* `channel` string
Removes all listeners, or those of the specified `channel`.
###
`ipcRenderer.send(channel, ...args)`[](#ipcrenderersendchannel-args "Direct link to heading")
* `channel` string
* `...args` any[]
Send an asynchronous message to the main process via `channel`, along with arguments. Arguments will be serialized with the [Structured Clone Algorithm](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm), just like [`window.postMessage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage), so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.
>
> **NOTE:** Sending non-standard JavaScript types such as DOM objects or special Electron objects will throw an exception.
>
>
> Since the main process does not have support for DOM objects such as `ImageBitmap`, `File`, `DOMMatrix` and so on, such objects cannot be sent over Electron's IPC to the main process, as the main process would have no way to decode them. Attempting to send such objects over IPC will result in an error.
>
>
>
The main process handles it by listening for `channel` with the [`ipcMain`](ipc-main) module.
If you need to transfer a [`MessagePort`](https://developer.mozilla.org/en-US/docs/Web/API/MessagePort) to the main process, use [`ipcRenderer.postMessage`](#ipcrendererpostmessagechannel-message-transfer).
If you want to receive a single response from the main process, like the result of a method call, consider using [`ipcRenderer.invoke`](#ipcrendererinvokechannel-args).
###
`ipcRenderer.invoke(channel, ...args)`[](#ipcrendererinvokechannel-args "Direct link to heading")
* `channel` string
* `...args` any[]
Returns `Promise<any>` - Resolves with the response from the main process.
Send a message to the main process via `channel` and expect a result asynchronously. Arguments will be serialized with the [Structured Clone Algorithm](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm), just like [`window.postMessage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage), so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.
>
> **NOTE:** Sending non-standard JavaScript types such as DOM objects or special Electron objects will throw an exception.
>
>
> Since the main process does not have support for DOM objects such as `ImageBitmap`, `File`, `DOMMatrix` and so on, such objects cannot be sent over Electron's IPC to the main process, as the main process would have no way to decode them. Attempting to send such objects over IPC will result in an error.
>
>
>
The main process should listen for `channel` with [`ipcMain.handle()`](ipc-main#ipcmainhandlechannel-listener).
For example:
```
// Renderer process
ipcRenderer.invoke('some-name', someArgument).then((result) => {
// ...
})
// Main process
ipcMain.handle('some-name', async (event, someArgument) => {
const result = await doSomeWork(someArgument)
return result
})
```
If you need to transfer a [`MessagePort`](https://developer.mozilla.org/en-US/docs/Web/API/MessagePort) to the main process, use [`ipcRenderer.postMessage`](#ipcrendererpostmessagechannel-message-transfer).
If you do not need a response to the message, consider using [`ipcRenderer.send`](#ipcrenderersendchannel-args).
###
`ipcRenderer.sendSync(channel, ...args)`[](#ipcrenderersendsyncchannel-args "Direct link to heading")
* `channel` string
* `...args` any[]
Returns `any` - The value sent back by the [`ipcMain`](ipc-main) handler.
Send a message to the main process via `channel` and expect a result synchronously. Arguments will be serialized with the [Structured Clone Algorithm](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm), just like [`window.postMessage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage), so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.
>
> **NOTE:** Sending non-standard JavaScript types such as DOM objects or special Electron objects will throw an exception.
>
>
> Since the main process does not have support for DOM objects such as `ImageBitmap`, `File`, `DOMMatrix` and so on, such objects cannot be sent over Electron's IPC to the main process, as the main process would have no way to decode them. Attempting to send such objects over IPC will result in an error.
>
>
>
The main process handles it by listening for `channel` with [`ipcMain`](ipc-main) module, and replies by setting `event.returnValue`.
> ⚠️ **WARNING**: Sending a synchronous message will block the whole renderer process until the reply is received, so use this method only as a last resort. It's much better to use the asynchronous version, [`invoke()`](ipc-renderer#ipcrendererinvokechannel-args).
>
>
###
`ipcRenderer.postMessage(channel, message, [transfer])`[](#ipcrendererpostmessagechannel-message-transfer "Direct link to heading")
* `channel` string
* `message` any
* `transfer` MessagePort[] (optional)
Send a message to the main process, optionally transferring ownership of zero or more [`MessagePort`](https://developer.mozilla.org/en-US/docs/Web/API/MessagePort) objects.
The transferred `MessagePort` objects will be available in the main process as [`MessagePortMain`](message-port-main) objects by accessing the `ports` property of the emitted event.
For example:
```
// Renderer process
const { port1, port2 } = new MessageChannel()
ipcRenderer.postMessage('port', { message: 'hello' }, [port1])
// Main process
ipcMain.on('port', (e, msg) => {
const [port] = e.ports
// ...
})
```
For more information on using `MessagePort` and `MessageChannel`, see the [MDN documentation](https://developer.mozilla.org/en-US/docs/Web/API/MessageChannel).
###
`ipcRenderer.sendTo(webContentsId, channel, ...args)`[](#ipcrenderersendtowebcontentsid-channel-args "Direct link to heading")
* `webContentsId` number
* `channel` string
* `...args` any[]
Sends a message to a window with `webContentsId` via `channel`.
###
`ipcRenderer.sendToHost(channel, ...args)`[](#ipcrenderersendtohostchannel-args "Direct link to heading")
* `channel` string
* `...args` any[]
Like `ipcRenderer.send` but the event will be sent to the `<webview>` element in the host page instead of the main process.
Event object[](#event-object "Direct link to heading")
-------------------------------------------------------
The documentation for the `event` object passed to the `callback` can be found in the [ipc-renderer-event](structures/ipc-renderer-event) structure docs.
electron netLog netLog
======
> Logging network events for a session.
>
>
Process: [Main](../glossary#main-process)
```
const { netLog } = require('electron')
app.whenReady().then(async () => {
await netLog.startLogging('/path/to/net-log')
// After some network events
const path = await netLog.stopLogging()
console.log('Net-logs written to', path)
})
```
See [`--log-net-log`](command-line-switches#--log-net-logpath) to log network events throughout the app's lifecycle.
**Note:** All methods unless specified can only be used after the `ready` event of the `app` module gets emitted.
Methods[](#methods "Direct link to heading")
---------------------------------------------
###
`netLog.startLogging(path[, options])`[](#netlogstartloggingpath-options "Direct link to heading")
* `path` string - File path to record network logs.
* `options` Object (optional)
+ `captureMode` string (optional) - What kinds of data should be captured. By default, only metadata about requests will be captured. Setting this to `includeSensitive` will include cookies and authentication data. Setting it to `everything` will include all bytes transferred on sockets. Can be `default`, `includeSensitive` or `everything`.
+ `maxFileSize` number (optional) - When the log grows beyond this size, logging will automatically stop. Defaults to unlimited.
Returns `Promise<void>` - resolves when the net log has begun recording.
Starts recording network events to `path`.
###
`netLog.stopLogging()`[](#netlogstoplogging "Direct link to heading")
Returns `Promise<void>` - resolves when the net log has been flushed to disk.
Stops recording network events. If not called, net logging will automatically end when app quits.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
###
`netLog.currentlyLogging` *Readonly*[](#netlogcurrentlylogging-readonly "Direct link to heading")
A `boolean` property that indicates whether network logs are currently being recorded.
| programming_docs |
electron Class: CommandLine Class: CommandLine[](#class-commandline "Direct link to heading")
------------------------------------------------------------------
> Manipulate the command line arguments for your app that Chromium reads
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
The following example shows how to check if the `--disable-gpu` flag is set.
```
const { app } = require('electron')
app.commandLine.hasSwitch('disable-gpu')
```
For more information on what kinds of flags and switches you can use, check out the [Command Line Switches](command-line-switches) document.
### Instance Methods[](#instance-methods "Direct link to heading")
####
`commandLine.appendSwitch(switch[, value])`[](#commandlineappendswitchswitch-value "Direct link to heading")
* `switch` string - A command-line switch, without the leading `--`
* `value` string (optional) - A value for the given switch
Append a switch (with optional `value`) to Chromium's command line.
**Note:** This will not affect `process.argv`. The intended usage of this function is to control Chromium's behavior.
####
`commandLine.appendArgument(value)`[](#commandlineappendargumentvalue "Direct link to heading")
* `value` string - The argument to append to the command line
Append an argument to Chromium's command line. The argument will be quoted correctly. Switches will precede arguments regardless of appending order.
If you're appending an argument like `--switch=value`, consider using `appendSwitch('switch', 'value')` instead.
**Note:** This will not affect `process.argv`. The intended usage of this function is to control Chromium's behavior.
####
`commandLine.hasSwitch(switch)`[](#commandlinehasswitchswitch "Direct link to heading")
* `switch` string - A command-line switch
Returns `boolean` - Whether the command-line switch is present.
####
`commandLine.getSwitchValue(switch)`[](#commandlinegetswitchvalueswitch "Direct link to heading")
* `switch` string - A command-line switch
Returns `string` - The command-line switch value.
**Note:** When the switch is not present or has no value, it returns empty string.
####
`commandLine.removeSwitch(switch)`[](#commandlineremoveswitchswitch "Direct link to heading")
* `switch` string - A command-line switch
Removes the specified switch from Chromium's command line.
**Note:** This will not affect `process.argv`. The intended usage of this function is to control Chromium's behavior.
electron Class: ClientRequest Class: ClientRequest[](#class-clientrequest "Direct link to heading")
----------------------------------------------------------------------
> Make HTTP/HTTPS requests.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
`ClientRequest` implements the [Writable Stream](https://nodejs.org/api/stream.html#stream_writable_streams) interface and is therefore an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter).
###
`new ClientRequest(options)`[](#new-clientrequestoptions "Direct link to heading")
* `options` (Object | string) - If `options` is a string, it is interpreted as the request URL. If it is an object, it is expected to fully specify an HTTP request via the following properties:
+ `method` string (optional) - The HTTP request method. Defaults to the GET method.
+ `url` string (optional) - The request URL. Must be provided in the absolute form with the protocol scheme specified as http or https.
+ `session` Session (optional) - The [`Session`](session) instance with which the request is associated.
+ `partition` string (optional) - The name of the [`partition`](session) with which the request is associated. Defaults to the empty string. The `session` option supersedes `partition`. Thus if a `session` is explicitly specified, `partition` is ignored.
+ `credentials` string (optional) - Can be `include` or `omit`. Whether to send [credentials](https://fetch.spec.whatwg.org/#credentials) with this request. If set to `include`, credentials from the session associated with the request will be used. If set to `omit`, credentials will not be sent with the request (and the `'login'` event will not be triggered in the event of a 401). This matches the behavior of the [fetch](https://fetch.spec.whatwg.org/#concept-request-credentials-mode) option of the same name. If this option is not specified, authentication data from the session will be sent, and cookies will not be sent (unless `useSessionCookies` is set).
+ `useSessionCookies` boolean (optional) - Whether to send cookies with this request from the provided session. If `credentials` is specified, this option has no effect. Default is `false`.
+ `protocol` string (optional) - Can be `http:` or `https:`. The protocol scheme in the form 'scheme:'. Defaults to 'http:'.
+ `host` string (optional) - The server host provided as a concatenation of the hostname and the port number 'hostname:port'.
+ `hostname` string (optional) - The server host name.
+ `port` Integer (optional) - The server's listening port number.
+ `path` string (optional) - The path part of the request URL.
+ `redirect` string (optional) - Can be `follow`, `error` or `manual`. The redirect mode for this request. When mode is `error`, any redirection will be aborted. When mode is `manual` the redirection will be cancelled unless [`request.followRedirect`](#requestfollowredirect) is invoked synchronously during the [`redirect`](#event-redirect) event. Defaults to `follow`.
+ `origin` string (optional) - The origin URL of the request.
`options` properties such as `protocol`, `host`, `hostname`, `port` and `path` strictly follow the Node.js model as described in the [URL](https://nodejs.org/api/url.html) module.
For instance, we could have created the same request to 'github.com' as follows:
```
const request = net.request({
method: 'GET',
protocol: 'https:',
hostname: 'github.com',
port: 443,
path: '/'
})
```
### Instance Events[](#instance-events "Direct link to heading")
#### Event: 'response'[](#event-response "Direct link to heading")
Returns:
* `response` [IncomingMessage](incoming-message) - An object representing the HTTP response message.
#### Event: 'login'[](#event-login "Direct link to heading")
Returns:
* `authInfo` Object
+ `isProxy` boolean
+ `scheme` string
+ `host` string
+ `port` Integer
+ `realm` string
* `callback` Function
+ `username` string (optional)
+ `password` string (optional)
Emitted when an authenticating proxy is asking for user credentials.
The `callback` function is expected to be called back with user credentials:
* `username` string
* `password` string
```
request.on('login', (authInfo, callback) => {
callback('username', 'password')
})
```
Providing empty credentials will cancel the request and report an authentication error on the response object:
```
request.on('response', (response) => {
console.log(`STATUS: ${response.statusCode}`);
response.on('error', (error) => {
console.log(`ERROR: ${JSON.stringify(error)}`)
})
})
request.on('login', (authInfo, callback) => {
callback()
})
```
#### Event: 'finish'[](#event-finish "Direct link to heading")
Emitted just after the last chunk of the `request`'s data has been written into the `request` object.
#### Event: 'abort'[](#event-abort "Direct link to heading")
Emitted when the `request` is aborted. The `abort` event will not be fired if the `request` is already closed.
#### Event: 'error'[](#event-error "Direct link to heading")
Returns:
* `error` Error - an error object providing some information about the failure.
Emitted when the `net` module fails to issue a network request. Typically when the `request` object emits an `error` event, a `close` event will subsequently follow and no response object will be provided.
#### Event: 'close'[](#event-close "Direct link to heading")
Emitted as the last event in the HTTP request-response transaction. The `close` event indicates that no more events will be emitted on either the `request` or `response` objects.
#### Event: 'redirect'[](#event-redirect "Direct link to heading")
Returns:
* `statusCode` Integer
* `method` string
* `redirectUrl` string
* `responseHeaders` Record<string, string[]>
Emitted when the server returns a redirect response (e.g. 301 Moved Permanently). Calling [`request.followRedirect`](#requestfollowredirect) will continue with the redirection. If this event is handled, [`request.followRedirect`](#requestfollowredirect) must be called **synchronously**, otherwise the request will be cancelled.
### Instance Properties[](#instance-properties "Direct link to heading")
####
`request.chunkedEncoding`[](#requestchunkedencoding "Direct link to heading")
A `boolean` specifying whether the request will use HTTP chunked transfer encoding or not. Defaults to false. The property is readable and writable, however it can be set only before the first write operation as the HTTP headers are not yet put on the wire. Trying to set the `chunkedEncoding` property after the first write will throw an error.
Using chunked encoding is strongly recommended if you need to send a large request body as data will be streamed in small chunks instead of being internally buffered inside Electron process memory.
### Instance Methods[](#instance-methods "Direct link to heading")
####
`request.setHeader(name, value)`[](#requestsetheadername-value "Direct link to heading")
* `name` string - An extra HTTP header name.
* `value` string - An extra HTTP header value.
Adds an extra HTTP header. The header name will be issued as-is without lowercasing. It can be called only before first write. Calling this method after the first write will throw an error. If the passed value is not a `string`, its `toString()` method will be called to obtain the final value.
Certain headers are restricted from being set by apps. These headers are listed below. More information on restricted headers can be found in [Chromium's header utils](https://source.chromium.org/chromium/chromium/src/+/main:services/network/public/cpp/header_util.cc;drc=1562cab3f1eda927938f8f4a5a91991fefde66d3;bpv=1;bpt=1;l=22).
* `Content-Length`
* `Host`
* `Trailer` or `Te`
* `Upgrade`
* `Cookie2`
* `Keep-Alive`
* `Transfer-Encoding`
Additionally, setting the `Connection` header to the value `upgrade` is also disallowed.
####
`request.getHeader(name)`[](#requestgetheadername "Direct link to heading")
* `name` string - Specify an extra header name.
Returns `string` - The value of a previously set extra header name.
####
`request.removeHeader(name)`[](#requestremoveheadername "Direct link to heading")
* `name` string - Specify an extra header name.
Removes a previously set extra header name. This method can be called only before first write. Trying to call it after the first write will throw an error.
####
`request.write(chunk[, encoding][, callback])`[](#requestwritechunk-encoding-callback "Direct link to heading")
* `chunk` (string | Buffer) - A chunk of the request body's data. If it is a string, it is converted into a Buffer using the specified encoding.
* `encoding` string (optional) - Used to convert string chunks into Buffer objects. Defaults to 'utf-8'.
* `callback` Function (optional) - Called after the write operation ends.
`callback` is essentially a dummy function introduced in the purpose of keeping similarity with the Node.js API. It is called asynchronously in the next tick after `chunk` content have been delivered to the Chromium networking layer. Contrary to the Node.js implementation, it is not guaranteed that `chunk` content have been flushed on the wire before `callback` is called.
Adds a chunk of data to the request body. The first write operation may cause the request headers to be issued on the wire. After the first write operation, it is not allowed to add or remove a custom header.
####
`request.end([chunk][, encoding][, callback])`[](#requestendchunk-encoding-callback "Direct link to heading")
* `chunk` (string | Buffer) (optional)
* `encoding` string (optional)
* `callback` Function (optional)
Sends the last chunk of the request data. Subsequent write or end operations will not be allowed. The `finish` event is emitted just after the end operation.
####
`request.abort()`[](#requestabort "Direct link to heading")
Cancels an ongoing HTTP transaction. If the request has already emitted the `close` event, the abort operation will have no effect. Otherwise an ongoing event will emit `abort` and `close` events. Additionally, if there is an ongoing response object,it will emit the `aborted` event.
####
`request.followRedirect()`[](#requestfollowredirect "Direct link to heading")
Continues any pending redirection. Can only be called during a `'redirect'` event.
####
`request.getUploadProgress()`[](#requestgetuploadprogress "Direct link to heading")
Returns `Object`:
* `active` boolean - Whether the request is currently active. If this is false no other properties will be set
* `started` boolean - Whether the upload has started. If this is false both `current` and `total` will be set to 0.
* `current` Integer - The number of bytes that have been uploaded so far
* `total` Integer - The number of bytes that will be uploaded this request
You can use this method in conjunction with `POST` requests to get the progress of a file upload or other data transfer.
electron autoUpdater autoUpdater
===========
> Enable apps to automatically update themselves.
>
>
Process: [Main](../glossary#main-process)
**See also: [A detailed guide about how to implement updates in your application](../tutorial/updates).**
`autoUpdater` is an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter).
Platform Notices[](#platform-notices "Direct link to heading")
---------------------------------------------------------------
Currently, only macOS and Windows are supported. There is no built-in support for auto-updater on Linux, so it is recommended to use the distribution's package manager to update your app.
In addition, there are some subtle differences on each platform:
### macOS[](#macos "Direct link to heading")
On macOS, the `autoUpdater` module is built upon [Squirrel.Mac](https://github.com/Squirrel/Squirrel.Mac), meaning you don't need any special setup to make it work. For server-side requirements, you can read [Server Support](https://github.com/Squirrel/Squirrel.Mac#server-support). Note that [App Transport Security](https://developer.apple.com/library/content/documentation/General/Reference/InfoPlistKeyReference/Articles/CocoaKeys.html#//apple_ref/doc/uid/TP40009251-SW35) (ATS) applies to all requests made as part of the update process. Apps that need to disable ATS can add the `NSAllowsArbitraryLoads` key to their app's plist.
**Note:** Your application must be signed for automatic updates on macOS. This is a requirement of `Squirrel.Mac`.
### Windows[](#windows "Direct link to heading")
On Windows, you have to install your app into a user's machine before you can use the `autoUpdater`, so it is recommended that you use the [electron-winstaller](https://github.com/electron/windows-installer), [electron-forge](https://github.com/electron-userland/electron-forge) or the [grunt-electron-installer](https://github.com/electron/grunt-electron-installer) package to generate a Windows installer.
When using [electron-winstaller](https://github.com/electron/windows-installer) or [electron-forge](https://github.com/electron-userland/electron-forge) make sure you do not try to update your app [the first time it runs](https://github.com/electron/windows-installer#handling-squirrel-events) (Also see [this issue for more info](https://github.com/electron/electron/issues/7155)). It's also recommended to use [electron-squirrel-startup](https://github.com/mongodb-js/electron-squirrel-startup) to get desktop shortcuts for your app.
The installer generated with Squirrel will create a shortcut icon with an [Application User Model ID](https://msdn.microsoft.com/en-us/library/windows/desktop/dd378459(v=vs.85).aspx) in the format of `com.squirrel.PACKAGE_ID.YOUR_EXE_WITHOUT_DOT_EXE`, examples are `com.squirrel.slack.Slack` and `com.squirrel.code.Code`. You have to use the same ID for your app with `app.setAppUserModelId` API, otherwise Windows will not be able to pin your app properly in task bar.
Like Squirrel.Mac, Windows can host updates on S3 or any other static file host. You can read the documents of [Squirrel.Windows](https://github.com/Squirrel/Squirrel.Windows) to get more details about how Squirrel.Windows works.
Events[](#events "Direct link to heading")
-------------------------------------------
The `autoUpdater` object emits the following events:
### Event: 'error'[](#event-error "Direct link to heading")
Returns:
* `error` Error
Emitted when there is an error while updating.
### Event: 'checking-for-update'[](#event-checking-for-update "Direct link to heading")
Emitted when checking if an update has started.
### Event: 'update-available'[](#event-update-available "Direct link to heading")
Emitted when there is an available update. The update is downloaded automatically.
### Event: 'update-not-available'[](#event-update-not-available "Direct link to heading")
Emitted when there is no available update.
### Event: 'update-downloaded'[](#event-update-downloaded "Direct link to heading")
Returns:
* `event` Event
* `releaseNotes` string
* `releaseName` string
* `releaseDate` Date
* `updateURL` string
Emitted when an update has been downloaded.
On Windows only `releaseName` is available.
**Note:** It is not strictly necessary to handle this event. A successfully downloaded update will still be applied the next time the application starts.
### Event: 'before-quit-for-update'[](#event-before-quit-for-update "Direct link to heading")
This event is emitted after a user calls `quitAndInstall()`.
When this API is called, the `before-quit` event is not emitted before all windows are closed. As a result you should listen to this event if you wish to perform actions before the windows are closed while a process is quitting, as well as listening to `before-quit`.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `autoUpdater` object has the following methods:
###
`autoUpdater.setFeedURL(options)`[](#autoupdatersetfeedurloptions "Direct link to heading")
* `options` Object
+ `url` string
+ `headers` Record<string, string> (optional) *macOS* - HTTP request headers.
+ `serverType` string (optional) *macOS* - Can be `json` or `default`, see the [Squirrel.Mac](https://github.com/Squirrel/Squirrel.Mac) README for more information.
Sets the `url` and initialize the auto updater.
###
`autoUpdater.getFeedURL()`[](#autoupdatergetfeedurl "Direct link to heading")
Returns `string` - The current update feed URL.
###
`autoUpdater.checkForUpdates()`[](#autoupdatercheckforupdates "Direct link to heading")
Asks the server whether there is an update. You must call `setFeedURL` before using this API.
**Note:** If an update is available it will be downloaded automatically. Calling `autoUpdater.checkForUpdates()` twice will download the update two times.
###
`autoUpdater.quitAndInstall()`[](#autoupdaterquitandinstall "Direct link to heading")
Restarts the app and installs the update after it has been downloaded. It should only be called after `update-downloaded` has been emitted.
Under the hood calling `autoUpdater.quitAndInstall()` will close all application windows first, and automatically call `app.quit()` after all windows have been closed.
**Note:** It is not strictly necessary to call this function to apply an update, as a successfully downloaded update will always be applied the next time the application starts.
| programming_docs |
electron Accelerator Accelerator
===========
> Define keyboard shortcuts.
>
>
Accelerators are strings that can contain multiple modifiers and a single key code, combined by the `+` character, and are used to define keyboard shortcuts throughout your application.
Examples:
* `CommandOrControl+A`
* `CommandOrControl+Shift+Z`
Shortcuts are registered with the [`globalShortcut`](global-shortcut) module using the [`register`](global-shortcut#globalshortcutregisteraccelerator-callback) method, i.e.
```
const { app, globalShortcut } = require('electron')
app.whenReady().then(() => {
// Register a 'CommandOrControl+Y' shortcut listener.
globalShortcut.register('CommandOrControl+Y', () => {
// Do stuff when Y and either Command/Control is pressed.
})
})
```
Platform notice[](#platform-notice "Direct link to heading")
-------------------------------------------------------------
On Linux and Windows, the `Command` key does not have any effect so use `CommandOrControl` which represents `Command` on macOS and `Control` on Linux and Windows to define some accelerators.
Use `Alt` instead of `Option`. The `Option` key only exists on macOS, whereas the `Alt` key is available on all platforms.
The `Super` (or `Meta`) key is mapped to the `Windows` key on Windows and Linux and `Cmd` on macOS.
Available modifiers[](#available-modifiers "Direct link to heading")
---------------------------------------------------------------------
* `Command` (or `Cmd` for short)
* `Control` (or `Ctrl` for short)
* `CommandOrControl` (or `CmdOrCtrl` for short)
* `Alt`
* `Option`
* `AltGr`
* `Shift`
* `Super`
* `Meta`
Available key codes[](#available-key-codes "Direct link to heading")
---------------------------------------------------------------------
* `0` to `9`
* `A` to `Z`
* `F1` to `F24`
* Punctuation like `~`, `!`, `@`, `#`, `$`, etc.
* `Plus`
* `Space`
* `Tab`
* `Capslock`
* `Numlock`
* `Scrolllock`
* `Backspace`
* `Delete`
* `Insert`
* `Return` (or `Enter` as alias)
* `Up`, `Down`, `Left` and `Right`
* `Home` and `End`
* `PageUp` and `PageDown`
* `Escape` (or `Esc` for short)
* `VolumeUp`, `VolumeDown` and `VolumeMute`
* `MediaNextTrack`, `MediaPreviousTrack`, `MediaStop` and `MediaPlayPause`
* `PrintScreen`
* NumPad Keys
+ `num0` - `num9`
+ `numdec` - decimal key
+ `numadd` - numpad `+` key
+ `numsub` - numpad `-` key
+ `nummult` - numpad `*` key
+ `numdiv` - numpad `÷` key
electron Class: TouchBarPopover Class: TouchBarPopover[](#class-touchbarpopover "Direct link to heading")
--------------------------------------------------------------------------
> Create a popover in the touch bar for native macOS applications
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarPopover(options)`[](#new-touchbarpopoveroptions "Direct link to heading")
* `options` Object
+ `label` string (optional) - Popover button text.
+ `icon` [NativeImage](native-image) (optional) - Popover button icon.
+ `items` [TouchBar](touch-bar) - Items to display in the popover.
+ `showCloseButton` boolean (optional) - `true` to display a close button on the left of the popover, `false` to not show it. Default is `true`.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBarPopover`:
####
`touchBarPopover.label`[](#touchbarpopoverlabel "Direct link to heading")
A `string` representing the popover's current button text. Changing this value immediately updates the popover in the touch bar.
####
`touchBarPopover.icon`[](#touchbarpopovericon "Direct link to heading")
A `NativeImage` representing the popover's current button icon. Changing this value immediately updates the popover in the touch bar.
electron BrowserWindow BrowserWindow
=============
> Create and control browser windows.
>
>
Process: [Main](../glossary#main-process)
This module cannot be used until the `ready` event of the `app` module is emitted.
```
// In the main process.
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ width: 800, height: 600 })
// Load a remote URL
win.loadURL('https://github.com')
// Or load a local HTML file
win.loadFile('index.html')
```
Window customization[](#window-customization "Direct link to heading")
-----------------------------------------------------------------------
The `BrowserWindow` class exposes various ways to modify the look and behavior of your app's windows. For more details, see the [Window Customization](../tutorial/window-customization) tutorial.
Showing the window gracefully[](#showing-the-window-gracefully "Direct link to heading")
-----------------------------------------------------------------------------------------
When loading a page in the window directly, users may see the page load incrementally, which is not a good experience for a native app. To make the window display without a visual flash, there are two solutions for different situations.
### Using the `ready-to-show` event[](#using-the-ready-to-show-event "Direct link to heading")
While loading the page, the `ready-to-show` event will be emitted when the renderer process has rendered the page for the first time if the window has not been shown yet. Showing the window after this event will have no visual flash:
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ show: false })
win.once('ready-to-show', () => {
win.show()
})
```
This event is usually emitted after the `did-finish-load` event, but for pages with many remote resources, it may be emitted before the `did-finish-load` event.
Please note that using this event implies that the renderer will be considered "visible" and paint even though `show` is false. This event will never fire if you use `paintWhenInitiallyHidden: false`
### Setting the `backgroundColor` property[](#setting-the-backgroundcolor-property "Direct link to heading")
For a complex app, the `ready-to-show` event could be emitted too late, making the app feel slow. In this case, it is recommended to show the window immediately, and use a `backgroundColor` close to your app's background:
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ backgroundColor: '#2e2c29' })
win.loadURL('https://github.com')
```
Note that even for apps that use `ready-to-show` event, it is still recommended to set `backgroundColor` to make the app feel more native.
Some examples of valid `backgroundColor` values include:
```
const win = new BrowserWindow()
win.setBackgroundColor('hsl(230, 100%, 50%)')
win.setBackgroundColor('rgb(255, 145, 145)')
win.setBackgroundColor('#ff00a3')
win.setBackgroundColor('blueviolet')
```
For more information about these color types see valid options in [win.setBackgroundColor](browser-window#winsetbackgroundcolorbackgroundcolor).
Parent and child windows[](#parent-and-child-windows "Direct link to heading")
-------------------------------------------------------------------------------
By using `parent` option, you can create child windows:
```
const { BrowserWindow } = require('electron')
const top = new BrowserWindow()
const child = new BrowserWindow({ parent: top })
child.show()
top.show()
```
The `child` window will always show on top of the `top` window.
Modal windows[](#modal-windows "Direct link to heading")
---------------------------------------------------------
A modal window is a child window that disables parent window, to create a modal window, you have to set both `parent` and `modal` options:
```
const { BrowserWindow } = require('electron')
const child = new BrowserWindow({ parent: top, modal: true, show: false })
child.loadURL('https://github.com')
child.once('ready-to-show', () => {
child.show()
})
```
Page visibility[](#page-visibility "Direct link to heading")
-------------------------------------------------------------
The [Page Visibility API](https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API) works as follows:
* On all platforms, the visibility state tracks whether the window is hidden/minimized or not.
* Additionally, on macOS, the visibility state also tracks the window occlusion state. If the window is occluded (i.e. fully covered) by another window, the visibility state will be `hidden`. On other platforms, the visibility state will be `hidden` only when the window is minimized or explicitly hidden with `win.hide()`.
* If a `BrowserWindow` is created with `show: false`, the initial visibility state will be `visible` despite the window actually being hidden.
* If `backgroundThrottling` is disabled, the visibility state will remain `visible` even if the window is minimized, occluded, or hidden.
It is recommended that you pause expensive operations when the visibility state is `hidden` in order to minimize power consumption.
Platform notices[](#platform-notices "Direct link to heading")
---------------------------------------------------------------
* On macOS modal windows will be displayed as sheets attached to the parent window.
* On macOS the child windows will keep the relative position to parent window when parent window moves, while on Windows and Linux child windows will not move.
* On Linux the type of modal windows will be changed to `dialog`.
* On Linux many desktop environments do not support hiding a modal window.
Class: BrowserWindow[](#class-browserwindow "Direct link to heading")
----------------------------------------------------------------------
> Create and control browser windows.
>
>
Process: [Main](../glossary#main-process)
`BrowserWindow` is an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter).
It creates a new `BrowserWindow` with native properties as set by the `options`.
###
`new BrowserWindow([options])`[](#new-browserwindowoptions "Direct link to heading")
* `options` Object (optional)
+ `width` Integer (optional) - Window's width in pixels. Default is `800`.
+ `height` Integer (optional) - Window's height in pixels. Default is `600`.
+ `x` Integer (optional) - (**required** if y is used) Window's left offset from screen. Default is to center the window.
+ `y` Integer (optional) - (**required** if x is used) Window's top offset from screen. Default is to center the window.
+ `useContentSize` boolean (optional) - The `width` and `height` would be used as web page's size, which means the actual window's size will include window frame's size and be slightly larger. Default is `false`.
+ `center` boolean (optional) - Show window in the center of the screen. Default is `false`.
+ `minWidth` Integer (optional) - Window's minimum width. Default is `0`.
+ `minHeight` Integer (optional) - Window's minimum height. Default is `0`.
+ `maxWidth` Integer (optional) - Window's maximum width. Default is no limit.
+ `maxHeight` Integer (optional) - Window's maximum height. Default is no limit.
+ `resizable` boolean (optional) - Whether window is resizable. Default is `true`.
+ `movable` boolean (optional) *macOS* *Windows* - Whether window is movable. This is not implemented on Linux. Default is `true`.
+ `minimizable` boolean (optional) *macOS* *Windows* - Whether window is minimizable. This is not implemented on Linux. Default is `true`.
+ `maximizable` boolean (optional) *macOS* *Windows* - Whether window is maximizable. This is not implemented on Linux. Default is `true`.
+ `closable` boolean (optional) *macOS* *Windows* - Whether window is closable. This is not implemented on Linux. Default is `true`.
+ `focusable` boolean (optional) - Whether the window can be focused. Default is `true`. On Windows setting `focusable: false` also implies setting `skipTaskbar: true`. On Linux setting `focusable: false` makes the window stop interacting with wm, so the window will always stay on top in all workspaces.
+ `alwaysOnTop` boolean (optional) - Whether the window should always stay on top of other windows. Default is `false`.
+ `fullscreen` boolean (optional) - Whether the window should show in fullscreen. When explicitly set to `false` the fullscreen button will be hidden or disabled on macOS. Default is `false`.
+ `fullscreenable` boolean (optional) - Whether the window can be put into fullscreen mode. On macOS, also whether the maximize/zoom button should toggle full screen mode or maximize window. Default is `true`.
+ `simpleFullscreen` boolean (optional) *macOS* - Use pre-Lion fullscreen on macOS. Default is `false`.
+ `skipTaskbar` boolean (optional) *macOS* *Windows* - Whether to show the window in taskbar. Default is `false`.
+ `kiosk` boolean (optional) - Whether the window is in kiosk mode. Default is `false`.
+ `title` string (optional) - Default window title. Default is `"Electron"`. If the HTML tag `<title>` is defined in the HTML file loaded by `loadURL()`, this property will be ignored.
+ `icon` ([NativeImage](native-image) | string) (optional) - The window icon. On Windows it is recommended to use `ICO` icons to get best visual effects, you can also leave it undefined so the executable's icon will be used.
+ `show` boolean (optional) - Whether window should be shown when created. Default is `true`.
+ `paintWhenInitiallyHidden` boolean (optional) - Whether the renderer should be active when `show` is `false` and it has just been created. In order for `document.visibilityState` to work correctly on first load with `show: false` you should set this to `false`. Setting this to `false` will cause the `ready-to-show` event to not fire. Default is `true`.
+ `frame` boolean (optional) - Specify `false` to create a [frameless window](../tutorial/window-customization#create-frameless-windows). Default is `true`.
+ `parent` BrowserWindow (optional) - Specify parent window. Default is `null`.
+ `modal` boolean (optional) - Whether this is a modal window. This only works when the window is a child window. Default is `false`.
+ `acceptFirstMouse` boolean (optional) *macOS* - Whether clicking an inactive window will also click through to the web contents. Default is `false` on macOS. This option is not configurable on other platforms.
+ `disableAutoHideCursor` boolean (optional) - Whether to hide cursor when typing. Default is `false`.
+ `autoHideMenuBar` boolean (optional) - Auto hide the menu bar unless the `Alt` key is pressed. Default is `false`.
+ `enableLargerThanScreen` boolean (optional) *macOS* - Enable the window to be resized larger than screen. Only relevant for macOS, as other OSes allow larger-than-screen windows by default. Default is `false`.
+ `backgroundColor` string (optional) - The window's background color in Hex, RGB, RGBA, HSL, HSLA or named CSS color format. Alpha in #AARRGGBB format is supported if `transparent` is set to `true`. Default is `#FFF` (white). See [win.setBackgroundColor](browser-window#winsetbackgroundcolorbackgroundcolor) for more information.
+ `hasShadow` boolean (optional) - Whether window should have a shadow. Default is `true`.
+ `opacity` number (optional) *macOS* *Windows* - Set the initial opacity of the window, between 0.0 (fully transparent) and 1.0 (fully opaque). This is only implemented on Windows and macOS.
+ `darkTheme` boolean (optional) - Forces using dark theme for the window, only works on some GTK+3 desktop environments. Default is `false`.
+ `transparent` boolean (optional) - Makes the window [transparent](../tutorial/window-customization#create-transparent-windows). Default is `false`. On Windows, does not work unless the window is frameless.
+ `type` string (optional) - The type of window, default is normal window. See more about this below.
+ `visualEffectState` string (optional) *macOS* - Specify how the material appearance should reflect window activity state on macOS. Must be used with the `vibrancy` property. Possible values are:
- `followWindow` - The backdrop should automatically appear active when the window is active, and inactive when it is not. This is the default.
- `active` - The backdrop should always appear active.
- `inactive` - The backdrop should always appear inactive.
+ `titleBarStyle` string (optional) *macOS* *Windows* - The style of window title bar. Default is `default`. Possible values are:
- `default` - Results in the standard title bar for macOS or Windows respectively.
- `hidden` - Results in a hidden title bar and a full size content window. On macOS, the window still has the standard window controls (“traffic lights”) in the top left. On Windows, when combined with `titleBarOverlay: true` it will activate the Window Controls Overlay (see `titleBarOverlay` for more information), otherwise no window controls will be shown.
- `hiddenInset` *macOS* - Only on macOS, results in a hidden title bar with an alternative look where the traffic light buttons are slightly more inset from the window edge.
- `customButtonsOnHover` *macOS* - Only on macOS, results in a hidden title bar and a full size content window, the traffic light buttons will display when being hovered over in the top left of the window. **Note:** This option is currently experimental.
+ `trafficLightPosition` [Point](structures/point) (optional) *macOS* - Set a custom position for the traffic light buttons in frameless windows.
+ `roundedCorners` boolean (optional) *macOS* - Whether frameless window should have rounded corners on macOS. Default is `true`. Setting this property to `false` will prevent the window from being fullscreenable.
+ `fullscreenWindowTitle` boolean (optional) *macOS* *Deprecated* - Shows the title in the title bar in full screen mode on macOS for `hiddenInset` titleBarStyle. Default is `false`.
+ `thickFrame` boolean (optional) - Use `WS_THICKFRAME` style for frameless windows on Windows, which adds standard window frame. Setting it to `false` will remove window shadow and window animations. Default is `true`.
+ `vibrancy` string (optional) *macOS* - Add a type of vibrancy effect to the window, only on macOS. Can be `appearance-based`, `light`, `dark`, `titlebar`, `selection`, `menu`, `popover`, `sidebar`, `medium-light`, `ultra-dark`, `header`, `sheet`, `window`, `hud`, `fullscreen-ui`, `tooltip`, `content`, `under-window`, or `under-page`. Please note that `appearance-based`, `light`, `dark`, `medium-light`, and `ultra-dark` are deprecated and have been removed in macOS Catalina (10.15).
+ `zoomToPageWidth` boolean (optional) *macOS* - Controls the behavior on macOS when option-clicking the green stoplight button on the toolbar or by clicking the Window > Zoom menu item. If `true`, the window will grow to the preferred width of the web page when zoomed, `false` will cause it to zoom to the width of the screen. This will also affect the behavior when calling `maximize()` directly. Default is `false`.
+ `tabbingIdentifier` string (optional) *macOS* - Tab group name, allows opening the window as a native tab on macOS 10.12+. Windows with the same tabbing identifier will be grouped together. This also adds a native new tab button to your window's tab bar and allows your `app` and window to receive the `new-window-for-tab` event.
+ `webPreferences` Object (optional) - Settings of web page's features.
- `devTools` boolean (optional) - Whether to enable DevTools. If it is set to `false`, can not use `BrowserWindow.webContents.openDevTools()` to open DevTools. Default is `true`.
- `nodeIntegration` boolean (optional) - Whether node integration is enabled. Default is `false`.
- `nodeIntegrationInWorker` boolean (optional) - Whether node integration is enabled in web workers. Default is `false`. More about this can be found in [Multithreading](../tutorial/multithreading).
- `nodeIntegrationInSubFrames` boolean (optional) - Experimental option for enabling Node.js support in sub-frames such as iframes and child windows. All your preloads will load for every iframe, you can use `process.isMainFrame` to determine if you are in the main frame or not.
- `preload` string (optional) - Specifies a script that will be loaded before other scripts run in the page. This script will always have access to node APIs no matter whether node integration is turned on or off. The value should be the absolute file path to the script. When node integration is turned off, the preload script can reintroduce Node global symbols back to the global scope. See example [here](context-bridge#exposing-node-global-symbols).
- `sandbox` boolean (optional) - If set, this will sandbox the renderer associated with the window, making it compatible with the Chromium OS-level sandbox and disabling the Node.js engine. This is not the same as the `nodeIntegration` option and the APIs available to the preload script are more limited. Read more about the option [here](../tutorial/sandbox).
- `session` [Session](session#class-session) (optional) - Sets the session used by the page. Instead of passing the Session object directly, you can also choose to use the `partition` option instead, which accepts a partition string. When both `session` and `partition` are provided, `session` will be preferred. Default is the default session.
- `partition` string (optional) - Sets the session used by the page according to the session's partition string. If `partition` starts with `persist:`, the page will use a persistent session available to all pages in the app with the same `partition`. If there is no `persist:` prefix, the page will use an in-memory session. By assigning the same `partition`, multiple pages can share the same session. Default is the default session.
- `zoomFactor` number (optional) - The default zoom factor of the page, `3.0` represents `300%`. Default is `1.0`.
- `javascript` boolean (optional) - Enables JavaScript support. Default is `true`.
- `webSecurity` boolean (optional) - When `false`, it will disable the same-origin policy (usually using testing websites by people), and set `allowRunningInsecureContent` to `true` if this options has not been set by user. Default is `true`.
- `allowRunningInsecureContent` boolean (optional) - Allow an https page to run JavaScript, CSS or plugins from http URLs. Default is `false`.
- `images` boolean (optional) - Enables image support. Default is `true`.
- `imageAnimationPolicy` string (optional) - Specifies how to run image animations (E.g. GIFs). Can be `animate`, `animateOnce` or `noAnimation`. Default is `animate`.
- `textAreasAreResizable` boolean (optional) - Make TextArea elements resizable. Default is `true`.
- `webgl` boolean (optional) - Enables WebGL support. Default is `true`.
- `plugins` boolean (optional) - Whether plugins should be enabled. Default is `false`.
- `experimentalFeatures` boolean (optional) - Enables Chromium's experimental features. Default is `false`.
- `scrollBounce` boolean (optional) *macOS* - Enables scroll bounce (rubber banding) effect on macOS. Default is `false`.
- `enableBlinkFeatures` string (optional) - A list of feature strings separated by `,`, like `CSSVariables,KeyboardEventKey` to enable. The full list of supported feature strings can be found in the [RuntimeEnabledFeatures.json5](https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/runtime_enabled_features.json5?l=70) file.
- `disableBlinkFeatures` string (optional) - A list of feature strings separated by `,`, like `CSSVariables,KeyboardEventKey` to disable. The full list of supported feature strings can be found in the [RuntimeEnabledFeatures.json5](https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/runtime_enabled_features.json5?l=70) file.
- `defaultFontFamily` Object (optional) - Sets the default font for the font-family.
* `standard` string (optional) - Defaults to `Times New Roman`.
* `serif` string (optional) - Defaults to `Times New Roman`.
* `sansSerif` string (optional) - Defaults to `Arial`.
* `monospace` string (optional) - Defaults to `Courier New`.
* `cursive` string (optional) - Defaults to `Script`.
* `fantasy` string (optional) - Defaults to `Impact`.
- `defaultFontSize` Integer (optional) - Defaults to `16`.
- `defaultMonospaceFontSize` Integer (optional) - Defaults to `13`.
- `minimumFontSize` Integer (optional) - Defaults to `0`.
- `defaultEncoding` string (optional) - Defaults to `ISO-8859-1`.
- `backgroundThrottling` boolean (optional) - Whether to throttle animations and timers when the page becomes background. This also affects the [Page Visibility API](#page-visibility). Defaults to `true`.
- `offscreen` boolean (optional) - Whether to enable offscreen rendering for the browser window. Defaults to `false`. See the [offscreen rendering tutorial](../tutorial/offscreen-rendering) for more details.
- `contextIsolation` boolean (optional) - Whether to run Electron APIs and the specified `preload` script in a separate JavaScript context. Defaults to `true`. The context that the `preload` script runs in will only have access to its own dedicated `document` and `window` globals, as well as its own set of JavaScript builtins (`Array`, `Object`, `JSON`, etc.), which are all invisible to the loaded content. The Electron API will only be available in the `preload` script and not the loaded page. This option should be used when loading potentially untrusted remote content to ensure the loaded content cannot tamper with the `preload` script and any Electron APIs being used. This option uses the same technique used by [Chrome Content Scripts](https://developer.chrome.com/extensions/content_scripts#execution-environment). You can access this context in the dev tools by selecting the 'Electron Isolated Context' entry in the combo box at the top of the Console tab.
- `webviewTag` boolean (optional) - Whether to enable the [`<webview>` tag](webview-tag). Defaults to `false`. **Note:** The `preload` script configured for the `<webview>` will have node integration enabled when it is executed so you should ensure remote/untrusted content is not able to create a `<webview>` tag with a possibly malicious `preload` script. You can use the `will-attach-webview` event on [webContents](web-contents) to strip away the `preload` script and to validate or alter the `<webview>`'s initial settings.
- `additionalArguments` string[] (optional) - A list of strings that will be appended to `process.argv` in the renderer process of this app. Useful for passing small bits of data down to renderer process preload scripts.
- `safeDialogs` boolean (optional) - Whether to enable browser style consecutive dialog protection. Default is `false`.
- `safeDialogsMessage` string (optional) - The message to display when consecutive dialog protection is triggered. If not defined the default message would be used, note that currently the default message is in English and not localized.
- `disableDialogs` boolean (optional) - Whether to disable dialogs completely. Overrides `safeDialogs`. Default is `false`.
- `navigateOnDragDrop` boolean (optional) - Whether dragging and dropping a file or link onto the page causes a navigation. Default is `false`.
- `autoplayPolicy` string (optional) - Autoplay policy to apply to content in the window, can be `no-user-gesture-required`, `user-gesture-required`, `document-user-activation-required`. Defaults to `no-user-gesture-required`.
- `disableHtmlFullscreenWindowResize` boolean (optional) - Whether to prevent the window from resizing when entering HTML Fullscreen. Default is `false`.
- `accessibleTitle` string (optional) - An alternative title string provided only to accessibility tools such as screen readers. This string is not directly visible to users.
- `spellcheck` boolean (optional) - Whether to enable the builtin spellchecker. Default is `true`.
- `enableWebSQL` boolean (optional) - Whether to enable the [WebSQL api](https://www.w3.org/TR/webdatabase/). Default is `true`.
- `v8CacheOptions` string (optional) - Enforces the v8 code caching policy used by blink. Accepted values are
* `none` - Disables code caching
* `code` - Heuristic based code caching
* `bypassHeatCheck` - Bypass code caching heuristics but with lazy compilation
* `bypassHeatCheckAndEagerCompile` - Same as above except compilation is eager. Default policy is `code`.
- `enablePreferredSizeMode` boolean (optional) - Whether to enable preferred size mode. The preferred size is the minimum size needed to contain the layout of the document—without requiring scrolling. Enabling this will cause the `preferred-size-changed` event to be emitted on the `WebContents` when the preferred size changes. Default is `false`.
+ `titleBarOverlay` Object | Boolean (optional) - When using a frameless window in conjunction with `win.setWindowButtonVisibility(true)` on macOS or using a `titleBarStyle` so that the standard window controls ("traffic lights" on macOS) are visible, this property enables the Window Controls Overlay [JavaScript APIs](https://github.com/WICG/window-controls-overlay/blob/main/explainer.md#javascript-apis) and [CSS Environment Variables](https://github.com/WICG/window-controls-overlay/blob/main/explainer.md#css-environment-variables). Specifying `true` will result in an overlay with default system colors. Default is `false`.
- `color` String (optional) *Windows* - The CSS color of the Window Controls Overlay when enabled. Default is the system color.
- `symbolColor` String (optional) *Windows* - The CSS color of the symbols on the Window Controls Overlay when enabled. Default is the system color.
- `height` Integer (optional) *macOS* *Windows* - The height of the title bar and Window Controls Overlay in pixels. Default is system height.
When setting minimum or maximum window size with `minWidth`/`maxWidth`/ `minHeight`/`maxHeight`, it only constrains the users. It won't prevent you from passing a size that does not follow size constraints to `setBounds`/`setSize` or to the constructor of `BrowserWindow`.
The possible values and behaviors of the `type` option are platform dependent. Possible values are:
* On Linux, possible types are `desktop`, `dock`, `toolbar`, `splash`, `notification`.
* On macOS, possible types are `desktop`, `textured`, `panel`.
+ The `textured` type adds metal gradient appearance (`NSWindowStyleMaskTexturedBackground`).
+ The `desktop` type places the window at the desktop background window level (`kCGDesktopWindowLevel - 1`). Note that desktop window will not receive focus, keyboard or mouse events, but you can use `globalShortcut` to receive input sparingly.
+ The `panel` type enables the window to float on top of full-screened apps by adding the `NSWindowStyleMaskNonactivatingPanel` style mask,normally reserved for NSPanel, at runtime. Also, the window will appear on all spaces (desktops).
* On Windows, possible type is `toolbar`.
### Instance Events[](#instance-events "Direct link to heading")
Objects created with `new BrowserWindow` emit the following events:
**Note:** Some events are only available on specific operating systems and are labeled as such.
#### Event: 'page-title-updated'[](#event-page-title-updated "Direct link to heading")
Returns:
* `event` Event
* `title` string
* `explicitSet` boolean
Emitted when the document changed its title, calling `event.preventDefault()` will prevent the native window's title from changing. `explicitSet` is false when title is synthesized from file URL.
#### Event: 'close'[](#event-close "Direct link to heading")
Returns:
* `event` Event
Emitted when the window is going to be closed. It's emitted before the `beforeunload` and `unload` event of the DOM. Calling `event.preventDefault()` will cancel the close.
Usually you would want to use the `beforeunload` handler to decide whether the window should be closed, which will also be called when the window is reloaded. In Electron, returning any value other than `undefined` would cancel the close. For example:
```
window.onbeforeunload = (e) => {
console.log('I do not want to be closed')
// Unlike usual browsers that a message box will be prompted to users, returning
// a non-void value will silently cancel the close.
// It is recommended to use the dialog API to let the user confirm closing the
// application.
e.returnValue = false
}
```
***Note**: There is a subtle difference between the behaviors of `window.onbeforeunload = handler` and `window.addEventListener('beforeunload', handler)`. It is recommended to always set the `event.returnValue` explicitly, instead of only returning a value, as the former works more consistently within Electron.*
#### Event: 'closed'[](#event-closed "Direct link to heading")
Emitted when the window is closed. After you have received this event you should remove the reference to the window and avoid using it any more.
#### Event: 'session-end' *Windows*[](#event-session-end-windows "Direct link to heading")
Emitted when window session is going to end due to force shutdown or machine restart or session log off.
#### Event: 'unresponsive'[](#event-unresponsive "Direct link to heading")
Emitted when the web page becomes unresponsive.
#### Event: 'responsive'[](#event-responsive "Direct link to heading")
Emitted when the unresponsive web page becomes responsive again.
#### Event: 'blur'[](#event-blur "Direct link to heading")
Emitted when the window loses focus.
#### Event: 'focus'[](#event-focus "Direct link to heading")
Emitted when the window gains focus.
#### Event: 'show'[](#event-show "Direct link to heading")
Emitted when the window is shown.
#### Event: 'hide'[](#event-hide "Direct link to heading")
Emitted when the window is hidden.
#### Event: 'ready-to-show'[](#event-ready-to-show "Direct link to heading")
Emitted when the web page has been rendered (while not being shown) and window can be displayed without a visual flash.
Please note that using this event implies that the renderer will be considered "visible" and paint even though `show` is false. This event will never fire if you use `paintWhenInitiallyHidden: false`
#### Event: 'maximize'[](#event-maximize "Direct link to heading")
Emitted when window is maximized.
#### Event: 'unmaximize'[](#event-unmaximize "Direct link to heading")
Emitted when the window exits from a maximized state.
#### Event: 'minimize'[](#event-minimize "Direct link to heading")
Emitted when the window is minimized.
#### Event: 'restore'[](#event-restore "Direct link to heading")
Emitted when the window is restored from a minimized state.
#### Event: 'will-resize' *macOS* *Windows*[](#event-will-resize-macos-windows "Direct link to heading")
Returns:
* `event` Event
* `newBounds` [Rectangle](structures/rectangle) - Size the window is being resized to.
* `details` Object
+ `edge` (string) - The edge of the window being dragged for resizing. Can be `bottom`, `left`, `right`, `top-left`, `top-right`, `bottom-left` or `bottom-right`.
Emitted before the window is resized. Calling `event.preventDefault()` will prevent the window from being resized.
Note that this is only emitted when the window is being resized manually. Resizing the window with `setBounds`/`setSize` will not emit this event.
The possible values and behaviors of the `edge` option are platform dependent. Possible values are:
* On Windows, possible values are `bottom`, `top`, `left`, `right`, `top-left`, `top-right`, `bottom-left`, `bottom-right`.
* On macOS, possible values are `bottom` and `right`.
+ The value `bottom` is used to denote vertical resizing.
+ The value `right` is used to denote horizontal resizing.
#### Event: 'resize'[](#event-resize "Direct link to heading")
Emitted after the window has been resized.
#### Event: 'resized' *macOS* *Windows*[](#event-resized-macos-windows "Direct link to heading")
Emitted once when the window has finished being resized.
This is usually emitted when the window has been resized manually. On macOS, resizing the window with `setBounds`/`setSize` and setting the `animate` parameter to `true` will also emit this event once resizing has finished.
#### Event: 'will-move' *macOS* *Windows*[](#event-will-move-macos-windows "Direct link to heading")
Returns:
* `event` Event
* `newBounds` [Rectangle](structures/rectangle) - Location the window is being moved to.
Emitted before the window is moved. On Windows, calling `event.preventDefault()` will prevent the window from being moved.
Note that this is only emitted when the window is being moved manually. Moving the window with `setPosition`/`setBounds`/`center` will not emit this event.
#### Event: 'move'[](#event-move "Direct link to heading")
Emitted when the window is being moved to a new position.
#### Event: 'moved' *macOS* *Windows*[](#event-moved-macos-windows "Direct link to heading")
Emitted once when the window is moved to a new position.
**Note**: On macOS this event is an alias of `move`.
#### Event: 'enter-full-screen'[](#event-enter-full-screen "Direct link to heading")
Emitted when the window enters a full-screen state.
#### Event: 'leave-full-screen'[](#event-leave-full-screen "Direct link to heading")
Emitted when the window leaves a full-screen state.
#### Event: 'enter-html-full-screen'[](#event-enter-html-full-screen "Direct link to heading")
Emitted when the window enters a full-screen state triggered by HTML API.
#### Event: 'leave-html-full-screen'[](#event-leave-html-full-screen "Direct link to heading")
Emitted when the window leaves a full-screen state triggered by HTML API.
#### Event: 'always-on-top-changed'[](#event-always-on-top-changed "Direct link to heading")
Returns:
* `event` Event
* `isAlwaysOnTop` boolean
Emitted when the window is set or unset to show always on top of other windows.
#### Event: 'app-command' *Windows* *Linux*[](#event-app-command-windows-linux "Direct link to heading")
Returns:
* `event` Event
* `command` string
Emitted when an [App Command](https://msdn.microsoft.com/en-us/library/windows/desktop/ms646275(v=vs.85).aspx) is invoked. These are typically related to keyboard media keys or browser commands, as well as the "Back" button built into some mice on Windows.
Commands are lowercased, underscores are replaced with hyphens, and the `APPCOMMAND_` prefix is stripped off. e.g. `APPCOMMAND_BROWSER_BACKWARD` is emitted as `browser-backward`.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.on('app-command', (e, cmd) => {
// Navigate the window back when the user hits their mouse back button
if (cmd === 'browser-backward' && win.webContents.canGoBack()) {
win.webContents.goBack()
}
})
```
The following app commands are explicitly supported on Linux:
* `browser-backward`
* `browser-forward`
#### Event: 'scroll-touch-begin' *macOS*[](#event-scroll-touch-begin-macos "Direct link to heading")
Emitted when scroll wheel event phase has begun.
#### Event: 'scroll-touch-end' *macOS*[](#event-scroll-touch-end-macos "Direct link to heading")
Emitted when scroll wheel event phase has ended.
#### Event: 'scroll-touch-edge' *macOS*[](#event-scroll-touch-edge-macos "Direct link to heading")
Emitted when scroll wheel event phase filed upon reaching the edge of element.
#### Event: 'swipe' *macOS*[](#event-swipe-macos "Direct link to heading")
Returns:
* `event` Event
* `direction` string
Emitted on 3-finger swipe. Possible directions are `up`, `right`, `down`, `left`.
The method underlying this event is built to handle older macOS-style trackpad swiping, where the content on the screen doesn't move with the swipe. Most macOS trackpads are not configured to allow this kind of swiping anymore, so in order for it to emit properly the 'Swipe between pages' preference in `System Preferences > Trackpad > More Gestures` must be set to 'Swipe with two or three fingers'.
#### Event: 'rotate-gesture' *macOS*[](#event-rotate-gesture-macos "Direct link to heading")
Returns:
* `event` Event
* `rotation` Float
Emitted on trackpad rotation gesture. Continually emitted until rotation gesture is ended. The `rotation` value on each emission is the angle in degrees rotated since the last emission. The last emitted event upon a rotation gesture will always be of value `0`. Counter-clockwise rotation values are positive, while clockwise ones are negative.
#### Event: 'sheet-begin' *macOS*[](#event-sheet-begin-macos "Direct link to heading")
Emitted when the window opens a sheet.
#### Event: 'sheet-end' *macOS*[](#event-sheet-end-macos "Direct link to heading")
Emitted when the window has closed a sheet.
#### Event: 'new-window-for-tab' *macOS*[](#event-new-window-for-tab-macos "Direct link to heading")
Emitted when the native new tab button is clicked.
#### Event: 'system-context-menu' *Windows*[](#event-system-context-menu-windows "Direct link to heading")
Returns:
* `event` Event
* `point` [Point](structures/point) - The screen coordinates the context menu was triggered at
Emitted when the system context menu is triggered on the window, this is normally only triggered when the user right clicks on the non-client area of your window. This is the window titlebar or any area you have declared as `-webkit-app-region: drag` in a frameless window.
Calling `event.preventDefault()` will prevent the menu from being displayed.
### Static Methods[](#static-methods "Direct link to heading")
The `BrowserWindow` class has the following static methods:
####
`BrowserWindow.getAllWindows()`[](#browserwindowgetallwindows "Direct link to heading")
Returns `BrowserWindow[]` - An array of all opened browser windows.
####
`BrowserWindow.getFocusedWindow()`[](#browserwindowgetfocusedwindow "Direct link to heading")
Returns `BrowserWindow | null` - The window that is focused in this application, otherwise returns `null`.
####
`BrowserWindow.fromWebContents(webContents)`[](#browserwindowfromwebcontentswebcontents "Direct link to heading")
* `webContents` [WebContents](web-contents)
Returns `BrowserWindow | null` - The window that owns the given `webContents` or `null` if the contents are not owned by a window.
####
`BrowserWindow.fromBrowserView(browserView)`[](#browserwindowfrombrowserviewbrowserview "Direct link to heading")
* `browserView` [BrowserView](browser-view)
Returns `BrowserWindow | null` - The window that owns the given `browserView`. If the given view is not attached to any window, returns `null`.
####
`BrowserWindow.fromId(id)`[](#browserwindowfromidid "Direct link to heading")
* `id` Integer
Returns `BrowserWindow | null` - The window with the given `id`.
### Instance Properties[](#instance-properties "Direct link to heading")
Objects created with `new BrowserWindow` have the following properties:
```
const { BrowserWindow } = require('electron')
// In this example `win` is our instance
const win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL('https://github.com')
```
####
`win.webContents` *Readonly*[](#winwebcontents-readonly "Direct link to heading")
A `WebContents` object this window owns. All web page related events and operations will be done via it.
See the [`webContents` documentation](web-contents) for its methods and events.
####
`win.id` *Readonly*[](#winid-readonly "Direct link to heading")
A `Integer` property representing the unique ID of the window. Each ID is unique among all `BrowserWindow` instances of the entire Electron application.
####
`win.autoHideMenuBar`[](#winautohidemenubar "Direct link to heading")
A `boolean` property that determines whether the window menu bar should hide itself automatically. Once set, the menu bar will only show when users press the single `Alt` key.
If the menu bar is already visible, setting this property to `true` won't hide it immediately.
####
`win.simpleFullScreen`[](#winsimplefullscreen "Direct link to heading")
A `boolean` property that determines whether the window is in simple (pre-Lion) fullscreen mode.
####
`win.fullScreen`[](#winfullscreen "Direct link to heading")
A `boolean` property that determines whether the window is in fullscreen mode.
####
`win.focusable` *Windows* *macOS*[](#winfocusable-windows-macos "Direct link to heading")
A `boolean` property that determines whether the window is focusable.
####
`win.visibleOnAllWorkspaces` *macOS* *Linux*[](#winvisibleonallworkspaces-macos-linux "Direct link to heading")
A `boolean` property that determines whether the window is visible on all workspaces.
**Note:** Always returns false on Windows.
####
`win.shadow`[](#winshadow "Direct link to heading")
A `boolean` property that determines whether the window has a shadow.
####
`win.menuBarVisible` *Windows* *Linux*[](#winmenubarvisible-windows-linux "Direct link to heading")
A `boolean` property that determines whether the menu bar should be visible.
**Note:** If the menu bar is auto-hide, users can still bring up the menu bar by pressing the single `Alt` key.
####
`win.kiosk`[](#winkiosk "Direct link to heading")
A `boolean` property that determines whether the window is in kiosk mode.
####
`win.documentEdited` *macOS*[](#windocumentedited-macos "Direct link to heading")
A `boolean` property that specifies whether the window’s document has been edited.
The icon in title bar will become gray when set to `true`.
####
`win.representedFilename` *macOS*[](#winrepresentedfilename-macos "Direct link to heading")
A `string` property that determines the pathname of the file the window represents, and the icon of the file will show in window's title bar.
####
`win.title`[](#wintitle "Direct link to heading")
A `string` property that determines the title of the native window.
**Note:** The title of the web page can be different from the title of the native window.
####
`win.minimizable` *macOS* *Windows*[](#winminimizable-macos-windows "Direct link to heading")
A `boolean` property that determines whether the window can be manually minimized by user.
On Linux the setter is a no-op, although the getter returns `true`.
####
`win.maximizable` *macOS* *Windows*[](#winmaximizable-macos-windows "Direct link to heading")
A `boolean` property that determines whether the window can be manually maximized by user.
On Linux the setter is a no-op, although the getter returns `true`.
####
`win.fullScreenable`[](#winfullscreenable "Direct link to heading")
A `boolean` property that determines whether the maximize/zoom window button toggles fullscreen mode or maximizes the window.
####
`win.resizable`[](#winresizable "Direct link to heading")
A `boolean` property that determines whether the window can be manually resized by user.
####
`win.closable` *macOS* *Windows*[](#winclosable-macos-windows "Direct link to heading")
A `boolean` property that determines whether the window can be manually closed by user.
On Linux the setter is a no-op, although the getter returns `true`.
####
`win.movable` *macOS* *Windows*[](#winmovable-macos-windows "Direct link to heading")
A `boolean` property that determines Whether the window can be moved by user.
On Linux the setter is a no-op, although the getter returns `true`.
####
`win.excludedFromShownWindowsMenu` *macOS*[](#winexcludedfromshownwindowsmenu-macos "Direct link to heading")
A `boolean` property that determines whether the window is excluded from the application’s Windows menu. `false` by default.
```
const win = new BrowserWindow({ height: 600, width: 600 })
const template = [
{
role: 'windowmenu'
}
]
win.excludedFromShownWindowsMenu = true
const menu = Menu.buildFromTemplate(template)
Menu.setApplicationMenu(menu)
```
####
`win.accessibleTitle`[](#winaccessibletitle "Direct link to heading")
A `string` property that defines an alternative title provided only to accessibility tools such as screen readers. This string is not directly visible to users.
### Instance Methods[](#instance-methods "Direct link to heading")
Objects created with `new BrowserWindow` have the following instance methods:
**Note:** Some methods are only available on specific operating systems and are labeled as such.
####
`win.destroy()`[](#windestroy "Direct link to heading")
Force closing the window, the `unload` and `beforeunload` event won't be emitted for the web page, and `close` event will also not be emitted for this window, but it guarantees the `closed` event will be emitted.
####
`win.close()`[](#winclose "Direct link to heading")
Try to close the window. This has the same effect as a user manually clicking the close button of the window. The web page may cancel the close though. See the [close event](#event-close).
####
`win.focus()`[](#winfocus "Direct link to heading")
Focuses on the window.
####
`win.blur()`[](#winblur "Direct link to heading")
Removes focus from the window.
####
`win.isFocused()`[](#winisfocused "Direct link to heading")
Returns `boolean` - Whether the window is focused.
####
`win.isDestroyed()`[](#winisdestroyed "Direct link to heading")
Returns `boolean` - Whether the window is destroyed.
####
`win.show()`[](#winshow "Direct link to heading")
Shows and gives focus to the window.
####
`win.showInactive()`[](#winshowinactive "Direct link to heading")
Shows the window but doesn't focus on it.
####
`win.hide()`[](#winhide "Direct link to heading")
Hides the window.
####
`win.isVisible()`[](#winisvisible "Direct link to heading")
Returns `boolean` - Whether the window is visible to the user.
####
`win.isModal()`[](#winismodal "Direct link to heading")
Returns `boolean` - Whether current window is a modal window.
####
`win.maximize()`[](#winmaximize "Direct link to heading")
Maximizes the window. This will also show (but not focus) the window if it isn't being displayed already.
####
`win.unmaximize()`[](#winunmaximize "Direct link to heading")
Unmaximizes the window.
####
`win.isMaximized()`[](#winismaximized "Direct link to heading")
Returns `boolean` - Whether the window is maximized.
####
`win.minimize()`[](#winminimize "Direct link to heading")
Minimizes the window. On some platforms the minimized window will be shown in the Dock.
####
`win.restore()`[](#winrestore "Direct link to heading")
Restores the window from minimized state to its previous state.
####
`win.isMinimized()`[](#winisminimized "Direct link to heading")
Returns `boolean` - Whether the window is minimized.
####
`win.setFullScreen(flag)`[](#winsetfullscreenflag "Direct link to heading")
* `flag` boolean
Sets whether the window should be in fullscreen mode.
####
`win.isFullScreen()`[](#winisfullscreen "Direct link to heading")
Returns `boolean` - Whether the window is in fullscreen mode.
####
`win.setSimpleFullScreen(flag)` *macOS*[](#winsetsimplefullscreenflag-macos "Direct link to heading")
* `flag` boolean
Enters or leaves simple fullscreen mode.
Simple fullscreen mode emulates the native fullscreen behavior found in versions of macOS prior to Lion (10.7).
####
`win.isSimpleFullScreen()` *macOS*[](#winissimplefullscreen-macos "Direct link to heading")
Returns `boolean` - Whether the window is in simple (pre-Lion) fullscreen mode.
####
`win.isNormal()`[](#winisnormal "Direct link to heading")
Returns `boolean` - Whether the window is in normal state (not maximized, not minimized, not in fullscreen mode).
####
`win.setAspectRatio(aspectRatio[, extraSize])`[](#winsetaspectratioaspectratio-extrasize "Direct link to heading")
* `aspectRatio` Float - The aspect ratio to maintain for some portion of the content view.
* `extraSize` [Size](structures/size) (optional) *macOS* - The extra size not to be included while maintaining the aspect ratio.
This will make a window maintain an aspect ratio. The extra size allows a developer to have space, specified in pixels, not included within the aspect ratio calculations. This API already takes into account the difference between a window's size and its content size.
Consider a normal window with an HD video player and associated controls. Perhaps there are 15 pixels of controls on the left edge, 25 pixels of controls on the right edge and 50 pixels of controls below the player. In order to maintain a 16:9 aspect ratio (standard aspect ratio for HD @1920x1080) within the player itself we would call this function with arguments of 16/9 and { width: 40, height: 50 }. The second argument doesn't care where the extra width and height are within the content view--only that they exist. Sum any extra width and height areas you have within the overall content view.
The aspect ratio is not respected when window is resized programmatically with APIs like `win.setSize`.
####
`win.setBackgroundColor(backgroundColor)`[](#winsetbackgroundcolorbackgroundcolor "Direct link to heading")
* `backgroundColor` string - Color in Hex, RGB, RGBA, HSL, HSLA or named CSS color format. The alpha channel is optional for the hex type.
Examples of valid `backgroundColor` values:
* Hex
+ #fff (shorthand RGB)
+ #ffff (shorthand ARGB)
+ #ffffff (RGB)
+ #ffffffff (ARGB)
* RGB
+ rgb(([\d]+),\s*([\d]+),\s*([\d]+))
- e.g. rgb(255, 255, 255)
* RGBA
+ rgba(([\d]+),\s*([\d]+),\s*([\d]+),\s\*([\d.]+))
- e.g. rgba(255, 255, 255, 1.0)
* HSL
+ hsl((-?[\d.]+),\s*([\d.]+)%,\s*([\d.]+)%)
- e.g. hsl(200, 20%, 50%)
* HSLA
+ hsla((-?[\d.]+),\s*([\d.]+)%,\s*([\d.]+)%,\s\*([\d.]+))
- e.g. hsla(200, 20%, 50%, 0.5)
* Color name
+ Options are listed in [SkParseColor.cpp](https://source.chromium.org/chromium/chromium/src/+/main:third_party/skia/src/utils/SkParseColor.cpp;l=11-152;drc=eea4bf52cb0d55e2a39c828b017c80a5ee054148)
+ Similar to CSS Color Module Level 3 keywords, but case-sensitive.
- e.g. `blueviolet` or `red`
Sets the background color of the window. See [Setting `backgroundColor`](#setting-the-backgroundcolor-property).
####
`win.previewFile(path[, displayName])` *macOS*[](#winpreviewfilepath-displayname-macos "Direct link to heading")
* `path` string - The absolute path to the file to preview with QuickLook. This is important as Quick Look uses the file name and file extension on the path to determine the content type of the file to open.
* `displayName` string (optional) - The name of the file to display on the Quick Look modal view. This is purely visual and does not affect the content type of the file. Defaults to `path`.
Uses [Quick Look](https://en.wikipedia.org/wiki/Quick_Look) to preview a file at a given path.
####
`win.closeFilePreview()` *macOS*[](#winclosefilepreview-macos "Direct link to heading")
Closes the currently open [Quick Look](https://en.wikipedia.org/wiki/Quick_Look) panel.
####
`win.setBounds(bounds[, animate])`[](#winsetboundsbounds-animate "Direct link to heading")
* `bounds` Partial<[Rectangle](structures/rectangle)>
* `animate` boolean (optional) *macOS*
Resizes and moves the window to the supplied bounds. Any properties that are not supplied will default to their current values.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
// set all bounds properties
win.setBounds({ x: 440, y: 225, width: 800, height: 600 })
// set a single bounds property
win.setBounds({ width: 100 })
// { x: 440, y: 225, width: 100, height: 600 }
console.log(win.getBounds())
```
####
`win.getBounds()`[](#wingetbounds "Direct link to heading")
Returns [Rectangle](structures/rectangle) - The `bounds` of the window as `Object`.
####
`win.getBackgroundColor()`[](#wingetbackgroundcolor "Direct link to heading")
Returns `string` - Gets the background color of the window in Hex (`#RRGGBB`) format.
See [Setting `backgroundColor`](#setting-the-backgroundcolor-property).
**Note:** The alpha value is *not* returned alongside the red, green, and blue values.
####
`win.setContentBounds(bounds[, animate])`[](#winsetcontentboundsbounds-animate "Direct link to heading")
* `bounds` [Rectangle](structures/rectangle)
* `animate` boolean (optional) *macOS*
Resizes and moves the window's client area (e.g. the web page) to the supplied bounds.
####
`win.getContentBounds()`[](#wingetcontentbounds "Direct link to heading")
Returns [Rectangle](structures/rectangle) - The `bounds` of the window's client area as `Object`.
####
`win.getNormalBounds()`[](#wingetnormalbounds "Direct link to heading")
Returns [Rectangle](structures/rectangle) - Contains the window bounds of the normal state
**Note:** whatever the current state of the window : maximized, minimized or in fullscreen, this function always returns the position and size of the window in normal state. In normal state, getBounds and getNormalBounds returns the same [Rectangle](structures/rectangle).
####
`win.setEnabled(enable)`[](#winsetenabledenable "Direct link to heading")
* `enable` boolean
Disable or enable the window.
####
`win.isEnabled()`[](#winisenabled "Direct link to heading")
Returns `boolean` - whether the window is enabled.
####
`win.setSize(width, height[, animate])`[](#winsetsizewidth-height-animate "Direct link to heading")
* `width` Integer
* `height` Integer
* `animate` boolean (optional) *macOS*
Resizes the window to `width` and `height`. If `width` or `height` are below any set minimum size constraints the window will snap to its minimum size.
####
`win.getSize()`[](#wingetsize "Direct link to heading")
Returns `Integer[]` - Contains the window's width and height.
####
`win.setContentSize(width, height[, animate])`[](#winsetcontentsizewidth-height-animate "Direct link to heading")
* `width` Integer
* `height` Integer
* `animate` boolean (optional) *macOS*
Resizes the window's client area (e.g. the web page) to `width` and `height`.
####
`win.getContentSize()`[](#wingetcontentsize "Direct link to heading")
Returns `Integer[]` - Contains the window's client area's width and height.
####
`win.setMinimumSize(width, height)`[](#winsetminimumsizewidth-height "Direct link to heading")
* `width` Integer
* `height` Integer
Sets the minimum size of window to `width` and `height`.
####
`win.getMinimumSize()`[](#wingetminimumsize "Direct link to heading")
Returns `Integer[]` - Contains the window's minimum width and height.
####
`win.setMaximumSize(width, height)`[](#winsetmaximumsizewidth-height "Direct link to heading")
* `width` Integer
* `height` Integer
Sets the maximum size of window to `width` and `height`.
####
`win.getMaximumSize()`[](#wingetmaximumsize "Direct link to heading")
Returns `Integer[]` - Contains the window's maximum width and height.
####
`win.setResizable(resizable)`[](#winsetresizableresizable "Direct link to heading")
* `resizable` boolean
Sets whether the window can be manually resized by the user.
####
`win.isResizable()`[](#winisresizable "Direct link to heading")
Returns `boolean` - Whether the window can be manually resized by the user.
####
`win.setMovable(movable)` *macOS* *Windows*[](#winsetmovablemovable-macos-windows "Direct link to heading")
* `movable` boolean
Sets whether the window can be moved by user. On Linux does nothing.
####
`win.isMovable()` *macOS* *Windows*[](#winismovable-macos-windows "Direct link to heading")
Returns `boolean` - Whether the window can be moved by user.
On Linux always returns `true`.
####
`win.setMinimizable(minimizable)` *macOS* *Windows*[](#winsetminimizableminimizable-macos-windows "Direct link to heading")
* `minimizable` boolean
Sets whether the window can be manually minimized by user. On Linux does nothing.
####
`win.isMinimizable()` *macOS* *Windows*[](#winisminimizable-macos-windows "Direct link to heading")
Returns `boolean` - Whether the window can be manually minimized by the user.
On Linux always returns `true`.
####
`win.setMaximizable(maximizable)` *macOS* *Windows*[](#winsetmaximizablemaximizable-macos-windows "Direct link to heading")
* `maximizable` boolean
Sets whether the window can be manually maximized by user. On Linux does nothing.
####
`win.isMaximizable()` *macOS* *Windows*[](#winismaximizable-macos-windows "Direct link to heading")
Returns `boolean` - Whether the window can be manually maximized by user.
On Linux always returns `true`.
####
`win.setFullScreenable(fullscreenable)`[](#winsetfullscreenablefullscreenable "Direct link to heading")
* `fullscreenable` boolean
Sets whether the maximize/zoom window button toggles fullscreen mode or maximizes the window.
####
`win.isFullScreenable()`[](#winisfullscreenable "Direct link to heading")
Returns `boolean` - Whether the maximize/zoom window button toggles fullscreen mode or maximizes the window.
####
`win.setClosable(closable)` *macOS* *Windows*[](#winsetclosableclosable-macos-windows "Direct link to heading")
* `closable` boolean
Sets whether the window can be manually closed by user. On Linux does nothing.
####
`win.isClosable()` *macOS* *Windows*[](#winisclosable-macos-windows "Direct link to heading")
Returns `boolean` - Whether the window can be manually closed by user.
On Linux always returns `true`.
####
`win.setAlwaysOnTop(flag[, level][, relativeLevel])`[](#winsetalwaysontopflag-level-relativelevel "Direct link to heading")
* `flag` boolean
* `level` string (optional) *macOS* *Windows* - Values include `normal`, `floating`, `torn-off-menu`, `modal-panel`, `main-menu`, `status`, `pop-up-menu`, `screen-saver`, and ~~`dock`~~ (Deprecated). The default is `floating` when `flag` is true. The `level` is reset to `normal` when the flag is false. Note that from `floating` to `status` included, the window is placed below the Dock on macOS and below the taskbar on Windows. From `pop-up-menu` to a higher it is shown above the Dock on macOS and above the taskbar on Windows. See the [macOS docs](https://developer.apple.com/documentation/appkit/nswindow/level) for more details.
* `relativeLevel` Integer (optional) *macOS* - The number of layers higher to set this window relative to the given `level`. The default is `0`. Note that Apple discourages setting levels higher than 1 above `screen-saver`.
Sets whether the window should show always on top of other windows. After setting this, the window is still a normal window, not a toolbox window which can not be focused on.
####
`win.isAlwaysOnTop()`[](#winisalwaysontop "Direct link to heading")
Returns `boolean` - Whether the window is always on top of other windows.
####
`win.moveAbove(mediaSourceId)`[](#winmoveabovemediasourceid "Direct link to heading")
* `mediaSourceId` string - Window id in the format of DesktopCapturerSource's id. For example "window:1869:0".
Moves window above the source window in the sense of z-order. If the `mediaSourceId` is not of type window or if the window does not exist then this method throws an error.
####
`win.moveTop()`[](#winmovetop "Direct link to heading")
Moves window to top(z-order) regardless of focus
####
`win.center()`[](#wincenter "Direct link to heading")
Moves window to the center of the screen.
####
`win.setPosition(x, y[, animate])`[](#winsetpositionx-y-animate "Direct link to heading")
* `x` Integer
* `y` Integer
* `animate` boolean (optional) *macOS*
Moves window to `x` and `y`.
####
`win.getPosition()`[](#wingetposition "Direct link to heading")
Returns `Integer[]` - Contains the window's current position.
####
`win.setTitle(title)`[](#winsettitletitle "Direct link to heading")
* `title` string
Changes the title of native window to `title`.
####
`win.getTitle()`[](#wingettitle "Direct link to heading")
Returns `string` - The title of the native window.
**Note:** The title of the web page can be different from the title of the native window.
####
`win.setSheetOffset(offsetY[, offsetX])` *macOS*[](#winsetsheetoffsetoffsety-offsetx-macos "Direct link to heading")
* `offsetY` Float
* `offsetX` Float (optional)
Changes the attachment point for sheets on macOS. By default, sheets are attached just below the window frame, but you may want to display them beneath a HTML-rendered toolbar. For example:
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
const toolbarRect = document.getElementById('toolbar').getBoundingClientRect()
win.setSheetOffset(toolbarRect.height)
```
####
`win.flashFrame(flag)`[](#winflashframeflag "Direct link to heading")
* `flag` boolean
Starts or stops flashing the window to attract user's attention.
####
`win.setSkipTaskbar(skip)` *macOS* *Windows*[](#winsetskiptaskbarskip-macos-windows "Direct link to heading")
* `skip` boolean
Makes the window not show in the taskbar.
####
`win.setKiosk(flag)`[](#winsetkioskflag "Direct link to heading")
* `flag` boolean
Enters or leaves kiosk mode.
####
`win.isKiosk()`[](#winiskiosk "Direct link to heading")
Returns `boolean` - Whether the window is in kiosk mode.
####
`win.isTabletMode()` *Windows*[](#winistabletmode-windows "Direct link to heading")
Returns `boolean` - Whether the window is in Windows 10 tablet mode.
Since Windows 10 users can [use their PC as tablet](https://support.microsoft.com/en-us/help/17210/windows-10-use-your-pc-like-a-tablet), under this mode apps can choose to optimize their UI for tablets, such as enlarging the titlebar and hiding titlebar buttons.
This API returns whether the window is in tablet mode, and the `resize` event can be be used to listen to changes to tablet mode.
####
`win.getMediaSourceId()`[](#wingetmediasourceid "Direct link to heading")
Returns `string` - Window id in the format of DesktopCapturerSource's id. For example "window:1324:0".
More precisely the format is `window:id:other_id` where `id` is `HWND` on Windows, `CGWindowID` (`uint64_t`) on macOS and `Window` (`unsigned long`) on Linux. `other_id` is used to identify web contents (tabs) so within the same top level window.
####
`win.getNativeWindowHandle()`[](#wingetnativewindowhandle "Direct link to heading")
Returns `Buffer` - The platform-specific handle of the window.
The native type of the handle is `HWND` on Windows, `NSView*` on macOS, and `Window` (`unsigned long`) on Linux.
####
`win.hookWindowMessage(message, callback)` *Windows*[](#winhookwindowmessagemessage-callback-windows "Direct link to heading")
* `message` Integer
* `callback` Function
+ `wParam` any - The `wParam` provided to the WndProc
+ `lParam` any - The `lParam` provided to the WndProc
Hooks a windows message. The `callback` is called when the message is received in the WndProc.
####
`win.isWindowMessageHooked(message)` *Windows*[](#winiswindowmessagehookedmessage-windows "Direct link to heading")
* `message` Integer
Returns `boolean` - `true` or `false` depending on whether the message is hooked.
####
`win.unhookWindowMessage(message)` *Windows*[](#winunhookwindowmessagemessage-windows "Direct link to heading")
* `message` Integer
Unhook the window message.
####
`win.unhookAllWindowMessages()` *Windows*[](#winunhookallwindowmessages-windows "Direct link to heading")
Unhooks all of the window messages.
####
`win.setRepresentedFilename(filename)` *macOS*[](#winsetrepresentedfilenamefilename-macos "Direct link to heading")
* `filename` string
Sets the pathname of the file the window represents, and the icon of the file will show in window's title bar.
####
`win.getRepresentedFilename()` *macOS*[](#wingetrepresentedfilename-macos "Direct link to heading")
Returns `string` - The pathname of the file the window represents.
####
`win.setDocumentEdited(edited)` *macOS*[](#winsetdocumenteditededited-macos "Direct link to heading")
* `edited` boolean
Specifies whether the window’s document has been edited, and the icon in title bar will become gray when set to `true`.
####
`win.isDocumentEdited()` *macOS*[](#winisdocumentedited-macos "Direct link to heading")
Returns `boolean` - Whether the window's document has been edited.
####
`win.focusOnWebView()`[](#winfocusonwebview "Direct link to heading")
####
`win.blurWebView()`[](#winblurwebview "Direct link to heading")
####
`win.capturePage([rect])`[](#wincapturepagerect "Direct link to heading")
* `rect` [Rectangle](structures/rectangle) (optional) - The bounds to capture
Returns `Promise<NativeImage>` - Resolves with a [NativeImage](native-image)
Captures a snapshot of the page within `rect`. Omitting `rect` will capture the whole visible page. If the page is not visible, `rect` may be empty.
####
`win.loadURL(url[, options])`[](#winloadurlurl-options "Direct link to heading")
* `url` string
* `options` Object (optional)
+ `httpReferrer` (string | [Referrer](structures/referrer)) (optional) - An HTTP Referrer URL.
+ `userAgent` string (optional) - A user agent originating the request.
+ `extraHeaders` string (optional) - Extra headers separated by "\n"
+ `postData` ([UploadRawData](structures/upload-raw-data) | [UploadFile](structures/upload-file))[] (optional)
+ `baseURLForDataURL` string (optional) - Base URL (with trailing path separator) for files to be loaded by the data URL. This is needed only if the specified `url` is a data URL and needs to load other files.
Returns `Promise<void>` - the promise will resolve when the page has finished loading (see [`did-finish-load`](web-contents#event-did-finish-load)), and rejects if the page fails to load (see [`did-fail-load`](web-contents#event-did-fail-load)).
Same as [`webContents.loadURL(url[, options])`](web-contents#contentsloadurlurl-options).
The `url` can be a remote address (e.g. `http://`) or a path to a local HTML file using the `file://` protocol.
To ensure that file URLs are properly formatted, it is recommended to use Node's [`url.format`](https://nodejs.org/api/url.html#url_url_format_urlobject) method:
```
const url = require('url').format({
protocol: 'file',
slashes: true,
pathname: require('path').join(__dirname, 'index.html')
})
win.loadURL(url)
```
You can load a URL using a `POST` request with URL-encoded data by doing the following:
```
win.loadURL('http://localhost:8000/post', {
postData: [{
type: 'rawData',
bytes: Buffer.from('hello=world')
}],
extraHeaders: 'Content-Type: application/x-www-form-urlencoded'
})
```
####
`win.loadFile(filePath[, options])`[](#winloadfilefilepath-options "Direct link to heading")
* `filePath` string
* `options` Object (optional)
+ `query` Record<string, string> (optional) - Passed to `url.format()`.
+ `search` string (optional) - Passed to `url.format()`.
+ `hash` string (optional) - Passed to `url.format()`.
Returns `Promise<void>` - the promise will resolve when the page has finished loading (see [`did-finish-load`](web-contents#event-did-finish-load)), and rejects if the page fails to load (see [`did-fail-load`](web-contents#event-did-fail-load)).
Same as `webContents.loadFile`, `filePath` should be a path to an HTML file relative to the root of your application. See the `webContents` docs for more information.
####
`win.reload()`[](#winreload "Direct link to heading")
Same as `webContents.reload`.
####
`win.setMenu(menu)` *Linux* *Windows*[](#winsetmenumenu-linux-windows "Direct link to heading")
* `menu` Menu | null
Sets the `menu` as the window's menu bar.
####
`win.removeMenu()` *Linux* *Windows*[](#winremovemenu-linux-windows "Direct link to heading")
Remove the window's menu bar.
####
`win.setProgressBar(progress[, options])`[](#winsetprogressbarprogress-options "Direct link to heading")
* `progress` Double
* `options` Object (optional)
+ `mode` string *Windows* - Mode for the progress bar. Can be `none`, `normal`, `indeterminate`, `error` or `paused`.
Sets progress value in progress bar. Valid range is [0, 1.0].
Remove progress bar when progress < 0; Change to indeterminate mode when progress > 1.
On Linux platform, only supports Unity desktop environment, you need to specify the `*.desktop` file name to `desktopName` field in `package.json`. By default, it will assume `{app.name}.desktop`.
On Windows, a mode can be passed. Accepted values are `none`, `normal`, `indeterminate`, `error`, and `paused`. If you call `setProgressBar` without a mode set (but with a value within the valid range), `normal` will be assumed.
####
`win.setOverlayIcon(overlay, description)` *Windows*[](#winsetoverlayiconoverlay-description-windows "Direct link to heading")
* `overlay` [NativeImage](native-image) | null - the icon to display on the bottom right corner of the taskbar icon. If this parameter is `null`, the overlay is cleared
* `description` string - a description that will be provided to Accessibility screen readers
Sets a 16 x 16 pixel overlay onto the current taskbar icon, usually used to convey some sort of application status or to passively notify the user.
####
`win.setHasShadow(hasShadow)`[](#winsethasshadowhasshadow "Direct link to heading")
* `hasShadow` boolean
Sets whether the window should have a shadow.
####
`win.hasShadow()`[](#winhasshadow "Direct link to heading")
Returns `boolean` - Whether the window has a shadow.
####
`win.setOpacity(opacity)` *Windows* *macOS*[](#winsetopacityopacity-windows-macos "Direct link to heading")
* `opacity` number - between 0.0 (fully transparent) and 1.0 (fully opaque)
Sets the opacity of the window. On Linux, does nothing. Out of bound number values are clamped to the [0, 1] range.
####
`win.getOpacity()`[](#wingetopacity "Direct link to heading")
Returns `number` - between 0.0 (fully transparent) and 1.0 (fully opaque). On Linux, always returns 1.
####
`win.setShape(rects)` *Windows* *Linux* *Experimental*[](#winsetshaperects-windows-linux-experimental "Direct link to heading")
* `rects` [Rectangle[]](structures/rectangle) - Sets a shape on the window. Passing an empty list reverts the window to being rectangular.
Setting a window shape determines the area within the window where the system permits drawing and user interaction. Outside of the given region, no pixels will be drawn and no mouse events will be registered. Mouse events outside of the region will not be received by that window, but will fall through to whatever is behind the window.
####
`win.setThumbarButtons(buttons)` *Windows*[](#winsetthumbarbuttonsbuttons-windows "Direct link to heading")
* `buttons` [ThumbarButton[]](structures/thumbar-button)
Returns `boolean` - Whether the buttons were added successfully
Add a thumbnail toolbar with a specified set of buttons to the thumbnail image of a window in a taskbar button layout. Returns a `boolean` object indicates whether the thumbnail has been added successfully.
The number of buttons in thumbnail toolbar should be no greater than 7 due to the limited room. Once you setup the thumbnail toolbar, the toolbar cannot be removed due to the platform's limitation. But you can call the API with an empty array to clean the buttons.
The `buttons` is an array of `Button` objects:
* `Button` Object
+ `icon` [NativeImage](native-image) - The icon showing in thumbnail toolbar.
+ `click` Function
+ `tooltip` string (optional) - The text of the button's tooltip.
+ `flags` string[] (optional) - Control specific states and behaviors of the button. By default, it is `['enabled']`.
The `flags` is an array that can include following `string`s:
* `enabled` - The button is active and available to the user.
* `disabled` - The button is disabled. It is present, but has a visual state indicating it will not respond to user action.
* `dismissonclick` - When the button is clicked, the thumbnail window closes immediately.
* `nobackground` - Do not draw a button border, use only the image.
* `hidden` - The button is not shown to the user.
* `noninteractive` - The button is enabled but not interactive; no pressed button state is drawn. This value is intended for instances where the button is used in a notification.
####
`win.setThumbnailClip(region)` *Windows*[](#winsetthumbnailclipregion-windows "Direct link to heading")
* `region` [Rectangle](structures/rectangle) - Region of the window
Sets the region of the window to show as the thumbnail image displayed when hovering over the window in the taskbar. You can reset the thumbnail to be the entire window by specifying an empty region: `{ x: 0, y: 0, width: 0, height: 0 }`.
####
`win.setThumbnailToolTip(toolTip)` *Windows*[](#winsetthumbnailtooltiptooltip-windows "Direct link to heading")
* `toolTip` string
Sets the toolTip that is displayed when hovering over the window thumbnail in the taskbar.
####
`win.setAppDetails(options)` *Windows*[](#winsetappdetailsoptions-windows "Direct link to heading")
* `options` Object
+ `appId` string (optional) - Window's [App User Model ID](https://msdn.microsoft.com/en-us/library/windows/desktop/dd391569(v=vs.85).aspx). It has to be set, otherwise the other options will have no effect.
+ `appIconPath` string (optional) - Window's [Relaunch Icon](https://msdn.microsoft.com/en-us/library/windows/desktop/dd391573(v=vs.85).aspx).
+ `appIconIndex` Integer (optional) - Index of the icon in `appIconPath`. Ignored when `appIconPath` is not set. Default is `0`.
+ `relaunchCommand` string (optional) - Window's [Relaunch Command](https://msdn.microsoft.com/en-us/library/windows/desktop/dd391571(v=vs.85).aspx).
+ `relaunchDisplayName` string (optional) - Window's [Relaunch Display Name](https://msdn.microsoft.com/en-us/library/windows/desktop/dd391572(v=vs.85).aspx).
Sets the properties for the window's taskbar button.
**Note:** `relaunchCommand` and `relaunchDisplayName` must always be set together. If one of those properties is not set, then neither will be used.
####
`win.showDefinitionForSelection()` *macOS*[](#winshowdefinitionforselection-macos "Direct link to heading")
Same as `webContents.showDefinitionForSelection()`.
####
`win.setIcon(icon)` *Windows* *Linux*[](#winseticonicon-windows-linux "Direct link to heading")
* `icon` [NativeImage](native-image) | string
Changes window icon.
####
`win.setWindowButtonVisibility(visible)` *macOS*[](#winsetwindowbuttonvisibilityvisible-macos "Direct link to heading")
* `visible` boolean
Sets whether the window traffic light buttons should be visible.
####
`win.setAutoHideMenuBar(hide)` *Windows* *Linux*[](#winsetautohidemenubarhide-windows-linux "Direct link to heading")
* `hide` boolean
Sets whether the window menu bar should hide itself automatically. Once set the menu bar will only show when users press the single `Alt` key.
If the menu bar is already visible, calling `setAutoHideMenuBar(true)` won't hide it immediately.
####
`win.isMenuBarAutoHide()` *Windows* *Linux*[](#winismenubarautohide-windows-linux "Direct link to heading")
Returns `boolean` - Whether menu bar automatically hides itself.
####
`win.setMenuBarVisibility(visible)` *Windows* *Linux*[](#winsetmenubarvisibilityvisible-windows-linux "Direct link to heading")
* `visible` boolean
Sets whether the menu bar should be visible. If the menu bar is auto-hide, users can still bring up the menu bar by pressing the single `Alt` key.
####
`win.isMenuBarVisible()` *Windows* *Linux*[](#winismenubarvisible-windows-linux "Direct link to heading")
Returns `boolean` - Whether the menu bar is visible.
####
`win.setVisibleOnAllWorkspaces(visible[, options])` *macOS* *Linux*[](#winsetvisibleonallworkspacesvisible-options-macos-linux "Direct link to heading")
* `visible` boolean
* `options` Object (optional)
+ `visibleOnFullScreen` boolean (optional) *macOS* - Sets whether the window should be visible above fullscreen windows.
+ `skipTransformProcessType` boolean (optional) *macOS* - Calling setVisibleOnAllWorkspaces will by default transform the process type between UIElementApplication and ForegroundApplication to ensure the correct behavior. However, this will hide the window and dock for a short time every time it is called. If your window is already of type UIElementApplication, you can bypass this transformation by passing true to skipTransformProcessType.
Sets whether the window should be visible on all workspaces.
**Note:** This API does nothing on Windows.
####
`win.isVisibleOnAllWorkspaces()` *macOS* *Linux*[](#winisvisibleonallworkspaces-macos-linux "Direct link to heading")
Returns `boolean` - Whether the window is visible on all workspaces.
**Note:** This API always returns false on Windows.
####
`win.setIgnoreMouseEvents(ignore[, options])`[](#winsetignoremouseeventsignore-options "Direct link to heading")
* `ignore` boolean
* `options` Object (optional)
+ `forward` boolean (optional) *macOS* *Windows* - If true, forwards mouse move messages to Chromium, enabling mouse related events such as `mouseleave`. Only used when `ignore` is true. If `ignore` is false, forwarding is always disabled regardless of this value.
Makes the window ignore all mouse events.
All mouse events happened in this window will be passed to the window below this window, but if this window has focus, it will still receive keyboard events.
####
`win.setContentProtection(enable)` *macOS* *Windows*[](#winsetcontentprotectionenable-macos-windows "Direct link to heading")
* `enable` boolean
Prevents the window contents from being captured by other apps.
On macOS it sets the NSWindow's sharingType to NSWindowSharingNone. On Windows it calls SetWindowDisplayAffinity with `WDA_EXCLUDEFROMCAPTURE`. For Windows 10 version 2004 and up the window will be removed from capture entirely, older Windows versions behave as if `WDA_MONITOR` is applied capturing a black window.
####
`win.setFocusable(focusable)` *macOS* *Windows*[](#winsetfocusablefocusable-macos-windows "Direct link to heading")
* `focusable` boolean
Changes whether the window can be focused.
On macOS it does not remove the focus from the window.
####
`win.isFocusable()` *macOS* *Windows*[](#winisfocusable-macos-windows "Direct link to heading")
Returns whether the window can be focused.
####
`win.setParentWindow(parent)`[](#winsetparentwindowparent "Direct link to heading")
* `parent` BrowserWindow | null
Sets `parent` as current window's parent window, passing `null` will turn current window into a top-level window.
####
`win.getParentWindow()`[](#wingetparentwindow "Direct link to heading")
Returns `BrowserWindow | null` - The parent window or `null` if there is no parent.
####
`win.getChildWindows()`[](#wingetchildwindows "Direct link to heading")
Returns `BrowserWindow[]` - All child windows.
####
`win.setAutoHideCursor(autoHide)` *macOS*[](#winsetautohidecursorautohide-macos "Direct link to heading")
* `autoHide` boolean
Controls whether to hide cursor when typing.
####
`win.selectPreviousTab()` *macOS*[](#winselectprevioustab-macos "Direct link to heading")
Selects the previous tab when native tabs are enabled and there are other tabs in the window.
####
`win.selectNextTab()` *macOS*[](#winselectnexttab-macos "Direct link to heading")
Selects the next tab when native tabs are enabled and there are other tabs in the window.
####
`win.mergeAllWindows()` *macOS*[](#winmergeallwindows-macos "Direct link to heading")
Merges all windows into one window with multiple tabs when native tabs are enabled and there is more than one open window.
####
`win.moveTabToNewWindow()` *macOS*[](#winmovetabtonewwindow-macos "Direct link to heading")
Moves the current tab into a new window if native tabs are enabled and there is more than one tab in the current window.
####
`win.toggleTabBar()` *macOS*[](#wintoggletabbar-macos "Direct link to heading")
Toggles the visibility of the tab bar if native tabs are enabled and there is only one tab in the current window.
####
`win.addTabbedWindow(browserWindow)` *macOS*[](#winaddtabbedwindowbrowserwindow-macos "Direct link to heading")
* `browserWindow` BrowserWindow
Adds a window as a tab on this window, after the tab for the window instance.
####
`win.setVibrancy(type)` *macOS*[](#winsetvibrancytype-macos "Direct link to heading")
* `type` string | null - Can be `appearance-based`, `light`, `dark`, `titlebar`, `selection`, `menu`, `popover`, `sidebar`, `medium-light`, `ultra-dark`, `header`, `sheet`, `window`, `hud`, `fullscreen-ui`, `tooltip`, `content`, `under-window`, or `under-page`. See the [macOS documentation](https://developer.apple.com/documentation/appkit/nsvisualeffectview?preferredLanguage=objc) for more details.
Adds a vibrancy effect to the browser window. Passing `null` or an empty string will remove the vibrancy effect on the window.
Note that `appearance-based`, `light`, `dark`, `medium-light`, and `ultra-dark` have been deprecated and will be removed in an upcoming version of macOS.
####
`win.setTrafficLightPosition(position)` *macOS*[](#winsettrafficlightpositionposition-macos "Direct link to heading")
* `position` [Point](structures/point)
Set a custom position for the traffic light buttons in frameless window.
####
`win.getTrafficLightPosition()` *macOS*[](#wingettrafficlightposition-macos "Direct link to heading")
Returns `Point` - The custom position for the traffic light buttons in frameless window.
####
`win.setTouchBar(touchBar)` *macOS*[](#winsettouchbartouchbar-macos "Direct link to heading")
* `touchBar` TouchBar | null
Sets the touchBar layout for the current window. Specifying `null` or `undefined` clears the touch bar. This method only has an effect if the machine has a touch bar and is running on macOS 10.12.1+.
**Note:** The TouchBar API is currently experimental and may change or be removed in future Electron releases.
####
`win.setBrowserView(browserView)` *Experimental*[](#winsetbrowserviewbrowserview-experimental "Direct link to heading")
* `browserView` [BrowserView](browser-view) | null - Attach `browserView` to `win`. If there are other `BrowserView`s attached, they will be removed from this window.
####
`win.getBrowserView()` *Experimental*[](#wingetbrowserview-experimental "Direct link to heading")
Returns `BrowserView | null` - The `BrowserView` attached to `win`. Returns `null` if one is not attached. Throws an error if multiple `BrowserView`s are attached.
####
`win.addBrowserView(browserView)` *Experimental*[](#winaddbrowserviewbrowserview-experimental "Direct link to heading")
* `browserView` [BrowserView](browser-view)
Replacement API for setBrowserView supporting work with multi browser views.
####
`win.removeBrowserView(browserView)` *Experimental*[](#winremovebrowserviewbrowserview-experimental "Direct link to heading")
* `browserView` [BrowserView](browser-view)
####
`win.setTopBrowserView(browserView)` *Experimental*[](#winsettopbrowserviewbrowserview-experimental "Direct link to heading")
* `browserView` [BrowserView](browser-view)
Raises `browserView` above other `BrowserView`s attached to `win`. Throws an error if `browserView` is not attached to `win`.
####
`win.getBrowserViews()` *Experimental*[](#wingetbrowserviews-experimental "Direct link to heading")
Returns `BrowserView[]` - an array of all BrowserViews that have been attached with `addBrowserView` or `setBrowserView`.
**Note:** The BrowserView API is currently experimental and may change or be removed in future Electron releases.
####
`win.setTitleBarOverlay(options)` *Windows*[](#winsettitlebaroverlayoptions-windows "Direct link to heading")
* `options` Object
+ `color` String (optional) *Windows* - The CSS color of the Window Controls Overlay when enabled.
+ `symbolColor` String (optional) *Windows* - The CSS color of the symbols on the Window Controls Overlay when enabled.
+ `height` Integer (optional) *Windows* - The height of the title bar and Window Controls Overlay in pixels.
On a Window with Window Controls Overlay already enabled, this method updates the style of the title bar overlay.
| programming_docs |
electron safeStorage safeStorage
===========
> Allows access to simple encryption and decryption of strings for storage on the local machine.
>
>
Process: [Main](../glossary#main-process)
This module protects data stored on disk from being accessed by other applications or users with full disk access.
Note that on Mac, access to the system Keychain is required and these calls can block the current thread to collect user input. The same is true for Linux, if a password management tool is available.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `safeStorage` module has the following methods:
###
`safeStorage.isEncryptionAvailable()`[](#safestorageisencryptionavailable "Direct link to heading")
Returns `boolean` - Whether encryption is available.
On Linux, returns true if the app has emitted the `ready` event and the secret key is available. On MacOS, returns true if Keychain is available. On Windows, returns true once the app has emitted the `ready` event.
###
`safeStorage.encryptString(plainText)`[](#safestorageencryptstringplaintext "Direct link to heading")
* `plainText` string
Returns `Buffer` - An array of bytes representing the encrypted string.
This function will throw an error if encryption fails.
###
`safeStorage.decryptString(encrypted)`[](#safestoragedecryptstringencrypted "Direct link to heading")
* `encrypted` Buffer
Returns `string` - the decrypted string. Decrypts the encrypted buffer obtained with `safeStorage.encryptString` back into a string.
This function will throw an error if decryption fails.
electron nativeTheme nativeTheme
===========
> Read and respond to changes in Chromium's native color theme.
>
>
Process: [Main](../glossary#main-process)
Events[](#events "Direct link to heading")
-------------------------------------------
The `nativeTheme` module emits the following events:
### Event: 'updated'[](#event-updated "Direct link to heading")
Emitted when something in the underlying NativeTheme has changed. This normally means that either the value of `shouldUseDarkColors`, `shouldUseHighContrastColors` or `shouldUseInvertedColorScheme` has changed. You will have to check them to determine which one has changed.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
The `nativeTheme` module has the following properties:
###
`nativeTheme.shouldUseDarkColors` *Readonly*[](#nativethemeshouldusedarkcolors-readonly "Direct link to heading")
A `boolean` for if the OS / Chromium currently has a dark mode enabled or is being instructed to show a dark-style UI. If you want to modify this value you should use `themeSource` below.
###
`nativeTheme.themeSource`[](#nativethemethemesource "Direct link to heading")
A `string` property that can be `system`, `light` or `dark`. It is used to override and supersede the value that Chromium has chosen to use internally.
Setting this property to `system` will remove the override and everything will be reset to the OS default. By default `themeSource` is `system`.
Settings this property to `dark` will have the following effects:
* `nativeTheme.shouldUseDarkColors` will be `true` when accessed
* Any UI Electron renders on Linux and Windows including context menus, devtools, etc. will use the dark UI.
* Any UI the OS renders on macOS including menus, window frames, etc. will use the dark UI.
* The [`prefers-color-scheme`](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme) CSS query will match `dark` mode.
* The `updated` event will be emitted
Settings this property to `light` will have the following effects:
* `nativeTheme.shouldUseDarkColors` will be `false` when accessed
* Any UI Electron renders on Linux and Windows including context menus, devtools, etc. will use the light UI.
* Any UI the OS renders on macOS including menus, window frames, etc. will use the light UI.
* The [`prefers-color-scheme`](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme) CSS query will match `light` mode.
* The `updated` event will be emitted
The usage of this property should align with a classic "dark mode" state machine in your application where the user has three options.
* `Follow OS` --> `themeSource = 'system'`
* `Dark Mode` --> `themeSource = 'dark'`
* `Light Mode` --> `themeSource = 'light'`
Your application should then always use `shouldUseDarkColors` to determine what CSS to apply.
###
`nativeTheme.shouldUseHighContrastColors` *macOS* *Windows* *Readonly*[](#nativethemeshouldusehighcontrastcolors-macos-windows-readonly "Direct link to heading")
A `boolean` for if the OS / Chromium currently has high-contrast mode enabled or is being instructed to show a high-contrast UI.
###
`nativeTheme.shouldUseInvertedColorScheme` *macOS* *Windows* *Readonly*[](#nativethemeshoulduseinvertedcolorscheme-macos-windows-readonly "Direct link to heading")
A `boolean` for if the OS / Chromium currently has an inverted color scheme or is being instructed to use an inverted color scheme.
###
`nativeTheme.inForcedColorsMode` *Windows* *Readonly*[](#nativethemeinforcedcolorsmode-windows-readonly "Direct link to heading")
A `boolean` indicating whether Chromium is in forced colors mode, controlled by system accessibility settings. Currently, Windows high contrast is the only system setting that triggers forced colors mode.
electron Class: DownloadItem Class: DownloadItem[](#class-downloaditem "Direct link to heading")
--------------------------------------------------------------------
> Control file downloads from remote sources.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
`DownloadItem` is an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter) that represents a download item in Electron. It is used in `will-download` event of `Session` class, and allows users to control the download item.
```
// In the main process.
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.webContents.session.on('will-download', (event, item, webContents) => {
// Set the save path, making Electron not to prompt a save dialog.
item.setSavePath('/tmp/save.pdf')
item.on('updated', (event, state) => {
if (state === 'interrupted') {
console.log('Download is interrupted but can be resumed')
} else if (state === 'progressing') {
if (item.isPaused()) {
console.log('Download is paused')
} else {
console.log(`Received bytes: ${item.getReceivedBytes()}`)
}
}
})
item.once('done', (event, state) => {
if (state === 'completed') {
console.log('Download successfully')
} else {
console.log(`Download failed: ${state}`)
}
})
})
```
### Instance Events[](#instance-events "Direct link to heading")
#### Event: 'updated'[](#event-updated "Direct link to heading")
Returns:
* `event` Event
* `state` string - Can be `progressing` or `interrupted`.
Emitted when the download has been updated and is not done.
The `state` can be one of following:
* `progressing` - The download is in-progress.
* `interrupted` - The download has interrupted and can be resumed.
#### Event: 'done'[](#event-done "Direct link to heading")
Returns:
* `event` Event
* `state` string - Can be `completed`, `cancelled` or `interrupted`.
Emitted when the download is in a terminal state. This includes a completed download, a cancelled download (via `downloadItem.cancel()`), and interrupted download that can't be resumed.
The `state` can be one of following:
* `completed` - The download completed successfully.
* `cancelled` - The download has been cancelled.
* `interrupted` - The download has interrupted and can not resume.
### Instance Methods[](#instance-methods "Direct link to heading")
The `downloadItem` object has the following methods:
####
`downloadItem.setSavePath(path)`[](#downloaditemsetsavepathpath "Direct link to heading")
* `path` string - Set the save file path of the download item.
The API is only available in session's `will-download` callback function. If `path` doesn't exist, Electron will try to make the directory recursively. If user doesn't set the save path via the API, Electron will use the original routine to determine the save path; this usually prompts a save dialog.
####
`downloadItem.getSavePath()`[](#downloaditemgetsavepath "Direct link to heading")
Returns `string` - The save path of the download item. This will be either the path set via `downloadItem.setSavePath(path)` or the path selected from the shown save dialog.
####
`downloadItem.setSaveDialogOptions(options)`[](#downloaditemsetsavedialogoptionsoptions "Direct link to heading")
* `options` SaveDialogOptions - Set the save file dialog options. This object has the same properties as the `options` parameter of [`dialog.showSaveDialog()`](dialog).
This API allows the user to set custom options for the save dialog that opens for the download item by default. The API is only available in session's `will-download` callback function.
####
`downloadItem.getSaveDialogOptions()`[](#downloaditemgetsavedialogoptions "Direct link to heading")
Returns `SaveDialogOptions` - Returns the object previously set by `downloadItem.setSaveDialogOptions(options)`.
####
`downloadItem.pause()`[](#downloaditempause "Direct link to heading")
Pauses the download.
####
`downloadItem.isPaused()`[](#downloaditemispaused "Direct link to heading")
Returns `boolean` - Whether the download is paused.
####
`downloadItem.resume()`[](#downloaditemresume "Direct link to heading")
Resumes the download that has been paused.
**Note:** To enable resumable downloads the server you are downloading from must support range requests and provide both `Last-Modified` and `ETag` header values. Otherwise `resume()` will dismiss previously received bytes and restart the download from the beginning.
####
`downloadItem.canResume()`[](#downloaditemcanresume "Direct link to heading")
Returns `boolean` - Whether the download can resume.
####
`downloadItem.cancel()`[](#downloaditemcancel "Direct link to heading")
Cancels the download operation.
####
`downloadItem.getURL()`[](#downloaditemgeturl "Direct link to heading")
Returns `string` - The origin URL where the item is downloaded from.
####
`downloadItem.getMimeType()`[](#downloaditemgetmimetype "Direct link to heading")
Returns `string` - The files mime type.
####
`downloadItem.hasUserGesture()`[](#downloaditemhasusergesture "Direct link to heading")
Returns `boolean` - Whether the download has user gesture.
####
`downloadItem.getFilename()`[](#downloaditemgetfilename "Direct link to heading")
Returns `string` - The file name of the download item.
**Note:** The file name is not always the same as the actual one saved in local disk. If user changes the file name in a prompted download saving dialog, the actual name of saved file will be different.
####
`downloadItem.getTotalBytes()`[](#downloaditemgettotalbytes "Direct link to heading")
Returns `Integer` - The total size in bytes of the download item.
If the size is unknown, it returns 0.
####
`downloadItem.getReceivedBytes()`[](#downloaditemgetreceivedbytes "Direct link to heading")
Returns `Integer` - The received bytes of the download item.
####
`downloadItem.getContentDisposition()`[](#downloaditemgetcontentdisposition "Direct link to heading")
Returns `string` - The Content-Disposition field from the response header.
####
`downloadItem.getState()`[](#downloaditemgetstate "Direct link to heading")
Returns `string` - The current state. Can be `progressing`, `completed`, `cancelled` or `interrupted`.
**Note:** The following methods are useful specifically to resume a `cancelled` item when session is restarted.
####
`downloadItem.getURLChain()`[](#downloaditemgeturlchain "Direct link to heading")
Returns `string[]` - The complete URL chain of the item including any redirects.
####
`downloadItem.getLastModifiedTime()`[](#downloaditemgetlastmodifiedtime "Direct link to heading")
Returns `string` - Last-Modified header value.
####
`downloadItem.getETag()`[](#downloaditemgetetag "Direct link to heading")
Returns `string` - ETag header value.
####
`downloadItem.getStartTime()`[](#downloaditemgetstarttime "Direct link to heading")
Returns `Double` - Number of seconds since the UNIX epoch when the download was started.
### Instance Properties[](#instance-properties "Direct link to heading")
####
`downloadItem.savePath`[](#downloaditemsavepath "Direct link to heading")
A `string` property that determines the save file path of the download item.
The property is only available in session's `will-download` callback function. If user doesn't set the save path via the property, Electron will use the original routine to determine the save path; this usually prompts a save dialog.
electron contentTracing contentTracing
==============
> Collect tracing data from Chromium to find performance bottlenecks and slow operations.
>
>
Process: [Main](../glossary#main-process)
This module does not include a web interface. To view recorded traces, use [trace viewer](https://chromium.googlesource.com/catapult/+/HEAD/tracing/README.md), available at `chrome://tracing` in Chrome.
**Note:** You should not use this module until the `ready` event of the app module is emitted.
```
const { app, contentTracing } = require('electron')
app.whenReady().then(() => {
(async () => {
await contentTracing.startRecording({
included_categories: ['*']
})
console.log('Tracing started')
await new Promise(resolve => setTimeout(resolve, 5000))
const path = await contentTracing.stopRecording()
console.log('Tracing data recorded to ' + path)
})()
})
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `contentTracing` module has the following methods:
###
`contentTracing.getCategories()`[](#contenttracinggetcategories "Direct link to heading")
Returns `Promise<string[]>` - resolves with an array of category groups once all child processes have acknowledged the `getCategories` request
Get a set of category groups. The category groups can change as new code paths are reached. See also the [list of built-in tracing categories](https://chromium.googlesource.com/chromium/src/+/main/base/trace_event/builtin_categories.h).
> **NOTE:** Electron adds a non-default tracing category called `"electron"`. This category can be used to capture Electron-specific tracing events.
>
>
###
`contentTracing.startRecording(options)`[](#contenttracingstartrecordingoptions "Direct link to heading")
* `options` ([TraceConfig](structures/trace-config) | [TraceCategoriesAndOptions](structures/trace-categories-and-options))
Returns `Promise<void>` - resolved once all child processes have acknowledged the `startRecording` request.
Start recording on all processes.
Recording begins immediately locally and asynchronously on child processes as soon as they receive the EnableRecording request.
If a recording is already running, the promise will be immediately resolved, as only one trace operation can be in progress at a time.
###
`contentTracing.stopRecording([resultFilePath])`[](#contenttracingstoprecordingresultfilepath "Direct link to heading")
* `resultFilePath` string (optional)
Returns `Promise<string>` - resolves with a path to a file that contains the traced data once all child processes have acknowledged the `stopRecording` request
Stop recording on all processes.
Child processes typically cache trace data and only rarely flush and send trace data back to the main process. This helps to minimize the runtime overhead of tracing since sending trace data over IPC can be an expensive operation. So, to end tracing, Chromium asynchronously asks all child processes to flush any pending trace data.
Trace data will be written into `resultFilePath`. If `resultFilePath` is empty or not provided, trace data will be written to a temporary file, and the path will be returned in the promise.
###
`contentTracing.getTraceBufferUsage()`[](#contenttracinggettracebufferusage "Direct link to heading")
Returns `Promise<Object>` - Resolves with an object containing the `value` and `percentage` of trace buffer maximum usage
* `value` number
* `percentage` number
Get the maximum usage across processes of trace buffer as a percentage of the full state.
electron webContents webContents
===========
> Render and control web pages.
>
>
Process: [Main](../glossary#main-process)
`webContents` is an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter). It is responsible for rendering and controlling a web page and is a property of the [`BrowserWindow`](browser-window) object. An example of accessing the `webContents` object:
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ width: 800, height: 1500 })
win.loadURL('http://github.com')
const contents = win.webContents
console.log(contents)
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
These methods can be accessed from the `webContents` module:
```
const { webContents } = require('electron')
console.log(webContents)
```
###
`webContents.getAllWebContents()`[](#webcontentsgetallwebcontents "Direct link to heading")
Returns `WebContents[]` - An array of all `WebContents` instances. This will contain web contents for all windows, webviews, opened devtools, and devtools extension background pages.
###
`webContents.getFocusedWebContents()`[](#webcontentsgetfocusedwebcontents "Direct link to heading")
Returns `WebContents` | null - The web contents that is focused in this application, otherwise returns `null`.
###
`webContents.fromId(id)`[](#webcontentsfromidid "Direct link to heading")
* `id` Integer
Returns `WebContents` | undefined - A WebContents instance with the given ID, or `undefined` if there is no WebContents associated with the given ID.
###
`webContents.fromDevToolsTargetId(targetId)`[](#webcontentsfromdevtoolstargetidtargetid "Direct link to heading")
* `targetId` string - The Chrome DevTools Protocol [TargetID](https://chromedevtools.github.io/devtools-protocol/tot/Target/#type-TargetID) associated with the WebContents instance.
Returns `WebContents` | undefined - A WebContents instance with the given TargetID, or `undefined` if there is no WebContents associated with the given TargetID.
When communicating with the [Chrome DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/), it can be useful to lookup a WebContents instance based on its assigned TargetID.
```
async function lookupTargetId (browserWindow) {
const wc = browserWindow.webContents
await wc.debugger.attach('1.3')
const { targetInfo } = await wc.debugger.sendCommand('Target.getTargetInfo')
const { targetId } = targetInfo
const targetWebContents = await webContents.fromDevToolsTargetId(targetId)
}
```
Class: WebContents[](#class-webcontents "Direct link to heading")
------------------------------------------------------------------
> Render and control the contents of a BrowserWindow instance.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
### Instance Events[](#instance-events "Direct link to heading")
#### Event: 'did-finish-load'[](#event-did-finish-load "Direct link to heading")
Emitted when the navigation is done, i.e. the spinner of the tab has stopped spinning, and the `onload` event was dispatched.
#### Event: 'did-fail-load'[](#event-did-fail-load "Direct link to heading")
Returns:
* `event` Event
* `errorCode` Integer
* `errorDescription` string
* `validatedURL` string
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
This event is like `did-finish-load` but emitted when the load failed. The full list of error codes and their meaning is available [here](https://source.chromium.org/chromium/chromium/src/+/main:net/base/net_error_list.h).
#### Event: 'did-fail-provisional-load'[](#event-did-fail-provisional-load "Direct link to heading")
Returns:
* `event` Event
* `errorCode` Integer
* `errorDescription` string
* `validatedURL` string
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
This event is like `did-fail-load` but emitted when the load was cancelled (e.g. `window.stop()` was invoked).
#### Event: 'did-frame-finish-load'[](#event-did-frame-finish-load "Direct link to heading")
Returns:
* `event` Event
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted when a frame has done navigation.
#### Event: 'did-start-loading'[](#event-did-start-loading "Direct link to heading")
Corresponds to the points in time when the spinner of the tab started spinning.
#### Event: 'did-stop-loading'[](#event-did-stop-loading "Direct link to heading")
Corresponds to the points in time when the spinner of the tab stopped spinning.
#### Event: 'dom-ready'[](#event-dom-ready "Direct link to heading")
Returns:
* `event` Event
Emitted when the document in the top-level frame is loaded.
#### Event: 'page-title-updated'[](#event-page-title-updated "Direct link to heading")
Returns:
* `event` Event
* `title` string
* `explicitSet` boolean
Fired when page title is set during navigation. `explicitSet` is false when title is synthesized from file url.
#### Event: 'page-favicon-updated'[](#event-page-favicon-updated "Direct link to heading")
Returns:
* `event` Event
* `favicons` string[] - Array of URLs.
Emitted when page receives favicon urls.
#### Event: 'new-window' *Deprecated*[](#event-new-window-deprecated "Direct link to heading")
Returns:
* `event` NewWindowWebContentsEvent
* `url` string
* `frameName` string
* `disposition` string - Can be `default`, `foreground-tab`, `background-tab`, `new-window`, `save-to-disk` and `other`.
* `options` BrowserWindowConstructorOptions - The options which will be used for creating the new [`BrowserWindow`](browser-window).
* `additionalFeatures` string[] - The non-standard features (features not handled by Chromium or Electron) given to `window.open()`. Deprecated, and will now always be the empty array `[]`.
* `referrer` [Referrer](structures/referrer) - The referrer that will be passed to the new window. May or may not result in the `Referer` header being sent, depending on the referrer policy.
* `postBody` [PostBody](structures/post-body) (optional) - The post data that will be sent to the new window, along with the appropriate headers that will be set. If no post data is to be sent, the value will be `null`. Only defined when the window is being created by a form that set `target=_blank`.
Deprecated in favor of [`webContents.setWindowOpenHandler`](web-contents#contentssetwindowopenhandlerhandler).
Emitted when the page requests to open a new window for a `url`. It could be requested by `window.open` or an external link like `<a target='_blank'>`.
By default a new `BrowserWindow` will be created for the `url`.
Calling `event.preventDefault()` will prevent Electron from automatically creating a new [`BrowserWindow`](browser-window). If you call `event.preventDefault()` and manually create a new [`BrowserWindow`](browser-window) then you must set `event.newGuest` to reference the new [`BrowserWindow`](browser-window) instance, failing to do so may result in unexpected behavior. For example:
```
myBrowserWindow.webContents.on('new-window', (event, url, frameName, disposition, options, additionalFeatures, referrer, postBody) => {
event.preventDefault()
const win = new BrowserWindow({
webContents: options.webContents, // use existing webContents if provided
show: false
})
win.once('ready-to-show', () => win.show())
if (!options.webContents) {
const loadOptions = {
httpReferrer: referrer
}
if (postBody != null) {
const { data, contentType, boundary } = postBody
loadOptions.postData = postBody.data
loadOptions.extraHeaders = `content-type: ${contentType}; boundary=${boundary}`
}
win.loadURL(url, loadOptions) // existing webContents will be navigated automatically
}
event.newGuest = win
})
```
#### Event: 'did-create-window'[](#event-did-create-window "Direct link to heading")
Returns:
* `window` BrowserWindow
* `details` Object
+ `url` string - URL for the created window.
+ `frameName` string - Name given to the created window in the `window.open()` call.
+ `options` BrowserWindowConstructorOptions - The options used to create the BrowserWindow. They are merged in increasing precedence: parsed options from the `features` string from `window.open()`, security-related webPreferences inherited from the parent, and options given by [`webContents.setWindowOpenHandler`](web-contents#contentssetwindowopenhandlerhandler). Unrecognized options are not filtered out.
+ `referrer` [Referrer](structures/referrer) - The referrer that will be passed to the new window. May or may not result in the `Referer` header being sent, depending on the referrer policy.
+ `postBody` [PostBody](structures/post-body) (optional) - The post data that will be sent to the new window, along with the appropriate headers that will be set. If no post data is to be sent, the value will be `null`. Only defined when the window is being created by a form that set `target=_blank`.
+ `disposition` string - Can be `default`, `foreground-tab`, `background-tab`, `new-window`, `save-to-disk` and `other`.
Emitted *after* successful creation of a window via `window.open` in the renderer. Not emitted if the creation of the window is canceled from [`webContents.setWindowOpenHandler`](web-contents#contentssetwindowopenhandlerhandler).
See [`window.open()`](window-open) for more details and how to use this in conjunction with `webContents.setWindowOpenHandler`.
#### Event: 'will-navigate'[](#event-will-navigate "Direct link to heading")
Returns:
* `event` Event
* `url` string
Emitted when a user or the page wants to start navigation. It can happen when the `window.location` object is changed or a user clicks a link in the page.
This event will not emit when the navigation is started programmatically with APIs like `webContents.loadURL` and `webContents.back`.
It is also not emitted for in-page navigations, such as clicking anchor links or updating the `window.location.hash`. Use `did-navigate-in-page` event for this purpose.
Calling `event.preventDefault()` will prevent the navigation.
#### Event: 'did-start-navigation'[](#event-did-start-navigation "Direct link to heading")
Returns:
* `event` Event
* `url` string
* `isInPlace` boolean
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted when any frame (including main) starts navigating. `isInPlace` will be `true` for in-page navigations.
#### Event: 'will-redirect'[](#event-will-redirect "Direct link to heading")
Returns:
* `event` Event
* `url` string
* `isInPlace` boolean
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted when a server side redirect occurs during navigation. For example a 302 redirect.
This event will be emitted after `did-start-navigation` and always before the `did-redirect-navigation` event for the same navigation.
Calling `event.preventDefault()` will prevent the navigation (not just the redirect).
#### Event: 'did-redirect-navigation'[](#event-did-redirect-navigation "Direct link to heading")
Returns:
* `event` Event
* `url` string
* `isInPlace` boolean
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted after a server side redirect occurs during navigation. For example a 302 redirect.
This event cannot be prevented, if you want to prevent redirects you should checkout out the `will-redirect` event above.
#### Event: 'did-navigate'[](#event-did-navigate "Direct link to heading")
Returns:
* `event` Event
* `url` string
* `httpResponseCode` Integer - -1 for non HTTP navigations
* `httpStatusText` string - empty for non HTTP navigations
Emitted when a main frame navigation is done.
This event is not emitted for in-page navigations, such as clicking anchor links or updating the `window.location.hash`. Use `did-navigate-in-page` event for this purpose.
#### Event: 'did-frame-navigate'[](#event-did-frame-navigate "Direct link to heading")
Returns:
* `event` Event
* `url` string
* `httpResponseCode` Integer - -1 for non HTTP navigations
* `httpStatusText` string - empty for non HTTP navigations,
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted when any frame navigation is done.
This event is not emitted for in-page navigations, such as clicking anchor links or updating the `window.location.hash`. Use `did-navigate-in-page` event for this purpose.
#### Event: 'did-navigate-in-page'[](#event-did-navigate-in-page "Direct link to heading")
Returns:
* `event` Event
* `url` string
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted when an in-page navigation happened in any frame.
When in-page navigation happens, the page URL changes but does not cause navigation outside of the page. Examples of this occurring are when anchor links are clicked or when the DOM `hashchange` event is triggered.
#### Event: 'will-prevent-unload'[](#event-will-prevent-unload "Direct link to heading")
Returns:
* `event` Event
Emitted when a `beforeunload` event handler is attempting to cancel a page unload.
Calling `event.preventDefault()` will ignore the `beforeunload` event handler and allow the page to be unloaded.
```
const { BrowserWindow, dialog } = require('electron')
const win = new BrowserWindow({ width: 800, height: 600 })
win.webContents.on('will-prevent-unload', (event) => {
const choice = dialog.showMessageBoxSync(win, {
type: 'question',
buttons: ['Leave', 'Stay'],
title: 'Do you want to leave this site?',
message: 'Changes you made may not be saved.',
defaultId: 0,
cancelId: 1
})
const leave = (choice === 0)
if (leave) {
event.preventDefault()
}
})
```
**Note:** This will be emitted for `BrowserViews` but will *not* be respected - this is because we have chosen not to tie the `BrowserView` lifecycle to its owning BrowserWindow should one exist per the [specification](https://developer.mozilla.org/en-US/docs/Web/API/Window/beforeunload_event).
#### Event: 'crashed' *Deprecated*[](#event-crashed-deprecated "Direct link to heading")
Returns:
* `event` Event
* `killed` boolean
Emitted when the renderer process crashes or is killed.
**Deprecated:** This event is superceded by the `render-process-gone` event which contains more information about why the render process disappeared. It isn't always because it crashed. The `killed` boolean can be replaced by checking `reason === 'killed'` when you switch to that event.
#### Event: 'render-process-gone'[](#event-render-process-gone "Direct link to heading")
Returns:
* `event` Event
* `details` Object
+ `reason` string - The reason the render process is gone. Possible values:
- `clean-exit` - Process exited with an exit code of zero
- `abnormal-exit` - Process exited with a non-zero exit code
- `killed` - Process was sent a SIGTERM or otherwise killed externally
- `crashed` - Process crashed
- `oom` - Process ran out of memory
- `launch-failed` - Process never successfully launched
- `integrity-failure` - Windows code integrity checks failed
+ `exitCode` Integer - The exit code of the process, unless `reason` is `launch-failed`, in which case `exitCode` will be a platform-specific launch failure error code.
Emitted when the renderer process unexpectedly disappears. This is normally because it was crashed or killed.
#### Event: 'unresponsive'[](#event-unresponsive "Direct link to heading")
Emitted when the web page becomes unresponsive.
#### Event: 'responsive'[](#event-responsive "Direct link to heading")
Emitted when the unresponsive web page becomes responsive again.
#### Event: 'plugin-crashed'[](#event-plugin-crashed "Direct link to heading")
Returns:
* `event` Event
* `name` string
* `version` string
Emitted when a plugin process has crashed.
#### Event: 'destroyed'[](#event-destroyed "Direct link to heading")
Emitted when `webContents` is destroyed.
#### Event: 'before-input-event'[](#event-before-input-event "Direct link to heading")
Returns:
* `event` Event
* `input` Object - Input properties.
+ `type` string - Either `keyUp` or `keyDown`.
+ `key` string - Equivalent to [KeyboardEvent.key](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `code` string - Equivalent to [KeyboardEvent.code](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `isAutoRepeat` boolean - Equivalent to [KeyboardEvent.repeat](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `isComposing` boolean - Equivalent to [KeyboardEvent.isComposing](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `shift` boolean - Equivalent to [KeyboardEvent.shiftKey](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `control` boolean - Equivalent to [KeyboardEvent.controlKey](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `alt` boolean - Equivalent to [KeyboardEvent.altKey](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `meta` boolean - Equivalent to [KeyboardEvent.metaKey](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `location` number - Equivalent to [KeyboardEvent.location](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent).
+ `modifiers` string[] - See [InputEvent.modifiers](structures/input-event).
Emitted before dispatching the `keydown` and `keyup` events in the page. Calling `event.preventDefault` will prevent the page `keydown`/`keyup` events and the menu shortcuts.
To only prevent the menu shortcuts, use [`setIgnoreMenuShortcuts`](#contentssetignoremenushortcutsignore):
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ width: 800, height: 600 })
win.webContents.on('before-input-event', (event, input) => {
// For example, only enable application menu keyboard shortcuts when
// Ctrl/Cmd are down.
win.webContents.setIgnoreMenuShortcuts(!input.control && !input.meta)
})
```
#### Event: 'enter-html-full-screen'[](#event-enter-html-full-screen "Direct link to heading")
Emitted when the window enters a full-screen state triggered by HTML API.
#### Event: 'leave-html-full-screen'[](#event-leave-html-full-screen "Direct link to heading")
Emitted when the window leaves a full-screen state triggered by HTML API.
#### Event: 'zoom-changed'[](#event-zoom-changed "Direct link to heading")
Returns:
* `event` Event
* `zoomDirection` string - Can be `in` or `out`.
Emitted when the user is requesting to change the zoom level using the mouse wheel.
#### Event: 'blur'[](#event-blur "Direct link to heading")
Emitted when the `WebContents` loses focus.
#### Event: 'focus'[](#event-focus "Direct link to heading")
Emitted when the `WebContents` gains focus.
Note that on macOS, having focus means the `WebContents` is the first responder of window, so switching focus between windows would not trigger the `focus` and `blur` events of `WebContents`, as the first responder of each window is not changed.
The `focus` and `blur` events of `WebContents` should only be used to detect focus change between different `WebContents` and `BrowserView` in the same window.
#### Event: 'devtools-opened'[](#event-devtools-opened "Direct link to heading")
Emitted when DevTools is opened.
#### Event: 'devtools-closed'[](#event-devtools-closed "Direct link to heading")
Emitted when DevTools is closed.
#### Event: 'devtools-focused'[](#event-devtools-focused "Direct link to heading")
Emitted when DevTools is focused / opened.
#### Event: 'certificate-error'[](#event-certificate-error "Direct link to heading")
Returns:
* `event` Event
* `url` string
* `error` string - The error code.
* `certificate` [Certificate](structures/certificate)
* `callback` Function
+ `isTrusted` boolean - Indicates whether the certificate can be considered trusted.
* `isMainFrame` boolean
Emitted when failed to verify the `certificate` for `url`.
The usage is the same with [the `certificate-error` event of `app`](app#event-certificate-error).
#### Event: 'select-client-certificate'[](#event-select-client-certificate "Direct link to heading")
Returns:
* `event` Event
* `url` URL
* `certificateList` [Certificate[]](structures/certificate)
* `callback` Function
+ `certificate` [Certificate](structures/certificate) - Must be a certificate from the given list.
Emitted when a client certificate is requested.
The usage is the same with [the `select-client-certificate` event of `app`](app#event-select-client-certificate).
#### Event: 'login'[](#event-login "Direct link to heading")
Returns:
* `event` Event
* `authenticationResponseDetails` Object
+ `url` URL
* `authInfo` Object
+ `isProxy` boolean
+ `scheme` string
+ `host` string
+ `port` Integer
+ `realm` string
* `callback` Function
+ `username` string (optional)
+ `password` string (optional)
Emitted when `webContents` wants to do basic auth.
The usage is the same with [the `login` event of `app`](app#event-login).
#### Event: 'found-in-page'[](#event-found-in-page "Direct link to heading")
Returns:
* `event` Event
* `result` Object
+ `requestId` Integer
+ `activeMatchOrdinal` Integer - Position of the active match.
+ `matches` Integer - Number of Matches.
+ `selectionArea` Rectangle - Coordinates of first match region.
+ `finalUpdate` boolean
Emitted when a result is available for [`webContents.findInPage`] request.
#### Event: 'media-started-playing'[](#event-media-started-playing "Direct link to heading")
Emitted when media starts playing.
#### Event: 'media-paused'[](#event-media-paused "Direct link to heading")
Emitted when media is paused or done playing.
#### Event: 'did-change-theme-color'[](#event-did-change-theme-color "Direct link to heading")
Returns:
* `event` Event
* `color` (string | null) - Theme color is in format of '#rrggbb'. It is `null` when no theme color is set.
Emitted when a page's theme color changes. This is usually due to encountering a meta tag:
```
<meta name='theme-color' content='#ff0000'>
```
#### Event: 'update-target-url'[](#event-update-target-url "Direct link to heading")
Returns:
* `event` Event
* `url` string
Emitted when mouse moves over a link or the keyboard moves the focus to a link.
#### Event: 'cursor-changed'[](#event-cursor-changed "Direct link to heading")
Returns:
* `event` Event
* `type` string
* `image` [NativeImage](native-image) (optional)
* `scale` Float (optional) - scaling factor for the custom cursor.
* `size` [Size](structures/size) (optional) - the size of the `image`.
* `hotspot` [Point](structures/point) (optional) - coordinates of the custom cursor's hotspot.
Emitted when the cursor's type changes. The `type` parameter can be `default`, `crosshair`, `pointer`, `text`, `wait`, `help`, `e-resize`, `n-resize`, `ne-resize`, `nw-resize`, `s-resize`, `se-resize`, `sw-resize`, `w-resize`, `ns-resize`, `ew-resize`, `nesw-resize`, `nwse-resize`, `col-resize`, `row-resize`, `m-panning`, `e-panning`, `n-panning`, `ne-panning`, `nw-panning`, `s-panning`, `se-panning`, `sw-panning`, `w-panning`, `move`, `vertical-text`, `cell`, `context-menu`, `alias`, `progress`, `nodrop`, `copy`, `none`, `not-allowed`, `zoom-in`, `zoom-out`, `grab`, `grabbing` or `custom`.
If the `type` parameter is `custom`, the `image` parameter will hold the custom cursor image in a [`NativeImage`](native-image), and `scale`, `size` and `hotspot` will hold additional information about the custom cursor.
#### Event: 'context-menu'[](#event-context-menu "Direct link to heading")
Returns:
* `event` Event
* `params` Object
+ `x` Integer - x coordinate.
+ `y` Integer - y coordinate.
+ `frame` WebFrameMain - Frame from which the context menu was invoked.
+ `linkURL` string - URL of the link that encloses the node the context menu was invoked on.
+ `linkText` string - Text associated with the link. May be an empty string if the contents of the link are an image.
+ `pageURL` string - URL of the top level page that the context menu was invoked on.
+ `frameURL` string - URL of the subframe that the context menu was invoked on.
+ `srcURL` string - Source URL for the element that the context menu was invoked on. Elements with source URLs are images, audio and video.
+ `mediaType` string - Type of the node the context menu was invoked on. Can be `none`, `image`, `audio`, `video`, `canvas`, `file` or `plugin`.
+ `hasImageContents` boolean - Whether the context menu was invoked on an image which has non-empty contents.
+ `isEditable` boolean - Whether the context is editable.
+ `selectionText` string - Text of the selection that the context menu was invoked on.
+ `titleText` string - Title text of the selection that the context menu was invoked on.
+ `altText` string - Alt text of the selection that the context menu was invoked on.
+ `suggestedFilename` string - Suggested filename to be used when saving file through 'Save Link As' option of context menu.
+ `selectionRect` [Rectangle](structures/rectangle) - Rect representing the coordinates in the document space of the selection.
+ `selectionStartOffset` number - Start position of the selection text.
+ `referrerPolicy` [Referrer](structures/referrer) - The referrer policy of the frame on which the menu is invoked.
+ `misspelledWord` string - The misspelled word under the cursor, if any.
+ `dictionarySuggestions` string[] - An array of suggested words to show the user to replace the `misspelledWord`. Only available if there is a misspelled word and spellchecker is enabled.
+ `frameCharset` string - The character encoding of the frame on which the menu was invoked.
+ `inputFieldType` string - If the context menu was invoked on an input field, the type of that field. Possible values are `none`, `plainText`, `password`, `other`.
+ `spellcheckEnabled` boolean - If the context is editable, whether or not spellchecking is enabled.
+ `menuSourceType` string - Input source that invoked the context menu. Can be `none`, `mouse`, `keyboard`, `touch`, `touchMenu`, `longPress`, `longTap`, `touchHandle`, `stylus`, `adjustSelection`, or `adjustSelectionReset`.
+ `mediaFlags` Object - The flags for the media element the context menu was invoked on.
- `inError` boolean - Whether the media element has crashed.
- `isPaused` boolean - Whether the media element is paused.
- `isMuted` boolean - Whether the media element is muted.
- `hasAudio` boolean - Whether the media element has audio.
- `isLooping` boolean - Whether the media element is looping.
- `isControlsVisible` boolean - Whether the media element's controls are visible.
- `canToggleControls` boolean - Whether the media element's controls are toggleable.
- `canPrint` boolean - Whether the media element can be printed.
- `canSave` boolean - Whether or not the media element can be downloaded.
- `canShowPictureInPicture` boolean - Whether the media element can show picture-in-picture.
- `isShowingPictureInPicture` boolean - Whether the media element is currently showing picture-in-picture.
- `canRotate` boolean - Whether the media element can be rotated.
- `canLoop` boolean - Whether the media element can be looped.
+ `editFlags` Object - These flags indicate whether the renderer believes it is able to perform the corresponding action.
- `canUndo` boolean - Whether the renderer believes it can undo.
- `canRedo` boolean - Whether the renderer believes it can redo.
- `canCut` boolean - Whether the renderer believes it can cut.
- `canCopy` boolean - Whether the renderer believes it can copy.
- `canPaste` boolean - Whether the renderer believes it can paste.
- `canDelete` boolean - Whether the renderer believes it can delete.
- `canSelectAll` boolean - Whether the renderer believes it can select all.
- `canEditRichly` boolean - Whether the renderer believes it can edit text richly.
Emitted when there is a new context menu that needs to be handled.
#### Event: 'select-bluetooth-device'[](#event-select-bluetooth-device "Direct link to heading")
Returns:
* `event` Event
* `devices` [BluetoothDevice[]](structures/bluetooth-device)
* `callback` Function
+ `deviceId` string
Emitted when bluetooth device needs to be selected on call to `navigator.bluetooth.requestDevice`. To use `navigator.bluetooth` api `webBluetooth` should be enabled. If `event.preventDefault` is not called, first available device will be selected. `callback` should be called with `deviceId` to be selected, passing empty string to `callback` will cancel the request.
If no event listener is added for this event, all bluetooth requests will be cancelled.
```
const { app, BrowserWindow } = require('electron')
let win = null
app.commandLine.appendSwitch('enable-experimental-web-platform-features')
app.whenReady().then(() => {
win = new BrowserWindow({ width: 800, height: 600 })
win.webContents.on('select-bluetooth-device', (event, deviceList, callback) => {
event.preventDefault()
const result = deviceList.find((device) => {
return device.deviceName === 'test'
})
if (!result) {
callback('')
} else {
callback(result.deviceId)
}
})
})
```
#### Event: 'paint'[](#event-paint "Direct link to heading")
Returns:
* `event` Event
* `dirtyRect` [Rectangle](structures/rectangle)
* `image` [NativeImage](native-image) - The image data of the whole frame.
Emitted when a new frame is generated. Only the dirty area is passed in the buffer.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ webPreferences: { offscreen: true } })
win.webContents.on('paint', (event, dirty, image) => {
// updateBitmap(dirty, image.getBitmap())
})
win.loadURL('http://github.com')
```
#### Event: 'devtools-reload-page'[](#event-devtools-reload-page "Direct link to heading")
Emitted when the devtools window instructs the webContents to reload
#### Event: 'will-attach-webview'[](#event-will-attach-webview "Direct link to heading")
Returns:
* `event` Event
* `webPreferences` WebPreferences - The web preferences that will be used by the guest page. This object can be modified to adjust the preferences for the guest page.
* `params` Record<string, string> - The other `<webview>` parameters such as the `src` URL. This object can be modified to adjust the parameters of the guest page.
Emitted when a `<webview>`'s web contents is being attached to this web contents. Calling `event.preventDefault()` will destroy the guest page.
This event can be used to configure `webPreferences` for the `webContents` of a `<webview>` before it's loaded, and provides the ability to set settings that can't be set via `<webview>` attributes.
#### Event: 'did-attach-webview'[](#event-did-attach-webview "Direct link to heading")
Returns:
* `event` Event
* `webContents` WebContents - The guest web contents that is used by the `<webview>`.
Emitted when a `<webview>` has been attached to this web contents.
#### Event: 'console-message'[](#event-console-message "Direct link to heading")
Returns:
* `event` Event
* `level` Integer - The log level, from 0 to 3. In order it matches `verbose`, `info`, `warning` and `error`.
* `message` string - The actual console message
* `line` Integer - The line number of the source that triggered this console message
* `sourceId` string
Emitted when the associated window logs a console message.
#### Event: 'preload-error'[](#event-preload-error "Direct link to heading")
Returns:
* `event` Event
* `preloadPath` string
* `error` Error
Emitted when the preload script `preloadPath` throws an unhandled exception `error`.
#### Event: 'ipc-message'[](#event-ipc-message "Direct link to heading")
Returns:
* `event` Event
* `channel` string
* `...args` any[]
Emitted when the renderer process sends an asynchronous message via `ipcRenderer.send()`.
#### Event: 'ipc-message-sync'[](#event-ipc-message-sync "Direct link to heading")
Returns:
* `event` Event
* `channel` string
* `...args` any[]
Emitted when the renderer process sends a synchronous message via `ipcRenderer.sendSync()`.
#### Event: 'preferred-size-changed'[](#event-preferred-size-changed "Direct link to heading")
Returns:
* `event` Event
* `preferredSize` [Size](structures/size) - The minimum size needed to contain the layout of the document—without requiring scrolling.
Emitted when the `WebContents` preferred size has changed.
This event will only be emitted when `enablePreferredSizeMode` is set to `true` in `webPreferences`.
#### Event: 'frame-created'[](#event-frame-created "Direct link to heading")
Returns:
* `event` Event
* `details` Object
+ `frame` WebFrameMain
Emitted when the [mainFrame](web-contents#contentsmainframe-readonly), an `<iframe>`, or a nested `<iframe>` is loaded within the page.
### Instance Methods[](#instance-methods "Direct link to heading")
####
`contents.loadURL(url[, options])`[](#contentsloadurlurl-options "Direct link to heading")
* `url` string
* `options` Object (optional)
+ `httpReferrer` (string | [Referrer](structures/referrer)) (optional) - An HTTP Referrer url.
+ `userAgent` string (optional) - A user agent originating the request.
+ `extraHeaders` string (optional) - Extra headers separated by "\n".
+ `postData` ([UploadRawData](structures/upload-raw-data) | [UploadFile](structures/upload-file))[] (optional)
+ `baseURLForDataURL` string (optional) - Base url (with trailing path separator) for files to be loaded by the data url. This is needed only if the specified `url` is a data url and needs to load other files.
Returns `Promise<void>` - the promise will resolve when the page has finished loading (see [`did-finish-load`](web-contents#event-did-finish-load)), and rejects if the page fails to load (see [`did-fail-load`](web-contents#event-did-fail-load)). A noop rejection handler is already attached, which avoids unhandled rejection errors.
Loads the `url` in the window. The `url` must contain the protocol prefix, e.g. the `http://` or `file://`. If the load should bypass http cache then use the `pragma` header to achieve it.
```
const { webContents } = require('electron')
const options = { extraHeaders: 'pragma: no-cache\n' }
webContents.loadURL('https://github.com', options)
```
####
`contents.loadFile(filePath[, options])`[](#contentsloadfilefilepath-options "Direct link to heading")
* `filePath` string
* `options` Object (optional)
+ `query` Record<string, string> (optional) - Passed to `url.format()`.
+ `search` string (optional) - Passed to `url.format()`.
+ `hash` string (optional) - Passed to `url.format()`.
Returns `Promise<void>` - the promise will resolve when the page has finished loading (see [`did-finish-load`](web-contents#event-did-finish-load)), and rejects if the page fails to load (see [`did-fail-load`](web-contents#event-did-fail-load)).
Loads the given file in the window, `filePath` should be a path to an HTML file relative to the root of your application. For instance an app structure like this:
```
| root
| - package.json
| - src
| - main.js
| - index.html
```
Would require code like this
```
win.loadFile('src/index.html')
```
####
`contents.downloadURL(url)`[](#contentsdownloadurlurl "Direct link to heading")
* `url` string
Initiates a download of the resource at `url` without navigating. The `will-download` event of `session` will be triggered.
####
`contents.getURL()`[](#contentsgeturl "Direct link to heading")
Returns `string` - The URL of the current web page.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL('http://github.com').then(() => {
const currentURL = win.webContents.getURL()
console.log(currentURL)
})
```
####
`contents.getTitle()`[](#contentsgettitle "Direct link to heading")
Returns `string` - The title of the current web page.
####
`contents.isDestroyed()`[](#contentsisdestroyed "Direct link to heading")
Returns `boolean` - Whether the web page is destroyed.
####
`contents.focus()`[](#contentsfocus "Direct link to heading")
Focuses the web page.
####
`contents.isFocused()`[](#contentsisfocused "Direct link to heading")
Returns `boolean` - Whether the web page is focused.
####
`contents.isLoading()`[](#contentsisloading "Direct link to heading")
Returns `boolean` - Whether web page is still loading resources.
####
`contents.isLoadingMainFrame()`[](#contentsisloadingmainframe "Direct link to heading")
Returns `boolean` - Whether the main frame (and not just iframes or frames within it) is still loading.
####
`contents.isWaitingForResponse()`[](#contentsiswaitingforresponse "Direct link to heading")
Returns `boolean` - Whether the web page is waiting for a first-response from the main resource of the page.
####
`contents.stop()`[](#contentsstop "Direct link to heading")
Stops any pending navigation.
####
`contents.reload()`[](#contentsreload "Direct link to heading")
Reloads the current web page.
####
`contents.reloadIgnoringCache()`[](#contentsreloadignoringcache "Direct link to heading")
Reloads current page and ignores cache.
####
`contents.canGoBack()`[](#contentscangoback "Direct link to heading")
Returns `boolean` - Whether the browser can go back to previous web page.
####
`contents.canGoForward()`[](#contentscangoforward "Direct link to heading")
Returns `boolean` - Whether the browser can go forward to next web page.
####
`contents.canGoToOffset(offset)`[](#contentscangotooffsetoffset "Direct link to heading")
* `offset` Integer
Returns `boolean` - Whether the web page can go to `offset`.
####
`contents.clearHistory()`[](#contentsclearhistory "Direct link to heading")
Clears the navigation history.
####
`contents.goBack()`[](#contentsgoback "Direct link to heading")
Makes the browser go back a web page.
####
`contents.goForward()`[](#contentsgoforward "Direct link to heading")
Makes the browser go forward a web page.
####
`contents.goToIndex(index)`[](#contentsgotoindexindex "Direct link to heading")
* `index` Integer
Navigates browser to the specified absolute web page index.
####
`contents.goToOffset(offset)`[](#contentsgotooffsetoffset "Direct link to heading")
* `offset` Integer
Navigates to the specified offset from the "current entry".
####
`contents.isCrashed()`[](#contentsiscrashed "Direct link to heading")
Returns `boolean` - Whether the renderer process has crashed.
####
`contents.forcefullyCrashRenderer()`[](#contentsforcefullycrashrenderer "Direct link to heading")
Forcefully terminates the renderer process that is currently hosting this `webContents`. This will cause the `render-process-gone` event to be emitted with the `reason=killed || reason=crashed`. Please note that some webContents share renderer processes and therefore calling this method may also crash the host process for other webContents as well.
Calling `reload()` immediately after calling this method will force the reload to occur in a new process. This should be used when this process is unstable or unusable, for instance in order to recover from the `unresponsive` event.
```
contents.on('unresponsive', async () => {
const { response } = await dialog.showMessageBox({
message: 'App X has become unresponsive',
title: 'Do you want to try forcefully reloading the app?',
buttons: ['OK', 'Cancel'],
cancelId: 1
})
if (response === 0) {
contents.forcefullyCrashRenderer()
contents.reload()
}
})
```
####
`contents.setUserAgent(userAgent)`[](#contentssetuseragentuseragent "Direct link to heading")
* `userAgent` string
Overrides the user agent for this web page.
####
`contents.getUserAgent()`[](#contentsgetuseragent "Direct link to heading")
Returns `string` - The user agent for this web page.
####
`contents.insertCSS(css[, options])`[](#contentsinsertcsscss-options "Direct link to heading")
* `css` string
* `options` Object (optional)
+ `cssOrigin` string (optional) - Can be either 'user' or 'author'. Sets the [cascade origin](https://www.w3.org/TR/css3-cascade/#cascade-origin) of the inserted stylesheet. Default is 'author'.
Returns `Promise<string>` - A promise that resolves with a key for the inserted CSS that can later be used to remove the CSS via `contents.removeInsertedCSS(key)`.
Injects CSS into the current web page and returns a unique key for the inserted stylesheet.
```
contents.on('did-finish-load', () => {
contents.insertCSS('html, body { background-color: #f00; }')
})
```
####
`contents.removeInsertedCSS(key)`[](#contentsremoveinsertedcsskey "Direct link to heading")
* `key` string
Returns `Promise<void>` - Resolves if the removal was successful.
Removes the inserted CSS from the current web page. The stylesheet is identified by its key, which is returned from `contents.insertCSS(css)`.
```
contents.on('did-finish-load', async () => {
const key = await contents.insertCSS('html, body { background-color: #f00; }')
contents.removeInsertedCSS(key)
})
```
####
`contents.executeJavaScript(code[, userGesture])`[](#contentsexecutejavascriptcode-usergesture "Direct link to heading")
* `code` string
* `userGesture` boolean (optional) - Default is `false`.
Returns `Promise<any>` - A promise that resolves with the result of the executed code or is rejected if the result of the code is a rejected promise.
Evaluates `code` in page.
In the browser window some HTML APIs like `requestFullScreen` can only be invoked by a gesture from the user. Setting `userGesture` to `true` will remove this limitation.
Code execution will be suspended until web page stop loading.
```
contents.executeJavaScript('fetch("https://jsonplaceholder.typicode.com/users/1").then(resp => resp.json())', true)
.then((result) => {
console.log(result) // Will be the JSON object from the fetch call
})
```
####
`contents.executeJavaScriptInIsolatedWorld(worldId, scripts[, userGesture])`[](#contentsexecutejavascriptinisolatedworldworldid-scripts-usergesture "Direct link to heading")
* `worldId` Integer - The ID of the world to run the javascript in, `0` is the default world, `999` is the world used by Electron's `contextIsolation` feature. You can provide any integer here.
* `scripts` [WebSource[]](structures/web-source)
* `userGesture` boolean (optional) - Default is `false`.
Returns `Promise<any>` - A promise that resolves with the result of the executed code or is rejected if the result of the code is a rejected promise.
Works like `executeJavaScript` but evaluates `scripts` in an isolated context.
####
`contents.setIgnoreMenuShortcuts(ignore)`[](#contentssetignoremenushortcutsignore "Direct link to heading")
* `ignore` boolean
Ignore application menu shortcuts while this web contents is focused.
####
`contents.setWindowOpenHandler(handler)`[](#contentssetwindowopenhandlerhandler "Direct link to heading")
* `handler` Function<{action: 'deny'} | {action: 'allow', overrideBrowserWindowOptions?: BrowserWindowConstructorOptions}>
+ `details` Object
- `url` string - The *resolved* version of the URL passed to `window.open()`. e.g. opening a window with `window.open('foo')` will yield something like `https://the-origin/the/current/path/foo`.
- `frameName` string - Name of the window provided in `window.open()`
- `features` string - Comma separated list of window features provided to `window.open()`.
- `disposition` string - Can be `default`, `foreground-tab`, `background-tab`, `new-window`, `save-to-disk` or `other`.
- `referrer` [Referrer](structures/referrer) - The referrer that will be passed to the new window. May or may not result in the `Referer` header being sent, depending on the referrer policy.
- `postBody` [PostBody](structures/post-body) (optional) - The post data that will be sent to the new window, along with the appropriate headers that will be set. If no post data is to be sent, the value will be `null`. Only defined when the window is being created by a form that set `target=_blank`.Returns `{action: 'deny'} | {action: 'allow', overrideBrowserWindowOptions?: BrowserWindowConstructorOptions}` - `deny` cancels the creation of the new window. `allow` will allow the new window to be created. Specifying `overrideBrowserWindowOptions` allows customization of the created window. Returning an unrecognized value such as a null, undefined, or an object without a recognized 'action' value will result in a console error and have the same effect as returning `{action: 'deny'}`.
Called before creating a window a new window is requested by the renderer, e.g. by `window.open()`, a link with `target="_blank"`, shift+clicking on a link, or submitting a form with `<form target="_blank">`. See [`window.open()`](window-open) for more details and how to use this in conjunction with `did-create-window`.
####
`contents.setAudioMuted(muted)`[](#contentssetaudiomutedmuted "Direct link to heading")
* `muted` boolean
Mute the audio on the current web page.
####
`contents.isAudioMuted()`[](#contentsisaudiomuted "Direct link to heading")
Returns `boolean` - Whether this page has been muted.
####
`contents.isCurrentlyAudible()`[](#contentsiscurrentlyaudible "Direct link to heading")
Returns `boolean` - Whether audio is currently playing.
####
`contents.setZoomFactor(factor)`[](#contentssetzoomfactorfactor "Direct link to heading")
* `factor` Double - Zoom factor; default is 1.0.
Changes the zoom factor to the specified factor. Zoom factor is zoom percent divided by 100, so 300% = 3.0.
The factor must be greater than 0.0.
####
`contents.getZoomFactor()`[](#contentsgetzoomfactor "Direct link to heading")
Returns `number` - the current zoom factor.
####
`contents.setZoomLevel(level)`[](#contentssetzoomlevellevel "Direct link to heading")
* `level` number - Zoom level.
Changes the zoom level to the specified level. The original size is 0 and each increment above or below represents zooming 20% larger or smaller to default limits of 300% and 50% of original size, respectively. The formula for this is `scale := 1.2 ^ level`.
> **NOTE**: The zoom policy at the Chromium level is same-origin, meaning that the zoom level for a specific domain propagates across all instances of windows with the same domain. Differentiating the window URLs will make zoom work per-window.
>
>
####
`contents.getZoomLevel()`[](#contentsgetzoomlevel "Direct link to heading")
Returns `number` - the current zoom level.
####
`contents.setVisualZoomLevelLimits(minimumLevel, maximumLevel)`[](#contentssetvisualzoomlevellimitsminimumlevel-maximumlevel "Direct link to heading")
* `minimumLevel` number
* `maximumLevel` number
Returns `Promise<void>`
Sets the maximum and minimum pinch-to-zoom level.
>
> **NOTE**: Visual zoom is disabled by default in Electron. To re-enable it, call:
>
>
>
>
> ```
> contents.setVisualZoomLevelLimits(1, 3)
> ```
>
>
>
####
`contents.undo()`[](#contentsundo "Direct link to heading")
Executes the editing command `undo` in web page.
####
`contents.redo()`[](#contentsredo "Direct link to heading")
Executes the editing command `redo` in web page.
####
`contents.cut()`[](#contentscut "Direct link to heading")
Executes the editing command `cut` in web page.
####
`contents.copy()`[](#contentscopy "Direct link to heading")
Executes the editing command `copy` in web page.
####
`contents.copyImageAt(x, y)`[](#contentscopyimageatx-y "Direct link to heading")
* `x` Integer
* `y` Integer
Copy the image at the given position to the clipboard.
####
`contents.paste()`[](#contentspaste "Direct link to heading")
Executes the editing command `paste` in web page.
####
`contents.pasteAndMatchStyle()`[](#contentspasteandmatchstyle "Direct link to heading")
Executes the editing command `pasteAndMatchStyle` in web page.
####
`contents.delete()`[](#contentsdelete "Direct link to heading")
Executes the editing command `delete` in web page.
####
`contents.selectAll()`[](#contentsselectall "Direct link to heading")
Executes the editing command `selectAll` in web page.
####
`contents.unselect()`[](#contentsunselect "Direct link to heading")
Executes the editing command `unselect` in web page.
####
`contents.replace(text)`[](#contentsreplacetext "Direct link to heading")
* `text` string
Executes the editing command `replace` in web page.
####
`contents.replaceMisspelling(text)`[](#contentsreplacemisspellingtext "Direct link to heading")
* `text` string
Executes the editing command `replaceMisspelling` in web page.
####
`contents.insertText(text)`[](#contentsinserttexttext "Direct link to heading")
* `text` string
Returns `Promise<void>`
Inserts `text` to the focused element.
####
`contents.findInPage(text[, options])`[](#contentsfindinpagetext-options "Direct link to heading")
* `text` string - Content to be searched, must not be empty.
* `options` Object (optional)
+ `forward` boolean (optional) - Whether to search forward or backward, defaults to `true`.
+ `findNext` boolean (optional) - Whether to begin a new text finding session with this request. Should be `true` for initial requests, and `false` for follow-up requests. Defaults to `false`.
+ `matchCase` boolean (optional) - Whether search should be case-sensitive, defaults to `false`.
Returns `Integer` - The request id used for the request.
Starts a request to find all matches for the `text` in the web page. The result of the request can be obtained by subscribing to [`found-in-page`](web-contents#event-found-in-page) event.
####
`contents.stopFindInPage(action)`[](#contentsstopfindinpageaction "Direct link to heading")
* `action` string - Specifies the action to take place when ending [`webContents.findInPage`] request.
+ `clearSelection` - Clear the selection.
+ `keepSelection` - Translate the selection into a normal selection.
+ `activateSelection` - Focus and click the selection node.
Stops any `findInPage` request for the `webContents` with the provided `action`.
```
const { webContents } = require('electron')
webContents.on('found-in-page', (event, result) => {
if (result.finalUpdate) webContents.stopFindInPage('clearSelection')
})
const requestId = webContents.findInPage('api')
console.log(requestId)
```
####
`contents.capturePage([rect])`[](#contentscapturepagerect "Direct link to heading")
* `rect` [Rectangle](structures/rectangle) (optional) - The area of the page to be captured.
Returns `Promise<NativeImage>` - Resolves with a [NativeImage](native-image)
Captures a snapshot of the page within `rect`. Omitting `rect` will capture the whole visible page.
####
`contents.isBeingCaptured()`[](#contentsisbeingcaptured "Direct link to heading")
Returns `boolean` - Whether this page is being captured. It returns true when the capturer count is large then 0.
####
`contents.incrementCapturerCount([size, stayHidden, stayAwake])`[](#contentsincrementcapturercountsize-stayhidden-stayawake "Direct link to heading")
* `size` [Size](structures/size) (optional) - The preferred size for the capturer.
* `stayHidden` boolean (optional) - Keep the page hidden instead of visible.
* `stayAwake` boolean (optional) - Keep the system awake instead of allowing it to sleep.
Increase the capturer count by one. The page is considered visible when its browser window is hidden and the capturer count is non-zero. If you would like the page to stay hidden, you should ensure that `stayHidden` is set to true.
This also affects the Page Visibility API.
####
`contents.decrementCapturerCount([stayHidden, stayAwake])`[](#contentsdecrementcapturercountstayhidden-stayawake "Direct link to heading")
* `stayHidden` boolean (optional) - Keep the page in hidden state instead of visible.
* `stayAwake` boolean (optional) - Keep the system awake instead of allowing it to sleep.
Decrease the capturer count by one. The page will be set to hidden or occluded state when its browser window is hidden or occluded and the capturer count reaches zero. If you want to decrease the hidden capturer count instead you should set `stayHidden` to true.
####
`contents.getPrinters()` *Deprecated*[](#contentsgetprinters-deprecated "Direct link to heading")
Get the system printer list.
Returns [PrinterInfo[]](structures/printer-info)
**Deprecated:** Should use the new [`contents.getPrintersAsync`](web-contents#contentsgetprintersasync) API.
####
`contents.getPrintersAsync()`[](#contentsgetprintersasync "Direct link to heading")
Get the system printer list.
Returns `Promise<PrinterInfo[]>` - Resolves with a [PrinterInfo[]](structures/printer-info)
####
`contents.print([options], [callback])`[](#contentsprintoptions-callback "Direct link to heading")
* `options` Object (optional)
+ `silent` boolean (optional) - Don't ask user for print settings. Default is `false`.
+ `printBackground` boolean (optional) - Prints the background color and image of the web page. Default is `false`.
+ `deviceName` string (optional) - Set the printer device name to use. Must be the system-defined name and not the 'friendly' name, e.g 'Brother\_QL\_820NWB' and not 'Brother QL-820NWB'.
+ `color` boolean (optional) - Set whether the printed web page will be in color or grayscale. Default is `true`.
+ `margins` Object (optional)
- `marginType` string (optional) - Can be `default`, `none`, `printableArea`, or `custom`. If `custom` is chosen, you will also need to specify `top`, `bottom`, `left`, and `right`.
- `top` number (optional) - The top margin of the printed web page, in pixels.
- `bottom` number (optional) - The bottom margin of the printed web page, in pixels.
- `left` number (optional) - The left margin of the printed web page, in pixels.
- `right` number (optional) - The right margin of the printed web page, in pixels.
+ `landscape` boolean (optional) - Whether the web page should be printed in landscape mode. Default is `false`.
+ `scaleFactor` number (optional) - The scale factor of the web page.
+ `pagesPerSheet` number (optional) - The number of pages to print per page sheet.
+ `collate` boolean (optional) - Whether the web page should be collated.
+ `copies` number (optional) - The number of copies of the web page to print.
+ `pageRanges` Object[] (optional) - The page range to print. On macOS, only one range is honored.
- `from` number - Index of the first page to print (0-based).
- `to` number - Index of the last page to print (inclusive) (0-based).
+ `duplexMode` string (optional) - Set the duplex mode of the printed web page. Can be `simplex`, `shortEdge`, or `longEdge`.
+ `dpi` Record<string, number> (optional)
- `horizontal` number (optional) - The horizontal dpi.
- `vertical` number (optional) - The vertical dpi.
+ `header` string (optional) - string to be printed as page header.
+ `footer` string (optional) - string to be printed as page footer.
+ `pageSize` string | Size (optional) - Specify page size of the printed document. Can be `A3`, `A4`, `A5`, `Legal`, `Letter`, `Tabloid` or an Object containing `height`.
* `callback` Function (optional)
+ `success` boolean - Indicates success of the print call.
+ `failureReason` string - Error description called back if the print fails.
When a custom `pageSize` is passed, Chromium attempts to validate platform specific minimum values for `width_microns` and `height_microns`. Width and height must both be minimum 353 microns but may be higher on some operating systems.
Prints window's web page. When `silent` is set to `true`, Electron will pick the system's default printer if `deviceName` is empty and the default settings for printing.
Use `page-break-before: always;` CSS style to force to print to a new page.
Example usage:
```
const options = {
silent: true,
deviceName: 'My-Printer',
pageRanges: [{
from: 0,
to: 1
}]
}
win.webContents.print(options, (success, errorType) => {
if (!success) console.log(errorType)
})
```
####
`contents.printToPDF(options)`[](#contentsprinttopdfoptions "Direct link to heading")
* `options` Object
+ `headerFooter` Record<string, string> (optional) - the header and footer for the PDF.
- `title` string - The title for the PDF header.
- `url` string - the url for the PDF footer.
+ `landscape` boolean (optional) - `true` for landscape, `false` for portrait.
+ `marginsType` Integer (optional) - Specifies the type of margins to use. Uses 0 for default margin, 1 for no margin, and 2 for minimum margin.
+ `scaleFactor` number (optional) - The scale factor of the web page. Can range from 0 to 100.
+ `pageRanges` Record<string, number> (optional) - The page range to print.
- `from` number - Index of the first page to print (0-based).
- `to` number - Index of the last page to print (inclusive) (0-based).
+ `pageSize` string | Size (optional) - Specify page size of the generated PDF. Can be `A3`, `A4`, `A5`, `Legal`, `Letter`, `Tabloid` or an Object containing `height` and `width` in microns.
+ `printBackground` boolean (optional) - Whether to print CSS backgrounds.
+ `printSelectionOnly` boolean (optional) - Whether to print selection only.
Returns `Promise<Buffer>` - Resolves with the generated PDF data.
Prints window's web page as PDF with Chromium's preview printing custom settings.
The `landscape` will be ignored if `@page` CSS at-rule is used in the web page.
By default, an empty `options` will be regarded as:
```
{
marginsType: 0,
printBackground: false,
printSelectionOnly: false,
landscape: false,
pageSize: 'A4',
scaleFactor: 100
}
```
Use `page-break-before: always;` CSS style to force to print to a new page.
An example of `webContents.printToPDF`:
```
const { BrowserWindow } = require('electron')
const fs = require('fs')
const path = require('path')
const os = require('os')
const win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL('http://github.com')
win.webContents.on('did-finish-load', () => {
// Use default printing options
const pdfPath = path.join(os.homedir(), 'Desktop', 'temp.pdf')
win.webContents.printToPDF({}).then(data => {
fs.writeFile(pdfPath, data, (error) => {
if (error) throw error
console.log(`Wrote PDF successfully to ${pdfPath}`)
})
}).catch(error => {
console.log(`Failed to write PDF to ${pdfPath}: `, error)
})
})
```
####
`contents.addWorkSpace(path)`[](#contentsaddworkspacepath "Direct link to heading")
* `path` string
Adds the specified path to DevTools workspace. Must be used after DevTools creation:
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.webContents.on('devtools-opened', () => {
win.webContents.addWorkSpace(__dirname)
})
```
####
`contents.removeWorkSpace(path)`[](#contentsremoveworkspacepath "Direct link to heading")
* `path` string
Removes the specified path from DevTools workspace.
####
`contents.setDevToolsWebContents(devToolsWebContents)`[](#contentssetdevtoolswebcontentsdevtoolswebcontents "Direct link to heading")
* `devToolsWebContents` WebContents
Uses the `devToolsWebContents` as the target `WebContents` to show devtools.
The `devToolsWebContents` must not have done any navigation, and it should not be used for other purposes after the call.
By default Electron manages the devtools by creating an internal `WebContents` with native view, which developers have very limited control of. With the `setDevToolsWebContents` method, developers can use any `WebContents` to show the devtools in it, including `BrowserWindow`, `BrowserView` and `<webview>` tag.
Note that closing the devtools does not destroy the `devToolsWebContents`, it is caller's responsibility to destroy `devToolsWebContents`.
An example of showing devtools in a `<webview>` tag:
```
<html>
<head>
<style type="text/css">
* { margin: 0; }
#browser { height: 70%; }
#devtools { height: 30%; }
</style>
</head>
<body>
<webview id="browser" src="https://github.com"></webview>
<webview id="devtools" src="about:blank"></webview>
<script>
const { ipcRenderer } = require('electron')
const emittedOnce = (element, eventName) => new Promise(resolve => {
element.addEventListener(eventName, event => resolve(event), { once: true })
})
const browserView = document.getElementById('browser')
const devtoolsView = document.getElementById('devtools')
const browserReady = emittedOnce(browserView, 'dom-ready')
const devtoolsReady = emittedOnce(devtoolsView, 'dom-ready')
Promise.all([browserReady, devtoolsReady]).then(() => {
const targetId = browserView.getWebContentsId()
const devtoolsId = devtoolsView.getWebContentsId()
ipcRenderer.send('open-devtools', targetId, devtoolsId)
})
</script>
</body>
</html>
```
```
// Main process
const { ipcMain, webContents } = require('electron')
ipcMain.on('open-devtools', (event, targetContentsId, devtoolsContentsId) => {
const target = webContents.fromId(targetContentsId)
const devtools = webContents.fromId(devtoolsContentsId)
target.setDevToolsWebContents(devtools)
target.openDevTools()
})
```
An example of showing devtools in a `BrowserWindow`:
```
const { app, BrowserWindow } = require('electron')
let win = null
let devtools = null
app.whenReady().then(() => {
win = new BrowserWindow()
devtools = new BrowserWindow()
win.loadURL('https://github.com')
win.webContents.setDevToolsWebContents(devtools.webContents)
win.webContents.openDevTools({ mode: 'detach' })
})
```
####
`contents.openDevTools([options])`[](#contentsopendevtoolsoptions "Direct link to heading")
* `options` Object (optional)
+ `mode` string - Opens the devtools with specified dock state, can be `left`, `right`, `bottom`, `undocked`, `detach`. Defaults to last used dock state. In `undocked` mode it's possible to dock back. In `detach` mode it's not.
+ `activate` boolean (optional) - Whether to bring the opened devtools window to the foreground. The default is `true`.
Opens the devtools.
When `contents` is a `<webview>` tag, the `mode` would be `detach` by default, explicitly passing an empty `mode` can force using last used dock state.
On Windows, if Windows Control Overlay is enabled, Devtools will be opened with `mode: 'detach'`.
####
`contents.closeDevTools()`[](#contentsclosedevtools "Direct link to heading")
Closes the devtools.
####
`contents.isDevToolsOpened()`[](#contentsisdevtoolsopened "Direct link to heading")
Returns `boolean` - Whether the devtools is opened.
####
`contents.isDevToolsFocused()`[](#contentsisdevtoolsfocused "Direct link to heading")
Returns `boolean` - Whether the devtools view is focused .
####
`contents.toggleDevTools()`[](#contentstoggledevtools "Direct link to heading")
Toggles the developer tools.
####
`contents.inspectElement(x, y)`[](#contentsinspectelementx-y "Direct link to heading")
* `x` Integer
* `y` Integer
Starts inspecting element at position (`x`, `y`).
####
`contents.inspectSharedWorker()`[](#contentsinspectsharedworker "Direct link to heading")
Opens the developer tools for the shared worker context.
####
`contents.inspectSharedWorkerById(workerId)`[](#contentsinspectsharedworkerbyidworkerid "Direct link to heading")
* `workerId` string
Inspects the shared worker based on its ID.
####
`contents.getAllSharedWorkers()`[](#contentsgetallsharedworkers "Direct link to heading")
Returns [SharedWorkerInfo[]](structures/shared-worker-info) - Information about all Shared Workers.
####
`contents.inspectServiceWorker()`[](#contentsinspectserviceworker "Direct link to heading")
Opens the developer tools for the service worker context.
####
`contents.send(channel, ...args)`[](#contentssendchannel-args "Direct link to heading")
* `channel` string
* `...args` any[]
Send an asynchronous message to the renderer process via `channel`, along with arguments. Arguments will be serialized with the [Structured Clone Algorithm](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm), just like [`postMessage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage), so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.
> **NOTE**: Sending non-standard JavaScript types such as DOM objects or special Electron objects will throw an exception.
>
>
The renderer process can handle the message by listening to `channel` with the [`ipcRenderer`](ipc-renderer) module.
An example of sending messages from the main process to the renderer process:
```
// In the main process.
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL(`file://${__dirname}/index.html`)
win.webContents.on('did-finish-load', () => {
win.webContents.send('ping', 'whoooooooh!')
})
})
```
```
<!-- index.html -->
<html>
<body>
<script>
require('electron').ipcRenderer.on('ping', (event, message) => {
console.log(message) // Prints 'whoooooooh!'
})
</script>
</body>
</html>
```
####
`contents.sendToFrame(frameId, channel, ...args)`[](#contentssendtoframeframeid-channel-args "Direct link to heading")
* `frameId` Integer | [number, number] - the ID of the frame to send to, or a pair of `[processId, frameId]` if the frame is in a different process to the main frame.
* `channel` string
* `...args` any[]
Send an asynchronous message to a specific frame in a renderer process via `channel`, along with arguments. Arguments will be serialized with the [Structured Clone Algorithm](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm), just like [`postMessage`](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage), so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.
> **NOTE:** Sending non-standard JavaScript types such as DOM objects or special Electron objects will throw an exception.
>
>
The renderer process can handle the message by listening to `channel` with the [`ipcRenderer`](ipc-renderer) module.
If you want to get the `frameId` of a given renderer context you should use the `webFrame.routingId` value. E.g.
```
// In a renderer process
console.log('My frameId is:', require('electron').webFrame.routingId)
```
You can also read `frameId` from all incoming IPC messages in the main process.
```
// In the main process
ipcMain.on('ping', (event) => {
console.info('Message came from frameId:', event.frameId)
})
```
####
`contents.postMessage(channel, message, [transfer])`[](#contentspostmessagechannel-message-transfer "Direct link to heading")
* `channel` string
* `message` any
* `transfer` MessagePortMain[] (optional)
Send a message to the renderer process, optionally transferring ownership of zero or more [`MessagePortMain`][] objects.
The transferred `MessagePortMain` objects will be available in the renderer process by accessing the `ports` property of the emitted event. When they arrive in the renderer, they will be native DOM `MessagePort` objects.
For example:
```
// Main process
const { port1, port2 } = new MessageChannelMain()
webContents.postMessage('port', { message: 'hello' }, [port1])
// Renderer process
ipcRenderer.on('port', (e, msg) => {
const [port] = e.ports
// ...
})
```
####
`contents.enableDeviceEmulation(parameters)`[](#contentsenabledeviceemulationparameters "Direct link to heading")
* `parameters` Object
+ `screenPosition` string - Specify the screen type to emulate (default: `desktop`):
- `desktop` - Desktop screen type.
- `mobile` - Mobile screen type.
+ `screenSize` [Size](structures/size) - Set the emulated screen size (screenPosition == mobile).
+ `viewPosition` [Point](structures/point) - Position the view on the screen (screenPosition == mobile) (default: `{ x: 0, y: 0 }`).
+ `deviceScaleFactor` Integer - Set the device scale factor (if zero defaults to original device scale factor) (default: `0`).
+ `viewSize` [Size](structures/size) - Set the emulated view size (empty means no override)
+ `scale` Float - Scale of emulated view inside available space (not in fit to view mode) (default: `1`).
Enable device emulation with the given parameters.
####
`contents.disableDeviceEmulation()`[](#contentsdisabledeviceemulation "Direct link to heading")
Disable device emulation enabled by `webContents.enableDeviceEmulation`.
####
`contents.sendInputEvent(inputEvent)`[](#contentssendinputeventinputevent "Direct link to heading")
* `inputEvent` [MouseInputEvent](structures/mouse-input-event) | [MouseWheelInputEvent](structures/mouse-wheel-input-event) | [KeyboardInputEvent](structures/keyboard-input-event)
Sends an input `event` to the page. **Note:** The [`BrowserWindow`](browser-window) containing the contents needs to be focused for `sendInputEvent()` to work.
####
`contents.beginFrameSubscription([onlyDirty ,]callback)`[](#contentsbeginframesubscriptiononlydirty-callback "Direct link to heading")
* `onlyDirty` boolean (optional) - Defaults to `false`.
* `callback` Function
+ `image` [NativeImage](native-image)
+ `dirtyRect` [Rectangle](structures/rectangle)
Begin subscribing for presentation events and captured frames, the `callback` will be called with `callback(image, dirtyRect)` when there is a presentation event.
The `image` is an instance of [NativeImage](native-image) that stores the captured frame.
The `dirtyRect` is an object with `x, y, width, height` properties that describes which part of the page was repainted. If `onlyDirty` is set to `true`, `image` will only contain the repainted area. `onlyDirty` defaults to `false`.
####
`contents.endFrameSubscription()`[](#contentsendframesubscription "Direct link to heading")
End subscribing for frame presentation events.
####
`contents.startDrag(item)`[](#contentsstartdragitem "Direct link to heading")
* `item` Object
+ `file` string - The path to the file being dragged.
+ `files` string[] (optional) - The paths to the files being dragged. (`files` will override `file` field)
+ `icon` [NativeImage](native-image) | string - The image must be non-empty on macOS.
Sets the `item` as dragging item for current drag-drop operation, `file` is the absolute path of the file to be dragged, and `icon` is the image showing under the cursor when dragging.
####
`contents.savePage(fullPath, saveType)`[](#contentssavepagefullpath-savetype "Direct link to heading")
* `fullPath` string - The absolute file path.
* `saveType` string - Specify the save type.
+ `HTMLOnly` - Save only the HTML of the page.
+ `HTMLComplete` - Save complete-html page.
+ `MHTML` - Save complete-html page as MHTML.
Returns `Promise<void>` - resolves if the page is saved.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.loadURL('https://github.com')
win.webContents.on('did-finish-load', async () => {
win.webContents.savePage('/tmp/test.html', 'HTMLComplete').then(() => {
console.log('Page was saved successfully.')
}).catch(err => {
console.log(err)
})
})
```
####
`contents.showDefinitionForSelection()` *macOS*[](#contentsshowdefinitionforselection-macos "Direct link to heading")
Shows pop-up dictionary that searches the selected word on the page.
####
`contents.isOffscreen()`[](#contentsisoffscreen "Direct link to heading")
Returns `boolean` - Indicates whether *offscreen rendering* is enabled.
####
`contents.startPainting()`[](#contentsstartpainting "Direct link to heading")
If *offscreen rendering* is enabled and not painting, start painting.
####
`contents.stopPainting()`[](#contentsstoppainting "Direct link to heading")
If *offscreen rendering* is enabled and painting, stop painting.
####
`contents.isPainting()`[](#contentsispainting "Direct link to heading")
Returns `boolean` - If *offscreen rendering* is enabled returns whether it is currently painting.
####
`contents.setFrameRate(fps)`[](#contentssetframeratefps "Direct link to heading")
* `fps` Integer
If *offscreen rendering* is enabled sets the frame rate to the specified number. Only values between 1 and 240 are accepted.
####
`contents.getFrameRate()`[](#contentsgetframerate "Direct link to heading")
Returns `Integer` - If *offscreen rendering* is enabled returns the current frame rate.
####
`contents.invalidate()`[](#contentsinvalidate "Direct link to heading")
Schedules a full repaint of the window this web contents is in.
If *offscreen rendering* is enabled invalidates the frame and generates a new one through the `'paint'` event.
####
`contents.getWebRTCIPHandlingPolicy()`[](#contentsgetwebrtciphandlingpolicy "Direct link to heading")
Returns `string` - Returns the WebRTC IP Handling Policy.
####
`contents.setWebRTCIPHandlingPolicy(policy)`[](#contentssetwebrtciphandlingpolicypolicy "Direct link to heading")
* `policy` string - Specify the WebRTC IP Handling Policy.
+ `default` - Exposes user's public and local IPs. This is the default behavior. When this policy is used, WebRTC has the right to enumerate all interfaces and bind them to discover public interfaces.
+ `default_public_interface_only` - Exposes user's public IP, but does not expose user's local IP. When this policy is used, WebRTC should only use the default route used by http. This doesn't expose any local addresses.
+ `default_public_and_private_interfaces` - Exposes user's public and local IPs. When this policy is used, WebRTC should only use the default route used by http. This also exposes the associated default private address. Default route is the route chosen by the OS on a multi-homed endpoint.
+ `disable_non_proxied_udp` - Does not expose public or local IPs. When this policy is used, WebRTC should only use TCP to contact peers or servers unless the proxy server supports UDP.
Setting the WebRTC IP handling policy allows you to control which IPs are exposed via WebRTC. See [BrowserLeaks](https://browserleaks.com/webrtc) for more details.
####
`contents.getMediaSourceId(requestWebContents)`[](#contentsgetmediasourceidrequestwebcontents "Direct link to heading")
* `requestWebContents` WebContents - Web contents that the id will be registered to.
Returns `string` - The identifier of a WebContents stream. This identifier can be used with `navigator.mediaDevices.getUserMedia` using a `chromeMediaSource` of `tab`. The identifier is restricted to the web contents that it is registered to and is only valid for 10 seconds.
####
`contents.getOSProcessId()`[](#contentsgetosprocessid "Direct link to heading")
Returns `Integer` - The operating system `pid` of the associated renderer process.
####
`contents.getProcessId()`[](#contentsgetprocessid "Direct link to heading")
Returns `Integer` - The Chromium internal `pid` of the associated renderer. Can be compared to the `frameProcessId` passed by frame specific navigation events (e.g. `did-frame-navigate`)
####
`contents.takeHeapSnapshot(filePath)`[](#contentstakeheapsnapshotfilepath "Direct link to heading")
* `filePath` string - Path to the output file.
Returns `Promise<void>` - Indicates whether the snapshot has been created successfully.
Takes a V8 heap snapshot and saves it to `filePath`.
####
`contents.getBackgroundThrottling()`[](#contentsgetbackgroundthrottling "Direct link to heading")
Returns `boolean` - whether or not this WebContents will throttle animations and timers when the page becomes backgrounded. This also affects the Page Visibility API.
####
`contents.setBackgroundThrottling(allowed)`[](#contentssetbackgroundthrottlingallowed "Direct link to heading")
* `allowed` boolean
Controls whether or not this WebContents will throttle animations and timers when the page becomes backgrounded. This also affects the Page Visibility API.
####
`contents.getType()`[](#contentsgettype "Direct link to heading")
Returns `string` - the type of the webContent. Can be `backgroundPage`, `window`, `browserView`, `remote`, `webview` or `offscreen`.
####
`contents.setImageAnimationPolicy(policy)`[](#contentssetimageanimationpolicypolicy "Direct link to heading")
* `policy` string - Can be `animate`, `animateOnce` or `noAnimation`.
Sets the image animation policy for this webContents. The policy only affects *new* images, existing images that are currently being animated are unaffected. This is a known limitation in Chromium, you can force image animation to be recalculated with `img.src = img.src` which will result in no network traffic but will update the animation policy.
This corresponds to the [animationPolicy](https://developer.chrome.com/docs/extensions/reference/accessibilityFeatures/#property-animationPolicy) accessibility feature in Chromium.
### Instance Properties[](#instance-properties "Direct link to heading")
####
`contents.audioMuted`[](#contentsaudiomuted "Direct link to heading")
A `boolean` property that determines whether this page is muted.
####
`contents.userAgent`[](#contentsuseragent "Direct link to heading")
A `string` property that determines the user agent for this web page.
####
`contents.zoomLevel`[](#contentszoomlevel "Direct link to heading")
A `number` property that determines the zoom level for this web contents.
The original size is 0 and each increment above or below represents zooming 20% larger or smaller to default limits of 300% and 50% of original size, respectively. The formula for this is `scale := 1.2 ^ level`.
####
`contents.zoomFactor`[](#contentszoomfactor "Direct link to heading")
A `number` property that determines the zoom factor for this web contents.
The zoom factor is the zoom percent divided by 100, so 300% = 3.0.
####
`contents.frameRate`[](#contentsframerate "Direct link to heading")
An `Integer` property that sets the frame rate of the web contents to the specified number. Only values between 1 and 240 are accepted.
Only applicable if *offscreen rendering* is enabled.
####
`contents.id` *Readonly*[](#contentsid-readonly "Direct link to heading")
A `Integer` representing the unique ID of this WebContents. Each ID is unique among all `WebContents` instances of the entire Electron application.
####
`contents.session` *Readonly*[](#contentssession-readonly "Direct link to heading")
A [`Session`](session) used by this webContents.
####
`contents.hostWebContents` *Readonly*[](#contentshostwebcontents-readonly "Direct link to heading")
A [`WebContents`](web-contents) instance that might own this `WebContents`.
####
`contents.devToolsWebContents` *Readonly*[](#contentsdevtoolswebcontents-readonly "Direct link to heading")
A `WebContents | null` property that represents the of DevTools `WebContents` associated with a given `WebContents`.
**Note:** Users should never store this object because it may become `null` when the DevTools has been closed.
####
`contents.debugger` *Readonly*[](#contentsdebugger-readonly "Direct link to heading")
A [`Debugger`](debugger) instance for this webContents.
####
`contents.backgroundThrottling`[](#contentsbackgroundthrottling "Direct link to heading")
A `boolean` property that determines whether or not this WebContents will throttle animations and timers when the page becomes backgrounded. This also affects the Page Visibility API.
####
`contents.mainFrame` *Readonly*[](#contentsmainframe-readonly "Direct link to heading")
A [`WebFrameMain`](web-frame-main) property that represents the top frame of the page's frame hierarchy.
| programming_docs |
electron Class: MenuItem Class: MenuItem[](#class-menuitem "Direct link to heading")
------------------------------------------------------------
> Add items to native application menus and context menus.
>
>
Process: [Main](../glossary#main-process)
See [`Menu`](menu) for examples.
###
`new MenuItem(options)`[](#new-menuitemoptions "Direct link to heading")
* `options` Object
+ `click` Function (optional) - Will be called with `click(menuItem, browserWindow, event)` when the menu item is clicked.
- `menuItem` MenuItem
- `browserWindow` [BrowserWindow](browser-window) | undefined - This will not be defined if no window is open.
- `event` [KeyboardEvent](structures/keyboard-event)
+ `role` string (optional) - Can be `undo`, `redo`, `cut`, `copy`, `paste`, `pasteAndMatchStyle`, `delete`, `selectAll`, `reload`, `forceReload`, `toggleDevTools`, `resetZoom`, `zoomIn`, `zoomOut`, `toggleSpellChecker`, `togglefullscreen`, `window`, `minimize`, `close`, `help`, `about`, `services`, `hide`, `hideOthers`, `unhide`, `quit`, 'showSubstitutions', 'toggleSmartQuotes', 'toggleSmartDashes', 'toggleTextReplacement', `startSpeaking`, `stopSpeaking`, `zoom`, `front`, `appMenu`, `fileMenu`, `editMenu`, `viewMenu`, `shareMenu`, `recentDocuments`, `toggleTabBar`, `selectNextTab`, `selectPreviousTab`, `mergeAllWindows`, `clearRecentDocuments`, `moveTabToNewWindow` or `windowMenu` - Define the action of the menu item, when specified the `click` property will be ignored. See [roles](#roles).
+ `type` string (optional) - Can be `normal`, `separator`, `submenu`, `checkbox` or `radio`.
+ `label` string (optional)
+ `sublabel` string (optional)
+ `toolTip` string (optional) *macOS* - Hover text for this menu item.
+ `accelerator` [Accelerator](accelerator) (optional)
+ `icon` ([NativeImage](native-image) | string) (optional)
+ `enabled` boolean (optional) - If false, the menu item will be greyed out and unclickable.
+ `acceleratorWorksWhenHidden` boolean (optional) *macOS* - default is `true`, and when `false` will prevent the accelerator from triggering the item if the item is not visible`.
+ `visible` boolean (optional) - If false, the menu item will be entirely hidden.
+ `checked` boolean (optional) - Should only be specified for `checkbox` or `radio` type menu items.
+ `registerAccelerator` boolean (optional) *Linux* *Windows* - If false, the accelerator won't be registered with the system, but it will still be displayed. Defaults to true.
+ `sharingItem` SharingItem (optional) *macOS* - The item to share when the `role` is `shareMenu`.
+ `submenu` (MenuItemConstructorOptions[] | [Menu](menu)) (optional) - Should be specified for `submenu` type menu items. If `submenu` is specified, the `type: 'submenu'` can be omitted. If the value is not a [`Menu`](menu) then it will be automatically converted to one using `Menu.buildFromTemplate`.
+ `id` string (optional) - Unique within a single menu. If defined then it can be used as a reference to this item by the position attribute.
+ `before` string[] (optional) - Inserts this item before the item with the specified label. If the referenced item doesn't exist the item will be inserted at the end of the menu. Also implies that the menu item in question should be placed in the same “group” as the item.
+ `after` string[] (optional) - Inserts this item after the item with the specified label. If the referenced item doesn't exist the item will be inserted at the end of the menu.
+ `beforeGroupContaining` string[] (optional) - Provides a means for a single context menu to declare the placement of their containing group before the containing group of the item with the specified label.
+ `afterGroupContaining` string[] (optional) - Provides a means for a single context menu to declare the placement of their containing group after the containing group of the item with the specified label.
**Note:** `acceleratorWorksWhenHidden` is specified as being macOS-only because accelerators always work when items are hidden on Windows and Linux. The option is exposed to users to give them the option to turn it off, as this is possible in native macOS development. This property is only usable on macOS High Sierra 10.13 or newer.
### Roles[](#roles "Direct link to heading")
Roles allow menu items to have predefined behaviors.
It is best to specify `role` for any menu item that matches a standard role, rather than trying to manually implement the behavior in a `click` function. The built-in `role` behavior will give the best native experience.
The `label` and `accelerator` values are optional when using a `role` and will default to appropriate values for each platform.
Every menu item must have either a `role`, `label`, or in the case of a separator a `type`.
The `role` property can have following values:
* `undo`
* `about` - Trigger a native about panel (custom message box on Window, which does not provide its own).
* `redo`
* `cut`
* `copy`
* `paste`
* `pasteAndMatchStyle`
* `selectAll`
* `delete`
* `minimize` - Minimize current window.
* `close` - Close current window.
* `quit` - Quit the application.
* `reload` - Reload the current window.
* `forceReload` - Reload the current window ignoring the cache.
* `toggleDevTools` - Toggle developer tools in the current window.
* `togglefullscreen` - Toggle full screen mode on the current window.
* `resetZoom` - Reset the focused page's zoom level to the original size.
* `zoomIn` - Zoom in the focused page by 10%.
* `zoomOut` - Zoom out the focused page by 10%.
* `toggleSpellChecker` - Enable/disable builtin spell checker.
* `fileMenu` - Whole default "File" menu (Close / Quit)
* `editMenu` - Whole default "Edit" menu (Undo, Copy, etc.).
* `viewMenu` - Whole default "View" menu (Reload, Toggle Developer Tools, etc.)
* `windowMenu` - Whole default "Window" menu (Minimize, Zoom, etc.).
The following additional roles are available on *macOS*:
* `appMenu` - Whole default "App" menu (About, Services, etc.)
* `hide` - Map to the `hide` action.
* `hideOthers` - Map to the `hideOtherApplications` action.
* `unhide` - Map to the `unhideAllApplications` action.
* `showSubstitutions` - Map to the `orderFrontSubstitutionsPanel` action.
* `toggleSmartQuotes` - Map to the `toggleAutomaticQuoteSubstitution` action.
* `toggleSmartDashes` - Map to the `toggleAutomaticDashSubstitution` action.
* `toggleTextReplacement` - Map to the `toggleAutomaticTextReplacement` action.
* `startSpeaking` - Map to the `startSpeaking` action.
* `stopSpeaking` - Map to the `stopSpeaking` action.
* `front` - Map to the `arrangeInFront` action.
* `zoom` - Map to the `performZoom` action.
* `toggleTabBar` - Map to the `toggleTabBar` action.
* `selectNextTab` - Map to the `selectNextTab` action.
* `selectPreviousTab` - Map to the `selectPreviousTab` action.
* `mergeAllWindows` - Map to the `mergeAllWindows` action.
* `moveTabToNewWindow` - Map to the `moveTabToNewWindow` action.
* `window` - The submenu is a "Window" menu.
* `help` - The submenu is a "Help" menu.
* `services` - The submenu is a ["Services"](https://developer.apple.com/documentation/appkit/nsapplication/1428608-servicesmenu?language=objc) menu. This is only intended for use in the Application Menu and is *not* the same as the "Services" submenu used in context menus in macOS apps, which is not implemented in Electron.
* `recentDocuments` - The submenu is an "Open Recent" menu.
* `clearRecentDocuments` - Map to the `clearRecentDocuments` action.
* `shareMenu` - The submenu is [share menu](https://developer.apple.com/design/human-interface-guidelines/macos/extensions/share-extensions/). The `sharingItem` property must also be set to indicate the item to share.
When specifying a `role` on macOS, `label` and `accelerator` are the only options that will affect the menu item. All other options will be ignored. Lowercase `role`, e.g. `toggledevtools`, is still supported.
**Note:** The `enabled` and `visibility` properties are not available for top-level menu items in the tray on macOS.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `MenuItem`:
####
`menuItem.id`[](#menuitemid "Direct link to heading")
A `string` indicating the item's unique id, this property can be dynamically changed.
####
`menuItem.label`[](#menuitemlabel "Direct link to heading")
A `string` indicating the item's visible label.
####
`menuItem.click`[](#menuitemclick "Direct link to heading")
A `Function` that is fired when the MenuItem receives a click event. It can be called with `menuItem.click(event, focusedWindow, focusedWebContents)`.
* `event` [KeyboardEvent](structures/keyboard-event)
* `focusedWindow` [BrowserWindow](browser-window)
* `focusedWebContents` [WebContents](web-contents)
####
`menuItem.submenu`[](#menuitemsubmenu "Direct link to heading")
A `Menu` (optional) containing the menu item's submenu, if present.
####
`menuItem.type`[](#menuitemtype "Direct link to heading")
A `string` indicating the type of the item. Can be `normal`, `separator`, `submenu`, `checkbox` or `radio`.
####
`menuItem.role`[](#menuitemrole "Direct link to heading")
A `string` (optional) indicating the item's role, if set. Can be `undo`, `redo`, `cut`, `copy`, `paste`, `pasteAndMatchStyle`, `delete`, `selectAll`, `reload`, `forceReload`, `toggleDevTools`, `resetZoom`, `zoomIn`, `zoomOut`, `toggleSpellChecker`, `togglefullscreen`, `window`, `minimize`, `close`, `help`, `about`, `services`, `hide`, `hideOthers`, `unhide`, `quit`, `startSpeaking`, `stopSpeaking`, `zoom`, `front`, `appMenu`, `fileMenu`, `editMenu`, `viewMenu`, `shareMenu`, `recentDocuments`, `toggleTabBar`, `selectNextTab`, `selectPreviousTab`, `mergeAllWindows`, `clearRecentDocuments`, `moveTabToNewWindow` or `windowMenu`
####
`menuItem.accelerator`[](#menuitemaccelerator "Direct link to heading")
An `Accelerator` (optional) indicating the item's accelerator, if set.
####
`menuItem.userAccelerator` *Readonly* *macOS*[](#menuitemuseraccelerator-readonly-macos "Direct link to heading")
An `Accelerator | null` indicating the item's [user-assigned accelerator](https://developer.apple.com/documentation/appkit/nsmenuitem/1514850-userkeyequivalent?language=objc) for the menu item.
**Note:** This property is only initialized after the `MenuItem` has been added to a `Menu`. Either via `Menu.buildFromTemplate` or via `Menu.append()/insert()`. Accessing before initialization will just return `null`.
####
`menuItem.icon`[](#menuitemicon "Direct link to heading")
A `NativeImage | string` (optional) indicating the item's icon, if set.
####
`menuItem.sublabel`[](#menuitemsublabel "Direct link to heading")
A `string` indicating the item's sublabel.
####
`menuItem.toolTip` *macOS*[](#menuitemtooltip-macos "Direct link to heading")
A `string` indicating the item's hover text.
####
`menuItem.enabled`[](#menuitemenabled "Direct link to heading")
A `boolean` indicating whether the item is enabled, this property can be dynamically changed.
####
`menuItem.visible`[](#menuitemvisible "Direct link to heading")
A `boolean` indicating whether the item is visible, this property can be dynamically changed.
####
`menuItem.checked`[](#menuitemchecked "Direct link to heading")
A `boolean` indicating whether the item is checked, this property can be dynamically changed.
A `checkbox` menu item will toggle the `checked` property on and off when selected.
A `radio` menu item will turn on its `checked` property when clicked, and will turn off that property for all adjacent items in the same menu.
You can add a `click` function for additional behavior.
####
`menuItem.registerAccelerator`[](#menuitemregisteraccelerator "Direct link to heading")
A `boolean` indicating if the accelerator should be registered with the system or just displayed.
This property can be dynamically changed.
####
`menuItem.sharingItem` *macOS*[](#menuitemsharingitem-macos "Direct link to heading")
A `SharingItem` indicating the item to share when the `role` is `shareMenu`.
This property can be dynamically changed.
####
`menuItem.commandId`[](#menuitemcommandid "Direct link to heading")
A `number` indicating an item's sequential unique id.
####
`menuItem.menu`[](#menuitemmenu "Direct link to heading")
A `Menu` that the item is a part of.
electron Class: TouchBarButton Class: TouchBarButton[](#class-touchbarbutton "Direct link to heading")
------------------------------------------------------------------------
> Create a button in the touch bar for native macOS applications
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarButton(options)`[](#new-touchbarbuttonoptions "Direct link to heading")
* `options` Object
+ `label` string (optional) - Button text.
+ `accessibilityLabel` string (optional) - A short description of the button for use by screenreaders like VoiceOver.
+ `backgroundColor` string (optional) - Button background color in hex format, i.e `#ABCDEF`.
+ `icon` [NativeImage](native-image) | string (optional) - Button icon.
+ `iconPosition` string (optional) - Can be `left`, `right` or `overlay`. Defaults to `overlay`.
+ `click` Function (optional) - Function to call when the button is clicked.
+ `enabled` boolean (optional) - Whether the button is in an enabled state. Default is `true`.
When defining `accessibilityLabel`, ensure you have considered macOS [best practices](https://developer.apple.com/documentation/appkit/nsaccessibilitybutton/1524910-accessibilitylabel?language=objc).
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBarButton`:
####
`touchBarButton.accessibilityLabel`[](#touchbarbuttonaccessibilitylabel "Direct link to heading")
A `string` representing the description of the button to be read by a screen reader. Will only be read by screen readers if no label is set.
####
`touchBarButton.label`[](#touchbarbuttonlabel "Direct link to heading")
A `string` representing the button's current text. Changing this value immediately updates the button in the touch bar.
####
`touchBarButton.backgroundColor`[](#touchbarbuttonbackgroundcolor "Direct link to heading")
A `string` hex code representing the button's current background color. Changing this value immediately updates the button in the touch bar.
####
`touchBarButton.icon`[](#touchbarbuttonicon "Direct link to heading")
A `NativeImage` representing the button's current icon. Changing this value immediately updates the button in the touch bar.
####
`touchBarButton.iconPosition`[](#touchbarbuttoniconposition "Direct link to heading")
A `string` - Can be `left`, `right` or `overlay`. Defaults to `overlay`.
####
`touchBarButton.enabled`[](#touchbarbuttonenabled "Direct link to heading")
A `boolean` representing whether the button is in an enabled state.
electron Class: TouchBarOtherItemsProxy Class: TouchBarOtherItemsProxy[](#class-touchbarotheritemsproxy "Direct link to heading")
------------------------------------------------------------------------------------------
>
> Instantiates a special "other items proxy", which nests TouchBar elements inherited from Chromium at the space indicated by the proxy. By default, this proxy is added to each TouchBar at the end of the input. For more information, see the AppKit docs on [NSTouchBarItemIdentifierOtherItemsProxy](https://developer.apple.com/documentation/appkit/nstouchbaritemidentifierotheritemsproxy)
>
>
> Note: Only one instance of this class can be added per TouchBar.
>
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
###
`new TouchBarOtherItemsProxy()`[](#new-touchbarotheritemsproxy "Direct link to heading")
electron systemPreferences systemPreferences
=================
> Get system preferences.
>
>
Process: [Main](../glossary#main-process)
```
const { systemPreferences } = require('electron')
console.log(systemPreferences.isDarkMode())
```
Events[](#events "Direct link to heading")
-------------------------------------------
The `systemPreferences` object emits the following events:
### Event: 'accent-color-changed' *Windows*[](#event-accent-color-changed-windows "Direct link to heading")
Returns:
* `event` Event
* `newColor` string - The new RGBA color the user assigned to be their system accent color.
### Event: 'color-changed' *Windows*[](#event-color-changed-windows "Direct link to heading")
Returns:
* `event` Event
### Event: 'inverted-color-scheme-changed' *Windows* *Deprecated*[](#event-inverted-color-scheme-changed-windows-deprecated "Direct link to heading")
Returns:
* `event` Event
* `invertedColorScheme` boolean - `true` if an inverted color scheme (a high contrast color scheme with light text and dark backgrounds) is being used, `false` otherwise.
**Deprecated:** Should use the new [`updated`](native-theme#event-updated) event on the `nativeTheme` module.
### Event: 'high-contrast-color-scheme-changed' *Windows* *Deprecated*[](#event-high-contrast-color-scheme-changed-windows-deprecated "Direct link to heading")
Returns:
* `event` Event
* `highContrastColorScheme` boolean - `true` if a high contrast theme is being used, `false` otherwise.
**Deprecated:** Should use the new [`updated`](native-theme#event-updated) event on the `nativeTheme` module.
Methods[](#methods "Direct link to heading")
---------------------------------------------
###
`systemPreferences.isDarkMode()` *macOS* *Windows* *Deprecated*[](#systempreferencesisdarkmode-macos-windows-deprecated "Direct link to heading")
Returns `boolean` - Whether the system is in Dark Mode.
**Deprecated:** Should use the new [`nativeTheme.shouldUseDarkColors`](native-theme#nativethemeshouldusedarkcolors-readonly) API.
###
`systemPreferences.isSwipeTrackingFromScrollEventsEnabled()` *macOS*[](#systempreferencesisswipetrackingfromscrolleventsenabled-macos "Direct link to heading")
Returns `boolean` - Whether the Swipe between pages setting is on.
###
`systemPreferences.postNotification(event, userInfo[, deliverImmediately])` *macOS*[](#systempreferencespostnotificationevent-userinfo-deliverimmediately-macos "Direct link to heading")
* `event` string
* `userInfo` Record<string, any>
* `deliverImmediately` boolean (optional) - `true` to post notifications immediately even when the subscribing app is inactive.
Posts `event` as native notifications of macOS. The `userInfo` is an Object that contains the user information dictionary sent along with the notification.
###
`systemPreferences.postLocalNotification(event, userInfo)` *macOS*[](#systempreferencespostlocalnotificationevent-userinfo-macos "Direct link to heading")
* `event` string
* `userInfo` Record<string, any>
Posts `event` as native notifications of macOS. The `userInfo` is an Object that contains the user information dictionary sent along with the notification.
###
`systemPreferences.postWorkspaceNotification(event, userInfo)` *macOS*[](#systempreferencespostworkspacenotificationevent-userinfo-macos "Direct link to heading")
* `event` string
* `userInfo` Record<string, any>
Posts `event` as native notifications of macOS. The `userInfo` is an Object that contains the user information dictionary sent along with the notification.
###
`systemPreferences.subscribeNotification(event, callback)` *macOS*[](#systempreferencessubscribenotificationevent-callback-macos "Direct link to heading")
* `event` string | null
* `callback` Function
+ `event` string
+ `userInfo` Record<string, unknown>
+ `object` string
Returns `number` - The ID of this subscription
Subscribes to native notifications of macOS, `callback` will be called with `callback(event, userInfo)` when the corresponding `event` happens. The `userInfo` is an Object that contains the user information dictionary sent along with the notification. The `object` is the sender of the notification, and only supports `NSString` values for now.
The `id` of the subscriber is returned, which can be used to unsubscribe the `event`.
Under the hood this API subscribes to `NSDistributedNotificationCenter`, example values of `event` are:
* `AppleInterfaceThemeChangedNotification`
* `AppleAquaColorVariantChanged`
* `AppleColorPreferencesChangedNotification`
* `AppleShowScrollBarsSettingChanged`
If `event` is null, the `NSDistributedNotificationCenter` doesn’t use it as criteria for delivery to the observer. See [docs](https://developer.apple.com/documentation/foundation/nsnotificationcenter/1411723-addobserverforname?language=objc) for more information.
###
`systemPreferences.subscribeLocalNotification(event, callback)` *macOS*[](#systempreferencessubscribelocalnotificationevent-callback-macos "Direct link to heading")
* `event` string | null
* `callback` Function
+ `event` string
+ `userInfo` Record<string, unknown>
+ `object` string
Returns `number` - The ID of this subscription
Same as `subscribeNotification`, but uses `NSNotificationCenter` for local defaults. This is necessary for events such as `NSUserDefaultsDidChangeNotification`.
If `event` is null, the `NSNotificationCenter` doesn’t use it as criteria for delivery to the observer. See [docs](https://developer.apple.com/documentation/foundation/nsnotificationcenter/1411723-addobserverforname?language=objc) for more information.
###
`systemPreferences.subscribeWorkspaceNotification(event, callback)` *macOS*[](#systempreferencessubscribeworkspacenotificationevent-callback-macos "Direct link to heading")
* `event` string | null
* `callback` Function
+ `event` string
+ `userInfo` Record<string, unknown>
+ `object` string
Returns `number` - The ID of this subscription
Same as `subscribeNotification`, but uses `NSWorkspace.sharedWorkspace.notificationCenter`. This is necessary for events such as `NSWorkspaceDidActivateApplicationNotification`.
If `event` is null, the `NSWorkspaceNotificationCenter` doesn’t use it as criteria for delivery to the observer. See [docs](https://developer.apple.com/documentation/foundation/nsnotificationcenter/1411723-addobserverforname?language=objc) for more information.
###
`systemPreferences.unsubscribeNotification(id)` *macOS*[](#systempreferencesunsubscribenotificationid-macos "Direct link to heading")
* `id` Integer
Removes the subscriber with `id`.
###
`systemPreferences.unsubscribeLocalNotification(id)` *macOS*[](#systempreferencesunsubscribelocalnotificationid-macos "Direct link to heading")
* `id` Integer
Same as `unsubscribeNotification`, but removes the subscriber from `NSNotificationCenter`.
###
`systemPreferences.unsubscribeWorkspaceNotification(id)` *macOS*[](#systempreferencesunsubscribeworkspacenotificationid-macos "Direct link to heading")
* `id` Integer
Same as `unsubscribeNotification`, but removes the subscriber from `NSWorkspace.sharedWorkspace.notificationCenter`.
###
`systemPreferences.registerDefaults(defaults)` *macOS*[](#systempreferencesregisterdefaultsdefaults-macos "Direct link to heading")
* `defaults` Record<string, string | boolean | number> - a dictionary of (`key: value`) user defaults
Add the specified defaults to your application's `NSUserDefaults`.
###
`systemPreferences.getUserDefault<Type extends keyof UserDefaultTypes>(key, type)` *macOS*[](#systempreferencesgetuserdefaulttype-extends-keyof-userdefaulttypeskey-type-macos "Direct link to heading")
* `key` string
* `type` Type - Can be `string`, `boolean`, `integer`, `float`, `double`, `url`, `array` or `dictionary`.
Returns [UserDefaultTypes[Type]](structures/user-default-types) - The value of `key` in `NSUserDefaults`.
Some popular `key` and `type`s are:
* `AppleInterfaceStyle`: `string`
* `AppleAquaColorVariant`: `integer`
* `AppleHighlightColor`: `string`
* `AppleShowScrollBars`: `string`
* `NSNavRecentPlaces`: `array`
* `NSPreferredWebServices`: `dictionary`
* `NSUserDictionaryReplacementItems`: `array`
###
`systemPreferences.setUserDefault<Type extends keyof UserDefaultTypes>(key, type, value)` *macOS*[](#systempreferencessetuserdefaulttype-extends-keyof-userdefaulttypeskey-type-value-macos "Direct link to heading")
* `key` string
* `type` Type - Can be `string`, `boolean`, `integer`, `float`, `double`, `url`, `array` or `dictionary`.
* `value` UserDefaultTypes[Type]
Set the value of `key` in `NSUserDefaults`.
Note that `type` should match actual type of `value`. An exception is thrown if they don't.
Some popular `key` and `type`s are:
* `ApplePressAndHoldEnabled`: `boolean`
###
`systemPreferences.removeUserDefault(key)` *macOS*[](#systempreferencesremoveuserdefaultkey-macos "Direct link to heading")
* `key` string
Removes the `key` in `NSUserDefaults`. This can be used to restore the default or global value of a `key` previously set with `setUserDefault`.
###
`systemPreferences.isAeroGlassEnabled()` *Windows*[](#systempreferencesisaeroglassenabled-windows "Direct link to heading")
Returns `boolean` - `true` if [DWM composition](https://msdn.microsoft.com/en-us/library/windows/desktop/aa969540.aspx) (Aero Glass) is enabled, and `false` otherwise.
An example of using it to determine if you should create a transparent window or not (transparent windows won't work correctly when DWM composition is disabled):
```
const { BrowserWindow, systemPreferences } = require('electron')
const browserOptions = { width: 1000, height: 800 }
// Make the window transparent only if the platform supports it.
if (process.platform !== 'win32' || systemPreferences.isAeroGlassEnabled()) {
browserOptions.transparent = true
browserOptions.frame = false
}
// Create the window.
const win = new BrowserWindow(browserOptions)
// Navigate.
if (browserOptions.transparent) {
win.loadURL(`file://${__dirname}/index.html`)
} else {
// No transparency, so we load a fallback that uses basic styles.
win.loadURL(`file://${__dirname}/fallback.html`)
}
```
###
`systemPreferences.getAccentColor()` *Windows* *macOS*[](#systempreferencesgetaccentcolor-windows-macos "Direct link to heading")
Returns `string` - The users current system wide accent color preference in RGBA hexadecimal form.
```
const color = systemPreferences.getAccentColor() // `"aabbccdd"`
const red = color.substr(0, 2) // "aa"
const green = color.substr(2, 2) // "bb"
const blue = color.substr(4, 2) // "cc"
const alpha = color.substr(6, 2) // "dd"
```
This API is only available on macOS 10.14 Mojave or newer.
###
`systemPreferences.getColor(color)` *Windows* *macOS*[](#systempreferencesgetcolorcolor-windows-macos "Direct link to heading")
* `color` string - One of the following values:
+ On **Windows**:
- `3d-dark-shadow` - Dark shadow for three-dimensional display elements.
- `3d-face` - Face color for three-dimensional display elements and for dialog box backgrounds.
- `3d-highlight` - Highlight color for three-dimensional display elements.
- `3d-light` - Light color for three-dimensional display elements.
- `3d-shadow` - Shadow color for three-dimensional display elements.
- `active-border` - Active window border.
- `active-caption` - Active window title bar. Specifies the left side color in the color gradient of an active window's title bar if the gradient effect is enabled.
- `active-caption-gradient` - Right side color in the color gradient of an active window's title bar.
- `app-workspace` - Background color of multiple document interface (MDI) applications.
- `button-text` - Text on push buttons.
- `caption-text` - Text in caption, size box, and scroll bar arrow box.
- `desktop` - Desktop background color.
- `disabled-text` - Grayed (disabled) text.
- `highlight` - Item(s) selected in a control.
- `highlight-text` - Text of item(s) selected in a control.
- `hotlight` - Color for a hyperlink or hot-tracked item.
- `inactive-border` - Inactive window border.
- `inactive-caption` - Inactive window caption. Specifies the left side color in the color gradient of an inactive window's title bar if the gradient effect is enabled.
- `inactive-caption-gradient` - Right side color in the color gradient of an inactive window's title bar.
- `inactive-caption-text` - Color of text in an inactive caption.
- `info-background` - Background color for tooltip controls.
- `info-text` - Text color for tooltip controls.
- `menu` - Menu background.
- `menu-highlight` - The color used to highlight menu items when the menu appears as a flat menu.
- `menubar` - The background color for the menu bar when menus appear as flat menus.
- `menu-text` - Text in menus.
- `scrollbar` - Scroll bar gray area.
- `window` - Window background.
- `window-frame` - Window frame.
- `window-text` - Text in windows.
+ On **macOS**
- `alternate-selected-control-text` - The text on a selected surface in a list or table. *deprecated*
- `control-background` - The background of a large interface element, such as a browser or table.
- `control` - The surface of a control.
- `control-text` -The text of a control that isn’t disabled.
- `disabled-control-text` - The text of a control that’s disabled.
- `find-highlight` - The color of a find indicator.
- `grid` - The gridlines of an interface element such as a table.
- `header-text` - The text of a header cell in a table.
- `highlight` - The virtual light source onscreen.
- `keyboard-focus-indicator` - The ring that appears around the currently focused control when using the keyboard for interface navigation.
- `label` - The text of a label containing primary content.
- `link` - A link to other content.
- `placeholder-text` - A placeholder string in a control or text view.
- `quaternary-label` - The text of a label of lesser importance than a tertiary label such as watermark text.
- `scrubber-textured-background` - The background of a scrubber in the Touch Bar.
- `secondary-label` - The text of a label of lesser importance than a normal label such as a label used to represent a subheading or additional information.
- `selected-content-background` - The background for selected content in a key window or view.
- `selected-control` - The surface of a selected control.
- `selected-control-text` - The text of a selected control.
- `selected-menu-item-text` - The text of a selected menu.
- `selected-text-background` - The background of selected text.
- `selected-text` - Selected text.
- `separator` - A separator between different sections of content.
- `shadow` - The virtual shadow cast by a raised object onscreen.
- `tertiary-label` - The text of a label of lesser importance than a secondary label such as a label used to represent disabled text.
- `text-background` - Text background.
- `text` - The text in a document.
- `under-page-background` - The background behind a document's content.
- `unemphasized-selected-content-background` - The selected content in a non-key window or view.
- `unemphasized-selected-text-background` - A background for selected text in a non-key window or view.
- `unemphasized-selected-text` - Selected text in a non-key window or view.
- `window-background` - The background of a window.
- `window-frame-text` - The text in the window's titlebar area.
Returns `string` - The system color setting in RGB hexadecimal form (`#ABCDEF`). See the [Windows docs](https://msdn.microsoft.com/en-us/library/windows/desktop/ms724371(v=vs.85).aspx) and the [macOS docs](https://developer.apple.com/design/human-interface-guidelines/macos/visual-design/color#dynamic-system-colors) for more details.
The following colors are only available on macOS 10.14: `find-highlight`, `selected-content-background`, `separator`, `unemphasized-selected-content-background`, `unemphasized-selected-text-background`, and `unemphasized-selected-text`.
###
`systemPreferences.getSystemColor(color)` *macOS*[](#systempreferencesgetsystemcolorcolor-macos "Direct link to heading")
* `color` string - One of the following values:
+ `blue`
+ `brown`
+ `gray`
+ `green`
+ `orange`
+ `pink`
+ `purple`
+ `red`
+ `yellow`
Returns `string` - The standard system color formatted as `#RRGGBBAA`.
Returns one of several standard system colors that automatically adapt to vibrancy and changes in accessibility settings like 'Increase contrast' and 'Reduce transparency'. See [Apple Documentation](https://developer.apple.com/design/human-interface-guidelines/macos/visual-design/color#system-colors) for more details.
###
`systemPreferences.isInvertedColorScheme()` *Windows* *Deprecated*[](#systempreferencesisinvertedcolorscheme-windows-deprecated "Direct link to heading")
Returns `boolean` - `true` if an inverted color scheme (a high contrast color scheme with light text and dark backgrounds) is active, `false` otherwise.
**Deprecated:** Should use the new [`nativeTheme.shouldUseInvertedColorScheme`](native-theme#nativethemeshoulduseinvertedcolorscheme-macos-windows-readonly) API.
###
`systemPreferences.isHighContrastColorScheme()` *macOS* *Windows* *Deprecated*[](#systempreferencesishighcontrastcolorscheme-macos-windows-deprecated "Direct link to heading")
Returns `boolean` - `true` if a high contrast theme is active, `false` otherwise.
**Deprecated:** Should use the new [`nativeTheme.shouldUseHighContrastColors`](native-theme#nativethemeshouldusehighcontrastcolors-macos-windows-readonly) API.
###
`systemPreferences.getEffectiveAppearance()` *macOS*[](#systempreferencesgeteffectiveappearance-macos "Direct link to heading")
Returns `string` - Can be `dark`, `light` or `unknown`.
Gets the macOS appearance setting that is currently applied to your application, maps to [NSApplication.effectiveAppearance](https://developer.apple.com/documentation/appkit/nsapplication/2967171-effectiveappearance?language=objc)
###
`systemPreferences.getAppLevelAppearance()` *macOS* *Deprecated*[](#systempreferencesgetapplevelappearance-macos-deprecated "Direct link to heading")
Returns `string` | `null` - Can be `dark`, `light` or `unknown`.
Gets the macOS appearance setting that you have declared you want for your application, maps to [NSApplication.appearance](https://developer.apple.com/documentation/appkit/nsapplication/2967170-appearance?language=objc). You can use the `setAppLevelAppearance` API to set this value.
###
`systemPreferences.setAppLevelAppearance(appearance)` *macOS* *Deprecated*[](#systempreferencessetapplevelappearanceappearance-macos-deprecated "Direct link to heading")
* `appearance` string | null - Can be `dark` or `light`
Sets the appearance setting for your application, this should override the system default and override the value of `getEffectiveAppearance`.
###
`systemPreferences.canPromptTouchID()` *macOS*[](#systempreferencescanprompttouchid-macos "Direct link to heading")
Returns `boolean` - whether or not this device has the ability to use Touch ID.
**NOTE:** This API will return `false` on macOS systems older than Sierra 10.12.2.
###
`systemPreferences.promptTouchID(reason)` *macOS*[](#systempreferencesprompttouchidreason-macos "Direct link to heading")
* `reason` string - The reason you are asking for Touch ID authentication
Returns `Promise<void>` - resolves if the user has successfully authenticated with Touch ID.
```
const { systemPreferences } = require('electron')
systemPreferences.promptTouchID('To get consent for a Security-Gated Thing').then(success => {
console.log('You have successfully authenticated with Touch ID!')
}).catch(err => {
console.log(err)
})
```
This API itself will not protect your user data; rather, it is a mechanism to allow you to do so. Native apps will need to set [Access Control Constants](https://developer.apple.com/documentation/security/secaccesscontrolcreateflags?language=objc) like [`kSecAccessControlUserPresence`](https://developer.apple.com/documentation/security/secaccesscontrolcreateflags/ksecaccesscontroluserpresence?language=objc) on their keychain entry so that reading it would auto-prompt for Touch ID biometric consent. This could be done with [`node-keytar`](https://github.com/atom/node-keytar), such that one would store an encryption key with `node-keytar` and only fetch it if `promptTouchID()` resolves.
**NOTE:** This API will return a rejected Promise on macOS systems older than Sierra 10.12.2.
###
`systemPreferences.isTrustedAccessibilityClient(prompt)` *macOS*[](#systempreferencesistrustedaccessibilityclientprompt-macos "Direct link to heading")
* `prompt` boolean - whether or not the user will be informed via prompt if the current process is untrusted.
Returns `boolean` - `true` if the current process is a trusted accessibility client and `false` if it is not.
###
`systemPreferences.getMediaAccessStatus(mediaType)` *Windows* *macOS*[](#systempreferencesgetmediaaccessstatusmediatype-windows-macos "Direct link to heading")
* `mediaType` string - Can be `microphone`, `camera` or `screen`.
Returns `string` - Can be `not-determined`, `granted`, `denied`, `restricted` or `unknown`.
This user consent was not required on macOS 10.13 High Sierra or lower so this method will always return `granted`. macOS 10.14 Mojave or higher requires consent for `microphone` and `camera` access. macOS 10.15 Catalina or higher requires consent for `screen` access.
Windows 10 has a global setting controlling `microphone` and `camera` access for all win32 applications. It will always return `granted` for `screen` and for all media types on older versions of Windows.
###
`systemPreferences.askForMediaAccess(mediaType)` *macOS*[](#systempreferencesaskformediaaccessmediatype-macos "Direct link to heading")
* `mediaType` string - the type of media being requested; can be `microphone`, `camera`.
Returns `Promise<boolean>` - A promise that resolves with `true` if consent was granted and `false` if it was denied. If an invalid `mediaType` is passed, the promise will be rejected. If an access request was denied and later is changed through the System Preferences pane, a restart of the app will be required for the new permissions to take effect. If access has already been requested and denied, it *must* be changed through the preference pane; an alert will not pop up and the promise will resolve with the existing access status.
**Important:** In order to properly leverage this API, you [must set](https://developer.apple.com/documentation/avfoundation/cameras_and_media_capture/requesting_authorization_for_media_capture_on_macos?language=objc) the `NSMicrophoneUsageDescription` and `NSCameraUsageDescription` strings in your app's `Info.plist` file. The values for these keys will be used to populate the permission dialogs so that the user will be properly informed as to the purpose of the permission request. See [Electron Application Distribution](../tutorial/application-distribution#macos) for more information about how to set these in the context of Electron.
This user consent was not required until macOS 10.14 Mojave, so this method will always return `true` if your system is running 10.13 High Sierra or lower.
###
`systemPreferences.getAnimationSettings()`[](#systempreferencesgetanimationsettings "Direct link to heading")
Returns `Object`:
* `shouldRenderRichAnimation` boolean - Returns true if rich animations should be rendered. Looks at session type (e.g. remote desktop) and accessibility settings to give guidance for heavy animations.
* `scrollAnimationsEnabledBySystem` boolean - Determines on a per-platform basis whether scroll animations (e.g. produced by home/end key) should be enabled.
* `prefersReducedMotion` boolean - Determines whether the user desires reduced motion based on platform APIs.
Returns an object with system animation settings.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
###
`systemPreferences.appLevelAppearance` *macOS*[](#systempreferencesapplevelappearance-macos "Direct link to heading")
A `string` property that can be `dark`, `light` or `unknown`. It determines the macOS appearance setting for your application. This maps to values in: [NSApplication.appearance](https://developer.apple.com/documentation/appkit/nsapplication/2967170-appearance?language=objc). Setting this will override the system default as well as the value of `getEffectiveAppearance`.
Possible values that can be set are `dark` and `light`, and possible return values are `dark`, `light`, and `unknown`.
This property is only available on macOS 10.14 Mojave or newer.
###
`systemPreferences.effectiveAppearance` *macOS* *Readonly*[](#systempreferenceseffectiveappearance-macos-readonly "Direct link to heading")
A `string` property that can be `dark`, `light` or `unknown`.
Returns the macOS appearance setting that is currently applied to your application, maps to [NSApplication.effectiveAppearance](https://developer.apple.com/documentation/appkit/nsapplication/2967171-effectiveappearance?language=objc)
| programming_docs |
electron app app
===
> Control your application's event lifecycle.
>
>
Process: [Main](../glossary#main-process)
The following example shows how to quit the application when the last window is closed:
```
const { app } = require('electron')
app.on('window-all-closed', () => {
app.quit()
})
```
Events[](#events "Direct link to heading")
-------------------------------------------
The `app` object emits the following events:
### Event: 'will-finish-launching'[](#event-will-finish-launching "Direct link to heading")
Emitted when the application has finished basic startup. On Windows and Linux, the `will-finish-launching` event is the same as the `ready` event; on macOS, this event represents the `applicationWillFinishLaunching` notification of `NSApplication`. You would usually set up listeners for the `open-file` and `open-url` events here, and start the crash reporter and auto updater.
In most cases, you should do everything in the `ready` event handler.
### Event: 'ready'[](#event-ready "Direct link to heading")
Returns:
* `event` Event
* `launchInfo` Record<string, any> | [NotificationResponse](structures/notification-response) *macOS*
Emitted once, when Electron has finished initializing. On macOS, `launchInfo` holds the `userInfo` of the [`NSUserNotification`](https://developer.apple.com/documentation/foundation/nsusernotification) or information from [`UNNotificationResponse`](https://developer.apple.com/documentation/usernotifications/unnotificationresponse) that was used to open the application, if it was launched from Notification Center. You can also call `app.isReady()` to check if this event has already fired and `app.whenReady()` to get a Promise that is fulfilled when Electron is initialized.
### Event: 'window-all-closed'[](#event-window-all-closed "Direct link to heading")
Emitted when all windows have been closed.
If you do not subscribe to this event and all windows are closed, the default behavior is to quit the app; however, if you subscribe, you control whether the app quits or not. If the user pressed `Cmd + Q`, or the developer called `app.quit()`, Electron will first try to close all the windows and then emit the `will-quit` event, and in this case the `window-all-closed` event would not be emitted.
### Event: 'before-quit'[](#event-before-quit "Direct link to heading")
Returns:
* `event` Event
Emitted before the application starts closing its windows. Calling `event.preventDefault()` will prevent the default behavior, which is terminating the application.
**Note:** If application quit was initiated by `autoUpdater.quitAndInstall()`, then `before-quit` is emitted *after* emitting `close` event on all windows and closing them.
**Note:** On Windows, this event will not be emitted if the app is closed due to a shutdown/restart of the system or a user logout.
### Event: 'will-quit'[](#event-will-quit "Direct link to heading")
Returns:
* `event` Event
Emitted when all windows have been closed and the application will quit. Calling `event.preventDefault()` will prevent the default behavior, which is terminating the application.
See the description of the `window-all-closed` event for the differences between the `will-quit` and `window-all-closed` events.
**Note:** On Windows, this event will not be emitted if the app is closed due to a shutdown/restart of the system or a user logout.
### Event: 'quit'[](#event-quit "Direct link to heading")
Returns:
* `event` Event
* `exitCode` Integer
Emitted when the application is quitting.
**Note:** On Windows, this event will not be emitted if the app is closed due to a shutdown/restart of the system or a user logout.
### Event: 'open-file' *macOS*[](#event-open-file-macos "Direct link to heading")
Returns:
* `event` Event
* `path` string
Emitted when the user wants to open a file with the application. The `open-file` event is usually emitted when the application is already open and the OS wants to reuse the application to open the file. `open-file` is also emitted when a file is dropped onto the dock and the application is not yet running. Make sure to listen for the `open-file` event very early in your application startup to handle this case (even before the `ready` event is emitted).
You should call `event.preventDefault()` if you want to handle this event.
On Windows, you have to parse `process.argv` (in the main process) to get the filepath.
### Event: 'open-url' *macOS*[](#event-open-url-macos "Direct link to heading")
Returns:
* `event` Event
* `url` string
Emitted when the user wants to open a URL with the application. Your application's `Info.plist` file must define the URL scheme within the `CFBundleURLTypes` key, and set `NSPrincipalClass` to `AtomApplication`.
You should call `event.preventDefault()` if you want to handle this event.
### Event: 'activate' *macOS*[](#event-activate-macos "Direct link to heading")
Returns:
* `event` Event
* `hasVisibleWindows` boolean
Emitted when the application is activated. Various actions can trigger this event, such as launching the application for the first time, attempting to re-launch the application when it's already running, or clicking on the application's dock or taskbar icon.
### Event: 'did-become-active' *macOS*[](#event-did-become-active-macos "Direct link to heading")
Returns:
* `event` Event
Emitted when mac application become active. Difference from `activate` event is that `did-become-active` is emitted every time the app becomes active, not only when Dock icon is clicked or application is re-launched.
### Event: 'continue-activity' *macOS*[](#event-continue-activity-macos "Direct link to heading")
Returns:
* `event` Event
* `type` string - A string identifying the activity. Maps to [`NSUserActivity.activityType`](https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSUserActivity_Class/index.html#//apple_ref/occ/instp/NSUserActivity/activityType).
* `userInfo` unknown - Contains app-specific state stored by the activity on another device.
* `details` Object
+ `webpageURL` string (optional) - A string identifying the URL of the webpage accessed by the activity on another device, if available.
Emitted during [Handoff](https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html) when an activity from a different device wants to be resumed. You should call `event.preventDefault()` if you want to handle this event.
A user activity can be continued only in an app that has the same developer Team ID as the activity's source app and that supports the activity's type. Supported activity types are specified in the app's `Info.plist` under the `NSUserActivityTypes` key.
### Event: 'will-continue-activity' *macOS*[](#event-will-continue-activity-macos "Direct link to heading")
Returns:
* `event` Event
* `type` string - A string identifying the activity. Maps to [`NSUserActivity.activityType`](https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSUserActivity_Class/index.html#//apple_ref/occ/instp/NSUserActivity/activityType).
Emitted during [Handoff](https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html) before an activity from a different device wants to be resumed. You should call `event.preventDefault()` if you want to handle this event.
### Event: 'continue-activity-error' *macOS*[](#event-continue-activity-error-macos "Direct link to heading")
Returns:
* `event` Event
* `type` string - A string identifying the activity. Maps to [`NSUserActivity.activityType`](https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSUserActivity_Class/index.html#//apple_ref/occ/instp/NSUserActivity/activityType).
* `error` string - A string with the error's localized description.
Emitted during [Handoff](https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html) when an activity from a different device fails to be resumed.
### Event: 'activity-was-continued' *macOS*[](#event-activity-was-continued-macos "Direct link to heading")
Returns:
* `event` Event
* `type` string - A string identifying the activity. Maps to [`NSUserActivity.activityType`](https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSUserActivity_Class/index.html#//apple_ref/occ/instp/NSUserActivity/activityType).
* `userInfo` unknown - Contains app-specific state stored by the activity.
Emitted during [Handoff](https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html) after an activity from this device was successfully resumed on another one.
### Event: 'update-activity-state' *macOS*[](#event-update-activity-state-macos "Direct link to heading")
Returns:
* `event` Event
* `type` string - A string identifying the activity. Maps to [`NSUserActivity.activityType`](https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSUserActivity_Class/index.html#//apple_ref/occ/instp/NSUserActivity/activityType).
* `userInfo` unknown - Contains app-specific state stored by the activity.
Emitted when [Handoff](https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html) is about to be resumed on another device. If you need to update the state to be transferred, you should call `event.preventDefault()` immediately, construct a new `userInfo` dictionary and call `app.updateCurrentActivity()` in a timely manner. Otherwise, the operation will fail and `continue-activity-error` will be called.
### Event: 'new-window-for-tab' *macOS*[](#event-new-window-for-tab-macos "Direct link to heading")
Returns:
* `event` Event
Emitted when the user clicks the native macOS new tab button. The new tab button is only visible if the current `BrowserWindow` has a `tabbingIdentifier`
### Event: 'browser-window-blur'[](#event-browser-window-blur "Direct link to heading")
Returns:
* `event` Event
* `window` [BrowserWindow](browser-window)
Emitted when a [browserWindow](browser-window) gets blurred.
### Event: 'browser-window-focus'[](#event-browser-window-focus "Direct link to heading")
Returns:
* `event` Event
* `window` [BrowserWindow](browser-window)
Emitted when a [browserWindow](browser-window) gets focused.
### Event: 'browser-window-created'[](#event-browser-window-created "Direct link to heading")
Returns:
* `event` Event
* `window` [BrowserWindow](browser-window)
Emitted when a new [browserWindow](browser-window) is created.
### Event: 'web-contents-created'[](#event-web-contents-created "Direct link to heading")
Returns:
* `event` Event
* `webContents` [WebContents](web-contents)
Emitted when a new [webContents](web-contents) is created.
### Event: 'certificate-error'[](#event-certificate-error "Direct link to heading")
Returns:
* `event` Event
* `webContents` [WebContents](web-contents)
* `url` string
* `error` string - The error code
* `certificate` [Certificate](structures/certificate)
* `callback` Function
+ `isTrusted` boolean - Whether to consider the certificate as trusted
* `isMainFrame` boolean
Emitted when failed to verify the `certificate` for `url`, to trust the certificate you should prevent the default behavior with `event.preventDefault()` and call `callback(true)`.
```
const { app } = require('electron')
app.on('certificate-error', (event, webContents, url, error, certificate, callback) => {
if (url === 'https://github.com') {
// Verification logic.
event.preventDefault()
callback(true)
} else {
callback(false)
}
})
```
### Event: 'select-client-certificate'[](#event-select-client-certificate "Direct link to heading")
Returns:
* `event` Event
* `webContents` [WebContents](web-contents)
* `url` URL
* `certificateList` [Certificate[]](structures/certificate)
* `callback` Function
+ `certificate` [Certificate](structures/certificate) (optional)
Emitted when a client certificate is requested.
The `url` corresponds to the navigation entry requesting the client certificate and `callback` can be called with an entry filtered from the list. Using `event.preventDefault()` prevents the application from using the first certificate from the store.
```
const { app } = require('electron')
app.on('select-client-certificate', (event, webContents, url, list, callback) => {
event.preventDefault()
callback(list[0])
})
```
### Event: 'login'[](#event-login "Direct link to heading")
Returns:
* `event` Event
* `webContents` [WebContents](web-contents)
* `authenticationResponseDetails` Object
+ `url` URL
* `authInfo` Object
+ `isProxy` boolean
+ `scheme` string
+ `host` string
+ `port` Integer
+ `realm` string
* `callback` Function
+ `username` string (optional)
+ `password` string (optional)
Emitted when `webContents` wants to do basic auth.
The default behavior is to cancel all authentications. To override this you should prevent the default behavior with `event.preventDefault()` and call `callback(username, password)` with the credentials.
```
const { app } = require('electron')
app.on('login', (event, webContents, details, authInfo, callback) => {
event.preventDefault()
callback('username', 'secret')
})
```
If `callback` is called without a username or password, the authentication request will be cancelled and the authentication error will be returned to the page.
### Event: 'gpu-info-update'[](#event-gpu-info-update "Direct link to heading")
Emitted whenever there is a GPU info update.
### Event: 'gpu-process-crashed' *Deprecated*[](#event-gpu-process-crashed-deprecated "Direct link to heading")
Returns:
* `event` Event
* `killed` boolean
Emitted when the GPU process crashes or is killed.
**Deprecated:** This event is superceded by the `child-process-gone` event which contains more information about why the child process disappeared. It isn't always because it crashed. The `killed` boolean can be replaced by checking `reason === 'killed'` when you switch to that event.
### Event: 'renderer-process-crashed' *Deprecated*[](#event-renderer-process-crashed-deprecated "Direct link to heading")
Returns:
* `event` Event
* `webContents` [WebContents](web-contents)
* `killed` boolean
Emitted when the renderer process of `webContents` crashes or is killed.
**Deprecated:** This event is superceded by the `render-process-gone` event which contains more information about why the render process disappeared. It isn't always because it crashed. The `killed` boolean can be replaced by checking `reason === 'killed'` when you switch to that event.
### Event: 'render-process-gone'[](#event-render-process-gone "Direct link to heading")
Returns:
* `event` Event
* `webContents` [WebContents](web-contents)
* `details` Object
+ `reason` string - The reason the render process is gone. Possible values:
- `clean-exit` - Process exited with an exit code of zero
- `abnormal-exit` - Process exited with a non-zero exit code
- `killed` - Process was sent a SIGTERM or otherwise killed externally
- `crashed` - Process crashed
- `oom` - Process ran out of memory
- `launch-failed` - Process never successfully launched
- `integrity-failure` - Windows code integrity checks failed
+ `exitCode` Integer - The exit code of the process, unless `reason` is `launch-failed`, in which case `exitCode` will be a platform-specific launch failure error code.
Emitted when the renderer process unexpectedly disappears. This is normally because it was crashed or killed.
### Event: 'child-process-gone'[](#event-child-process-gone "Direct link to heading")
Returns:
* `event` Event
* `details` Object
+ `type` string - Process type. One of the following values:
- `Utility`
- `Zygote`
- `Sandbox helper`
- `GPU`
- `Pepper Plugin`
- `Pepper Plugin Broker`
- `Unknown`
+ `reason` string - The reason the child process is gone. Possible values:
- `clean-exit` - Process exited with an exit code of zero
- `abnormal-exit` - Process exited with a non-zero exit code
- `killed` - Process was sent a SIGTERM or otherwise killed externally
- `crashed` - Process crashed
- `oom` - Process ran out of memory
- `launch-failed` - Process never successfully launched
- `integrity-failure` - Windows code integrity checks failed
+ `exitCode` number - The exit code for the process (e.g. status from waitpid if on posix, from GetExitCodeProcess on Windows).
+ `serviceName` string (optional) - The non-localized name of the process.
+ `name` string (optional) - The name of the process. Examples for utility: `Audio Service`, `Content Decryption Module Service`, `Network Service`, `Video Capture`, etc.
Emitted when the child process unexpectedly disappears. This is normally because it was crashed or killed. It does not include renderer processes.
### Event: 'accessibility-support-changed' *macOS* *Windows*[](#event-accessibility-support-changed-macos-windows "Direct link to heading")
Returns:
* `event` Event
* `accessibilitySupportEnabled` boolean - `true` when Chrome's accessibility support is enabled, `false` otherwise.
Emitted when Chrome's accessibility support changes. This event fires when assistive technologies, such as screen readers, are enabled or disabled. See <https://www.chromium.org/developers/design-documents/accessibility> for more details.
### Event: 'session-created'[](#event-session-created "Direct link to heading")
Returns:
* `session` [Session](session)
Emitted when Electron has created a new `session`.
```
const { app } = require('electron')
app.on('session-created', (session) => {
console.log(session)
})
```
### Event: 'second-instance'[](#event-second-instance "Direct link to heading")
Returns:
* `event` Event
* `argv` string[] - An array of the second instance's command line arguments
* `workingDirectory` string - The second instance's working directory
* `additionalData` unknown - A JSON object of additional data passed from the second instance
This event will be emitted inside the primary instance of your application when a second instance has been executed and calls `app.requestSingleInstanceLock()`.
`argv` is an Array of the second instance's command line arguments, and `workingDirectory` is its current working directory. Usually applications respond to this by making their primary window focused and non-minimized.
**Note:** If the second instance is started by a different user than the first, the `argv` array will not include the arguments.
This event is guaranteed to be emitted after the `ready` event of `app` gets emitted.
**Note:** Extra command line arguments might be added by Chromium, such as `--original-process-start-time`.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `app` object has the following methods:
**Note:** Some methods are only available on specific operating systems and are labeled as such.
###
`app.quit()`[](#appquit "Direct link to heading")
Try to close all windows. The `before-quit` event will be emitted first. If all windows are successfully closed, the `will-quit` event will be emitted and by default the application will terminate.
This method guarantees that all `beforeunload` and `unload` event handlers are correctly executed. It is possible that a window cancels the quitting by returning `false` in the `beforeunload` event handler.
###
`app.exit([exitCode])`[](#appexitexitcode "Direct link to heading")
* `exitCode` Integer (optional)
Exits immediately with `exitCode`. `exitCode` defaults to 0.
All windows will be closed immediately without asking the user, and the `before-quit` and `will-quit` events will not be emitted.
###
`app.relaunch([options])`[](#apprelaunchoptions "Direct link to heading")
* `options` Object (optional)
+ `args` string[] (optional)
+ `execPath` string (optional)
Relaunches the app when current instance exits.
By default, the new instance will use the same working directory and command line arguments with current instance. When `args` is specified, the `args` will be passed as command line arguments instead. When `execPath` is specified, the `execPath` will be executed for relaunch instead of current app.
Note that this method does not quit the app when executed, you have to call `app.quit` or `app.exit` after calling `app.relaunch` to make the app restart.
When `app.relaunch` is called for multiple times, multiple instances will be started after current instance exited.
An example of restarting current instance immediately and adding a new command line argument to the new instance:
```
const { app } = require('electron')
app.relaunch({ args: process.argv.slice(1).concat(['--relaunch']) })
app.exit(0)
```
###
`app.isReady()`[](#appisready "Direct link to heading")
Returns `boolean` - `true` if Electron has finished initializing, `false` otherwise. See also `app.whenReady()`.
###
`app.whenReady()`[](#appwhenready "Direct link to heading")
Returns `Promise<void>` - fulfilled when Electron is initialized. May be used as a convenient alternative to checking `app.isReady()` and subscribing to the `ready` event if the app is not ready yet.
###
`app.focus([options])`[](#appfocusoptions "Direct link to heading")
* `options` Object (optional)
+ `steal` boolean *macOS* - Make the receiver the active app even if another app is currently active.
On Linux, focuses on the first visible window. On macOS, makes the application the active app. On Windows, focuses on the application's first window.
You should seek to use the `steal` option as sparingly as possible.
###
`app.hide()` *macOS*[](#apphide-macos "Direct link to heading")
Hides all application windows without minimizing them.
###
`app.isHidden()` *macOS*[](#appishidden-macos "Direct link to heading")
Returns `boolean` - `true` if the application—including all of its windows—is hidden (e.g. with `Command-H`), `false` otherwise.
###
`app.show()` *macOS*[](#appshow-macos "Direct link to heading")
Shows application windows after they were hidden. Does not automatically focus them.
###
`app.setAppLogsPath([path])`[](#appsetapplogspathpath "Direct link to heading")
* `path` string (optional) - A custom path for your logs. Must be absolute.
Sets or creates a directory your app's logs which can then be manipulated with `app.getPath()` or `app.setPath(pathName, newPath)`.
Calling `app.setAppLogsPath()` without a `path` parameter will result in this directory being set to `~/Library/Logs/YourAppName` on *macOS*, and inside the `userData` directory on *Linux* and *Windows*.
###
`app.getAppPath()`[](#appgetapppath "Direct link to heading")
Returns `string` - The current application directory.
###
`app.getPath(name)`[](#appgetpathname "Direct link to heading")
* `name` string - You can request the following paths by the name:
+ `home` User's home directory.
+ `appData` Per-user application data directory, which by default points to:
- `%APPDATA%` on Windows
- `$XDG_CONFIG_HOME` or `~/.config` on Linux
- `~/Library/Application Support` on macOS
+ `userData` The directory for storing your app's configuration files, which by default is the `appData` directory appended with your app's name. By convention files storing user data should be written to this directory, and it is not recommended to write large files here because some environments may backup this directory to cloud storage.
+ `sessionData` The directory for storing data generated by `Session`, such as localStorage, cookies, disk cache, downloaded dictionaries, network state, devtools files. By default this points to `userData`. Chromium may write very large disk cache here, so if your app does not rely on browser storage like localStorage or cookies to save user data, it is recommended to set this directory to other locations to avoid polluting the `userData` directory.
+ `temp` Temporary directory.
+ `exe` The current executable file.
+ `module` The `libchromiumcontent` library.
+ `desktop` The current user's Desktop directory.
+ `documents` Directory for a user's "My Documents".
+ `downloads` Directory for a user's downloads.
+ `music` Directory for a user's music.
+ `pictures` Directory for a user's pictures.
+ `videos` Directory for a user's videos.
+ `recent` Directory for the user's recent files (Windows only).
+ `logs` Directory for your app's log folder.
+ `crashDumps` Directory where crash dumps are stored.
Returns `string` - A path to a special directory or file associated with `name`. On failure, an `Error` is thrown.
If `app.getPath('logs')` is called without called `app.setAppLogsPath()` being called first, a default log directory will be created equivalent to calling `app.setAppLogsPath()` without a `path` parameter.
###
`app.getFileIcon(path[, options])`[](#appgetfileiconpath-options "Direct link to heading")
* `path` string
* `options` Object (optional)
+ `size` string
- `small` - 16x16
- `normal` - 32x32
- `large` - 48x48 on *Linux*, 32x32 on *Windows*, unsupported on *macOS*.
Returns `Promise<NativeImage>` - fulfilled with the app's icon, which is a [NativeImage](native-image).
Fetches a path's associated icon.
On *Windows*, there a 2 kinds of icons:
* Icons associated with certain file extensions, like `.mp3`, `.png`, etc.
* Icons inside the file itself, like `.exe`, `.dll`, `.ico`.
On *Linux* and *macOS*, icons depend on the application associated with file mime type.
###
`app.setPath(name, path)`[](#appsetpathname-path "Direct link to heading")
* `name` string
* `path` string
Overrides the `path` to a special directory or file associated with `name`. If the path specifies a directory that does not exist, an `Error` is thrown. In that case, the directory should be created with `fs.mkdirSync` or similar.
You can only override paths of a `name` defined in `app.getPath`.
By default, web pages' cookies and caches will be stored under the `sessionData` directory. If you want to change this location, you have to override the `sessionData` path before the `ready` event of the `app` module is emitted.
###
`app.getVersion()`[](#appgetversion "Direct link to heading")
Returns `string` - The version of the loaded application. If no version is found in the application's `package.json` file, the version of the current bundle or executable is returned.
###
`app.getName()`[](#appgetname "Direct link to heading")
Returns `string` - The current application's name, which is the name in the application's `package.json` file.
Usually the `name` field of `package.json` is a short lowercase name, according to the npm modules spec. You should usually also specify a `productName` field, which is your application's full capitalized name, and which will be preferred over `name` by Electron.
###
`app.setName(name)`[](#appsetnamename "Direct link to heading")
* `name` string
Overrides the current application's name.
**Note:** This function overrides the name used internally by Electron; it does not affect the name that the OS uses.
###
`app.getLocale()`[](#appgetlocale "Direct link to heading")
Returns `string` - The current application locale, fetched using Chromium's `l10n_util` library. Possible return values are documented [here](https://source.chromium.org/chromium/chromium/src/+/main:ui/base/l10n/l10n_util.cc).
To set the locale, you'll want to use a command line switch at app startup, which may be found [here](command-line-switches).
**Note:** When distributing your packaged app, you have to also ship the `locales` folder.
**Note:** On Windows, you have to call it after the `ready` events gets emitted.
###
`app.getLocaleCountryCode()`[](#appgetlocalecountrycode "Direct link to heading")
Returns `string` - User operating system's locale two-letter [ISO 3166](https://www.iso.org/iso-3166-country-codes.html) country code. The value is taken from native OS APIs.
**Note:** When unable to detect locale country code, it returns empty string.
###
`app.addRecentDocument(path)` *macOS* *Windows*[](#appaddrecentdocumentpath-macos-windows "Direct link to heading")
* `path` string
Adds `path` to the recent documents list.
This list is managed by the OS. On Windows, you can visit the list from the task bar, and on macOS, you can visit it from dock menu.
###
`app.clearRecentDocuments()` *macOS* *Windows*[](#appclearrecentdocuments-macos-windows "Direct link to heading")
Clears the recent documents list.
###
`app.setAsDefaultProtocolClient(protocol[, path, args])`[](#appsetasdefaultprotocolclientprotocol-path-args "Direct link to heading")
* `protocol` string - The name of your protocol, without `://`. For example, if you want your app to handle `electron://` links, call this method with `electron` as the parameter.
* `path` string (optional) *Windows* - The path to the Electron executable. Defaults to `process.execPath`
* `args` string[] (optional) *Windows* - Arguments passed to the executable. Defaults to an empty array
Returns `boolean` - Whether the call succeeded.
Sets the current executable as the default handler for a protocol (aka URI scheme). It allows you to integrate your app deeper into the operating system. Once registered, all links with `your-protocol://` will be opened with the current executable. The whole link, including protocol, will be passed to your application as a parameter.
**Note:** On macOS, you can only register protocols that have been added to your app's `info.plist`, which cannot be modified at runtime. However, you can change the file during build time via [Electron Forge](https://www.electronforge.io/), [Electron Packager](https://github.com/electron/electron-packager), or by editing `info.plist` with a text editor. Please refer to [Apple's documentation](https://developer.apple.com/library/ios/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html#//apple_ref/doc/uid/TP40009249-102207-TPXREF115) for details.
**Note:** In a Windows Store environment (when packaged as an `appx`) this API will return `true` for all calls but the registry key it sets won't be accessible by other applications. In order to register your Windows Store application as a default protocol handler you must [declare the protocol in your manifest](https://docs.microsoft.com/en-us/uwp/schemas/appxpackage/uapmanifestschema/element-uap-protocol).
The API uses the Windows Registry and `LSSetDefaultHandlerForURLScheme` internally.
###
`app.removeAsDefaultProtocolClient(protocol[, path, args])` *macOS* *Windows*[](#appremoveasdefaultprotocolclientprotocol-path-args-macos-windows "Direct link to heading")
* `protocol` string - The name of your protocol, without `://`.
* `path` string (optional) *Windows* - Defaults to `process.execPath`
* `args` string[] (optional) *Windows* - Defaults to an empty array
Returns `boolean` - Whether the call succeeded.
This method checks if the current executable as the default handler for a protocol (aka URI scheme). If so, it will remove the app as the default handler.
###
`app.isDefaultProtocolClient(protocol[, path, args])`[](#appisdefaultprotocolclientprotocol-path-args "Direct link to heading")
* `protocol` string - The name of your protocol, without `://`.
* `path` string (optional) *Windows* - Defaults to `process.execPath`
* `args` string[] (optional) *Windows* - Defaults to an empty array
Returns `boolean` - Whether the current executable is the default handler for a protocol (aka URI scheme).
**Note:** On macOS, you can use this method to check if the app has been registered as the default protocol handler for a protocol. You can also verify this by checking `~/Library/Preferences/com.apple.LaunchServices.plist` on the macOS machine. Please refer to [Apple's documentation](https://developer.apple.com/library/mac/documentation/Carbon/Reference/LaunchServicesReference/#//apple_ref/c/func/LSCopyDefaultHandlerForURLScheme) for details.
The API uses the Windows Registry and `LSCopyDefaultHandlerForURLScheme` internally.
###
`app.getApplicationNameForProtocol(url)`[](#appgetapplicationnameforprotocolurl "Direct link to heading")
* `url` string - a URL with the protocol name to check. Unlike the other methods in this family, this accepts an entire URL, including `://` at a minimum (e.g. `https://`).
Returns `string` - Name of the application handling the protocol, or an empty string if there is no handler. For instance, if Electron is the default handler of the URL, this could be `Electron` on Windows and Mac. However, don't rely on the precise format which is not guaranteed to remain unchanged. Expect a different format on Linux, possibly with a `.desktop` suffix.
This method returns the application name of the default handler for the protocol (aka URI scheme) of a URL.
###
`app.getApplicationInfoForProtocol(url)` *macOS* *Windows*[](#appgetapplicationinfoforprotocolurl-macos-windows "Direct link to heading")
* `url` string - a URL with the protocol name to check. Unlike the other methods in this family, this accepts an entire URL, including `://` at a minimum (e.g. `https://`).
Returns `Promise<Object>` - Resolve with an object containing the following:
* `icon` NativeImage - the display icon of the app handling the protocol.
* `path` string - installation path of the app handling the protocol.
* `name` string - display name of the app handling the protocol.
This method returns a promise that contains the application name, icon and path of the default handler for the protocol (aka URI scheme) of a URL.
###
`app.setUserTasks(tasks)` *Windows*[](#appsetusertaskstasks-windows "Direct link to heading")
* `tasks` [Task[]](structures/task) - Array of `Task` objects
Adds `tasks` to the [Tasks](https://msdn.microsoft.com/en-us/library/windows/desktop/dd378460(v=vs.85).aspx#tasks) category of the Jump List on Windows.
`tasks` is an array of [Task](structures/task) objects.
Returns `boolean` - Whether the call succeeded.
**Note:** If you'd like to customize the Jump List even more use `app.setJumpList(categories)` instead.
###
`app.getJumpListSettings()` *Windows*[](#appgetjumplistsettings-windows "Direct link to heading")
Returns `Object`:
* `minItems` Integer - The minimum number of items that will be shown in the Jump List (for a more detailed description of this value see the [MSDN docs](https://msdn.microsoft.com/en-us/library/windows/desktop/dd378398(v=vs.85).aspx)).
* `removedItems` [JumpListItem[]](structures/jump-list-item) - Array of `JumpListItem` objects that correspond to items that the user has explicitly removed from custom categories in the Jump List. These items must not be re-added to the Jump List in the **next** call to `app.setJumpList()`, Windows will not display any custom category that contains any of the removed items.
###
`app.setJumpList(categories)` *Windows*[](#appsetjumplistcategories-windows "Direct link to heading")
* `categories` [JumpListCategory[]](structures/jump-list-category) | `null` - Array of `JumpListCategory` objects.
Returns `string`
Sets or removes a custom Jump List for the application, and returns one of the following strings:
* `ok` - Nothing went wrong.
* `error` - One or more errors occurred, enable runtime logging to figure out the likely cause.
* `invalidSeparatorError` - An attempt was made to add a separator to a custom category in the Jump List. Separators are only allowed in the standard `Tasks` category.
* `fileTypeRegistrationError` - An attempt was made to add a file link to the Jump List for a file type the app isn't registered to handle.
* `customCategoryAccessDeniedError` - Custom categories can't be added to the Jump List due to user privacy or group policy settings.
If `categories` is `null` the previously set custom Jump List (if any) will be replaced by the standard Jump List for the app (managed by Windows).
**Note:** If a `JumpListCategory` object has neither the `type` nor the `name` property set then its `type` is assumed to be `tasks`. If the `name` property is set but the `type` property is omitted then the `type` is assumed to be `custom`.
**Note:** Users can remove items from custom categories, and Windows will not allow a removed item to be added back into a custom category until **after** the next successful call to `app.setJumpList(categories)`. Any attempt to re-add a removed item to a custom category earlier than that will result in the entire custom category being omitted from the Jump List. The list of removed items can be obtained using `app.getJumpListSettings()`.
**Note:** The maximum length of a Jump List item's `description` property is 260 characters. Beyond this limit, the item will not be added to the Jump List, nor will it be displayed.
Here's a very simple example of creating a custom Jump List:
```
const { app } = require('electron')
app.setJumpList([
{
type: 'custom',
name: 'Recent Projects',
items: [
{ type: 'file', path: 'C:\\Projects\\project1.proj' },
{ type: 'file', path: 'C:\\Projects\\project2.proj' }
]
},
{ // has a name so `type` is assumed to be "custom"
name: 'Tools',
items: [
{
type: 'task',
title: 'Tool A',
program: process.execPath,
args: '--run-tool-a',
icon: process.execPath,
iconIndex: 0,
description: 'Runs Tool A'
},
{
type: 'task',
title: 'Tool B',
program: process.execPath,
args: '--run-tool-b',
icon: process.execPath,
iconIndex: 0,
description: 'Runs Tool B'
}
]
},
{ type: 'frequent' },
{ // has no name and no type so `type` is assumed to be "tasks"
items: [
{
type: 'task',
title: 'New Project',
program: process.execPath,
args: '--new-project',
description: 'Create a new project.'
},
{ type: 'separator' },
{
type: 'task',
title: 'Recover Project',
program: process.execPath,
args: '--recover-project',
description: 'Recover Project'
}
]
}
])
```
###
`app.requestSingleInstanceLock([additionalData])`[](#apprequestsingleinstancelockadditionaldata "Direct link to heading")
* `additionalData` Record<any, any> (optional) - A JSON object containing additional data to send to the first instance.
Returns `boolean`
The return value of this method indicates whether or not this instance of your application successfully obtained the lock. If it failed to obtain the lock, you can assume that another instance of your application is already running with the lock and exit immediately.
I.e. This method returns `true` if your process is the primary instance of your application and your app should continue loading. It returns `false` if your process should immediately quit as it has sent its parameters to another instance that has already acquired the lock.
On macOS, the system enforces single instance automatically when users try to open a second instance of your app in Finder, and the `open-file` and `open-url` events will be emitted for that. However when users start your app in command line, the system's single instance mechanism will be bypassed, and you have to use this method to ensure single instance.
An example of activating the window of primary instance when a second instance starts:
```
const { app } = require('electron')
let myWindow = null
const additionalData = { myKey: 'myValue' }
const gotTheLock = app.requestSingleInstanceLock(additionalData)
if (!gotTheLock) {
app.quit()
} else {
app.on('second-instance', (event, commandLine, workingDirectory, additionalData) => {
// Print out data received from the second instance.
console.log(additionalData)
// Someone tried to run a second instance, we should focus our window.
if (myWindow) {
if (myWindow.isMinimized()) myWindow.restore()
myWindow.focus()
}
})
// Create myWindow, load the rest of the app, etc...
app.whenReady().then(() => {
myWindow = createWindow()
})
}
```
###
`app.hasSingleInstanceLock()`[](#apphassingleinstancelock "Direct link to heading")
Returns `boolean`
This method returns whether or not this instance of your app is currently holding the single instance lock. You can request the lock with `app.requestSingleInstanceLock()` and release with `app.releaseSingleInstanceLock()`
###
`app.releaseSingleInstanceLock()`[](#appreleasesingleinstancelock "Direct link to heading")
Releases all locks that were created by `requestSingleInstanceLock`. This will allow multiple instances of the application to once again run side by side.
###
`app.setUserActivity(type, userInfo[, webpageURL])` *macOS*[](#appsetuseractivitytype-userinfo-webpageurl-macos "Direct link to heading")
* `type` string - Uniquely identifies the activity. Maps to [`NSUserActivity.activityType`](https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSUserActivity_Class/index.html#//apple_ref/occ/instp/NSUserActivity/activityType).
* `userInfo` any - App-specific state to store for use by another device.
* `webpageURL` string (optional) - The webpage to load in a browser if no suitable app is installed on the resuming device. The scheme must be `http` or `https`.
Creates an `NSUserActivity` and sets it as the current activity. The activity is eligible for [Handoff](https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html) to another device afterward.
###
`app.getCurrentActivityType()` *macOS*[](#appgetcurrentactivitytype-macos "Direct link to heading")
Returns `string` - The type of the currently running activity.
###
`app.invalidateCurrentActivity()` *macOS*[](#appinvalidatecurrentactivity-macos "Direct link to heading")
Invalidates the current [Handoff](https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html) user activity.
###
`app.resignCurrentActivity()` *macOS*[](#appresigncurrentactivity-macos "Direct link to heading")
Marks the current [Handoff](https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html) user activity as inactive without invalidating it.
###
`app.updateCurrentActivity(type, userInfo)` *macOS*[](#appupdatecurrentactivitytype-userinfo-macos "Direct link to heading")
* `type` string - Uniquely identifies the activity. Maps to [`NSUserActivity.activityType`](https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSUserActivity_Class/index.html#//apple_ref/occ/instp/NSUserActivity/activityType).
* `userInfo` any - App-specific state to store for use by another device.
Updates the current activity if its type matches `type`, merging the entries from `userInfo` into its current `userInfo` dictionary.
###
`app.setAppUserModelId(id)` *Windows*[](#appsetappusermodelidid-windows "Direct link to heading")
* `id` string
Changes the [Application User Model ID](https://msdn.microsoft.com/en-us/library/windows/desktop/dd378459(v=vs.85).aspx) to `id`.
###
`app.setActivationPolicy(policy)` *macOS*[](#appsetactivationpolicypolicy-macos "Direct link to heading")
* `policy` string - Can be 'regular', 'accessory', or 'prohibited'.
Sets the activation policy for a given app.
Activation policy types:
* 'regular' - The application is an ordinary app that appears in the Dock and may have a user interface.
* 'accessory' - The application doesn’t appear in the Dock and doesn’t have a menu bar, but it may be activated programmatically or by clicking on one of its windows.
* 'prohibited' - The application doesn’t appear in the Dock and may not create windows or be activated.
###
`app.importCertificate(options, callback)` *Linux*[](#appimportcertificateoptions-callback-linux "Direct link to heading")
* `options` Object
+ `certificate` string - Path for the pkcs12 file.
+ `password` string - Passphrase for the certificate.
* `callback` Function
+ `result` Integer - Result of import.
Imports the certificate in pkcs12 format into the platform certificate store. `callback` is called with the `result` of import operation, a value of `0` indicates success while any other value indicates failure according to Chromium [net\_error\_list](https://source.chromium.org/chromium/chromium/src/+/main:net/base/net_error_list.h).
###
`app.configureHostResolver(options)`[](#appconfigurehostresolveroptions "Direct link to heading")
* `options` Object
+ `enableBuiltInResolver` boolean (optional) - Whether the built-in host resolver is used in preference to getaddrinfo. When enabled, the built-in resolver will attempt to use the system's DNS settings to do DNS lookups itself. Enabled by default on macOS, disabled by default on Windows and Linux.
+ `secureDnsMode` string (optional) - Can be "off", "automatic" or "secure". Configures the DNS-over-HTTP mode. When "off", no DoH lookups will be performed. When "automatic", DoH lookups will be performed first if DoH is available, and insecure DNS lookups will be performed as a fallback. When "secure", only DoH lookups will be performed. Defaults to "automatic".
+ `secureDnsServers` string[] (optional) - A list of DNS-over-HTTP server templates. See [RFC8484 § 3](https://datatracker.ietf.org/doc/html/rfc8484#section-3) for details on the template format. Most servers support the POST method; the template for such servers is simply a URI. Note that for [some DNS providers](https://source.chromium.org/chromium/chromium/src/+/main:net/dns/public/doh_provider_entry.cc;l=31?q=%22DohProviderEntry::GetList()%22&ss=chromium%2Fchromium%2Fsrc), the resolver will automatically upgrade to DoH unless DoH is explicitly disabled, even if there are no DoH servers provided in this list.
+ `enableAdditionalDnsQueryTypes` boolean (optional) - Controls whether additional DNS query types, e.g. HTTPS (DNS type 65) will be allowed besides the traditional A and AAAA queries when a request is being made via insecure DNS. Has no effect on Secure DNS which always allows additional types. Defaults to true.
Configures host resolution (DNS and DNS-over-HTTPS). By default, the following resolvers will be used, in order:
1. DNS-over-HTTPS, if the [DNS provider supports it](https://source.chromium.org/chromium/chromium/src/+/main:net/dns/public/doh_provider_entry.cc;l=31?q=%22DohProviderEntry::GetList()%22&ss=chromium%2Fchromium%2Fsrc), then
2. the built-in resolver (enabled on macOS only by default), then
3. the system's resolver (e.g. `getaddrinfo`).
This can be configured to either restrict usage of non-encrypted DNS (`secureDnsMode: "secure"`), or disable DNS-over-HTTPS (`secureDnsMode:
"off"`). It is also possible to enable or disable the built-in resolver.
To disable insecure DNS, you can specify a `secureDnsMode` of `"secure"`. If you do so, you should make sure to provide a list of DNS-over-HTTPS servers to use, in case the user's DNS configuration does not include a provider that supports DoH.
```
app.configureHostResolver({
secureDnsMode: 'secure',
secureDnsServers: [
'https://cloudflare-dns.com/dns-query'
]
})
```
This API must be called after the `ready` event is emitted.
###
`app.disableHardwareAcceleration()`[](#appdisablehardwareacceleration "Direct link to heading")
Disables hardware acceleration for current app.
This method can only be called before app is ready.
###
`app.disableDomainBlockingFor3DAPIs()`[](#appdisabledomainblockingfor3dapis "Direct link to heading")
By default, Chromium disables 3D APIs (e.g. WebGL) until restart on a per domain basis if the GPU processes crashes too frequently. This function disables that behavior.
This method can only be called before app is ready.
###
`app.getAppMetrics()`[](#appgetappmetrics "Direct link to heading")
Returns [ProcessMetric[]](structures/process-metric): Array of `ProcessMetric` objects that correspond to memory and CPU usage statistics of all the processes associated with the app.
###
`app.getGPUFeatureStatus()`[](#appgetgpufeaturestatus "Direct link to heading")
Returns [GPUFeatureStatus](structures/gpu-feature-status) - The Graphics Feature Status from `chrome://gpu/`.
**Note:** This information is only usable after the `gpu-info-update` event is emitted.
###
`app.getGPUInfo(infoType)`[](#appgetgpuinfoinfotype "Direct link to heading")
* `infoType` string - Can be `basic` or `complete`.
Returns `Promise<unknown>`
For `infoType` equal to `complete`: Promise is fulfilled with `Object` containing all the GPU Information as in [chromium's GPUInfo object](https://chromium.googlesource.com/chromium/src/+/4178e190e9da409b055e5dff469911ec6f6b716f/gpu/config/gpu_info.cc). This includes the version and driver information that's shown on `chrome://gpu` page.
For `infoType` equal to `basic`: Promise is fulfilled with `Object` containing fewer attributes than when requested with `complete`. Here's an example of basic response:
```
{
auxAttributes:
{
amdSwitchable: true,
canSupportThreadedTextureMailbox: false,
directComposition: false,
directRendering: true,
glResetNotificationStrategy: 0,
inProcessGpu: true,
initializationTime: 0,
jpegDecodeAcceleratorSupported: false,
optimus: false,
passthroughCmdDecoder: false,
sandboxed: false,
softwareRendering: false,
supportsOverlays: false,
videoDecodeAcceleratorFlags: 0
},
gpuDevice:
[{ active: true, deviceId: 26657, vendorId: 4098 },
{ active: false, deviceId: 3366, vendorId: 32902 }],
machineModelName: 'MacBookPro',
machineModelVersion: '11.5'
}
```
Using `basic` should be preferred if only basic information like `vendorId` or `driverId` is needed.
###
`app.setBadgeCount([count])` *Linux* *macOS*[](#appsetbadgecountcount-linux-macos "Direct link to heading")
* `count` Integer (optional) - If a value is provided, set the badge to the provided value otherwise, on macOS, display a plain white dot (e.g. unknown number of notifications). On Linux, if a value is not provided the badge will not display.
Returns `boolean` - Whether the call succeeded.
Sets the counter badge for current app. Setting the count to `0` will hide the badge.
On macOS, it shows on the dock icon. On Linux, it only works for Unity launcher.
**Note:** Unity launcher requires a `.desktop` file to work. For more information, please read the [Unity integration documentation](https://help.ubuntu.com/community/UnityLaunchersAndDesktopFiles#Adding_shortcuts_to_a_launcher).
###
`app.getBadgeCount()` *Linux* *macOS*[](#appgetbadgecount-linux-macos "Direct link to heading")
Returns `Integer` - The current value displayed in the counter badge.
###
`app.isUnityRunning()` *Linux*[](#appisunityrunning-linux "Direct link to heading")
Returns `boolean` - Whether the current desktop environment is Unity launcher.
###
`app.getLoginItemSettings([options])` *macOS* *Windows*[](#appgetloginitemsettingsoptions-macos-windows "Direct link to heading")
* `options` Object (optional)
+ `path` string (optional) *Windows* - The executable path to compare against. Defaults to `process.execPath`.
+ `args` string[] (optional) *Windows* - The command-line arguments to compare against. Defaults to an empty array.
If you provided `path` and `args` options to `app.setLoginItemSettings`, then you need to pass the same arguments here for `openAtLogin` to be set correctly.
Returns `Object`:
* `openAtLogin` boolean - `true` if the app is set to open at login.
* `openAsHidden` boolean *macOS* - `true` if the app is set to open as hidden at login. This setting is not available on [MAS builds](../tutorial/mac-app-store-submission-guide).
* `wasOpenedAtLogin` boolean *macOS* - `true` if the app was opened at login automatically. This setting is not available on [MAS builds](../tutorial/mac-app-store-submission-guide).
* `wasOpenedAsHidden` boolean *macOS* - `true` if the app was opened as a hidden login item. This indicates that the app should not open any windows at startup. This setting is not available on [MAS builds](../tutorial/mac-app-store-submission-guide).
* `restoreState` boolean *macOS* - `true` if the app was opened as a login item that should restore the state from the previous session. This indicates that the app should restore the windows that were open the last time the app was closed. This setting is not available on [MAS builds](../tutorial/mac-app-store-submission-guide).
* `executableWillLaunchAtLogin` boolean *Windows* - `true` if app is set to open at login and its run key is not deactivated. This differs from `openAtLogin` as it ignores the `args` option, this property will be true if the given executable would be launched at login with **any** arguments.
* `launchItems` Object[] *Windows*
+ `name` string *Windows* - name value of a registry entry.
+ `path` string *Windows* - The executable to an app that corresponds to a registry entry.
+ `args` string[] *Windows* - the command-line arguments to pass to the executable.
+ `scope` string *Windows* - one of `user` or `machine`. Indicates whether the registry entry is under `HKEY_CURRENT USER` or `HKEY_LOCAL_MACHINE`.
+ `enabled` boolean *Windows* - `true` if the app registry key is startup approved and therefore shows as `enabled` in Task Manager and Windows settings.
###
`app.setLoginItemSettings(settings)` *macOS* *Windows*[](#appsetloginitemsettingssettings-macos-windows "Direct link to heading")
* `settings` Object
+ `openAtLogin` boolean (optional) - `true` to open the app at login, `false` to remove the app as a login item. Defaults to `false`.
+ `openAsHidden` boolean (optional) *macOS* - `true` to open the app as hidden. Defaults to `false`. The user can edit this setting from the System Preferences so `app.getLoginItemSettings().wasOpenedAsHidden` should be checked when the app is opened to know the current value. This setting is not available on [MAS builds](../tutorial/mac-app-store-submission-guide).
+ `path` string (optional) *Windows* - The executable to launch at login. Defaults to `process.execPath`.
+ `args` string[] (optional) *Windows* - The command-line arguments to pass to the executable. Defaults to an empty array. Take care to wrap paths in quotes.
+ `enabled` boolean (optional) *Windows* - `true` will change the startup approved registry key and `enable / disable` the App in Task Manager and Windows Settings. Defaults to `true`.
+ `name` string (optional) *Windows* - value name to write into registry. Defaults to the app's AppUserModelId(). Set the app's login item settings.
To work with Electron's `autoUpdater` on Windows, which uses [Squirrel](https://github.com/Squirrel/Squirrel.Windows), you'll want to set the launch path to Update.exe, and pass arguments that specify your application name. For example:
```
const appFolder = path.dirname(process.execPath)
const updateExe = path.resolve(appFolder, '..', 'Update.exe')
const exeName = path.basename(process.execPath)
app.setLoginItemSettings({
openAtLogin: true,
path: updateExe,
args: [
'--processStart', `"${exeName}"`,
'--process-start-args', `"--hidden"`
]
})
```
###
`app.isAccessibilitySupportEnabled()` *macOS* *Windows*[](#appisaccessibilitysupportenabled-macos-windows "Direct link to heading")
Returns `boolean` - `true` if Chrome's accessibility support is enabled, `false` otherwise. This API will return `true` if the use of assistive technologies, such as screen readers, has been detected. See <https://www.chromium.org/developers/design-documents/accessibility> for more details.
###
`app.setAccessibilitySupportEnabled(enabled)` *macOS* *Windows*[](#appsetaccessibilitysupportenabledenabled-macos-windows "Direct link to heading")
* `enabled` boolean - Enable or disable [accessibility tree](https://developers.google.com/web/fundamentals/accessibility/semantics-builtin/the-accessibility-tree) rendering
Manually enables Chrome's accessibility support, allowing to expose accessibility switch to users in application settings. See [Chromium's accessibility docs](https://www.chromium.org/developers/design-documents/accessibility) for more details. Disabled by default.
This API must be called after the `ready` event is emitted.
**Note:** Rendering accessibility tree can significantly affect the performance of your app. It should not be enabled by default.
###
`app.showAboutPanel()`[](#appshowaboutpanel "Direct link to heading")
Show the app's about panel options. These options can be overridden with `app.setAboutPanelOptions(options)`.
###
`app.setAboutPanelOptions(options)`[](#appsetaboutpaneloptionsoptions "Direct link to heading")
* `options` Object
+ `applicationName` string (optional) - The app's name.
+ `applicationVersion` string (optional) - The app's version.
+ `copyright` string (optional) - Copyright information.
+ `version` string (optional) *macOS* - The app's build version number.
+ `credits` string (optional) *macOS* *Windows* - Credit information.
+ `authors` string[] (optional) *Linux* - List of app authors.
+ `website` string (optional) *Linux* - The app's website.
+ `iconPath` string (optional) *Linux* *Windows* - Path to the app's icon in a JPEG or PNG file format. On Linux, will be shown as 64x64 pixels while retaining aspect ratio.
Set the about panel options. This will override the values defined in the app's `.plist` file on macOS. See the [Apple docs](https://developer.apple.com/reference/appkit/nsapplication/1428479-orderfrontstandardaboutpanelwith?language=objc) for more details. On Linux, values must be set in order to be shown; there are no defaults.
If you do not set `credits` but still wish to surface them in your app, AppKit will look for a file named "Credits.html", "Credits.rtf", and "Credits.rtfd", in that order, in the bundle returned by the NSBundle class method main. The first file found is used, and if none is found, the info area is left blank. See Apple [documentation](https://developer.apple.com/documentation/appkit/nsaboutpaneloptioncredits?language=objc) for more information.
###
`app.isEmojiPanelSupported()`[](#appisemojipanelsupported "Direct link to heading")
Returns `boolean` - whether or not the current OS version allows for native emoji pickers.
###
`app.showEmojiPanel()` *macOS* *Windows*[](#appshowemojipanel-macos-windows "Direct link to heading")
Show the platform's native emoji picker.
###
`app.startAccessingSecurityScopedResource(bookmarkData)` *mas*[](#appstartaccessingsecurityscopedresourcebookmarkdata-mas "Direct link to heading")
* `bookmarkData` string - The base64 encoded security scoped bookmark data returned by the `dialog.showOpenDialog` or `dialog.showSaveDialog` methods.
Returns `Function` - This function **must** be called once you have finished accessing the security scoped file. If you do not remember to stop accessing the bookmark, [kernel resources will be leaked](https://developer.apple.com/reference/foundation/nsurl/1417051-startaccessingsecurityscopedreso?language=objc) and your app will lose its ability to reach outside the sandbox completely, until your app is restarted.
```
// Start accessing the file.
const stopAccessingSecurityScopedResource = app.startAccessingSecurityScopedResource(data)
// You can now access the file outside of the sandbox 🎉
// Remember to stop accessing the file once you've finished with it.
stopAccessingSecurityScopedResource()
```
Start accessing a security scoped resource. With this method Electron applications that are packaged for the Mac App Store may reach outside their sandbox to access files chosen by the user. See [Apple's documentation](https://developer.apple.com/library/content/documentation/Security/Conceptual/AppSandboxDesignGuide/AppSandboxInDepth/AppSandboxInDepth.html#//apple_ref/doc/uid/TP40011183-CH3-SW16) for a description of how this system works.
###
`app.enableSandbox()`[](#appenablesandbox "Direct link to heading")
Enables full sandbox mode on the app. This means that all renderers will be launched sandboxed, regardless of the value of the `sandbox` flag in WebPreferences.
This method can only be called before app is ready.
###
`app.isInApplicationsFolder()` *macOS*[](#appisinapplicationsfolder-macos "Direct link to heading")
Returns `boolean` - Whether the application is currently running from the systems Application folder. Use in combination with `app.moveToApplicationsFolder()`
###
`app.moveToApplicationsFolder([options])` *macOS*[](#appmovetoapplicationsfolderoptions-macos "Direct link to heading")
* `options` Object (optional)
+ `conflictHandler` Function\<boolean> (optional) - A handler for potential conflict in move failure.
- `conflictType` string - The type of move conflict encountered by the handler; can be `exists` or `existsAndRunning`, where `exists` means that an app of the same name is present in the Applications directory and `existsAndRunning` means both that it exists and that it's presently running.
Returns `boolean` - Whether the move was successful. Please note that if the move is successful, your application will quit and relaunch.
No confirmation dialog will be presented by default. If you wish to allow the user to confirm the operation, you may do so using the [`dialog`](dialog) API.
**NOTE:** This method throws errors if anything other than the user causes the move to fail. For instance if the user cancels the authorization dialog, this method returns false. If we fail to perform the copy, then this method will throw an error. The message in the error should be informative and tell you exactly what went wrong.
By default, if an app of the same name as the one being moved exists in the Applications directory and is *not* running, the existing app will be trashed and the active app moved into its place. If it *is* running, the pre-existing running app will assume focus and the previously active app will quit itself. This behavior can be changed by providing the optional conflict handler, where the boolean returned by the handler determines whether or not the move conflict is resolved with default behavior. i.e. returning `false` will ensure no further action is taken, returning `true` will result in the default behavior and the method continuing.
For example:
```
app.moveToApplicationsFolder({
conflictHandler: (conflictType) => {
if (conflictType === 'exists') {
return dialog.showMessageBoxSync({
type: 'question',
buttons: ['Halt Move', 'Continue Move'],
defaultId: 0,
message: 'An app of this name already exists'
}) === 1
}
}
})
```
Would mean that if an app already exists in the user directory, if the user chooses to 'Continue Move' then the function would continue with its default behavior and the existing app will be trashed and the active app moved into its place.
###
`app.isSecureKeyboardEntryEnabled()` *macOS*[](#appissecurekeyboardentryenabled-macos "Direct link to heading")
Returns `boolean` - whether `Secure Keyboard Entry` is enabled.
By default this API will return `false`.
###
`app.setSecureKeyboardEntryEnabled(enabled)` *macOS*[](#appsetsecurekeyboardentryenabledenabled-macos "Direct link to heading")
* `enabled` boolean - Enable or disable `Secure Keyboard Entry`
Set the `Secure Keyboard Entry` is enabled in your application.
By using this API, important information such as password and other sensitive information can be prevented from being intercepted by other processes.
See [Apple's documentation](https://developer.apple.com/library/archive/technotes/tn2150/_index.html) for more details.
**Note:** Enable `Secure Keyboard Entry` only when it is needed and disable it when it is no longer needed.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
###
`app.accessibilitySupportEnabled` *macOS* *Windows*[](#appaccessibilitysupportenabled-macos-windows "Direct link to heading")
A `boolean` property that's `true` if Chrome's accessibility support is enabled, `false` otherwise. This property will be `true` if the use of assistive technologies, such as screen readers, has been detected. Setting this property to `true` manually enables Chrome's accessibility support, allowing developers to expose accessibility switch to users in application settings.
See [Chromium's accessibility docs](https://www.chromium.org/developers/design-documents/accessibility) for more details. Disabled by default.
This API must be called after the `ready` event is emitted.
**Note:** Rendering accessibility tree can significantly affect the performance of your app. It should not be enabled by default.
###
`app.applicationMenu`[](#appapplicationmenu "Direct link to heading")
A `Menu | null` property that returns [`Menu`](menu) if one has been set and `null` otherwise. Users can pass a [Menu](menu) to set this property.
###
`app.badgeCount` *Linux* *macOS*[](#appbadgecount-linux-macos "Direct link to heading")
An `Integer` property that returns the badge count for current app. Setting the count to `0` will hide the badge.
On macOS, setting this with any nonzero integer shows on the dock icon. On Linux, this property only works for Unity launcher.
**Note:** Unity launcher requires a `.desktop` file to work. For more information, please read the [Unity integration documentation](https://help.ubuntu.com/community/UnityLaunchersAndDesktopFiles#Adding_shortcuts_to_a_launcher).
**Note:** On macOS, you need to ensure that your application has the permission to display notifications for this property to take effect.
###
`app.commandLine` *Readonly*[](#appcommandline-readonly "Direct link to heading")
A [`CommandLine`](command-line) object that allows you to read and manipulate the command line arguments that Chromium uses.
###
`app.dock` *macOS* *Readonly*[](#appdock-macos-readonly "Direct link to heading")
A [`Dock`](dock) `| undefined` object that allows you to perform actions on your app icon in the user's dock on macOS.
###
`app.isPackaged` *Readonly*[](#appispackaged-readonly "Direct link to heading")
A `boolean` property that returns `true` if the app is packaged, `false` otherwise. For many apps, this property can be used to distinguish development and production environments.
###
`app.name`[](#appname "Direct link to heading")
A `string` property that indicates the current application's name, which is the name in the application's `package.json` file.
Usually the `name` field of `package.json` is a short lowercase name, according to the npm modules spec. You should usually also specify a `productName` field, which is your application's full capitalized name, and which will be preferred over `name` by Electron.
###
`app.userAgentFallback`[](#appuseragentfallback "Direct link to heading")
A `string` which is the user agent string Electron will use as a global fallback.
This is the user agent that will be used when no user agent is set at the `webContents` or `session` level. It is useful for ensuring that your entire app has the same user agent. Set to a custom value as early as possible in your app's initialization to ensure that your overridden value is used.
###
`app.runningUnderRosettaTranslation` *macOS* *Readonly* *Deprecated*[](#apprunningunderrosettatranslation-macos-readonly-deprecated "Direct link to heading")
A `boolean` which when `true` indicates that the app is currently running under the [Rosetta Translator Environment](https://en.wikipedia.org/wiki/Rosetta_(software)).
You can use this property to prompt users to download the arm64 version of your application when they are running the x64 version under Rosetta incorrectly.
**Deprecated:** This property is superceded by the `runningUnderARM64Translation` property which detects when the app is being translated to ARM64 in both macOS and Windows.
###
`app.runningUnderARM64Translation` *Readonly* *macOS* *Windows*[](#apprunningunderarm64translation-readonly-macos-windows "Direct link to heading")
A `boolean` which when `true` indicates that the app is currently running under an ARM64 translator (like the macOS [Rosetta Translator Environment](https://en.wikipedia.org/wiki/Rosetta_(software)) or Windows [WOW](https://en.wikipedia.org/wiki/Windows_on_Windows)).
You can use this property to prompt users to download the arm64 version of your application when they are running the x64 version under Rosetta incorrectly.
| programming_docs |
electron Class: WebRequest Class: WebRequest[](#class-webrequest "Direct link to heading")
----------------------------------------------------------------
> Intercept and modify the contents of a request at various stages of its lifetime.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
Instances of the `WebRequest` class are accessed by using the `webRequest` property of a `Session`.
The methods of `WebRequest` accept an optional `filter` and a `listener`. The `listener` will be called with `listener(details)` when the API's event has happened. The `details` object describes the request.
⚠️ Only the last attached `listener` will be used. Passing `null` as `listener` will unsubscribe from the event.
The `filter` object has a `urls` property which is an Array of URL patterns that will be used to filter out the requests that do not match the URL patterns. If the `filter` is omitted then all requests will be matched.
For certain events the `listener` is passed with a `callback`, which should be called with a `response` object when `listener` has done its work.
An example of adding `User-Agent` header for requests:
```
const { session } = require('electron')
// Modify the user agent for all requests to the following urls.
const filter = {
urls: ['https://*.github.com/*', '*://electron.github.io']
}
session.defaultSession.webRequest.onBeforeSendHeaders(filter, (details, callback) => {
details.requestHeaders['User-Agent'] = 'MyAgent'
callback({ requestHeaders: details.requestHeaders })
})
```
### Instance Methods[](#instance-methods "Direct link to heading")
The following methods are available on instances of `WebRequest`:
####
`webRequest.onBeforeRequest([filter, ]listener)`[](#webrequestonbeforerequestfilter-listener "Direct link to heading")
* `filter` [WebRequestFilter](structures/web-request-filter) (optional)
* `listener` Function | null
+ `details` Object
- `id` Integer
- `url` string
- `method` string
- `webContentsId` Integer (optional)
- `webContents` WebContents (optional)
- `frame` WebFrameMain (optional)
- `resourceType` string - Can be `mainFrame`, `subFrame`, `stylesheet`, `script`, `image`, `font`, `object`, `xhr`, `ping`, `cspReport`, `media`, `webSocket` or `other`.
- `referrer` string
- `timestamp` Double
- `uploadData` [UploadData[]](structures/upload-data)
+ `callback` Function
- `response` Object
* `cancel` boolean (optional)
* `redirectURL` string (optional) - The original request is prevented from being sent or completed and is instead redirected to the given URL.
The `listener` will be called with `listener(details, callback)` when a request is about to occur.
The `uploadData` is an array of `UploadData` objects.
The `callback` has to be called with an `response` object.
Some examples of valid `urls`:
```
'http://foo:1234/'
'http://foo.com/'
'http://foo:1234/bar'
'*://*/*'
'*://example.com/*'
'*://example.com/foo/*'
'http://*.foo:1234/'
'file://foo:1234/bar'
'http://foo:*/'
'*://www.foo.com/'
```
####
`webRequest.onBeforeSendHeaders([filter, ]listener)`[](#webrequestonbeforesendheadersfilter-listener "Direct link to heading")
* `filter` [WebRequestFilter](structures/web-request-filter) (optional)
* `listener` Function | null
+ `details` Object
- `id` Integer
- `url` string
- `method` string
- `webContentsId` Integer (optional)
- `webContents` WebContents (optional)
- `frame` WebFrameMain (optional)
- `resourceType` string - Can be `mainFrame`, `subFrame`, `stylesheet`, `script`, `image`, `font`, `object`, `xhr`, `ping`, `cspReport`, `media`, `webSocket` or `other`.
- `referrer` string
- `timestamp` Double
- `uploadData` [UploadData[]](structures/upload-data) (optional)
- `requestHeaders` Record<string, string>
+ `callback` Function
- `beforeSendResponse` Object
```
* `cancel` boolean (optional)
* `requestHeaders` Record<string, string | string[]> (optional) - When provided, request will be made
```
with these headers.
The `listener` will be called with `listener(details, callback)` before sending an HTTP request, once the request headers are available. This may occur after a TCP connection is made to the server, but before any http data is sent.
The `callback` has to be called with a `response` object.
####
`webRequest.onSendHeaders([filter, ]listener)`[](#webrequestonsendheadersfilter-listener "Direct link to heading")
* `filter` [WebRequestFilter](structures/web-request-filter) (optional)
* `listener` Function | null
+ `details` Object
- `id` Integer
- `url` string
- `method` string
- `webContentsId` Integer (optional)
- `webContents` WebContents (optional)
- `frame` WebFrameMain (optional)
- `resourceType` string - Can be `mainFrame`, `subFrame`, `stylesheet`, `script`, `image`, `font`, `object`, `xhr`, `ping`, `cspReport`, `media`, `webSocket` or `other`.
- `referrer` string
- `timestamp` Double
- `requestHeaders` Record<string, string>
The `listener` will be called with `listener(details)` just before a request is going to be sent to the server, modifications of previous `onBeforeSendHeaders` response are visible by the time this listener is fired.
####
`webRequest.onHeadersReceived([filter, ]listener)`[](#webrequestonheadersreceivedfilter-listener "Direct link to heading")
* `filter` [WebRequestFilter](structures/web-request-filter) (optional)
* `listener` Function | null
+ `details` Object
- `id` Integer
- `url` string
- `method` string
- `webContentsId` Integer (optional)
- `webContents` WebContents (optional)
- `frame` WebFrameMain (optional)
- `resourceType` string - Can be `mainFrame`, `subFrame`, `stylesheet`, `script`, `image`, `font`, `object`, `xhr`, `ping`, `cspReport`, `media`, `webSocket` or `other`.
- `referrer` string
- `timestamp` Double
- `statusLine` string
- `statusCode` Integer
- `responseHeaders` Record<string, string[]> (optional)
+ `callback` Function
- `headersReceivedResponse` Object
* `cancel` boolean (optional)
* `responseHeaders` Record<string, string | string[]> (optional) - When provided, the server is assumed to have responded with these headers.
* `statusLine` string (optional) - Should be provided when overriding `responseHeaders` to change header status otherwise original response header's status will be used.
The `listener` will be called with `listener(details, callback)` when HTTP response headers of a request have been received.
The `callback` has to be called with a `response` object.
####
`webRequest.onResponseStarted([filter, ]listener)`[](#webrequestonresponsestartedfilter-listener "Direct link to heading")
* `filter` [WebRequestFilter](structures/web-request-filter) (optional)
* `listener` Function | null
+ `details` Object
- `id` Integer
- `url` string
- `method` string
- `webContentsId` Integer (optional)
- `webContents` WebContents (optional)
- `frame` WebFrameMain (optional)
- `resourceType` string - Can be `mainFrame`, `subFrame`, `stylesheet`, `script`, `image`, `font`, `object`, `xhr`, `ping`, `cspReport`, `media`, `webSocket` or `other`.
- `referrer` string
- `timestamp` Double
- `responseHeaders` Record<string, string[]> (optional)
- `fromCache` boolean - Indicates whether the response was fetched from disk cache.
- `statusCode` Integer
- `statusLine` string
The `listener` will be called with `listener(details)` when first byte of the response body is received. For HTTP requests, this means that the status line and response headers are available.
####
`webRequest.onBeforeRedirect([filter, ]listener)`[](#webrequestonbeforeredirectfilter-listener "Direct link to heading")
* `filter` [WebRequestFilter](structures/web-request-filter) (optional)
* `listener` Function | null
+ `details` Object
- `id` Integer
- `url` string
- `method` string
- `webContentsId` Integer (optional)
- `webContents` WebContents (optional)
- `frame` WebFrameMain (optional)
- `resourceType` string - Can be `mainFrame`, `subFrame`, `stylesheet`, `script`, `image`, `font`, `object`, `xhr`, `ping`, `cspReport`, `media`, `webSocket` or `other`.
- `referrer` string
- `timestamp` Double
- `redirectURL` string
- `statusCode` Integer
- `statusLine` string
- `ip` string (optional) - The server IP address that the request was actually sent to.
- `fromCache` boolean
- `responseHeaders` Record<string, string[]> (optional)
The `listener` will be called with `listener(details)` when a server initiated redirect is about to occur.
####
`webRequest.onCompleted([filter, ]listener)`[](#webrequestoncompletedfilter-listener "Direct link to heading")
* `filter` [WebRequestFilter](structures/web-request-filter) (optional)
* `listener` Function | null
+ `details` Object
- `id` Integer
- `url` string
- `method` string
- `webContentsId` Integer (optional)
- `webContents` WebContents (optional)
- `frame` WebFrameMain (optional)
- `resourceType` string - Can be `mainFrame`, `subFrame`, `stylesheet`, `script`, `image`, `font`, `object`, `xhr`, `ping`, `cspReport`, `media`, `webSocket` or `other`.
- `referrer` string
- `timestamp` Double
- `responseHeaders` Record<string, string[]> (optional)
- `fromCache` boolean
- `statusCode` Integer
- `statusLine` string
- `error` string
The `listener` will be called with `listener(details)` when a request is completed.
####
`webRequest.onErrorOccurred([filter, ]listener)`[](#webrequestonerroroccurredfilter-listener "Direct link to heading")
* `filter` [WebRequestFilter](structures/web-request-filter) (optional)
* `listener` Function | null
+ `details` Object
- `id` Integer
- `url` string
- `method` string
- `webContentsId` Integer (optional)
- `webContents` WebContents (optional)
- `frame` WebFrameMain (optional)
- `resourceType` string - Can be `mainFrame`, `subFrame`, `stylesheet`, `script`, `image`, `font`, `object`, `xhr`, `ping`, `cspReport`, `media`, `webSocket` or `other`.
- `referrer` string
- `timestamp` Double
- `fromCache` boolean
- `error` string - The error description.
The `listener` will be called with `listener(details)` when an error occurs.
electron powerMonitor powerMonitor
============
> Monitor power state changes.
>
>
Process: [Main](../glossary#main-process)
Events[](#events "Direct link to heading")
-------------------------------------------
The `powerMonitor` module emits the following events:
### Event: 'suspend'[](#event-suspend "Direct link to heading")
Emitted when the system is suspending.
### Event: 'resume'[](#event-resume "Direct link to heading")
Emitted when system is resuming.
### Event: 'on-ac' *macOS* *Windows*[](#event-on-ac-macos-windows "Direct link to heading")
Emitted when the system changes to AC power.
### Event: 'on-battery' *macOS* *Windows*[](#event-on-battery-macos--windows "Direct link to heading")
Emitted when system changes to battery power.
### Event: 'shutdown' *Linux* *macOS*[](#event-shutdown-linux-macos "Direct link to heading")
Emitted when the system is about to reboot or shut down. If the event handler invokes `e.preventDefault()`, Electron will attempt to delay system shutdown in order for the app to exit cleanly. If `e.preventDefault()` is called, the app should exit as soon as possible by calling something like `app.quit()`.
### Event: 'lock-screen' *macOS* *Windows*[](#event-lock-screen-macos-windows "Direct link to heading")
Emitted when the system is about to lock the screen.
### Event: 'unlock-screen' *macOS* *Windows*[](#event-unlock-screen-macos-windows "Direct link to heading")
Emitted as soon as the systems screen is unlocked.
### Event: 'user-did-become-active' *macOS*[](#event-user-did-become-active-macos "Direct link to heading")
Emitted when a login session is activated. See [documentation](https://developer.apple.com/documentation/appkit/nsworkspacesessiondidbecomeactivenotification?language=objc) for more information.
### Event: 'user-did-resign-active' *macOS*[](#event-user-did-resign-active-macos "Direct link to heading")
Emitted when a login session is deactivated. See [documentation](https://developer.apple.com/documentation/appkit/nsworkspacesessiondidresignactivenotification?language=objc) for more information.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `powerMonitor` module has the following methods:
###
`powerMonitor.getSystemIdleState(idleThreshold)`[](#powermonitorgetsystemidlestateidlethreshold "Direct link to heading")
* `idleThreshold` Integer
Returns `string` - The system's current state. Can be `active`, `idle`, `locked` or `unknown`.
Calculate the system idle state. `idleThreshold` is the amount of time (in seconds) before considered idle. `locked` is available on supported systems only.
###
`powerMonitor.getSystemIdleTime()`[](#powermonitorgetsystemidletime "Direct link to heading")
Returns `Integer` - Idle time in seconds
Calculate system idle time in seconds.
###
`powerMonitor.isOnBatteryPower()`[](#powermonitorisonbatterypower "Direct link to heading")
Returns `boolean` - Whether the system is on battery power.
To monitor for changes in this property, use the `on-battery` and `on-ac` events.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
###
`powerMonitor.onBatteryPower`[](#powermonitoronbatterypower "Direct link to heading")
A `boolean` property. True if the system is on battery power.
See [`powerMonitor.isOnBatteryPower()`](#powermonitorisonbatterypower).
electron ipcMain ipcMain
=======
> Communicate asynchronously from the main process to renderer processes.
>
>
Process: [Main](../glossary#main-process)
The `ipcMain` module is an [Event Emitter](https://nodejs.org/api/events.html#events_class_eventemitter). When used in the main process, it handles asynchronous and synchronous messages sent from a renderer process (web page). Messages sent from a renderer will be emitted to this module.
For usage examples, check out the [IPC tutorial](../tutorial/ipc).
Sending messages[](#sending-messages "Direct link to heading")
---------------------------------------------------------------
It is also possible to send messages from the main process to the renderer process, see [webContents.send](web-contents#contentssendchannel-args) for more information.
* When sending a message, the event name is the `channel`.
* To reply to a synchronous message, you need to set `event.returnValue`.
* To send an asynchronous message back to the sender, you can use `event.reply(...)`. This helper method will automatically handle messages coming from frames that aren't the main frame (e.g. iframes) whereas `event.sender.send(...)` will always send to the main frame.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `ipcMain` module has the following method to listen for events:
###
`ipcMain.on(channel, listener)`[](#ipcmainonchannel-listener "Direct link to heading")
* `channel` string
* `listener` Function
+ `event` [IpcMainEvent](structures/ipc-main-event)
+ `...args` any[]
Listens to `channel`, when a new message arrives `listener` would be called with `listener(event, args...)`.
###
`ipcMain.once(channel, listener)`[](#ipcmainoncechannel-listener "Direct link to heading")
* `channel` string
* `listener` Function
+ `event` [IpcMainEvent](structures/ipc-main-event)
+ `...args` any[]
Adds a one time `listener` function for the event. This `listener` is invoked only the next time a message is sent to `channel`, after which it is removed.
###
`ipcMain.removeListener(channel, listener)`[](#ipcmainremovelistenerchannel-listener "Direct link to heading")
* `channel` string
* `listener` Function
+ `...args` any[]
Removes the specified `listener` from the listener array for the specified `channel`.
###
`ipcMain.removeAllListeners([channel])`[](#ipcmainremovealllistenerschannel "Direct link to heading")
* `channel` string (optional)
Removes listeners of the specified `channel`.
###
`ipcMain.handle(channel, listener)`[](#ipcmainhandlechannel-listener "Direct link to heading")
* `channel` string
* `listener` Function<Promise\<void> | any>
+ `event` [IpcMainInvokeEvent](structures/ipc-main-invoke-event)
+ `...args` any[]
Adds a handler for an `invoke`able IPC. This handler will be called whenever a renderer calls `ipcRenderer.invoke(channel, ...args)`.
If `listener` returns a Promise, the eventual result of the promise will be returned as a reply to the remote caller. Otherwise, the return value of the listener will be used as the value of the reply.
Main Process
```
ipcMain.handle('my-invokable-ipc', async (event, ...args) => {
const result = await somePromise(...args)
return result
})
```
Renderer Process
```
async () => {
const result = await ipcRenderer.invoke('my-invokable-ipc', arg1, arg2)
// ...
}
```
The `event` that is passed as the first argument to the handler is the same as that passed to a regular event listener. It includes information about which WebContents is the source of the invoke request.
Errors thrown through `handle` in the main process are not transparent as they are serialized and only the `message` property from the original error is provided to the renderer process. Please refer to [#24427](https://github.com/electron/electron/issues/24427) for details.
###
`ipcMain.handleOnce(channel, listener)`[](#ipcmainhandleoncechannel-listener "Direct link to heading")
* `channel` string
* `listener` Function<Promise\<void> | any>
+ `event` IpcMainInvokeEvent
+ `...args` any[]
Handles a single `invoke`able IPC message, then removes the listener. See `ipcMain.handle(channel, listener)`.
###
`ipcMain.removeHandler(channel)`[](#ipcmainremovehandlerchannel "Direct link to heading")
* `channel` string
Removes any handler for `channel`, if present.
IpcMainEvent object[](#ipcmainevent-object "Direct link to heading")
---------------------------------------------------------------------
The documentation for the `event` object passed to the `callback` can be found in the [`ipc-main-event`](structures/ipc-main-event) structure docs.
IpcMainInvokeEvent object[](#ipcmaininvokeevent-object "Direct link to heading")
---------------------------------------------------------------------------------
The documentation for the `event` object passed to `handle` callbacks can be found in the [`ipc-main-invoke-event`](structures/ipc-main-invoke-event) structure docs.
electron screen screen
======
> Retrieve information about screen size, displays, cursor position, etc.
>
>
Process: [Main](../glossary#main-process)
This module cannot be used until the `ready` event of the `app` module is emitted.
`screen` is an [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter).
**Note:** In the renderer / DevTools, `window.screen` is a reserved DOM property, so writing `let { screen } = require('electron')` will not work.
An example of creating a window that fills the whole screen:
[docs/fiddles/screen/fit-screen (20.1.0)](https://github.com/electron/electron/tree/v20.1.0/docs/fiddles/screen/fit-screen)[Open in Fiddle](https://fiddle.electronjs.org/launch?target=electron/v20.1.0/docs/fiddles/screen/fit-screen)
* main.js
```
// Retrieve information about screen size, displays, cursor position, etc.
//
// For more info, see:
// https://electronjs.org/docs/api/screen
const { app, BrowserWindow } = require('electron')
let mainWindow = null
app.whenReady().then(() => {
// We cannot require the screen module until the app is ready.
const { screen } = require('electron')
// Create a window that fills the screen's available work area.
const primaryDisplay = screen.getPrimaryDisplay()
const { width, height } = primaryDisplay.workAreaSize
mainWindow = new BrowserWindow({ width, height })
mainWindow.loadURL('https://electronjs.org')
})
```
Another example of creating a window in the external display:
```
const { app, BrowserWindow, screen } = require('electron')
let win
app.whenReady().then(() => {
const displays = screen.getAllDisplays()
const externalDisplay = displays.find((display) => {
return display.bounds.x !== 0 || display.bounds.y !== 0
})
if (externalDisplay) {
win = new BrowserWindow({
x: externalDisplay.bounds.x + 50,
y: externalDisplay.bounds.y + 50
})
win.loadURL('https://github.com')
}
})
```
Events[](#events "Direct link to heading")
-------------------------------------------
The `screen` module emits the following events:
### Event: 'display-added'[](#event-display-added "Direct link to heading")
Returns:
* `event` Event
* `newDisplay` [Display](structures/display)
Emitted when `newDisplay` has been added.
### Event: 'display-removed'[](#event-display-removed "Direct link to heading")
Returns:
* `event` Event
* `oldDisplay` [Display](structures/display)
Emitted when `oldDisplay` has been removed.
### Event: 'display-metrics-changed'[](#event-display-metrics-changed "Direct link to heading")
Returns:
* `event` Event
* `display` [Display](structures/display)
* `changedMetrics` string[]
Emitted when one or more metrics change in a `display`. The `changedMetrics` is an array of strings that describe the changes. Possible changes are `bounds`, `workArea`, `scaleFactor` and `rotation`.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `screen` module has the following methods:
###
`screen.getCursorScreenPoint()`[](#screengetcursorscreenpoint "Direct link to heading")
Returns [Point](structures/point)
The current absolute position of the mouse pointer.
**Note:** The return value is a DIP point, not a screen physical point.
###
`screen.getPrimaryDisplay()`[](#screengetprimarydisplay "Direct link to heading")
Returns [Display](structures/display) - The primary display.
###
`screen.getAllDisplays()`[](#screengetalldisplays "Direct link to heading")
Returns [Display[]](structures/display) - An array of displays that are currently available.
###
`screen.getDisplayNearestPoint(point)`[](#screengetdisplaynearestpointpoint "Direct link to heading")
* `point` [Point](structures/point)
Returns [Display](structures/display) - The display nearest the specified point.
###
`screen.getDisplayMatching(rect)`[](#screengetdisplaymatchingrect "Direct link to heading")
* `rect` [Rectangle](structures/rectangle)
Returns [Display](structures/display) - The display that most closely intersects the provided bounds.
###
`screen.screenToDipPoint(point)` *Windows*[](#screenscreentodippointpoint-windows "Direct link to heading")
* `point` [Point](structures/point)
Returns [Point](structures/point)
Converts a screen physical point to a screen DIP point. The DPI scale is performed relative to the display containing the physical point.
###
`screen.dipToScreenPoint(point)` *Windows*[](#screendiptoscreenpointpoint-windows "Direct link to heading")
* `point` [Point](structures/point)
Returns [Point](structures/point)
Converts a screen DIP point to a screen physical point. The DPI scale is performed relative to the display containing the DIP point.
###
`screen.screenToDipRect(window, rect)` *Windows*[](#screenscreentodiprectwindow-rect-windows "Direct link to heading")
* `window` [BrowserWindow](browser-window) | null
* `rect` [Rectangle](structures/rectangle)
Returns [Rectangle](structures/rectangle)
Converts a screen physical rect to a screen DIP rect. The DPI scale is performed relative to the display nearest to `window`. If `window` is null, scaling will be performed to the display nearest to `rect`.
###
`screen.dipToScreenRect(window, rect)` *Windows*[](#screendiptoscreenrectwindow-rect-windows "Direct link to heading")
* `window` [BrowserWindow](browser-window) | null
* `rect` [Rectangle](structures/rectangle)
Returns [Rectangle](structures/rectangle)
Converts a screen DIP rect to a screen physical rect. The DPI scale is performed relative to the display nearest to `window`. If `window` is null, scaling will be performed to the display nearest to `rect`.
| programming_docs |
electron session session
=======
> Manage browser sessions, cookies, cache, proxy settings, etc.
>
>
Process: [Main](../glossary#main-process)
The `session` module can be used to create new `Session` objects.
You can also access the `session` of existing pages by using the `session` property of [`WebContents`](web-contents), or from the `session` module.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL('http://github.com')
const ses = win.webContents.session
console.log(ses.getUserAgent())
```
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `session` module has the following methods:
###
`session.fromPartition(partition[, options])`[](#sessionfrompartitionpartition-options "Direct link to heading")
* `partition` string
* `options` Object (optional)
+ `cache` boolean - Whether to enable cache.
Returns `Session` - A session instance from `partition` string. When there is an existing `Session` with the same `partition`, it will be returned; otherwise a new `Session` instance will be created with `options`.
If `partition` starts with `persist:`, the page will use a persistent session available to all pages in the app with the same `partition`. if there is no `persist:` prefix, the page will use an in-memory session. If the `partition` is empty then default session of the app will be returned.
To create a `Session` with `options`, you have to ensure the `Session` with the `partition` has never been used before. There is no way to change the `options` of an existing `Session` object.
Properties[](#properties "Direct link to heading")
---------------------------------------------------
The `session` module has the following properties:
###
`session.defaultSession`[](#sessiondefaultsession "Direct link to heading")
A `Session` object, the default session object of the app.
Class: Session[](#class-session "Direct link to heading")
----------------------------------------------------------
> Get and set properties of a session.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
You can create a `Session` object in the `session` module:
```
const { session } = require('electron')
const ses = session.fromPartition('persist:name')
console.log(ses.getUserAgent())
```
### Instance Events[](#instance-events "Direct link to heading")
The following events are available on instances of `Session`:
#### Event: 'will-download'[](#event-will-download "Direct link to heading")
Returns:
* `event` Event
* `item` [DownloadItem](download-item)
* `webContents` [WebContents](web-contents)
Emitted when Electron is about to download `item` in `webContents`.
Calling `event.preventDefault()` will cancel the download and `item` will not be available from next tick of the process.
```
const { session } = require('electron')
session.defaultSession.on('will-download', (event, item, webContents) => {
event.preventDefault()
require('got')(item.getURL()).then((response) => {
require('fs').writeFileSync('/somewhere', response.body)
})
})
```
#### Event: 'extension-loaded'[](#event-extension-loaded "Direct link to heading")
Returns:
* `event` Event
* `extension` [Extension](structures/extension)
Emitted after an extension is loaded. This occurs whenever an extension is added to the "enabled" set of extensions. This includes:
* Extensions being loaded from `Session.loadExtension`.
* Extensions being reloaded:
+ from a crash.
+ if the extension requested it ([`chrome.runtime.reload()`](https://developer.chrome.com/extensions/runtime#method-reload)).
#### Event: 'extension-unloaded'[](#event-extension-unloaded "Direct link to heading")
Returns:
* `event` Event
* `extension` [Extension](structures/extension)
Emitted after an extension is unloaded. This occurs when `Session.removeExtension` is called.
#### Event: 'extension-ready'[](#event-extension-ready "Direct link to heading")
Returns:
* `event` Event
* `extension` [Extension](structures/extension)
Emitted after an extension is loaded and all necessary browser state is initialized to support the start of the extension's background page.
#### Event: 'preconnect'[](#event-preconnect "Direct link to heading")
Returns:
* `event` Event
* `preconnectUrl` string - The URL being requested for preconnection by the renderer.
* `allowCredentials` boolean - True if the renderer is requesting that the connection include credentials (see the [spec](https://w3c.github.io/resource-hints/#preconnect) for more details.)
Emitted when a render process requests preconnection to a URL, generally due to a [resource hint](https://w3c.github.io/resource-hints/).
#### Event: 'spellcheck-dictionary-initialized'[](#event-spellcheck-dictionary-initialized "Direct link to heading")
Returns:
* `event` Event
* `languageCode` string - The language code of the dictionary file
Emitted when a hunspell dictionary file has been successfully initialized. This occurs after the file has been downloaded.
#### Event: 'spellcheck-dictionary-download-begin'[](#event-spellcheck-dictionary-download-begin "Direct link to heading")
Returns:
* `event` Event
* `languageCode` string - The language code of the dictionary file
Emitted when a hunspell dictionary file starts downloading
#### Event: 'spellcheck-dictionary-download-success'[](#event-spellcheck-dictionary-download-success "Direct link to heading")
Returns:
* `event` Event
* `languageCode` string - The language code of the dictionary file
Emitted when a hunspell dictionary file has been successfully downloaded
#### Event: 'spellcheck-dictionary-download-failure'[](#event-spellcheck-dictionary-download-failure "Direct link to heading")
Returns:
* `event` Event
* `languageCode` string - The language code of the dictionary file
Emitted when a hunspell dictionary file download fails. For details on the failure you should collect a netlog and inspect the download request.
#### Event: 'select-hid-device'[](#event-select-hid-device "Direct link to heading")
Returns:
* `event` Event
* `details` Object
+ `deviceList` [HIDDevice[]](structures/hid-device)
+ `frame` [WebFrameMain](web-frame-main)
* `callback` Function
+ `deviceId` string | null (optional)
Emitted when a HID device needs to be selected when a call to `navigator.hid.requestDevice` is made. `callback` should be called with `deviceId` to be selected; passing no arguments to `callback` will cancel the request. Additionally, permissioning on `navigator.hid` can be further managed by using [ses.setPermissionCheckHandler(handler)](#sessetpermissioncheckhandlerhandler) and [ses.setDevicePermissionHandler(handler)`](#sessetdevicepermissionhandlerhandler).
```
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow()
win.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'hid') {
// Add logic here to determine if permission should be given to allow HID selection
return true
}
return false
})
// Optionally, retrieve previously persisted devices from a persistent store
const grantedDevices = fetchGrantedDevices()
win.webContents.session.setDevicePermissionHandler((details) => {
if (new URL(details.origin).hostname === 'some-host' && details.deviceType === 'hid') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.hid.requestDevice` first)
return true
}
// Search through the list of devices that have previously been granted permission
return grantedDevices.some((grantedDevice) => {
return grantedDevice.vendorId === details.device.vendorId &&
grantedDevice.productId === details.device.productId &&
grantedDevice.serialNumber && grantedDevice.serialNumber === details.device.serialNumber
})
}
return false
})
win.webContents.session.on('select-hid-device', (event, details, callback) => {
event.preventDefault()
const selectedDevice = details.deviceList.find((device) => {
return device.vendorId === '9025' && device.productId === '67'
})
callback(selectedPort?.deviceId)
})
})
```
#### Event: 'hid-device-added'[](#event-hid-device-added "Direct link to heading")
Returns:
* `event` Event
* `details` Object
+ `device` [HIDDevice[]](structures/hid-device)
+ `frame` [WebFrameMain](web-frame-main)
Emitted after `navigator.hid.requestDevice` has been called and `select-hid-device` has fired if a new device becomes available before the callback from `select-hid-device` is called. This event is intended for use when using a UI to ask users to pick a device so that the UI can be updated with the newly added device.
#### Event: 'hid-device-removed'[](#event-hid-device-removed "Direct link to heading")
Returns:
* `event` Event
* `details` Object
+ `device` [HIDDevice[]](structures/hid-device)
+ `frame` [WebFrameMain](web-frame-main)
Emitted after `navigator.hid.requestDevice` has been called and `select-hid-device` has fired if a device has been removed before the callback from `select-hid-device` is called. This event is intended for use when using a UI to ask users to pick a device so that the UI can be updated to remove the specified device.
#### Event: 'hid-device-revoked'[](#event-hid-device-revoked "Direct link to heading")
Returns:
* `event` Event
* `details` Object
+ `device` [HIDDevice[]](structures/hid-device)
+ `origin` string (optional) - The origin that the device has been revoked from.
Emitted after `HIDDevice.forget()` has been called. This event can be used to help maintain persistent storage of permissions when `setDevicePermissionHandler` is used.
#### Event: 'select-serial-port'[](#event-select-serial-port "Direct link to heading")
Returns:
* `event` Event
* `portList` [SerialPort[]](structures/serial-port)
* `webContents` [WebContents](web-contents)
* `callback` Function
+ `portId` string
Emitted when a serial port needs to be selected when a call to `navigator.serial.requestPort` is made. `callback` should be called with `portId` to be selected, passing an empty string to `callback` will cancel the request. Additionally, permissioning on `navigator.serial` can be managed by using [ses.setPermissionCheckHandler(handler)](#sessetpermissioncheckhandlerhandler) with the `serial` permission.
```
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow({
width: 800,
height: 600
})
win.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'serial') {
// Add logic here to determine if permission should be given to allow serial selection
return true
}
return false
})
// Optionally, retrieve previously persisted devices from a persistent store
const grantedDevices = fetchGrantedDevices()
win.webContents.session.setDevicePermissionHandler((details) => {
if (new URL(details.origin).hostname === 'some-host' && details.deviceType === 'serial') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.serial.requestPort` first)
return true
}
// Search through the list of devices that have previously been granted permission
return grantedDevices.some((grantedDevice) => {
return grantedDevice.vendorId === details.device.vendorId &&
grantedDevice.productId === details.device.productId &&
grantedDevice.serialNumber && grantedDevice.serialNumber === details.device.serialNumber
})
}
return false
})
win.webContents.session.on('select-serial-port', (event, portList, webContents, callback) => {
event.preventDefault()
const selectedPort = portList.find((device) => {
return device.vendorId === '9025' && device.productId === '67'
})
if (!selectedPort) {
callback('')
} else {
callback(selectedPort.portId)
}
})
})
```
#### Event: 'serial-port-added'[](#event-serial-port-added "Direct link to heading")
Returns:
* `event` Event
* `port` [SerialPort](structures/serial-port)
* `webContents` [WebContents](web-contents)
Emitted after `navigator.serial.requestPort` has been called and `select-serial-port` has fired if a new serial port becomes available before the callback from `select-serial-port` is called. This event is intended for use when using a UI to ask users to pick a port so that the UI can be updated with the newly added port.
#### Event: 'serial-port-removed'[](#event-serial-port-removed "Direct link to heading")
Returns:
* `event` Event
* `port` [SerialPort](structures/serial-port)
* `webContents` [WebContents](web-contents)
Emitted after `navigator.serial.requestPort` has been called and `select-serial-port` has fired if a serial port has been removed before the callback from `select-serial-port` is called. This event is intended for use when using a UI to ask users to pick a port so that the UI can be updated to remove the specified port.
### Instance Methods[](#instance-methods "Direct link to heading")
The following methods are available on instances of `Session`:
####
`ses.getCacheSize()`[](#sesgetcachesize "Direct link to heading")
Returns `Promise<Integer>` - the session's current cache size, in bytes.
####
`ses.clearCache()`[](#sesclearcache "Direct link to heading")
Returns `Promise<void>` - resolves when the cache clear operation is complete.
Clears the session’s HTTP cache.
####
`ses.clearStorageData([options])`[](#sesclearstoragedataoptions "Direct link to heading")
* `options` Object (optional)
+ `origin` string (optional) - Should follow `window.location.origin`’s representation `scheme://host:port`.
+ `storages` string[] (optional) - The types of storages to clear, can contain: `appcache`, `cookies`, `filesystem`, `indexdb`, `localstorage`, `shadercache`, `websql`, `serviceworkers`, `cachestorage`. If not specified, clear all storage types.
+ `quotas` string[] (optional) - The types of quotas to clear, can contain: `temporary`, `persistent`, `syncable`. If not specified, clear all quotas.
Returns `Promise<void>` - resolves when the storage data has been cleared.
####
`ses.flushStorageData()`[](#sesflushstoragedata "Direct link to heading")
Writes any unwritten DOMStorage data to disk.
####
`ses.setProxy(config)`[](#sessetproxyconfig "Direct link to heading")
* `config` Object
+ `mode` string (optional) - The proxy mode. Should be one of `direct`, `auto_detect`, `pac_script`, `fixed_servers` or `system`. If it's unspecified, it will be automatically determined based on other specified options.
- `direct` In direct mode all connections are created directly, without any proxy involved.
- `auto_detect` In auto\_detect mode the proxy configuration is determined by a PAC script that can be downloaded at http://wpad/wpad.dat.
- `pac_script` In pac\_script mode the proxy configuration is determined by a PAC script that is retrieved from the URL specified in the `pacScript`. This is the default mode if `pacScript` is specified.
- `fixed_servers` In fixed\_servers mode the proxy configuration is specified in `proxyRules`. This is the default mode if `proxyRules` is specified.
- `system` In system mode the proxy configuration is taken from the operating system. Note that the system mode is different from setting no proxy configuration. In the latter case, Electron falls back to the system settings only if no command-line options influence the proxy configuration.
+ `pacScript` string (optional) - The URL associated with the PAC file.
+ `proxyRules` string (optional) - Rules indicating which proxies to use.
+ `proxyBypassRules` string (optional) - Rules indicating which URLs should bypass the proxy settings.
Returns `Promise<void>` - Resolves when the proxy setting process is complete.
Sets the proxy settings.
When `mode` is unspecified, `pacScript` and `proxyRules` are provided together, the `proxyRules` option is ignored and `pacScript` configuration is applied.
You may need `ses.closeAllConnections` to close currently in flight connections to prevent pooled sockets using previous proxy from being reused by future requests.
The `proxyRules` has to follow the rules below:
```
proxyRules = schemeProxies[";"<schemeProxies>]
schemeProxies = [<urlScheme>"="]<proxyURIList>
urlScheme = "http" | "https" | "ftp" | "socks"
proxyURIList = <proxyURL>[","<proxyURIList>]
proxyURL = [<proxyScheme>"://"]<proxyHost>[":"<proxyPort>]
```
For example:
* `http=foopy:80;ftp=foopy2` - Use HTTP proxy `foopy:80` for `http://` URLs, and HTTP proxy `foopy2:80` for `ftp://` URLs.
* `foopy:80` - Use HTTP proxy `foopy:80` for all URLs.
* `foopy:80,bar,direct://` - Use HTTP proxy `foopy:80` for all URLs, failing over to `bar` if `foopy:80` is unavailable, and after that using no proxy.
* `socks4://foopy` - Use SOCKS v4 proxy `foopy:1080` for all URLs.
* `http=foopy,socks5://bar.com` - Use HTTP proxy `foopy` for http URLs, and fail over to the SOCKS5 proxy `bar.com` if `foopy` is unavailable.
* `http=foopy,direct://` - Use HTTP proxy `foopy` for http URLs, and use no proxy if `foopy` is unavailable.
* `http=foopy;socks=foopy2` - Use HTTP proxy `foopy` for http URLs, and use `socks4://foopy2` for all other URLs.
The `proxyBypassRules` is a comma separated list of rules described below:
* `[ URL_SCHEME "://" ] HOSTNAME_PATTERN [ ":" <port> ]`
Match all hostnames that match the pattern HOSTNAME\_PATTERN.
Examples: "foobar.com", "*foobar.com", "*.foobar.com", "*foobar.com:99", "https://x.*.y.com:99"
* `"." HOSTNAME_SUFFIX_PATTERN [ ":" PORT ]`
Match a particular domain suffix.
Examples: ".google.com", ".com", "http://.google.com"
* `[ SCHEME "://" ] IP_LITERAL [ ":" PORT ]`
Match URLs which are IP address literals.
Examples: "127.0.1", "[0:0::1]", "[::1]", "http://[::1]:99"
* `IP_LITERAL "/" PREFIX_LENGTH_IN_BITS`
Match any URL that is to an IP literal that falls between the given range. IP range is specified using CIDR notation.
Examples: "192.168.1.1/16", "fefe:13::abc/33".
* `<local>`
Match local addresses. The meaning of `<local>` is whether the host matches one of: "127.0.0.1", "::1", "localhost".
####
`ses.resolveProxy(url)`[](#sesresolveproxyurl "Direct link to heading")
* `url` URL
Returns `Promise<string>` - Resolves with the proxy information for `url`.
####
`ses.forceReloadProxyConfig()`[](#sesforcereloadproxyconfig "Direct link to heading")
Returns `Promise<void>` - Resolves when the all internal states of proxy service is reset and the latest proxy configuration is reapplied if it's already available. The pac script will be fetched from `pacScript` again if the proxy mode is `pac_script`.
####
`ses.setDownloadPath(path)`[](#sessetdownloadpathpath "Direct link to heading")
* `path` string - The download location.
Sets download saving directory. By default, the download directory will be the `Downloads` under the respective app folder.
####
`ses.enableNetworkEmulation(options)`[](#sesenablenetworkemulationoptions "Direct link to heading")
* `options` Object
+ `offline` boolean (optional) - Whether to emulate network outage. Defaults to false.
+ `latency` Double (optional) - RTT in ms. Defaults to 0 which will disable latency throttling.
+ `downloadThroughput` Double (optional) - Download rate in Bps. Defaults to 0 which will disable download throttling.
+ `uploadThroughput` Double (optional) - Upload rate in Bps. Defaults to 0 which will disable upload throttling.
Emulates network with the given configuration for the `session`.
```
// To emulate a GPRS connection with 50kbps throughput and 500 ms latency.
window.webContents.session.enableNetworkEmulation({
latency: 500,
downloadThroughput: 6400,
uploadThroughput: 6400
})
// To emulate a network outage.
window.webContents.session.enableNetworkEmulation({ offline: true })
```
####
`ses.preconnect(options)`[](#sespreconnectoptions "Direct link to heading")
* `options` Object
+ `url` string - URL for preconnect. Only the origin is relevant for opening the socket.
+ `numSockets` number (optional) - number of sockets to preconnect. Must be between 1 and 6. Defaults to 1.
Preconnects the given number of sockets to an origin.
####
`ses.closeAllConnections()`[](#sescloseallconnections "Direct link to heading")
Returns `Promise<void>` - Resolves when all connections are closed.
**Note:** It will terminate / fail all requests currently in flight.
####
`ses.disableNetworkEmulation()`[](#sesdisablenetworkemulation "Direct link to heading")
Disables any network emulation already active for the `session`. Resets to the original network configuration.
####
`ses.setCertificateVerifyProc(proc)`[](#sessetcertificateverifyprocproc "Direct link to heading")
* `proc` Function | null
+ `request` Object
- `hostname` string
- `certificate` [Certificate](structures/certificate)
- `validatedCertificate` [Certificate](structures/certificate)
- `isIssuedByKnownRoot` boolean - `true` if Chromium recognises the root CA as a standard root. If it isn't then it's probably the case that this certificate was generated by a MITM proxy whose root has been installed locally (for example, by a corporate proxy). This should not be trusted if the `verificationResult` is not `OK`.
- `verificationResult` string - `OK` if the certificate is trusted, otherwise an error like `CERT_REVOKED`.
- `errorCode` Integer - Error code.
+ `callback` Function
- `verificationResult` Integer - Value can be one of certificate error codes from [here](https://source.chromium.org/chromium/chromium/src/+/main:net/base/net_error_list.h). Apart from the certificate error codes, the following special codes can be used.
* `0` - Indicates success and disables Certificate Transparency verification.
* `-2` - Indicates failure.
* `-3` - Uses the verification result from chromium.
Sets the certificate verify proc for `session`, the `proc` will be called with `proc(request, callback)` whenever a server certificate verification is requested. Calling `callback(0)` accepts the certificate, calling `callback(-2)` rejects it.
Calling `setCertificateVerifyProc(null)` will revert back to default certificate verify proc.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.webContents.session.setCertificateVerifyProc((request, callback) => {
const { hostname } = request
if (hostname === 'github.com') {
callback(0)
} else {
callback(-2)
}
})
```
> **NOTE:** The result of this procedure is cached by the network service.
>
>
####
`ses.setPermissionRequestHandler(handler)`[](#sessetpermissionrequesthandlerhandler "Direct link to heading")
* `handler` Function | null
+ `webContents` [WebContents](web-contents) - WebContents requesting the permission. Please note that if the request comes from a subframe you should use `requestingUrl` to check the request origin.
+ `permission` string - The type of requested permission.
- `clipboard-read` - Request access to read from the clipboard.
- `media` - Request access to media devices such as camera, microphone and speakers.
- `display-capture` - Request access to capture the screen.
- `mediaKeySystem` - Request access to DRM protected content.
- `geolocation` - Request access to user's current location.
- `notifications` - Request notification creation and the ability to display them in the user's system tray.
- `midi` - Request MIDI access in the `webmidi` API.
- `midiSysex` - Request the use of system exclusive messages in the `webmidi` API.
- `pointerLock` - Request to directly interpret mouse movements as an input method. Click [here](https://developer.mozilla.org/en-US/docs/Web/API/Pointer_Lock_API) to know more.
- `fullscreen` - Request for the app to enter fullscreen mode.
- `openExternal` - Request to open links in external applications.
- `unknown` - An unrecognized permission request
+ `callback` Function
- `permissionGranted` boolean - Allow or deny the permission.
+ `details` Object - Some properties are only available on certain permission types.
- `externalURL` string (optional) - The url of the `openExternal` request.
- `securityOrigin` string (optional) - The security origin of the `media` request.
- `mediaTypes` string[] (optional) - The types of media access being requested, elements can be `video` or `audio`
- `requestingUrl` string - The last URL the requesting frame loaded
- `isMainFrame` boolean - Whether the frame making the request is the main frame
Sets the handler which can be used to respond to permission requests for the `session`. Calling `callback(true)` will allow the permission and `callback(false)` will reject it. To clear the handler, call `setPermissionRequestHandler(null)`. Please note that you must also implement `setPermissionCheckHandler` to get complete permission handling. Most web APIs do a permission check and then make a permission request if the check is denied.
```
const { session } = require('electron')
session.fromPartition('some-partition').setPermissionRequestHandler((webContents, permission, callback) => {
if (webContents.getURL() === 'some-host' && permission === 'notifications') {
return callback(false) // denied.
}
callback(true)
})
```
####
`ses.setPermissionCheckHandler(handler)`[](#sessetpermissioncheckhandlerhandler "Direct link to heading")
* `handler` Function\<boolean> | null
+ `webContents` ([WebContents](web-contents) | null) - WebContents checking the permission. Please note that if the request comes from a subframe you should use `requestingUrl` to check the request origin. All cross origin sub frames making permission checks will pass a `null` webContents to this handler, while certain other permission checks such as `notifications` checks will always pass `null`. You should use `embeddingOrigin` and `requestingOrigin` to determine what origin the owning frame and the requesting frame are on respectively.
+ `permission` string - Type of permission check. Valid values are `midiSysex`, `notifications`, `geolocation`, `media`,`mediaKeySystem`,`midi`, `pointerLock`, `fullscreen`, `openExternal`, `hid`, or `serial`.
+ `requestingOrigin` string - The origin URL of the permission check
+ `details` Object - Some properties are only available on certain permission types.
- `embeddingOrigin` string (optional) - The origin of the frame embedding the frame that made the permission check. Only set for cross-origin sub frames making permission checks.
- `securityOrigin` string (optional) - The security origin of the `media` check.
- `mediaType` string (optional) - The type of media access being requested, can be `video`, `audio` or `unknown`
- `requestingUrl` string (optional) - The last URL the requesting frame loaded. This is not provided for cross-origin sub frames making permission checks.
- `isMainFrame` boolean - Whether the frame making the request is the main frame
Sets the handler which can be used to respond to permission checks for the `session`. Returning `true` will allow the permission and `false` will reject it. Please note that you must also implement `setPermissionRequestHandler` to get complete permission handling. Most web APIs do a permission check and then make a permission request if the check is denied. To clear the handler, call `setPermissionCheckHandler(null)`.
```
const { session } = require('electron')
const url = require('url')
session.fromPartition('some-partition').setPermissionCheckHandler((webContents, permission, requestingOrigin) => {
if (new URL(requestingOrigin).hostname === 'some-host' && permission === 'notifications') {
return true // granted
}
return false // denied
})
```
####
`ses.setDevicePermissionHandler(handler)`[](#sessetdevicepermissionhandlerhandler "Direct link to heading")
* `handler` Function\<boolean> | null
+ `details` Object
- `deviceType` string - The type of device that permission is being requested on, can be `hid` or `serial`.
- `origin` string - The origin URL of the device permission check.
- `device` [HIDDevice](structures/hid-device) | [SerialPort](structures/serial-port)- the device that permission is being requested for.
Sets the handler which can be used to respond to device permission checks for the `session`. Returning `true` will allow the device to be permitted and `false` will reject it. To clear the handler, call `setDevicePermissionHandler(null)`. This handler can be used to provide default permissioning to devices without first calling for permission to devices (eg via `navigator.hid.requestDevice`). If this handler is not defined, the default device permissions as granted through device selection (eg via `navigator.hid.requestDevice`) will be used. Additionally, the default behavior of Electron is to store granted device permision in memory. If longer term storage is needed, a developer can store granted device permissions (eg when handling the `select-hid-device` event) and then read from that storage with `setDevicePermissionHandler`.
```
const { app, BrowserWindow } = require('electron')
let win = null
app.whenReady().then(() => {
win = new BrowserWindow()
win.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
if (permission === 'hid') {
// Add logic here to determine if permission should be given to allow HID selection
return true
} else if (permission === 'serial') {
// Add logic here to determine if permission should be given to allow serial port selection
}
return false
})
// Optionally, retrieve previously persisted devices from a persistent store
const grantedDevices = fetchGrantedDevices()
win.webContents.session.setDevicePermissionHandler((details) => {
if (new URL(details.origin).hostname === 'some-host' && details.deviceType === 'hid') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.hid.requestDevice` first)
return true
}
// Search through the list of devices that have previously been granted permission
return grantedDevices.some((grantedDevice) => {
return grantedDevice.vendorId === details.device.vendorId &&
grantedDevice.productId === details.device.productId &&
grantedDevice.serialNumber && grantedDevice.serialNumber === details.device.serialNumber
})
} else if (details.deviceType === 'serial') {
if (details.device.vendorId === 123 && details.device.productId === 345) {
// Always allow this type of device (this allows skipping the call to `navigator.hid.requestDevice` first)
return true
}
}
return false
})
win.webContents.session.on('select-hid-device', (event, details, callback) => {
event.preventDefault()
const selectedDevice = details.deviceList.find((device) => {
return device.vendorId === '9025' && device.productId === '67'
})
callback(selectedPort?.deviceId)
})
})
```
####
`ses.clearHostResolverCache()`[](#sesclearhostresolvercache "Direct link to heading")
Returns `Promise<void>` - Resolves when the operation is complete.
Clears the host resolver cache.
####
`ses.allowNTLMCredentialsForDomains(domains)`[](#sesallowntlmcredentialsfordomainsdomains "Direct link to heading")
* `domains` string - A comma-separated list of servers for which integrated authentication is enabled.
Dynamically sets whether to always send credentials for HTTP NTLM or Negotiate authentication.
```
const { session } = require('electron')
// consider any url ending with `example.com`, `foobar.com`, `baz`
// for integrated authentication.
session.defaultSession.allowNTLMCredentialsForDomains('*example.com, *foobar.com, *baz')
// consider all urls for integrated authentication.
session.defaultSession.allowNTLMCredentialsForDomains('*')
```
####
`ses.setUserAgent(userAgent[, acceptLanguages])`[](#sessetuseragentuseragent-acceptlanguages "Direct link to heading")
* `userAgent` string
* `acceptLanguages` string (optional)
Overrides the `userAgent` and `acceptLanguages` for this session.
The `acceptLanguages` must a comma separated ordered list of language codes, for example `"en-US,fr,de,ko,zh-CN,ja"`.
This doesn't affect existing `WebContents`, and each `WebContents` can use `webContents.setUserAgent` to override the session-wide user agent.
####
`ses.isPersistent()`[](#sesispersistent "Direct link to heading")
Returns `boolean` - Whether or not this session is a persistent one. The default `webContents` session of a `BrowserWindow` is persistent. When creating a session from a partition, session prefixed with `persist:` will be persistent, while others will be temporary.
####
`ses.getUserAgent()`[](#sesgetuseragent "Direct link to heading")
Returns `string` - The user agent for this session.
####
`ses.setSSLConfig(config)`[](#sessetsslconfigconfig "Direct link to heading")
* `config` Object
+ `minVersion` string (optional) - Can be `tls1`, `tls1.1`, `tls1.2` or `tls1.3`. The minimum SSL version to allow when connecting to remote servers. Defaults to `tls1`.
+ `maxVersion` string (optional) - Can be `tls1.2` or `tls1.3`. The maximum SSL version to allow when connecting to remote servers. Defaults to `tls1.3`.
+ `disabledCipherSuites` Integer[] (optional) - List of cipher suites which should be explicitly prevented from being used in addition to those disabled by the net built-in policy. Supported literal forms: 0xAABB, where AA is `cipher_suite[0]` and BB is `cipher_suite[1]`, as defined in RFC 2246, Section 7.4.1.2. Unrecognized but parsable cipher suites in this form will not return an error. Ex: To disable TLS\_RSA\_WITH\_RC4\_128\_MD5, specify 0x0004, while to disable TLS\_ECDH\_ECDSA\_WITH\_RC4\_128\_SHA, specify 0xC002. Note that TLSv1.3 ciphers cannot be disabled using this mechanism.
Sets the SSL configuration for the session. All subsequent network requests will use the new configuration. Existing network connections (such as WebSocket connections) will not be terminated, but old sockets in the pool will not be reused for new connections.
####
`ses.getBlobData(identifier)`[](#sesgetblobdataidentifier "Direct link to heading")
* `identifier` string - Valid UUID.
Returns `Promise<Buffer>` - resolves with blob data.
####
`ses.downloadURL(url)`[](#sesdownloadurlurl "Direct link to heading")
* `url` string
Initiates a download of the resource at `url`. The API will generate a [DownloadItem](download-item) that can be accessed with the [will-download](#event-will-download) event.
**Note:** This does not perform any security checks that relate to a page's origin, unlike [`webContents.downloadURL`](web-contents#contentsdownloadurlurl).
####
`ses.createInterruptedDownload(options)`[](#sescreateinterrupteddownloadoptions "Direct link to heading")
* `options` Object
+ `path` string - Absolute path of the download.
+ `urlChain` string[] - Complete URL chain for the download.
+ `mimeType` string (optional)
+ `offset` Integer - Start range for the download.
+ `length` Integer - Total length of the download.
+ `lastModified` string (optional) - Last-Modified header value.
+ `eTag` string (optional) - ETag header value.
+ `startTime` Double (optional) - Time when download was started in number of seconds since UNIX epoch.
Allows resuming `cancelled` or `interrupted` downloads from previous `Session`. The API will generate a [DownloadItem](download-item) that can be accessed with the [will-download](#event-will-download) event. The [DownloadItem](download-item) will not have any `WebContents` associated with it and the initial state will be `interrupted`. The download will start only when the `resume` API is called on the [DownloadItem](download-item).
####
`ses.clearAuthCache()`[](#sesclearauthcache "Direct link to heading")
Returns `Promise<void>` - resolves when the session’s HTTP authentication cache has been cleared.
####
`ses.setPreloads(preloads)`[](#sessetpreloadspreloads "Direct link to heading")
* `preloads` string[] - An array of absolute path to preload scripts
Adds scripts that will be executed on ALL web contents that are associated with this session just before normal `preload` scripts run.
####
`ses.getPreloads()`[](#sesgetpreloads "Direct link to heading")
Returns `string[]` an array of paths to preload scripts that have been registered.
####
`ses.setCodeCachePath(path)`[](#sessetcodecachepathpath "Direct link to heading")
* `path` String - Absolute path to store the v8 generated JS code cache from the renderer.
Sets the directory to store the generated JS [code cache](https://v8.dev/blog/code-caching-for-devs) for this session. The directory is not required to be created by the user before this call, the runtime will create if it does not exist otherwise will use the existing directory. If directory cannot be created, then code cache will not be used and all operations related to code cache will fail silently inside the runtime. By default, the directory will be `Code Cache` under the respective user data folder.
####
`ses.clearCodeCaches(options)`[](#sesclearcodecachesoptions "Direct link to heading")
* `options` Object
+ `urls` String[] (optional) - An array of url corresponding to the resource whose generated code cache needs to be removed. If the list is empty then all entries in the cache directory will be removed.
Returns `Promise<void>` - resolves when the code cache clear operation is complete.
####
`ses.setSpellCheckerEnabled(enable)`[](#sessetspellcheckerenabledenable "Direct link to heading")
* `enable` boolean
Sets whether to enable the builtin spell checker.
####
`ses.isSpellCheckerEnabled()`[](#sesisspellcheckerenabled "Direct link to heading")
Returns `boolean` - Whether the builtin spell checker is enabled.
####
`ses.setSpellCheckerLanguages(languages)`[](#sessetspellcheckerlanguageslanguages "Direct link to heading")
* `languages` string[] - An array of language codes to enable the spellchecker for.
The built in spellchecker does not automatically detect what language a user is typing in. In order for the spell checker to correctly check their words you must call this API with an array of language codes. You can get the list of supported language codes with the `ses.availableSpellCheckerLanguages` property.
**Note:** On macOS the OS spellchecker is used and will detect your language automatically. This API is a no-op on macOS.
####
`ses.getSpellCheckerLanguages()`[](#sesgetspellcheckerlanguages "Direct link to heading")
Returns `string[]` - An array of language codes the spellchecker is enabled for. If this list is empty the spellchecker will fallback to using `en-US`. By default on launch if this setting is an empty list Electron will try to populate this setting with the current OS locale. This setting is persisted across restarts.
**Note:** On macOS the OS spellchecker is used and has its own list of languages. This API is a no-op on macOS.
####
`ses.setSpellCheckerDictionaryDownloadURL(url)`[](#sessetspellcheckerdictionarydownloadurlurl "Direct link to heading")
* `url` string - A base URL for Electron to download hunspell dictionaries from.
By default Electron will download hunspell dictionaries from the Chromium CDN. If you want to override this behavior you can use this API to point the dictionary downloader at your own hosted version of the hunspell dictionaries. We publish a `hunspell_dictionaries.zip` file with each release which contains the files you need to host here.
The file server must be **case insensitive**. If you cannot do this, you must upload each file twice: once with the case it has in the ZIP file and once with the filename as all lowercase.
If the files present in `hunspell_dictionaries.zip` are available at `https://example.com/dictionaries/language-code.bdic` then you should call this api with `ses.setSpellCheckerDictionaryDownloadURL('https://example.com/dictionaries/')`. Please note the trailing slash. The URL to the dictionaries is formed as `${url}${filename}`.
**Note:** On macOS the OS spellchecker is used and therefore we do not download any dictionary files. This API is a no-op on macOS.
####
`ses.listWordsInSpellCheckerDictionary()`[](#seslistwordsinspellcheckerdictionary "Direct link to heading")
Returns `Promise<string[]>` - An array of all words in app's custom dictionary. Resolves when the full dictionary is loaded from disk.
####
`ses.addWordToSpellCheckerDictionary(word)`[](#sesaddwordtospellcheckerdictionaryword "Direct link to heading")
* `word` string - The word you want to add to the dictionary
Returns `boolean` - Whether the word was successfully written to the custom dictionary. This API will not work on non-persistent (in-memory) sessions.
**Note:** On macOS and Windows 10 this word will be written to the OS custom dictionary as well
####
`ses.removeWordFromSpellCheckerDictionary(word)`[](#sesremovewordfromspellcheckerdictionaryword "Direct link to heading")
* `word` string - The word you want to remove from the dictionary
Returns `boolean` - Whether the word was successfully removed from the custom dictionary. This API will not work on non-persistent (in-memory) sessions.
**Note:** On macOS and Windows 10 this word will be removed from the OS custom dictionary as well
####
`ses.loadExtension(path[, options])`[](#sesloadextensionpath-options "Direct link to heading")
* `path` string - Path to a directory containing an unpacked Chrome extension
* `options` Object (optional)
+ `allowFileAccess` boolean - Whether to allow the extension to read local files over `file://` protocol and inject content scripts into `file://` pages. This is required e.g. for loading devtools extensions on `file://` URLs. Defaults to false.
Returns `Promise<Extension>` - resolves when the extension is loaded.
This method will raise an exception if the extension could not be loaded. If there are warnings when installing the extension (e.g. if the extension requests an API that Electron does not support) then they will be logged to the console.
Note that Electron does not support the full range of Chrome extensions APIs. See [Supported Extensions APIs](extensions#supported-extensions-apis) for more details on what is supported.
Note that in previous versions of Electron, extensions that were loaded would be remembered for future runs of the application. This is no longer the case: `loadExtension` must be called on every boot of your app if you want the extension to be loaded.
```
const { app, session } = require('electron')
const path = require('path')
app.on('ready', async () => {
await session.defaultSession.loadExtension(
path.join(__dirname, 'react-devtools'),
// allowFileAccess is required to load the devtools extension on file:// URLs.
{ allowFileAccess: true }
)
// Note that in order to use the React DevTools extension, you'll need to
// download and unzip a copy of the extension.
})
```
This API does not support loading packed (.crx) extensions.
**Note:** This API cannot be called before the `ready` event of the `app` module is emitted.
**Note:** Loading extensions into in-memory (non-persistent) sessions is not supported and will throw an error.
####
`ses.removeExtension(extensionId)`[](#sesremoveextensionextensionid "Direct link to heading")
* `extensionId` string - ID of extension to remove
Unloads an extension.
**Note:** This API cannot be called before the `ready` event of the `app` module is emitted.
####
`ses.getExtension(extensionId)`[](#sesgetextensionextensionid "Direct link to heading")
* `extensionId` string - ID of extension to query
Returns `Extension` | `null` - The loaded extension with the given ID.
**Note:** This API cannot be called before the `ready` event of the `app` module is emitted.
####
`ses.getAllExtensions()`[](#sesgetallextensions "Direct link to heading")
Returns `Extension[]` - A list of all loaded extensions.
**Note:** This API cannot be called before the `ready` event of the `app` module is emitted.
####
`ses.getStoragePath()`[](#sesgetstoragepath "Direct link to heading")
Returns `string | null` - The absolute file system path where data for this session is persisted on disk. For in memory sessions this returns `null`.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `Session`:
####
`ses.availableSpellCheckerLanguages` *Readonly*[](#sesavailablespellcheckerlanguages-readonly "Direct link to heading")
A `string[]` array which consists of all the known available spell checker languages. Providing a language code to the `setSpellCheckerLanguages` API that isn't in this array will result in an error.
####
`ses.spellCheckerEnabled`[](#sesspellcheckerenabled "Direct link to heading")
A `boolean` indicating whether builtin spell checker is enabled.
####
`ses.storagePath` *Readonly*[](#sesstoragepath-readonly "Direct link to heading")
A `string | null` indicating the absolute file system path where data for this session is persisted on disk. For in memory sessions this returns `null`.
####
`ses.cookies` *Readonly*[](#sescookies-readonly "Direct link to heading")
A [`Cookies`](cookies) object for this session.
####
`ses.serviceWorkers` *Readonly*[](#sesserviceworkers-readonly "Direct link to heading")
A [`ServiceWorkers`](service-workers) object for this session.
####
`ses.webRequest` *Readonly*[](#seswebrequest-readonly "Direct link to heading")
A [`WebRequest`](web-request) object for this session.
####
`ses.protocol` *Readonly*[](#sesprotocol-readonly "Direct link to heading")
A [`Protocol`](protocol) object for this session.
```
const { app, session } = require('electron')
const path = require('path')
app.whenReady().then(() => {
const protocol = session.fromPartition('some-partition').protocol
if (!protocol.registerFileProtocol('atom', (request, callback) => {
const url = request.url.substr(7)
callback({ path: path.normalize(`${__dirname}/${url}`) })
})) {
console.error('Failed to register protocol')
}
})
```
####
`ses.netLog` *Readonly*[](#sesnetlog-readonly "Direct link to heading")
A [`NetLog`](net-log) object for this session.
```
const { app, session } = require('electron')
app.whenReady().then(async () => {
const netLog = session.fromPartition('some-partition').netLog
netLog.startLogging('/path/to/net-log')
// After some network events
const path = await netLog.stopLogging()
console.log('Net-logs written to', path)
})
```
| programming_docs |
electron ShareMenu ShareMenu
=========
The `ShareMenu` class creates [Share Menu](https://developer.apple.com/design/human-interface-guidelines/macos/extensions/share-extensions/) on macOS, which can be used to share information from the current context to apps, social media accounts, and other services.
For including the share menu as a submenu of other menus, please use the `shareMenu` role of [`MenuItem`](menu-item).
Class: ShareMenu[](#class-sharemenu "Direct link to heading")
--------------------------------------------------------------
> Create share menu on macOS.
>
>
Process: [Main](../glossary#main-process)
###
`new ShareMenu(sharingItem)`[](#new-sharemenusharingitem "Direct link to heading")
* `sharingItem` SharingItem - The item to share.
Creates a new share menu.
### Instance Methods[](#instance-methods "Direct link to heading")
The `shareMenu` object has the following instance methods:
####
`shareMenu.popup([options])`[](#sharemenupopupoptions "Direct link to heading")
* `options` PopupOptions (optional)
+ `browserWindow` [BrowserWindow](browser-window) (optional) - Default is the focused window.
+ `x` number (optional) - Default is the current mouse cursor position. Must be declared if `y` is declared.
+ `y` number (optional) - Default is the current mouse cursor position. Must be declared if `x` is declared.
+ `positioningItem` number (optional) *macOS* - The index of the menu item to be positioned under the mouse cursor at the specified coordinates. Default is -1.
+ `callback` Function (optional) - Called when menu is closed.
Pops up this menu as a context menu in the [`BrowserWindow`](browser-window).
####
`shareMenu.closePopup([browserWindow])`[](#sharemenuclosepopupbrowserwindow "Direct link to heading")
* `browserWindow` [BrowserWindow](browser-window) (optional) - Default is the focused window.
Closes the context menu in the `browserWindow`.
electron BrowserView BrowserView
===========
A `BrowserView` can be used to embed additional web content into a [`BrowserWindow`](browser-window). It is like a child window, except that it is positioned relative to its owning window. It is meant to be an alternative to the `webview` tag.
Class: BrowserView[](#class-browserview "Direct link to heading")
------------------------------------------------------------------
> Create and control views.
>
>
Process: [Main](../glossary#main-process)
This module cannot be used until the `ready` event of the `app` module is emitted.
### Example[](#example "Direct link to heading")
```
// In the main process.
const { app, BrowserView, BrowserWindow } = require('electron')
app.whenReady().then(() => {
const win = new BrowserWindow({ width: 800, height: 600 })
const view = new BrowserView()
win.setBrowserView(view)
view.setBounds({ x: 0, y: 0, width: 300, height: 300 })
view.webContents.loadURL('https://electronjs.org')
})
```
###
`new BrowserView([options])` *Experimental*[](#new-browserviewoptions-experimental "Direct link to heading")
* `options` Object (optional)
+ `webPreferences` Object (optional) - See [BrowserWindow](browser-window).
### Instance Properties[](#instance-properties "Direct link to heading")
Objects created with `new BrowserView` have the following properties:
####
`view.webContents` *Experimental*[](#viewwebcontents-experimental "Direct link to heading")
A [`WebContents`](web-contents) object owned by this view.
### Instance Methods[](#instance-methods "Direct link to heading")
Objects created with `new BrowserView` have the following instance methods:
####
`view.setAutoResize(options)` *Experimental*[](#viewsetautoresizeoptions-experimental "Direct link to heading")
* `options` Object
+ `width` boolean (optional) - If `true`, the view's width will grow and shrink together with the window. `false` by default.
+ `height` boolean (optional) - If `true`, the view's height will grow and shrink together with the window. `false` by default.
+ `horizontal` boolean (optional) - If `true`, the view's x position and width will grow and shrink proportionally with the window. `false` by default.
+ `vertical` boolean (optional) - If `true`, the view's y position and height will grow and shrink proportionally with the window. `false` by default.
####
`view.setBounds(bounds)` *Experimental*[](#viewsetboundsbounds-experimental "Direct link to heading")
* `bounds` [Rectangle](structures/rectangle)
Resizes and moves the view to the supplied bounds relative to the window.
####
`view.getBounds()` *Experimental*[](#viewgetbounds-experimental "Direct link to heading")
Returns [Rectangle](structures/rectangle)
The `bounds` of this BrowserView instance as `Object`.
####
`view.setBackgroundColor(color)` *Experimental*[](#viewsetbackgroundcolorcolor-experimental "Direct link to heading")
* `color` string - Color in Hex, RGB, ARGB, HSL, HSLA or named CSS color format. The alpha channel is optional for the hex type.
Examples of valid `color` values:
* Hex
+ #fff (RGB)
+ #ffff (ARGB)
+ #ffffff (RRGGBB)
+ #ffffffff (AARRGGBB)
* RGB
+ rgb(([\d]+),\s*([\d]+),\s*([\d]+))
- e.g. rgb(255, 255, 255)
* RGBA
+ rgba(([\d]+),\s*([\d]+),\s*([\d]+),\s\*([\d.]+))
- e.g. rgba(255, 255, 255, 1.0)
* HSL
+ hsl((-?[\d.]+),\s*([\d.]+)%,\s*([\d.]+)%)
- e.g. hsl(200, 20%, 50%)
* HSLA
+ hsla((-?[\d.]+),\s*([\d.]+)%,\s*([\d.]+)%,\s\*([\d.]+))
- e.g. hsla(200, 20%, 50%, 0.5)
* Color name
+ Options are listed in [SkParseColor.cpp](https://source.chromium.org/chromium/chromium/src/+/main:third_party/skia/src/utils/SkParseColor.cpp;l=11-152;drc=eea4bf52cb0d55e2a39c828b017c80a5ee054148)
+ Similar to CSS Color Module Level 3 keywords, but case-sensitive.
- e.g. `blueviolet` or `red`
**Note:** Hex format with alpha takes `AARRGGBB` or `ARGB`, *not* `RRGGBBA` or `RGA`.
electron
<webview> Tag
`<webview>` Tag
================
Warning[](#warning "Direct link to heading")
---------------------------------------------
Electron's `webview` tag is based on [Chromium's `webview`](https://developer.chrome.com/docs/extensions/reference/webviewTag/), which is undergoing dramatic architectural changes. This impacts the stability of `webviews`, including rendering, navigation, and event routing. We currently recommend to not use the `webview` tag and to consider alternatives, like `iframe`, [Electron's `BrowserView`](browser-view), or an architecture that avoids embedded content altogether.
Enabling[](#enabling "Direct link to heading")
-----------------------------------------------
By default the `webview` tag is disabled in Electron >= 5. You need to enable the tag by setting the `webviewTag` webPreferences option when constructing your `BrowserWindow`. For more information see the [BrowserWindow constructor docs](browser-window).
Overview[](#overview "Direct link to heading")
-----------------------------------------------
> Display external web content in an isolated frame and process.
>
>
Process: [Renderer](../glossary#renderer-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
Use the `webview` tag to embed 'guest' content (such as web pages) in your Electron app. The guest content is contained within the `webview` container. An embedded page within your app controls how the guest content is laid out and rendered.
Unlike an `iframe`, the `webview` runs in a separate process than your app. It doesn't have the same permissions as your web page and all interactions between your app and embedded content will be asynchronous. This keeps your app safe from the embedded content. **Note:** Most methods called on the webview from the host page require a synchronous call to the main process.
Example[](#example "Direct link to heading")
---------------------------------------------
To embed a web page in your app, add the `webview` tag to your app's embedder page (this is the app page that will display the guest content). In its simplest form, the `webview` tag includes the `src` of the web page and css styles that control the appearance of the `webview` container:
```
<webview id="foo" src="https://www.github.com/" style="display:inline-flex; width:640px; height:480px"></webview>
```
If you want to control the guest content in any way, you can write JavaScript that listens for `webview` events and responds to those events using the `webview` methods. Here's sample code with two event listeners: one that listens for the web page to start loading, the other for the web page to stop loading, and displays a "loading..." message during the load time:
```
<script>
onload = () => {
const webview = document.querySelector('webview')
const indicator = document.querySelector('.indicator')
const loadstart = () => {
indicator.innerText = 'loading...'
}
const loadstop = () => {
indicator.innerText = ''
}
webview.addEventListener('did-start-loading', loadstart)
webview.addEventListener('did-stop-loading', loadstop)
}
</script>
```
Internal implementation[](#internal-implementation "Direct link to heading")
-----------------------------------------------------------------------------
Under the hood `webview` is implemented with [Out-of-Process iframes (OOPIFs)](https://www.chromium.org/developers/design-documents/oop-iframes). The `webview` tag is essentially a custom element using shadow DOM to wrap an `iframe` element inside it.
So the behavior of `webview` is very similar to a cross-domain `iframe`, as examples:
* When clicking into a `webview`, the page focus will move from the embedder frame to `webview`.
* You can not add keyboard, mouse, and scroll event listeners to `webview`.
* All reactions between the embedder frame and `webview` are asynchronous.
CSS Styling Notes[](#css-styling-notes "Direct link to heading")
-----------------------------------------------------------------
Please note that the `webview` tag's style uses `display:flex;` internally to ensure the child `iframe` element fills the full height and width of its `webview` container when used with traditional and flexbox layouts. Please do not overwrite the default `display:flex;` CSS property, unless specifying `display:inline-flex;` for inline layout.
Tag Attributes[](#tag-attributes "Direct link to heading")
-----------------------------------------------------------
The `webview` tag has the following attributes:
###
`src`[](#src "Direct link to heading")
```
<webview src="https://www.github.com/"></webview>
```
A `string` representing the visible URL. Writing to this attribute initiates top-level navigation.
Assigning `src` its own value will reload the current page.
The `src` attribute can also accept data URLs, such as `data:text/plain,Hello, world!`.
###
`nodeintegration`[](#nodeintegration "Direct link to heading")
```
<webview src="http://www.google.com/" nodeintegration></webview>
```
A `boolean`. When this attribute is present the guest page in `webview` will have node integration and can use node APIs like `require` and `process` to access low level system resources. Node integration is disabled by default in the guest page.
###
`nodeintegrationinsubframes`[](#nodeintegrationinsubframes "Direct link to heading")
```
<webview src="http://www.google.com/" nodeintegrationinsubframes></webview>
```
A `boolean` for the experimental option for enabling NodeJS support in sub-frames such as iframes inside the `webview`. All your preloads will load for every iframe, you can use `process.isMainFrame` to determine if you are in the main frame or not. This option is disabled by default in the guest page.
###
`plugins`[](#plugins "Direct link to heading")
```
<webview src="https://www.github.com/" plugins></webview>
```
A `boolean`. When this attribute is present the guest page in `webview` will be able to use browser plugins. Plugins are disabled by default.
###
`preload`[](#preload "Direct link to heading")
```
<!-- from a file -->
<webview src="https://www.github.com/" preload="./test.js"></webview>
<!-- or if you want to load from an asar archive -->
<webview src="https://www.github.com/" preload="./app.asar/test.js"></webview>
```
A `string` that specifies a script that will be loaded before other scripts run in the guest page. The protocol of script's URL must be `file:` (even when using `asar:` archives) because it will be loaded by Node's `require` under the hood, which treats `asar:` archives as virtual directories.
When the guest page doesn't have node integration this script will still have access to all Node APIs, but global objects injected by Node will be deleted after this script has finished executing.
###
`httpreferrer`[](#httpreferrer "Direct link to heading")
```
<webview src="https://www.github.com/" httpreferrer="http://cheng.guru"></webview>
```
A `string` that sets the referrer URL for the guest page.
###
`useragent`[](#useragent "Direct link to heading")
```
<webview src="https://www.github.com/" useragent="Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko"></webview>
```
A `string` that sets the user agent for the guest page before the page is navigated to. Once the page is loaded, use the `setUserAgent` method to change the user agent.
###
`disablewebsecurity`[](#disablewebsecurity "Direct link to heading")
```
<webview src="https://www.github.com/" disablewebsecurity></webview>
```
A `boolean`. When this attribute is present the guest page will have web security disabled. Web security is enabled by default.
###
`partition`[](#partition "Direct link to heading")
```
<webview src="https://github.com" partition="persist:github"></webview>
<webview src="https://electronjs.org" partition="electron"></webview>
```
A `string` that sets the session used by the page. If `partition` starts with `persist:`, the page will use a persistent session available to all pages in the app with the same `partition`. if there is no `persist:` prefix, the page will use an in-memory session. By assigning the same `partition`, multiple pages can share the same session. If the `partition` is unset then default session of the app will be used.
This value can only be modified before the first navigation, since the session of an active renderer process cannot change. Subsequent attempts to modify the value will fail with a DOM exception.
###
`allowpopups`[](#allowpopups "Direct link to heading")
```
<webview src="https://www.github.com/" allowpopups></webview>
```
A `boolean`. When this attribute is present the guest page will be allowed to open new windows. Popups are disabled by default.
###
`webpreferences`[](#webpreferences "Direct link to heading")
```
<webview src="https://github.com" webpreferences="allowRunningInsecureContent, javascript=no"></webview>
```
A `string` which is a comma separated list of strings which specifies the web preferences to be set on the webview. The full list of supported preference strings can be found in [BrowserWindow](browser-window#new-browserwindowoptions).
The string follows the same format as the features string in `window.open`. A name by itself is given a `true` boolean value. A preference can be set to another value by including an `=`, followed by the value. Special values `yes` and `1` are interpreted as `true`, while `no` and `0` are interpreted as `false`.
###
`enableblinkfeatures`[](#enableblinkfeatures "Direct link to heading")
```
<webview src="https://www.github.com/" enableblinkfeatures="PreciseMemoryInfo, CSSVariables"></webview>
```
A `string` which is a list of strings which specifies the blink features to be enabled separated by `,`. The full list of supported feature strings can be found in the [RuntimeEnabledFeatures.json5](https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/runtime_enabled_features.json5?l=70) file.
###
`disableblinkfeatures`[](#disableblinkfeatures "Direct link to heading")
```
<webview src="https://www.github.com/" disableblinkfeatures="PreciseMemoryInfo, CSSVariables"></webview>
```
A `string` which is a list of strings which specifies the blink features to be disabled separated by `,`. The full list of supported feature strings can be found in the [RuntimeEnabledFeatures.json5](https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/runtime_enabled_features.json5?l=70) file.
Methods[](#methods "Direct link to heading")
---------------------------------------------
The `webview` tag has the following methods:
**Note:** The webview element must be loaded before using the methods.
**Example**
```
const webview = document.querySelector('webview')
webview.addEventListener('dom-ready', () => {
webview.openDevTools()
})
```
###
`<webview>.loadURL(url[, options])`[](#webviewloadurlurl-options "Direct link to heading")
* `url` URL
* `options` Object (optional)
+ `httpReferrer` (string | [Referrer](structures/referrer)) (optional) - An HTTP Referrer url.
+ `userAgent` string (optional) - A user agent originating the request.
+ `extraHeaders` string (optional) - Extra headers separated by "\n"
+ `postData` ([UploadRawData](structures/upload-raw-data) | [UploadFile](structures/upload-file))[] (optional)
+ `baseURLForDataURL` string (optional) - Base url (with trailing path separator) for files to be loaded by the data url. This is needed only if the specified `url` is a data url and needs to load other files.
Returns `Promise<void>` - The promise will resolve when the page has finished loading (see [`did-finish-load`](webview-tag#event-did-finish-load)), and rejects if the page fails to load (see [`did-fail-load`](webview-tag#event-did-fail-load)).
Loads the `url` in the webview, the `url` must contain the protocol prefix, e.g. the `http://` or `file://`.
###
`<webview>.downloadURL(url)`[](#webviewdownloadurlurl "Direct link to heading")
* `url` string
Initiates a download of the resource at `url` without navigating.
###
`<webview>.getURL()`[](#webviewgeturl "Direct link to heading")
Returns `string` - The URL of guest page.
###
`<webview>.getTitle()`[](#webviewgettitle "Direct link to heading")
Returns `string` - The title of guest page.
###
`<webview>.isLoading()`[](#webviewisloading "Direct link to heading")
Returns `boolean` - Whether guest page is still loading resources.
###
`<webview>.isLoadingMainFrame()`[](#webviewisloadingmainframe "Direct link to heading")
Returns `boolean` - Whether the main frame (and not just iframes or frames within it) is still loading.
###
`<webview>.isWaitingForResponse()`[](#webviewiswaitingforresponse "Direct link to heading")
Returns `boolean` - Whether the guest page is waiting for a first-response for the main resource of the page.
###
`<webview>.stop()`[](#webviewstop "Direct link to heading")
Stops any pending navigation.
###
`<webview>.reload()`[](#webviewreload "Direct link to heading")
Reloads the guest page.
###
`<webview>.reloadIgnoringCache()`[](#webviewreloadignoringcache "Direct link to heading")
Reloads the guest page and ignores cache.
###
`<webview>.canGoBack()`[](#webviewcangoback "Direct link to heading")
Returns `boolean` - Whether the guest page can go back.
###
`<webview>.canGoForward()`[](#webviewcangoforward "Direct link to heading")
Returns `boolean` - Whether the guest page can go forward.
###
`<webview>.canGoToOffset(offset)`[](#webviewcangotooffsetoffset "Direct link to heading")
* `offset` Integer
Returns `boolean` - Whether the guest page can go to `offset`.
###
`<webview>.clearHistory()`[](#webviewclearhistory "Direct link to heading")
Clears the navigation history.
###
`<webview>.goBack()`[](#webviewgoback "Direct link to heading")
Makes the guest page go back.
###
`<webview>.goForward()`[](#webviewgoforward "Direct link to heading")
Makes the guest page go forward.
###
`<webview>.goToIndex(index)`[](#webviewgotoindexindex "Direct link to heading")
* `index` Integer
Navigates to the specified absolute index.
###
`<webview>.goToOffset(offset)`[](#webviewgotooffsetoffset "Direct link to heading")
* `offset` Integer
Navigates to the specified offset from the "current entry".
###
`<webview>.isCrashed()`[](#webviewiscrashed "Direct link to heading")
Returns `boolean` - Whether the renderer process has crashed.
###
`<webview>.setUserAgent(userAgent)`[](#webviewsetuseragentuseragent "Direct link to heading")
* `userAgent` string
Overrides the user agent for the guest page.
###
`<webview>.getUserAgent()`[](#webviewgetuseragent "Direct link to heading")
Returns `string` - The user agent for guest page.
###
`<webview>.insertCSS(css)`[](#webviewinsertcsscss "Direct link to heading")
* `css` string
Returns `Promise<string>` - A promise that resolves with a key for the inserted CSS that can later be used to remove the CSS via `<webview>.removeInsertedCSS(key)`.
Injects CSS into the current web page and returns a unique key for the inserted stylesheet.
###
`<webview>.removeInsertedCSS(key)`[](#webviewremoveinsertedcsskey "Direct link to heading")
* `key` string
Returns `Promise<void>` - Resolves if the removal was successful.
Removes the inserted CSS from the current web page. The stylesheet is identified by its key, which is returned from `<webview>.insertCSS(css)`.
###
`<webview>.executeJavaScript(code[, userGesture])`[](#webviewexecutejavascriptcode-usergesture "Direct link to heading")
* `code` string
* `userGesture` boolean (optional) - Default `false`.
Returns `Promise<any>` - A promise that resolves with the result of the executed code or is rejected if the result of the code is a rejected promise.
Evaluates `code` in page. If `userGesture` is set, it will create the user gesture context in the page. HTML APIs like `requestFullScreen`, which require user action, can take advantage of this option for automation.
###
`<webview>.openDevTools()`[](#webviewopendevtools "Direct link to heading")
Opens a DevTools window for guest page.
###
`<webview>.closeDevTools()`[](#webviewclosedevtools "Direct link to heading")
Closes the DevTools window of guest page.
###
`<webview>.isDevToolsOpened()`[](#webviewisdevtoolsopened "Direct link to heading")
Returns `boolean` - Whether guest page has a DevTools window attached.
###
`<webview>.isDevToolsFocused()`[](#webviewisdevtoolsfocused "Direct link to heading")
Returns `boolean` - Whether DevTools window of guest page is focused.
###
`<webview>.inspectElement(x, y)`[](#webviewinspectelementx-y "Direct link to heading")
* `x` Integer
* `y` Integer
Starts inspecting element at position (`x`, `y`) of guest page.
###
`<webview>.inspectSharedWorker()`[](#webviewinspectsharedworker "Direct link to heading")
Opens the DevTools for the shared worker context present in the guest page.
###
`<webview>.inspectServiceWorker()`[](#webviewinspectserviceworker "Direct link to heading")
Opens the DevTools for the service worker context present in the guest page.
###
`<webview>.setAudioMuted(muted)`[](#webviewsetaudiomutedmuted "Direct link to heading")
* `muted` boolean
Set guest page muted.
###
`<webview>.isAudioMuted()`[](#webviewisaudiomuted "Direct link to heading")
Returns `boolean` - Whether guest page has been muted.
###
`<webview>.isCurrentlyAudible()`[](#webviewiscurrentlyaudible "Direct link to heading")
Returns `boolean` - Whether audio is currently playing.
###
`<webview>.undo()`[](#webviewundo "Direct link to heading")
Executes editing command `undo` in page.
###
`<webview>.redo()`[](#webviewredo "Direct link to heading")
Executes editing command `redo` in page.
###
`<webview>.cut()`[](#webviewcut "Direct link to heading")
Executes editing command `cut` in page.
###
`<webview>.copy()`[](#webviewcopy "Direct link to heading")
Executes editing command `copy` in page.
###
`<webview>.paste()`[](#webviewpaste "Direct link to heading")
Executes editing command `paste` in page.
###
`<webview>.pasteAndMatchStyle()`[](#webviewpasteandmatchstyle "Direct link to heading")
Executes editing command `pasteAndMatchStyle` in page.
###
`<webview>.delete()`[](#webviewdelete "Direct link to heading")
Executes editing command `delete` in page.
###
`<webview>.selectAll()`[](#webviewselectall "Direct link to heading")
Executes editing command `selectAll` in page.
###
`<webview>.unselect()`[](#webviewunselect "Direct link to heading")
Executes editing command `unselect` in page.
###
`<webview>.replace(text)`[](#webviewreplacetext "Direct link to heading")
* `text` string
Executes editing command `replace` in page.
###
`<webview>.replaceMisspelling(text)`[](#webviewreplacemisspellingtext "Direct link to heading")
* `text` string
Executes editing command `replaceMisspelling` in page.
###
`<webview>.insertText(text)`[](#webviewinserttexttext "Direct link to heading")
* `text` string
Returns `Promise<void>`
Inserts `text` to the focused element.
###
`<webview>.findInPage(text[, options])`[](#webviewfindinpagetext-options "Direct link to heading")
* `text` string - Content to be searched, must not be empty.
* `options` Object (optional)
+ `forward` boolean (optional) - Whether to search forward or backward, defaults to `true`.
+ `findNext` boolean (optional) - Whether to begin a new text finding session with this request. Should be `true` for initial requests, and `false` for follow-up requests. Defaults to `false`.
+ `matchCase` boolean (optional) - Whether search should be case-sensitive, defaults to `false`.
Returns `Integer` - The request id used for the request.
Starts a request to find all matches for the `text` in the web page. The result of the request can be obtained by subscribing to [`found-in-page`](webview-tag#event-found-in-page) event.
###
`<webview>.stopFindInPage(action)`[](#webviewstopfindinpageaction "Direct link to heading")
* `action` string - Specifies the action to take place when ending [`<webview>.findInPage`](#webviewfindinpagetext-options) request.
+ `clearSelection` - Clear the selection.
+ `keepSelection` - Translate the selection into a normal selection.
+ `activateSelection` - Focus and click the selection node.
Stops any `findInPage` request for the `webview` with the provided `action`.
###
`<webview>.print([options])`[](#webviewprintoptions "Direct link to heading")
* `options` Object (optional)
+ `silent` boolean (optional) - Don't ask user for print settings. Default is `false`.
+ `printBackground` boolean (optional) - Prints the background color and image of the web page. Default is `false`.
+ `deviceName` string (optional) - Set the printer device name to use. Must be the system-defined name and not the 'friendly' name, e.g 'Brother\_QL\_820NWB' and not 'Brother QL-820NWB'.
+ `color` boolean (optional) - Set whether the printed web page will be in color or grayscale. Default is `true`.
+ `margins` Object (optional)
- `marginType` string (optional) - Can be `default`, `none`, `printableArea`, or `custom`. If `custom` is chosen, you will also need to specify `top`, `bottom`, `left`, and `right`.
- `top` number (optional) - The top margin of the printed web page, in pixels.
- `bottom` number (optional) - The bottom margin of the printed web page, in pixels.
- `left` number (optional) - The left margin of the printed web page, in pixels.
- `right` number (optional) - The right margin of the printed web page, in pixels.
+ `landscape` boolean (optional) - Whether the web page should be printed in landscape mode. Default is `false`.
+ `scaleFactor` number (optional) - The scale factor of the web page.
+ `pagesPerSheet` number (optional) - The number of pages to print per page sheet.
+ `collate` boolean (optional) - Whether the web page should be collated.
+ `copies` number (optional) - The number of copies of the web page to print.
+ `pageRanges` Object[] (optional) - The page range to print.
- `from` number - Index of the first page to print (0-based).
- `to` number - Index of the last page to print (inclusive) (0-based).
+ `duplexMode` string (optional) - Set the duplex mode of the printed web page. Can be `simplex`, `shortEdge`, or `longEdge`.
+ `dpi` Record<string, number> (optional)
- `horizontal` number (optional) - The horizontal dpi.
- `vertical` number (optional) - The vertical dpi.
+ `header` string (optional) - string to be printed as page header.
+ `footer` string (optional) - string to be printed as page footer.
+ `pageSize` string | Size (optional) - Specify page size of the printed document. Can be `A3`, `A4`, `A5`, `Legal`, `Letter`, `Tabloid` or an Object containing `height` in microns.
Returns `Promise<void>`
Prints `webview`'s web page. Same as `webContents.print([options])`.
###
`<webview>.printToPDF(options)`[](#webviewprinttopdfoptions "Direct link to heading")
* `options` Object
+ `headerFooter` Record<string, string> (optional) - the header and footer for the PDF.
- `title` string - The title for the PDF header.
- `url` string - the url for the PDF footer.
+ `landscape` boolean (optional) - `true` for landscape, `false` for portrait.
+ `marginsType` Integer (optional) - Specifies the type of margins to use. Uses 0 for default margin, 1 for no margin, and 2 for minimum margin. and `width` in microns.
+ `scaleFactor` number (optional) - The scale factor of the web page. Can range from 0 to 100.
+ `pageRanges` Record<string, number> (optional) - The page range to print. On macOS, only the first range is honored.
- `from` number - Index of the first page to print (0-based).
- `to` number - Index of the last page to print (inclusive) (0-based).
+ `pageSize` string | Size (optional) - Specify page size of the generated PDF. Can be `A3`, `A4`, `A5`, `Legal`, `Letter`, `Tabloid` or an Object containing `height`
+ `printBackground` boolean (optional) - Whether to print CSS backgrounds.
+ `printSelectionOnly` boolean (optional) - Whether to print selection only.
Returns `Promise<Uint8Array>` - Resolves with the generated PDF data.
Prints `webview`'s web page as PDF, Same as `webContents.printToPDF(options)`.
###
`<webview>.capturePage([rect])`[](#webviewcapturepagerect "Direct link to heading")
* `rect` [Rectangle](structures/rectangle) (optional) - The area of the page to be captured.
Returns `Promise<NativeImage>` - Resolves with a [NativeImage](native-image)
Captures a snapshot of the page within `rect`. Omitting `rect` will capture the whole visible page.
###
`<webview>.send(channel, ...args)`[](#webviewsendchannel-args "Direct link to heading")
* `channel` string
* `...args` any[]
Returns `Promise<void>`
Send an asynchronous message to renderer process via `channel`, you can also send arbitrary arguments. The renderer process can handle the message by listening to the `channel` event with the [`ipcRenderer`](ipc-renderer) module.
See [webContents.send](web-contents#contentssendchannel-args) for examples.
###
`<webview>.sendToFrame(frameId, channel, ...args)`[](#webviewsendtoframeframeid-channel-args "Direct link to heading")
* `frameId` [number, number] - `[processId, frameId]`
* `channel` string
* `...args` any[]
Returns `Promise<void>`
Send an asynchronous message to renderer process via `channel`, you can also send arbitrary arguments. The renderer process can handle the message by listening to the `channel` event with the [`ipcRenderer`](ipc-renderer) module.
See [webContents.sendToFrame](web-contents#contentssendtoframeframeid-channel-args) for examples.
###
`<webview>.sendInputEvent(event)`[](#webviewsendinputeventevent "Direct link to heading")
* `event` [MouseInputEvent](structures/mouse-input-event) | [MouseWheelInputEvent](structures/mouse-wheel-input-event) | [KeyboardInputEvent](structures/keyboard-input-event)
Returns `Promise<void>`
Sends an input `event` to the page.
See [webContents.sendInputEvent](web-contents#contentssendinputeventinputevent) for detailed description of `event` object.
###
`<webview>.setZoomFactor(factor)`[](#webviewsetzoomfactorfactor "Direct link to heading")
* `factor` number - Zoom factor.
Changes the zoom factor to the specified factor. Zoom factor is zoom percent divided by 100, so 300% = 3.0.
###
`<webview>.setZoomLevel(level)`[](#webviewsetzoomlevellevel "Direct link to heading")
* `level` number - Zoom level.
Changes the zoom level to the specified level. The original size is 0 and each increment above or below represents zooming 20% larger or smaller to default limits of 300% and 50% of original size, respectively. The formula for this is `scale := 1.2 ^ level`.
> **NOTE**: The zoom policy at the Chromium level is same-origin, meaning that the zoom level for a specific domain propagates across all instances of windows with the same domain. Differentiating the window URLs will make zoom work per-window.
>
>
###
`<webview>.getZoomFactor()`[](#webviewgetzoomfactor "Direct link to heading")
Returns `number` - the current zoom factor.
###
`<webview>.getZoomLevel()`[](#webviewgetzoomlevel "Direct link to heading")
Returns `number` - the current zoom level.
###
`<webview>.setVisualZoomLevelLimits(minimumLevel, maximumLevel)`[](#webviewsetvisualzoomlevellimitsminimumlevel-maximumlevel "Direct link to heading")
* `minimumLevel` number
* `maximumLevel` number
Returns `Promise<void>`
Sets the maximum and minimum pinch-to-zoom level.
###
`<webview>.showDefinitionForSelection()` *macOS*[](#webviewshowdefinitionforselection-macos "Direct link to heading")
Shows pop-up dictionary that searches the selected word on the page.
###
`<webview>.getWebContentsId()`[](#webviewgetwebcontentsid "Direct link to heading")
Returns `number` - The WebContents ID of this `webview`.
DOM Events[](#dom-events "Direct link to heading")
---------------------------------------------------
The following DOM events are available to the `webview` tag:
### Event: 'load-commit'[](#event-load-commit "Direct link to heading")
Returns:
* `url` string
* `isMainFrame` boolean
Fired when a load has committed. This includes navigation within the current document as well as subframe document-level loads, but does not include asynchronous resource loads.
### Event: 'did-finish-load'[](#event-did-finish-load "Direct link to heading")
Fired when the navigation is done, i.e. the spinner of the tab will stop spinning, and the `onload` event is dispatched.
### Event: 'did-fail-load'[](#event-did-fail-load "Direct link to heading")
Returns:
* `errorCode` Integer
* `errorDescription` string
* `validatedURL` string
* `isMainFrame` boolean
This event is like `did-finish-load`, but fired when the load failed or was cancelled, e.g. `window.stop()` is invoked.
### Event: 'did-frame-finish-load'[](#event-did-frame-finish-load "Direct link to heading")
Returns:
* `isMainFrame` boolean
Fired when a frame has done navigation.
### Event: 'did-start-loading'[](#event-did-start-loading "Direct link to heading")
Corresponds to the points in time when the spinner of the tab starts spinning.
### Event: 'did-stop-loading'[](#event-did-stop-loading "Direct link to heading")
Corresponds to the points in time when the spinner of the tab stops spinning.
### Event: 'did-attach'[](#event-did-attach "Direct link to heading")
Fired when attached to the embedder web contents.
### Event: 'dom-ready'[](#event-dom-ready "Direct link to heading")
Fired when document in the given frame is loaded.
### Event: 'page-title-updated'[](#event-page-title-updated "Direct link to heading")
Returns:
* `title` string
* `explicitSet` boolean
Fired when page title is set during navigation. `explicitSet` is false when title is synthesized from file url.
### Event: 'page-favicon-updated'[](#event-page-favicon-updated "Direct link to heading")
Returns:
* `favicons` string[] - Array of URLs.
Fired when page receives favicon urls.
### Event: 'enter-html-full-screen'[](#event-enter-html-full-screen "Direct link to heading")
Fired when page enters fullscreen triggered by HTML API.
### Event: 'leave-html-full-screen'[](#event-leave-html-full-screen "Direct link to heading")
Fired when page leaves fullscreen triggered by HTML API.
### Event: 'console-message'[](#event-console-message "Direct link to heading")
Returns:
* `level` Integer - The log level, from 0 to 3. In order it matches `verbose`, `info`, `warning` and `error`.
* `message` string - The actual console message
* `line` Integer - The line number of the source that triggered this console message
* `sourceId` string
Fired when the guest window logs a console message.
The following example code forwards all log messages to the embedder's console without regard for log level or other properties.
```
const webview = document.querySelector('webview')
webview.addEventListener('console-message', (e) => {
console.log('Guest page logged a message:', e.message)
})
```
### Event: 'found-in-page'[](#event-found-in-page "Direct link to heading")
Returns:
* `result` Object
+ `requestId` Integer
+ `activeMatchOrdinal` Integer - Position of the active match.
+ `matches` Integer - Number of Matches.
+ `selectionArea` Rectangle - Coordinates of first match region.
+ `finalUpdate` boolean
Fired when a result is available for [`webview.findInPage`](#webviewfindinpagetext-options) request.
```
const webview = document.querySelector('webview')
webview.addEventListener('found-in-page', (e) => {
webview.stopFindInPage('keepSelection')
})
const requestId = webview.findInPage('test')
console.log(requestId)
```
### Event: 'new-window'[](#event-new-window "Direct link to heading")
Returns:
* `url` string
* `frameName` string
* `disposition` string - Can be `default`, `foreground-tab`, `background-tab`, `new-window`, `save-to-disk` and `other`.
* `options` BrowserWindowConstructorOptions - The options which should be used for creating the new [`BrowserWindow`](browser-window).
Fired when the guest page attempts to open a new browser window.
The following example code opens the new url in system's default browser.
```
const { shell } = require('electron')
const webview = document.querySelector('webview')
webview.addEventListener('new-window', async (e) => {
const protocol = (new URL(e.url)).protocol
if (protocol === 'http:' || protocol === 'https:') {
await shell.openExternal(e.url)
}
})
```
### Event: 'will-navigate'[](#event-will-navigate "Direct link to heading")
Returns:
* `url` string
Emitted when a user or the page wants to start navigation. It can happen when the `window.location` object is changed or a user clicks a link in the page.
This event will not emit when the navigation is started programmatically with APIs like `<webview>.loadURL` and `<webview>.back`.
It is also not emitted during in-page navigation, such as clicking anchor links or updating the `window.location.hash`. Use `did-navigate-in-page` event for this purpose.
Calling `event.preventDefault()` does **NOT** have any effect.
### Event: 'did-start-navigation'[](#event-did-start-navigation "Direct link to heading")
Returns:
* `url` string
* `isInPlace` boolean
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted when any frame (including main) starts navigating. `isInPlace` will be `true` for in-page navigations.
### Event: 'did-redirect-navigation'[](#event-did-redirect-navigation "Direct link to heading")
Returns:
* `url` string
* `isInPlace` boolean
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted after a server side redirect occurs during navigation. For example a 302 redirect.
### Event: 'did-navigate'[](#event-did-navigate "Direct link to heading")
Returns:
* `url` string
Emitted when a navigation is done.
This event is not emitted for in-page navigations, such as clicking anchor links or updating the `window.location.hash`. Use `did-navigate-in-page` event for this purpose.
### Event: 'did-frame-navigate'[](#event-did-frame-navigate "Direct link to heading")
Returns:
* `url` string
* `httpResponseCode` Integer - -1 for non HTTP navigations
* `httpStatusText` string - empty for non HTTP navigations,
* `isMainFrame` boolean
* `frameProcessId` Integer
* `frameRoutingId` Integer
Emitted when any frame navigation is done.
This event is not emitted for in-page navigations, such as clicking anchor links or updating the `window.location.hash`. Use `did-navigate-in-page` event for this purpose.
### Event: 'did-navigate-in-page'[](#event-did-navigate-in-page "Direct link to heading")
Returns:
* `isMainFrame` boolean
* `url` string
Emitted when an in-page navigation happened.
When in-page navigation happens, the page URL changes but does not cause navigation outside of the page. Examples of this occurring are when anchor links are clicked or when the DOM `hashchange` event is triggered.
### Event: 'close'[](#event-close "Direct link to heading")
Fired when the guest page attempts to close itself.
The following example code navigates the `webview` to `about:blank` when the guest attempts to close itself.
```
const webview = document.querySelector('webview')
webview.addEventListener('close', () => {
webview.src = 'about:blank'
})
```
### Event: 'ipc-message'[](#event-ipc-message "Direct link to heading")
Returns:
* `frameId` [number, number] - pair of `[processId, frameId]`.
* `channel` string
* `args` any[]
Fired when the guest page has sent an asynchronous message to embedder page.
With `sendToHost` method and `ipc-message` event you can communicate between guest page and embedder page:
```
// In embedder page.
const webview = document.querySelector('webview')
webview.addEventListener('ipc-message', (event) => {
console.log(event.channel)
// Prints "pong"
})
webview.send('ping')
```
```
// In guest page.
const { ipcRenderer } = require('electron')
ipcRenderer.on('ping', () => {
ipcRenderer.sendToHost('pong')
})
```
### Event: 'crashed'[](#event-crashed "Direct link to heading")
Fired when the renderer process is crashed.
### Event: 'plugin-crashed'[](#event-plugin-crashed "Direct link to heading")
Returns:
* `name` string
* `version` string
Fired when a plugin process is crashed.
### Event: 'destroyed'[](#event-destroyed "Direct link to heading")
Fired when the WebContents is destroyed.
### Event: 'media-started-playing'[](#event-media-started-playing "Direct link to heading")
Emitted when media starts playing.
### Event: 'media-paused'[](#event-media-paused "Direct link to heading")
Emitted when media is paused or done playing.
### Event: 'did-change-theme-color'[](#event-did-change-theme-color "Direct link to heading")
Returns:
* `themeColor` string
Emitted when a page's theme color changes. This is usually due to encountering a meta tag:
```
<meta name='theme-color' content='#ff0000'>
```
### Event: 'update-target-url'[](#event-update-target-url "Direct link to heading")
Returns:
* `url` string
Emitted when mouse moves over a link or the keyboard moves the focus to a link.
### Event: 'devtools-opened'[](#event-devtools-opened "Direct link to heading")
Emitted when DevTools is opened.
### Event: 'devtools-closed'[](#event-devtools-closed "Direct link to heading")
Emitted when DevTools is closed.
### Event: 'devtools-focused'[](#event-devtools-focused "Direct link to heading")
Emitted when DevTools is focused / opened.
### Event: 'context-menu'[](#event-context-menu "Direct link to heading")
Returns:
* `params` Object
+ `x` Integer - x coordinate.
+ `y` Integer - y coordinate.
+ `linkURL` string - URL of the link that encloses the node the context menu was invoked on.
+ `linkText` string - Text associated with the link. May be an empty string if the contents of the link are an image.
+ `pageURL` string - URL of the top level page that the context menu was invoked on.
+ `frameURL` string - URL of the subframe that the context menu was invoked on.
+ `srcURL` string - Source URL for the element that the context menu was invoked on. Elements with source URLs are images, audio and video.
+ `mediaType` string - Type of the node the context menu was invoked on. Can be `none`, `image`, `audio`, `video`, `canvas`, `file` or `plugin`.
+ `hasImageContents` boolean - Whether the context menu was invoked on an image which has non-empty contents.
+ `isEditable` boolean - Whether the context is editable.
+ `selectionText` string - Text of the selection that the context menu was invoked on.
+ `titleText` string - Title text of the selection that the context menu was invoked on.
+ `altText` string - Alt text of the selection that the context menu was invoked on.
+ `suggestedFilename` string - Suggested filename to be used when saving file through 'Save Link As' option of context menu.
+ `selectionRect` [Rectangle](structures/rectangle) - Rect representing the coordinates in the document space of the selection.
+ `selectionStartOffset` number - Start position of the selection text.
+ `referrerPolicy` [Referrer](structures/referrer) - The referrer policy of the frame on which the menu is invoked.
+ `misspelledWord` string - The misspelled word under the cursor, if any.
+ `dictionarySuggestions` string[] - An array of suggested words to show the user to replace the `misspelledWord`. Only available if there is a misspelled word and spellchecker is enabled.
+ `frameCharset` string - The character encoding of the frame on which the menu was invoked.
+ `inputFieldType` string - If the context menu was invoked on an input field, the type of that field. Possible values are `none`, `plainText`, `password`, `other`.
+ `spellcheckEnabled` boolean - If the context is editable, whether or not spellchecking is enabled.
+ `menuSourceType` string - Input source that invoked the context menu. Can be `none`, `mouse`, `keyboard`, `touch`, `touchMenu`, `longPress`, `longTap`, `touchHandle`, `stylus`, `adjustSelection`, or `adjustSelectionReset`.
+ `mediaFlags` Object - The flags for the media element the context menu was invoked on.
- `inError` boolean - Whether the media element has crashed.
- `isPaused` boolean - Whether the media element is paused.
- `isMuted` boolean - Whether the media element is muted.
- `hasAudio` boolean - Whether the media element has audio.
- `isLooping` boolean - Whether the media element is looping.
- `isControlsVisible` boolean - Whether the media element's controls are visible.
- `canToggleControls` boolean - Whether the media element's controls are toggleable.
- `canPrint` boolean - Whether the media element can be printed.
- `canSave` boolean - Whether or not the media element can be downloaded.
- `canShowPictureInPicture` boolean - Whether the media element can show picture-in-picture.
- `isShowingPictureInPicture` boolean - Whether the media element is currently showing picture-in-picture.
- `canRotate` boolean - Whether the media element can be rotated.
- `canLoop` boolean - Whether the media element can be looped.
+ `editFlags` Object - These flags indicate whether the renderer believes it is able to perform the corresponding action.
- `canUndo` boolean - Whether the renderer believes it can undo.
- `canRedo` boolean - Whether the renderer believes it can redo.
- `canCut` boolean - Whether the renderer believes it can cut.
- `canCopy` boolean - Whether the renderer believes it can copy.
- `canPaste` boolean - Whether the renderer believes it can paste.
- `canDelete` boolean - Whether the renderer believes it can delete.
- `canSelectAll` boolean - Whether the renderer believes it can select all.
- `canEditRichly` boolean - Whether the renderer believes it can edit text richly.
Emitted when there is a new context menu that needs to be handled.
| programming_docs |
electron Class: Debugger Class: Debugger[](#class-debugger "Direct link to heading")
------------------------------------------------------------
> An alternate transport for Chrome's remote debugging protocol.
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
Chrome Developer Tools has a [special binding](https://chromedevtools.github.io/devtools-protocol/) available at JavaScript runtime that allows interacting with pages and instrumenting them.
```
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
try {
win.webContents.debugger.attach('1.1')
} catch (err) {
console.log('Debugger attach failed : ', err)
}
win.webContents.debugger.on('detach', (event, reason) => {
console.log('Debugger detached due to : ', reason)
})
win.webContents.debugger.on('message', (event, method, params) => {
if (method === 'Network.requestWillBeSent') {
if (params.request.url === 'https://www.github.com') {
win.webContents.debugger.detach()
}
}
})
win.webContents.debugger.sendCommand('Network.enable')
```
### Instance Events[](#instance-events "Direct link to heading")
#### Event: 'detach'[](#event-detach "Direct link to heading")
Returns:
* `event` Event
* `reason` string - Reason for detaching debugger.
Emitted when the debugging session is terminated. This happens either when `webContents` is closed or devtools is invoked for the attached `webContents`.
#### Event: 'message'[](#event-message "Direct link to heading")
Returns:
* `event` Event
* `method` string - Method name.
* `params` any - Event parameters defined by the 'parameters' attribute in the remote debugging protocol.
* `sessionId` string - Unique identifier of attached debugging session, will match the value sent from `debugger.sendCommand`.
Emitted whenever the debugging target issues an instrumentation event.
### Instance Methods[](#instance-methods "Direct link to heading")
####
`debugger.attach([protocolVersion])`[](#debuggerattachprotocolversion "Direct link to heading")
* `protocolVersion` string (optional) - Requested debugging protocol version.
Attaches the debugger to the `webContents`.
####
`debugger.isAttached()`[](#debuggerisattached "Direct link to heading")
Returns `boolean` - Whether a debugger is attached to the `webContents`.
####
`debugger.detach()`[](#debuggerdetach "Direct link to heading")
Detaches the debugger from the `webContents`.
####
`debugger.sendCommand(method[, commandParams, sessionId])`[](#debuggersendcommandmethod-commandparams-sessionid "Direct link to heading")
* `method` string - Method name, should be one of the methods defined by the [remote debugging protocol](https://chromedevtools.github.io/devtools-protocol/).
* `commandParams` any (optional) - JSON object with request parameters.
* `sessionId` string (optional) - send command to the target with associated debugging session id. The initial value can be obtained by sending [Target.attachToTarget](https://chromedevtools.github.io/devtools-protocol/tot/Target/#method-attachToTarget) message.
Returns `Promise<any>` - A promise that resolves with the response defined by the 'returns' attribute of the command description in the remote debugging protocol or is rejected indicating the failure of the command.
Send given command to the debugging target.
electron TouchBar TouchBar
========
Class: TouchBar[](#class-touchbar "Direct link to heading")
------------------------------------------------------------
> Create TouchBar layouts for native macOS applications
>
>
Process: [Main](../glossary#main-process)
###
`new TouchBar(options)`[](#new-touchbaroptions "Direct link to heading")
* `options` Object
+ `items` ([TouchBarButton](touch-bar-button) | [TouchBarColorPicker](touch-bar-color-picker) | [TouchBarGroup](touch-bar-group) | [TouchBarLabel](touch-bar-label) | [TouchBarPopover](touch-bar-popover) | [TouchBarScrubber](touch-bar-scrubber) | [TouchBarSegmentedControl](touch-bar-segmented-control) | [TouchBarSlider](touch-bar-slider) | [TouchBarSpacer](touch-bar-spacer))[] (optional)
+ `escapeItem` ([TouchBarButton](touch-bar-button) | [TouchBarColorPicker](touch-bar-color-picker) | [TouchBarGroup](touch-bar-group) | [TouchBarLabel](touch-bar-label) | [TouchBarPopover](touch-bar-popover) | [TouchBarScrubber](touch-bar-scrubber) | [TouchBarSegmentedControl](touch-bar-segmented-control) | [TouchBarSlider](touch-bar-slider) | [TouchBarSpacer](touch-bar-spacer) | null) (optional)
Creates a new touch bar with the specified items. Use `BrowserWindow.setTouchBar` to add the `TouchBar` to a window.
**Note:** The TouchBar API is currently experimental and may change or be removed in future Electron releases.
**Tip:** If you don't have a MacBook with Touch Bar, you can use [Touch Bar Simulator](https://github.com/sindresorhus/touch-bar-simulator) to test Touch Bar usage in your app.
### Static Properties[](#static-properties "Direct link to heading")
####
`TouchBarButton`[](#touchbarbutton "Direct link to heading")
A [`typeof TouchBarButton`](touch-bar-button) reference to the `TouchBarButton` class.
####
`TouchBarColorPicker`[](#touchbarcolorpicker "Direct link to heading")
A [`typeof TouchBarColorPicker`](touch-bar-color-picker) reference to the `TouchBarColorPicker` class.
####
`TouchBarGroup`[](#touchbargroup "Direct link to heading")
A [`typeof TouchBarGroup`](touch-bar-group) reference to the `TouchBarGroup` class.
####
`TouchBarLabel`[](#touchbarlabel "Direct link to heading")
A [`typeof TouchBarLabel`](touch-bar-label) reference to the `TouchBarLabel` class.
####
`TouchBarPopover`[](#touchbarpopover "Direct link to heading")
A [`typeof TouchBarPopover`](touch-bar-popover) reference to the `TouchBarPopover` class.
####
`TouchBarScrubber`[](#touchbarscrubber "Direct link to heading")
A [`typeof TouchBarScrubber`](touch-bar-scrubber) reference to the `TouchBarScrubber` class.
####
`TouchBarSegmentedControl`[](#touchbarsegmentedcontrol "Direct link to heading")
A [`typeof TouchBarSegmentedControl`](touch-bar-segmented-control) reference to the `TouchBarSegmentedControl` class.
####
`TouchBarSlider`[](#touchbarslider "Direct link to heading")
A [`typeof TouchBarSlider`](touch-bar-slider) reference to the `TouchBarSlider` class.
####
`TouchBarSpacer`[](#touchbarspacer "Direct link to heading")
A [`typeof TouchBarSpacer`](touch-bar-spacer) reference to the `TouchBarSpacer` class.
####
`TouchBarOtherItemsProxy`[](#touchbarotheritemsproxy "Direct link to heading")
A [`typeof TouchBarOtherItemsProxy`](touch-bar-other-items-proxy) reference to the `TouchBarOtherItemsProxy` class.
### Instance Properties[](#instance-properties "Direct link to heading")
The following properties are available on instances of `TouchBar`:
####
`touchBar.escapeItem`[](#touchbarescapeitem "Direct link to heading")
A `TouchBarItem` that will replace the "esc" button on the touch bar when set. Setting to `null` restores the default "esc" button. Changing this value immediately updates the escape item in the touch bar.
Examples[](#examples "Direct link to heading")
-----------------------------------------------
Below is an example of a simple slot machine touch bar game with a button and some labels.
```
const { app, BrowserWindow, TouchBar } = require('electron')
const { TouchBarLabel, TouchBarButton, TouchBarSpacer } = TouchBar
let spinning = false
// Reel labels
const reel1 = new TouchBarLabel()
const reel2 = new TouchBarLabel()
const reel3 = new TouchBarLabel()
// Spin result label
const result = new TouchBarLabel()
// Spin button
const spin = new TouchBarButton({
label: '🎰 Spin',
backgroundColor: '#7851A9',
click: () => {
// Ignore clicks if already spinning
if (spinning) {
return
}
spinning = true
result.label = ''
let timeout = 10
const spinLength = 4 * 1000 // 4 seconds
const startTime = Date.now()
const spinReels = () => {
updateReels()
if ((Date.now() - startTime) >= spinLength) {
finishSpin()
} else {
// Slow down a bit on each spin
timeout *= 1.1
setTimeout(spinReels, timeout)
}
}
spinReels()
}
})
const getRandomValue = () => {
const values = ['🍒', '💎', '7️⃣', '🍊', '🔔', '⭐', '🍇', '🍀']
return values[Math.floor(Math.random() * values.length)]
}
const updateReels = () => {
reel1.label = getRandomValue()
reel2.label = getRandomValue()
reel3.label = getRandomValue()
}
const finishSpin = () => {
const uniqueValues = new Set([reel1.label, reel2.label, reel3.label]).size
if (uniqueValues === 1) {
// All 3 values are the same
result.label = '💰 Jackpot!'
result.textColor = '#FDFF00'
} else if (uniqueValues === 2) {
// 2 values are the same
result.label = '😍 Winner!'
result.textColor = '#FDFF00'
} else {
// No values are the same
result.label = '🙁 Spin Again'
result.textColor = null
}
spinning = false
}
const touchBar = new TouchBar({
items: [
spin,
new TouchBarSpacer({ size: 'large' }),
reel1,
new TouchBarSpacer({ size: 'small' }),
reel2,
new TouchBarSpacer({ size: 'small' }),
reel3,
new TouchBarSpacer({ size: 'large' }),
result
]
})
let window
app.whenReady().then(() => {
window = new BrowserWindow({
frame: false,
titleBarStyle: 'hiddenInset',
width: 200,
height: 200,
backgroundColor: '#000'
})
window.loadURL('about:blank')
window.setTouchBar(touchBar)
})
```
### Running the above example[](#running-the-above-example "Direct link to heading")
To run the example above, you'll need to (assuming you've got a terminal open in the directory you want to run the example):
1. Save the above file to your computer as `touchbar.js`
2. Install Electron via `npm install electron`
3. Run the example inside Electron: `./node_modules/.bin/electron touchbar.js`
You should then see a new Electron window and the app running in your touch bar (or touch bar emulator).
electron Class: Dock Class: Dock[](#class-dock "Direct link to heading")
----------------------------------------------------
> Control your app in the macOS dock
>
>
Process: [Main](../glossary#main-process)
*This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API.*
The following example shows how to bounce your icon on the dock.
```
const { app } = require('electron')
app.dock.bounce()
```
### Instance Methods[](#instance-methods "Direct link to heading")
####
`dock.bounce([type])` *macOS*[](#dockbouncetype-macos "Direct link to heading")
* `type` string (optional) - Can be `critical` or `informational`. The default is `informational`
Returns `Integer` - an ID representing the request.
When `critical` is passed, the dock icon will bounce until either the application becomes active or the request is canceled.
When `informational` is passed, the dock icon will bounce for one second. However, the request remains active until either the application becomes active or the request is canceled.
**Note:** This method can only be used while the app is not focused; when the app is focused it will return -1.
####
`dock.cancelBounce(id)` *macOS*[](#dockcancelbounceid-macos "Direct link to heading")
* `id` Integer
Cancel the bounce of `id`.
####
`dock.downloadFinished(filePath)` *macOS*[](#dockdownloadfinishedfilepath-macos "Direct link to heading")
* `filePath` string
Bounces the Downloads stack if the filePath is inside the Downloads folder.
####
`dock.setBadge(text)` *macOS*[](#docksetbadgetext-macos "Direct link to heading")
* `text` string
Sets the string to be displayed in the dock’s badging area.
####
`dock.getBadge()` *macOS*[](#dockgetbadge-macos "Direct link to heading")
Returns `string` - The badge string of the dock.
####
`dock.hide()` *macOS*[](#dockhide-macos "Direct link to heading")
Hides the dock icon.
####
`dock.show()` *macOS*[](#dockshow-macos "Direct link to heading")
Returns `Promise<void>` - Resolves when the dock icon is shown.
####
`dock.isVisible()` *macOS*[](#dockisvisible-macos "Direct link to heading")
Returns `boolean` - Whether the dock icon is visible.
####
`dock.setMenu(menu)` *macOS*[](#docksetmenumenu-macos "Direct link to heading")
* `menu` [Menu](menu)
Sets the application's [dock menu][dock-menu].
####
`dock.getMenu()` *macOS*[](#dockgetmenu-macos "Direct link to heading")
Returns `Menu | null` - The application's [dock menu][dock-menu].
####
`dock.setIcon(image)` *macOS*[](#dockseticonimage-macos "Direct link to heading")
* `image` ([NativeImage](native-image) | string)
Sets the `image` associated with this dock icon.
electron ProtocolResponseUploadData Object ProtocolResponseUploadData Object
=================================
* `contentType` string - MIME type of the content.
* `data` string | Buffer - Content to be sent.
electron ProtocolRequest Object ProtocolRequest Object
======================
* `url` string
* `referrer` string
* `method` string
* `uploadData` [UploadData[]](upload-data) (optional)
* `headers` Record<string, string>
electron MimeTypedBuffer Object MimeTypedBuffer Object
======================
* `mimeType` string (optional) - MIME type of the buffer.
* `charset` string (optional) - Charset of the buffer.
* `data` Buffer - The actual Buffer content.
electron WebRequestFilter Object WebRequestFilter Object
=======================
* `urls` string[] - Array of URL patterns that will be used to filter out the requests that do not match the URL patterns.
electron UploadData Object UploadData Object
=================
* `bytes` Buffer - Content being sent.
* `file` string (optional) - Path of file being uploaded.
* `blobUUID` string (optional) - UUID of blob data. Use [ses.getBlobData](../session#sesgetblobdataidentifier) method to retrieve the data.
electron SegmentedControlSegment Object SegmentedControlSegment Object
==============================
* `label` string (optional) - The text to appear in this segment.
* `icon` NativeImage (optional) - The image to appear in this segment.
* `enabled` boolean (optional) - Whether this segment is selectable. Default: true.
electron MouseWheelInputEvent Object extends MouseInputEvent
MouseWheelInputEvent Object extends `MouseInputEvent`
=====================================================
* `type` string - The type of the event, can be `mouseWheel`.
* `deltaX` Integer (optional)
* `deltaY` Integer (optional)
* `wheelTicksX` Integer (optional)
* `wheelTicksY` Integer (optional)
* `accelerationRatioX` Integer (optional)
* `accelerationRatioY` Integer (optional)
* `hasPreciseScrollingDeltas` boolean (optional)
* `canScroll` boolean (optional)
electron Extension Object Extension Object
================
* `id` string
* `manifest` any - Copy of the [extension's manifest data](https://developer.chrome.com/extensions/manifest).
* `name` string
* `path` string - The extension's file path.
* `version` string
* `url` string - The extension's `chrome-extension://` URL.
electron PrinterInfo Object PrinterInfo Object
==================
* `name` string - the name of the printer as understood by the OS.
* `displayName` string - the name of the printer as shown in Print Preview.
* `description` string - a longer description of the printer's type.
* `status` number - the current status of the printer.
* `isDefault` boolean - whether or not a given printer is set as the default printer on the OS.
* `options` Object - an object containing a variable number of platform-specific printer information.
The number represented by `status` means different things on different platforms: on Windows its potential values can be found [here](https://docs.microsoft.com/en-us/windows/win32/printdocs/printer-info-2), and on Linux and macOS they can be found [here](https://www.cups.org/doc/cupspm.html).
Example[](#example "Direct link to heading")
---------------------------------------------
Below is an example of some of the additional options that may be set which may be different on each platform.
```
{
name: 'Austin_4th_Floor_Printer___C02XK13BJHD4',
displayName: 'Austin 4th Floor Printer @ C02XK13BJHD4',
description: 'TOSHIBA ColorMFP',
status: 3,
isDefault: false,
options: {
copies: '1',
'device-uri': 'dnssd://Austin%204th%20Floor%20Printer%20%40%20C02XK13BJHD4._ipps._tcp.local./?uuid=71687f1e-1147-3274-6674-22de61b110bd',
finishings: '3',
'job-cancel-after': '10800',
'job-hold-until': 'no-hold',
'job-priority': '50',
'job-sheets': 'none,none',
'marker-change-time': '0',
'number-up': '1',
'printer-commands': 'ReportLevels,PrintSelfTestPage,com.toshiba.ColourProfiles.update,com.toshiba.EFiling.update,com.toshiba.EFiling.checkPassword',
'printer-info': 'Austin 4th Floor Printer @ C02XK13BJHD4',
'printer-is-accepting-jobs': 'true',
'printer-is-shared': 'false',
'printer-is-temporary': 'false',
'printer-location': '',
'printer-make-and-model': 'TOSHIBA ColorMFP',
'printer-state': '3',
'printer-state-change-time': '1573472937',
'printer-state-reasons': 'offline-report,com.toshiba.snmp.failed',
'printer-type': '10531038',
'printer-uri-supported': 'ipp://localhost/printers/Austin_4th_Floor_Printer___C02XK13BJHD4',
system_driverinfo: 'T'
}
}
```
electron Product Object Product Object
==============
* `productIdentifier` string - The string that identifies the product to the Apple App Store.
* `localizedDescription` string - A description of the product.
* `localizedTitle` string - The name of the product.
* `contentVersion` string - A string that identifies the version of the content.
* `contentLengths` number[] - The total size of the content, in bytes.
* `price` number - The cost of the product in the local currency.
* `formattedPrice` string - The locale formatted price of the product.
* `currencyCode` string - 3 character code presenting a product's currency based on the ISO 4217 standard.
* `introductoryPrice` [ProductDiscount](product-discount) (optional) - The object containing introductory price information for the product. available for the product.
* `discounts` [ProductDiscount](product-discount)[] - An array of discount offers
* `subscriptionGroupIdentifier` string - The identifier of the subscription group to which the subscription belongs.
* `subscriptionPeriod` [ProductSubscriptionPeriod](product-subscription-period) (optional) - The period details for products that are subscriptions.
* `isDownloadable` boolean - A boolean value that indicates whether the App Store has downloadable content for this product. `true` if at least one file has been associated with the product.
* `downloadContentVersion` string - A string that identifies the version of the content.
* `downloadContentLengths` number[] - The total size of the content, in bytes.
electron NotificationAction Object NotificationAction Object
=========================
* `type` string - The type of action, can be `button`.
* `text` string (optional) - The label for the given action.
Platform / Action Support[](#platform--action-support "Direct link to heading")
--------------------------------------------------------------------------------
| Action Type | Platform Support | Usage of `text` | Default `text` | Limitations |
| --- | --- | --- | --- | --- |
| `button` | macOS | Used as the label for the button | "Show" (or a localized string by system default if first of such `button`, otherwise empty) | Only the first one is used. If multiple are provided, those beyond the first will be listed as additional actions (displayed when mouse active over the action button). Any such action also is incompatible with `hasReply` and will be ignored if `hasReply` is `true`. |
### Button support on macOS[](#button-support-on-macos "Direct link to heading")
In order for extra notification buttons to work on macOS your app must meet the following criteria.
* App is signed
* App has it's `NSUserNotificationAlertStyle` set to `alert` in the `Info.plist`.
If either of these requirements are not met the button won't appear.
| programming_docs |
electron ProductDiscount Object ProductDiscount Object
======================
* `identifier` string - A string used to uniquely identify a discount offer for a product.
* `type` number - The type of discount offer.
* `price` number - The discount price of the product in the local currency.
* `priceLocale` string - The locale used to format the discount price of the product.
* `paymentMode` string - The payment mode for this product discount. Can be `payAsYouGo`, `payUpFront`, or `freeTrial`.
* `numberOfPeriods` number - An integer that indicates the number of periods the product discount is available.
* `subscriptionPeriod` [ProductSubscriptionPeriod](product-subscription-period) (optional) - An object that defines the period for the product discount.
electron Referrer Object Referrer Object
===============
* `url` string - HTTP Referrer URL.
* `policy` string - Can be `default`, `unsafe-url`, `no-referrer-when-downgrade`, `no-referrer`, `origin`, `strict-origin-when-cross-origin`, `same-origin` or `strict-origin`. See the [Referrer-Policy spec](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy) for more details on the meaning of these values.
electron HIDDevice Object HIDDevice Object
================
* `deviceId` string - Unique identifier for the device.
* `name` string - Name of the device.
* `vendorId` Integer - The USB vendor ID.
* `productId` Integer - The USB product ID.
* `serialNumber` string (optional) - The USB device serial number.
* `guid` string (optional) - Unique identifier for the HID interface. A device may have multiple HID interfaces.
electron CPUUsage Object CPUUsage Object
===============
* `percentCPUUsage` number - Percentage of CPU used since the last call to getCPUUsage. First call returns 0.
* `idleWakeupsPerSecond` number - The number of average idle CPU wakeups per second since the last call to getCPUUsage. First call returns 0. Will always return 0 on Windows.
electron Point Object Point Object
============
* `x` number
* `y` number
**Note:** Both `x` and `y` must be whole integers, when providing a point object as input to an Electron API we will automatically round your `x` and `y` values to the nearest whole integer.
electron PostBody Object PostBody Object
===============
* `data` ([UploadRawData](upload-raw-data) | [UploadFile](upload-file))[] - The post data to be sent to the new window.
* `contentType` string - The `content-type` header used for the data. One of `application/x-www-form-urlencoded` or `multipart/form-data`. Corresponds to the `enctype` attribute of the submitted HTML form.
* `boundary` string (optional) - The boundary used to separate multiple parts of the message. Only valid when `contentType` is `multipart/form-data`.
electron ThumbarButton Object ThumbarButton Object
====================
* `icon` [NativeImage](../native-image) - The icon showing in thumbnail toolbar.
* `click` Function
* `tooltip` string (optional) - The text of the button's tooltip.
* `flags` string[] (optional) - Control specific states and behaviors of the button. By default, it is `['enabled']`.
The `flags` is an array that can include following `string`s:
* `enabled` - The button is active and available to the user.
* `disabled` - The button is disabled. It is present, but has a visual state indicating it will not respond to user action.
* `dismissonclick` - When the button is clicked, the thumbnail window closes immediately.
* `nobackground` - Do not draw a button border, use only the image.
* `hidden` - The button is not shown to the user.
* `noninteractive` - The button is enabled but not interactive; no pressed button state is drawn. This value is intended for instances where the button is used in a notification.
electron GPUFeatureStatus Object GPUFeatureStatus Object
=======================
* `2d_canvas` string - Canvas.
* `flash_3d` string - Flash.
* `flash_stage3d` string - Flash Stage3D.
* `flash_stage3d_baseline` string - Flash Stage3D Baseline profile.
* `gpu_compositing` string - Compositing.
* `multiple_raster_threads` string - Multiple Raster Threads.
* `native_gpu_memory_buffers` string - Native GpuMemoryBuffers.
* `rasterization` string - Rasterization.
* `video_decode` string - Video Decode.
* `video_encode` string - Video Encode.
* `vpx_decode` string - VPx Video Decode.
* `webgl` string - WebGL.
* `webgl2` string - WebGL2.
Possible values:
* `disabled_software` - Software only. Hardware acceleration disabled (yellow)
* `disabled_off` - Disabled (red)
* `disabled_off_ok` - Disabled (yellow)
* `unavailable_software` - Software only, hardware acceleration unavailable (yellow)
* `unavailable_off` - Unavailable (red)
* `unavailable_off_ok` - Unavailable (yellow)
* `enabled_readback` - Hardware accelerated but at reduced performance (yellow)
* `enabled_force` - Hardware accelerated on all pages (green)
* `enabled` - Hardware accelerated (green)
* `enabled_on` - Enabled (green)
* `enabled_force_on` - Force enabled (green)
electron PaymentDiscount Object PaymentDiscount Object
======================
* `identifier` string - A string used to uniquely identify a discount offer for a product.
* `keyIdentifier` string - A string that identifies the key used to generate the signature.
* `nonce` string - A universally unique ID (UUID) value that you define.
* `signature` string - A UTF-8 string representing the properties of a specific discount offer, cryptographically signed.
* `timestamp` number - The date and time of the signature's creation in milliseconds, formatted in Unix epoch time.
electron KeyboardEvent Object KeyboardEvent Object
====================
* `ctrlKey` boolean (optional) - whether the Control key was used in an accelerator to trigger the Event
* `metaKey` boolean (optional) - whether a meta key was used in an accelerator to trigger the Event
* `shiftKey` boolean (optional) - whether a Shift key was used in an accelerator to trigger the Event
* `altKey` boolean (optional) - whether an Alt key was used in an accelerator to trigger the Event
* `triggeredByAccelerator` boolean (optional) - whether an accelerator was used to trigger the event as opposed to another user gesture like mouse click
electron TraceConfig Object TraceConfig Object
==================
* `recording_mode` string (optional) - Can be `record-until-full`, `record-continuously`, `record-as-much-as-possible` or `trace-to-console`. Defaults to `record-until-full`.
* `trace_buffer_size_in_kb` number (optional) - maximum size of the trace recording buffer in kilobytes. Defaults to 100MB.
* `trace_buffer_size_in_events` number (optional) - maximum size of the trace recording buffer in events.
* `enable_argument_filter` boolean (optional) - if true, filter event data according to a specific list of events that have been manually vetted to not include any PII. See [the implementation in Chromium](https://chromium.googlesource.com/chromium/src/+/main/services/tracing/public/cpp/trace_event_args_allowlist.cc) for specifics.
* `included_categories` string[] (optional) - a list of tracing categories to include. Can include glob-like patterns using `*` at the end of the category name. See [tracing categories](https://chromium.googlesource.com/chromium/src/+/main/base/trace_event/builtin_categories.h) for the list of categories.
* `excluded_categories` string[] (optional) - a list of tracing categories to exclude. Can include glob-like patterns using `*` at the end of the category name. See [tracing categories](https://chromium.googlesource.com/chromium/src/+/main/base/trace_event/builtin_categories.h) for the list of categories.
* `included_process_ids` number[] (optional) - a list of process IDs to include in the trace. If not specified, trace all processes.
* `histogram_names` string[] (optional) - a list of [histogram](https://chromium.googlesource.com/chromium/src.git/+/HEAD/tools/metrics/histograms/README.md) names to report with the trace.
* `memory_dump_config` Record<string, any> (optional) - if the `disabled-by-default-memory-infra` category is enabled, this contains optional additional configuration for data collection. See the [Chromium memory-infra docs](https://chromium.googlesource.com/chromium/src/+/main/docs/memory-infra/memory_infra_startup_tracing.md#the-advanced-way) for more information.
An example TraceConfig that roughly matches what Chrome DevTools records:
```
{
recording_mode: 'record-until-full',
included_categories: [
'devtools.timeline',
'disabled-by-default-devtools.timeline',
'disabled-by-default-devtools.timeline.frame',
'disabled-by-default-devtools.timeline.stack',
'v8.execute',
'blink.console',
'blink.user_timing',
'latencyInfo',
'disabled-by-default-v8.cpu_profiler',
'disabled-by-default-v8.cpu_profiler.hires'
],
excluded_categories: ['*']
}
```
electron KeyboardInputEvent Object extends InputEvent
KeyboardInputEvent Object extends `InputEvent`
==============================================
* `type` string - The type of the event, can be `keyDown`, `keyUp` or `char`.
* `keyCode` string - The character that will be sent as the keyboard event. Should only use the valid key codes in [Accelerator](../accelerator).
electron JumpListItem Object JumpListItem Object
===================
* `type` string (optional) - One of the following:
+ `task` - A task will launch an app with specific arguments.
+ `separator` - Can be used to separate items in the standard `Tasks` category.
+ `file` - A file link will open a file using the app that created the Jump List, for this to work the app must be registered as a handler for the file type (though it doesn't have to be the default handler).
* `path` string (optional) - Path of the file to open, should only be set if `type` is `file`.
* `program` string (optional) - Path of the program to execute, usually you should specify `process.execPath` which opens the current program. Should only be set if `type` is `task`.
* `args` string (optional) - The command line arguments when `program` is executed. Should only be set if `type` is `task`.
* `title` string (optional) - The text to be displayed for the item in the Jump List. Should only be set if `type` is `task`.
* `description` string (optional) - Description of the task (displayed in a tooltip). Should only be set if `type` is `task`. Maximum length 260 characters.
* `iconPath` string (optional) - The absolute path to an icon to be displayed in a Jump List, which can be an arbitrary resource file that contains an icon (e.g. `.ico`, `.exe`, `.dll`). You can usually specify `process.execPath` to show the program icon.
* `iconIndex` number (optional) - The index of the icon in the resource file. If a resource file contains multiple icons this value can be used to specify the zero-based index of the icon that should be displayed for this task. If a resource file contains only one icon, this property should be set to zero.
* `workingDirectory` string (optional) - The working directory. Default is empty.
electron MemoryInfo Object MemoryInfo Object
=================
* `workingSetSize` Integer - The amount of memory currently pinned to actual physical RAM.
* `peakWorkingSetSize` Integer - The maximum amount of memory that has ever been pinned to actual physical RAM.
* `privateBytes` Integer (optional) *Windows* - The amount of memory not shared by other processes, such as JS heap or HTML content.
Note that all statistics are reported in Kilobytes.
electron IpcMainEvent Object extends Event
IpcMainEvent Object extends `Event`
===================================
* `processId` Integer - The internal ID of the renderer process that sent this message
* `frameId` Integer - The ID of the renderer frame that sent this message
* `returnValue` any - Set this to the value to be returned in a synchronous message
* `sender` WebContents - Returns the `webContents` that sent the message
* `senderFrame` WebFrameMain *Readonly* - The frame that sent this message
* `ports` MessagePortMain[] - A list of MessagePorts that were transferred with this message
* `reply` Function - A function that will send an IPC message to the renderer frame that sent the original message that you are currently handling. You should use this method to "reply" to the sent message in order to guarantee the reply will go to the correct process and frame.
+ `channel` string
+ `...args` any[]
electron IOCounters Object IOCounters Object
=================
* `readOperationCount` number - The number of I/O read operations.
* `writeOperationCount` number - The number of I/O write operations.
* `otherOperationCount` number - Then number of I/O other operations.
* `readTransferCount` number - The number of I/O read transfers.
* `writeTransferCount` number - The number of I/O write transfers.
* `otherTransferCount` number - Then number of I/O other transfers.
electron ProcessMemoryInfo Object ProcessMemoryInfo Object
========================
* `residentSet` Integer *Linux* *Windows* - The amount of memory currently pinned to actual physical RAM in Kilobytes.
* `private` Integer - The amount of memory not shared by other processes, such as JS heap or HTML content in Kilobytes.
* `shared` Integer - The amount of memory shared between processes, typically memory consumed by the Electron code itself in Kilobytes.
electron DesktopCapturerSource Object DesktopCapturerSource Object
============================
* `id` string - The identifier of a window or screen that can be used as a `chromeMediaSourceId` constraint when calling [`navigator.webkitGetUserMedia`]. The format of the identifier will be `window:XX:YY` or `screen:ZZ:0`. XX is the windowID/handle. YY is 1 for the current process, and 0 for all others. ZZ is a sequential number that represents the screen, and it does not equal to the index in the source's name.
* `name` string - A screen source will be named either `Entire Screen` or `Screen <index>`, while the name of a window source will match the window title.
* `thumbnail` [NativeImage](../native-image) - A thumbnail image. **Note:** There is no guarantee that the size of the thumbnail is the same as the `thumbnailSize` specified in the `options` passed to `desktopCapturer.getSources`. The actual size depends on the scale of the screen or window.
* `display_id` string - A unique identifier that will correspond to the `id` of the matching [Display](display) returned by the [Screen API](../screen). On some platforms, this is equivalent to the `XX` portion of the `id` field above and on others it will differ. It will be an empty string if not available.
* `appIcon` [NativeImage](../native-image) - An icon image of the application that owns the window or null if the source has a type screen. The size of the icon is not known in advance and depends on what the application provides.
electron MouseInputEvent Object extends InputEvent
MouseInputEvent Object extends `InputEvent`
===========================================
* `type` string - The type of the event, can be `mouseDown`, `mouseUp`, `mouseEnter`, `mouseLeave`, `contextMenu`, `mouseWheel` or `mouseMove`.
* `x` Integer
* `y` Integer
* `button` string (optional) - The button pressed, can be `left`, `middle`, `right`.
* `globalX` Integer (optional)
* `globalY` Integer (optional)
* `movementX` Integer (optional)
* `movementY` Integer (optional)
* `clickCount` Integer (optional)
electron JumpListCategory Object JumpListCategory Object
=======================
* `type` string (optional) - One of the following:
+ `tasks` - Items in this category will be placed into the standard `Tasks` category. There can be only one such category, and it will always be displayed at the bottom of the Jump List.
+ `frequent` - Displays a list of files frequently opened by the app, the name of the category and its items are set by Windows.
+ `recent` - Displays a list of files recently opened by the app, the name of the category and its items are set by Windows. Items may be added to this category indirectly using `app.addRecentDocument(path)`.
+ `custom` - Displays tasks or file links, `name` must be set by the app.
* `name` string (optional) - Must be set if `type` is `custom`, otherwise it should be omitted.
* `items` JumpListItem[] (optional) - Array of [JumpListItem](jump-list-item) objects if `type` is `tasks` or `custom`, otherwise it should be omitted.
**Note:** If a `JumpListCategory` object has neither the `type` nor the `name` property set then its `type` is assumed to be `tasks`. If the `name` property is set but the `type` property is omitted then the `type` is assumed to be `custom`.
**Note:** The maximum length of a Jump List item's `description` property is 260 characters. Beyond this limit, the item will not be added to the Jump List, nor will it be displayed.
electron Certificate Object Certificate Object
==================
* `data` string - PEM encoded data
* `issuer` [CertificatePrincipal](certificate-principal) - Issuer principal
* `issuerName` string - Issuer's Common Name
* `issuerCert` Certificate - Issuer certificate (if not self-signed)
* `subject` [CertificatePrincipal](certificate-principal) - Subject principal
* `subjectName` string - Subject's Common Name
* `serialNumber` string - Hex value represented string
* `validStart` number - Start date of the certificate being valid in seconds
* `validExpiry` number - End date of the certificate being valid in seconds
* `fingerprint` string - Fingerprint of the certificate
electron NewWindowWebContentsEvent Object extends Event
NewWindowWebContentsEvent Object extends `Event`
================================================
* `newGuest` BrowserWindow (optional)
electron NotificationResponse Object NotificationResponse Object
===========================
* `actionIdentifier` string - The identifier string of the action that the user selected.
* `date` number - The delivery date of the notification.
* `identifier` string - The unique identifier for this notification request.
* `userInfo` Record<string, any> - A dictionary of custom information associated with the notification.
* `userText` string (optional) - The text entered or chosen by the user.
electron InputEvent Object InputEvent Object
=================
* `modifiers` string[] (optional) - An array of modifiers of the event, can be `shift`, `control`, `ctrl`, `alt`, `meta`, `command`, `cmd`, `isKeypad`, `isAutoRepeat`, `leftButtonDown`, `middleButtonDown`, `rightButtonDown`, `capsLock`, `numLock`, `left`, `right`.
electron UploadRawData Object UploadRawData Object
====================
* `type` 'rawData' - `rawData`.
* `bytes` Buffer - Data to be uploaded.
electron MemoryUsageDetails Object MemoryUsageDetails Object
=========================
* `count` number
* `size` number
* `liveSize` number
electron Display Object Display Object
==============
* `id` number - Unique identifier associated with the display.
* `rotation` number - Can be 0, 90, 180, 270, represents screen rotation in clock-wise degrees.
* `scaleFactor` number - Output device's pixel scale factor.
* `touchSupport` string - Can be `available`, `unavailable`, `unknown`.
* `monochrome` boolean - Whether or not the display is a monochrome display.
* `accelerometerSupport` string - Can be `available`, `unavailable`, `unknown`.
* `colorSpace` string - represent a color space (three-dimensional object which contains all realizable color combinations) for the purpose of color conversions
* `colorDepth` number - The number of bits per pixel.
* `depthPerComponent` number - The number of bits per color component.
* `displayFrequency` number - The display refresh rate.
* `bounds` [Rectangle](rectangle) - the bounds of the display in DIP points.
* `size` [Size](size)
* `workArea` [Rectangle](rectangle) - the work area of the display in DIP points.
* `workAreaSize` [Size](size)
* `internal` boolean - `true` for an internal display and `false` for an external display
The `Display` object represents a physical display connected to the system. A fake `Display` may exist on a headless system, or a `Display` may correspond to a remote, virtual display.
| programming_docs |
electron ProductSubscriptionPeriod Object ProductSubscriptionPeriod Object
================================
* `numberOfUnits` number - The number of units per subscription period.
* `unit` string - The increment of time that a subscription period is specified in. Can be `day`, `week`, `month`, `year`.
electron Event Object extends GlobalEvent
Event Object extends `GlobalEvent`
==================================
* `preventDefault` VoidFunction
electron SerialPort Object SerialPort Object
=================
* `portId` string - Unique identifier for the port.
* `portName` string - Name of the port.
* `displayName` string - A string suitable for display to the user for describing this device.
* `vendorId` string - Optional USB vendor ID.
* `productId` string - Optional USB product ID.
* `serialNumber` string - The USB device serial number.
* `usbDriverName` string (optional) - Represents a single serial port on macOS can be enumerated by multiple drivers.
* `deviceInstanceId` string (optional) - A stable identifier on Windows that can be used for device permissions.
electron SharingItem Object SharingItem Object
==================
* `texts` string[] (optional) - An array of text to share.
* `filePaths` string[] (optional) - An array of files to share.
* `urls` string[] (optional) - An array of URLs to share.
electron FilePathWithHeaders Object FilePathWithHeaders Object
==========================
* `path` string - The path to the file to send.
* `headers` Record<string, string> (optional) - Additional headers to be sent.
electron TraceCategoriesAndOptions Object TraceCategoriesAndOptions Object
================================
* `categoryFilter` string - A filter to control what category groups should be traced. A filter can have an optional '-' prefix to exclude category groups that contain a matching category. Having both included and excluded category patterns in the same list is not supported. Examples: `test_MyTest*`, `test_MyTest*,test_OtherStuff`, `-excluded_category1,-excluded_category2`.
* `traceOptions` string - Controls what kind of tracing is enabled, it is a comma-delimited sequence of the following strings: `record-until-full`, `record-continuously`, `trace-to-console`, `enable-sampling`, `enable-systrace`, e.g. `'record-until-full,enable-sampling'`. The first 3 options are trace recording modes and hence mutually exclusive. If more than one trace recording modes appear in the `traceOptions` string, the last one takes precedence. If none of the trace recording modes are specified, recording mode is `record-until-full`. The trace option will first be reset to the default option (`record_mode` set to `record-until-full`, `enable_sampling` and `enable_systrace` set to `false`) before options parsed from `traceOptions` are applied on it.
electron ServiceWorkerInfo Object ServiceWorkerInfo Object
========================
* `scriptUrl` string - The full URL to the script that this service worker runs
* `scope` string - The base URL that this service worker is active for.
* `renderProcessId` number - The virtual ID of the process that this service worker is running in. This is not an OS level PID. This aligns with the ID set used for `webContents.getProcessId()`.
electron Rectangle Object Rectangle Object
================
* `x` number - The x coordinate of the origin of the rectangle (must be an integer).
* `y` number - The y coordinate of the origin of the rectangle (must be an integer).
* `width` number - The width of the rectangle (must be an integer).
* `height` number - The height of the rectangle (must be an integer).
electron CustomScheme Object CustomScheme Object
===================
* `scheme` string - Custom schemes to be registered with options.
* `privileges` Object (optional)
+ `standard` boolean (optional) - Default false.
+ `secure` boolean (optional) - Default false.
+ `bypassCSP` boolean (optional) - Default false.
+ `allowServiceWorkers` boolean (optional) - Default false.
+ `supportFetchAPI` boolean (optional) - Default false.
+ `corsEnabled` boolean (optional) - Default false.
+ `stream` boolean (optional) - Default false.
electron Task Object Task Object
===========
* `program` string - Path of the program to execute, usually you should specify `process.execPath` which opens the current program.
* `arguments` string - The command line arguments when `program` is executed.
* `title` string - The string to be displayed in a JumpList.
* `description` string - Description of this task.
* `iconPath` string - The absolute path to an icon to be displayed in a JumpList, which can be an arbitrary resource file that contains an icon. You can usually specify `process.execPath` to show the icon of the program.
* `iconIndex` number - The icon index in the icon file. If an icon file consists of two or more icons, set this value to identify the icon. If an icon file consists of one icon, this value is 0.
* `workingDirectory` string (optional) - The working directory. Default is empty.
electron UserDefaultTypes Object UserDefaultTypes Object
=======================
* `string` string
* `boolean` boolean
* `integer` number
* `float` number
* `double` number
* `url` string
* `array` Array\<unknown>
* `dictionary` Record\<string, unknown>
This type is a helper alias, no object will never exist of this type.
electron CertificatePrincipal Object CertificatePrincipal Object
===========================
* `commonName` string - Common Name.
* `organizations` string[] - Organization names.
* `organizationUnits` string[] - Organization Unit names.
* `locality` string - Locality.
* `state` string - State or province.
* `country` string - Country or region.
electron ShortcutDetails Object ShortcutDetails Object
======================
* `target` string - The target to launch from this shortcut.
* `cwd` string (optional) - The working directory. Default is empty.
* `args` string (optional) - The arguments to be applied to `target` when launching from this shortcut. Default is empty.
* `description` string (optional) - The description of the shortcut. Default is empty.
* `icon` string (optional) - The path to the icon, can be a DLL or EXE. `icon` and `iconIndex` have to be set together. Default is empty, which uses the target's icon.
* `iconIndex` number (optional) - The resource ID of icon when `icon` is a DLL or EXE. Default is 0.
* `appUserModelId` string (optional) - The Application User Model ID. Default is empty.
* `toastActivatorClsid` string (optional) - The Application Toast Activator CLSID. Needed for participating in Action Center.
electron SharedWorkerInfo Object SharedWorkerInfo Object
=======================
* `id` string - The unique id of the shared worker.
* `url` string - The url of the shared worker.
electron UploadFile Object UploadFile Object
=================
* `type` 'file' - `file`.
* `filePath` string - Path of file to be uploaded.
* `offset` Integer - Defaults to `0`.
* `length` Integer - Number of bytes to read from `offset`. Defaults to `0`.
* `modificationTime` Double - Last Modification time in number of seconds since the UNIX epoch.
electron ScrubberItem Object ScrubberItem Object
===================
* `label` string (optional) - The text to appear in this item.
* `icon` NativeImage (optional) - The image to appear in this item.
electron Cookie Object Cookie Object
=============
* `name` string - The name of the cookie.
* `value` string - The value of the cookie.
* `domain` string (optional) - The domain of the cookie; this will be normalized with a preceding dot so that it's also valid for subdomains.
* `hostOnly` boolean (optional) - Whether the cookie is a host-only cookie; this will only be `true` if no domain was passed.
* `path` string (optional) - The path of the cookie.
* `secure` boolean (optional) - Whether the cookie is marked as secure.
* `httpOnly` boolean (optional) - Whether the cookie is marked as HTTP only.
* `session` boolean (optional) - Whether the cookie is a session cookie or a persistent cookie with an expiration date.
* `expirationDate` Double (optional) - The expiration date of the cookie as the number of seconds since the UNIX epoch. Not provided for session cookies.
* `sameSite` string - The [Same Site](https://developer.mozilla.org/en-US/docs/Web/HTTP/Cookies#SameSite_cookies) policy applied to this cookie. Can be `unspecified`, `no_restriction`, `lax` or `strict`.
electron ProcessMetric Object ProcessMetric Object
====================
* `pid` Integer - Process id of the process.
* `type` string - Process type. One of the following values:
+ `Browser`
+ `Tab`
+ `Utility`
+ `Zygote`
+ `Sandbox helper`
+ `GPU`
+ `Pepper Plugin`
+ `Pepper Plugin Broker`
+ `Unknown`
* `serviceName` string (optional) - The non-localized name of the process.
* `name` string (optional) - The name of the process. Examples for utility: `Audio Service`, `Content Decryption Module Service`, `Network Service`, `Video Capture`, etc.
* `cpu` [CPUUsage](cpu-usage) - CPU usage of the process.
* `creationTime` number - Creation time for this process. The time is represented as number of milliseconds since epoch. Since the `pid` can be reused after a process dies, it is useful to use both the `pid` and the `creationTime` to uniquely identify a process.
* `memory` [MemoryInfo](memory-info) - Memory information for the process.
* `sandboxed` boolean (optional) *macOS* *Windows* - Whether the process is sandboxed on OS level.
* `integrityLevel` string (optional) *Windows* - One of the following values:
+ `untrusted`
+ `low`
+ `medium`
+ `high`
+ `unknown`
electron IpcMainInvokeEvent Object extends Event
IpcMainInvokeEvent Object extends `Event`
=========================================
* `processId` Integer - The internal ID of the renderer process that sent this message
* `frameId` Integer - The ID of the renderer frame that sent this message
* `sender` WebContents - Returns the `webContents` that sent the message
* `senderFrame` WebFrameMain *Readonly* - The frame that sent this message
electron Transaction Object Transaction Object
==================
* `transactionIdentifier` string - A string that uniquely identifies a successful payment transaction.
* `transactionDate` string - The date the transaction was added to the App Store’s payment queue.
* `originalTransactionIdentifier` string - The identifier of the restored transaction by the App Store.
* `transactionState` string - The transaction state, can be `purchasing`, `purchased`, `failed`, `restored` or `deferred`.
* `errorCode` Integer - The error code if an error occurred while processing the transaction.
* `errorMessage` string - The error message if an error occurred while processing the transaction.
* `payment` Object
+ `productIdentifier` string - The identifier of the purchased product.
+ `quantity` Integer - The quantity purchased.
+ `applicationUsername` string - An opaque identifier for the user’s account on your system.
+ `paymentDiscount` [PaymentDiscount](payment-discount) (optional) - The details of the discount offer to apply to the payment.
electron ProtocolResponse Object ProtocolResponse Object
=======================
* `error` Integer (optional) - When assigned, the `request` will fail with the `error` number . For the available error numbers you can use, please see the [net error list](https://source.chromium.org/chromium/chromium/src/+/main:net/base/net_error_list.h).
* `statusCode` number (optional) - The HTTP response code, default is 200.
* `charset` string (optional) - The charset of response body, default is `"utf-8"`.
* `mimeType` string (optional) - The MIME type of response body, default is `"text/html"`. Setting `mimeType` would implicitly set the `content-type` header in response, but if `content-type` is already set in `headers`, the `mimeType` would be ignored.
* `headers` Record<string, string | string[]> (optional) - An object containing the response headers. The keys must be string, and values must be either string or Array of string.
* `data` (Buffer | string | ReadableStream) (optional) - The response body. When returning stream as response, this is a Node.js readable stream representing the response body. When returning `Buffer` as response, this is a `Buffer`. When returning `string` as response, this is a `string`. This is ignored for other types of responses.
* `path` string (optional) - Path to the file which would be sent as response body. This is only used for file responses.
* `url` string (optional) - Download the `url` and pipe the result as response body. This is only used for URL responses.
* `referrer` string (optional) - The `referrer` URL. This is only used for file and URL responses.
* `method` string (optional) - The HTTP `method`. This is only used for file and URL responses.
* `session` Session (optional) - The session used for requesting URL, by default the HTTP request will reuse the current session. Setting `session` to `null` would use a random independent session. This is only used for URL responses.
* `uploadData` [ProtocolResponseUploadData](protocol-response-upload-data) (optional) - The data used as upload data. This is only used for URL responses when `method` is `"POST"`.
electron IpcRendererEvent Object extends Event
IpcRendererEvent Object extends `Event`
=======================================
* `sender` IpcRenderer - The `IpcRenderer` instance that emitted the event originally
* `senderId` Integer - The `webContents.id` that sent the message, you can call `event.sender.sendTo(event.senderId, ...)` to reply to the message, see [ipcRenderer.sendTo](../ipc-renderer#ipcrenderersendtowebcontentsid-channel-args) for more information. This only applies to messages sent from a different renderer. Messages sent directly from the main process set `event.senderId` to `0`.
* `ports` MessagePort[] - A list of MessagePorts that were transferred with this message
pony MinHeap[A: Comparable[A] #read] MinHeap[A: [Comparable](builtin-comparable)[A] #read]
=====================================================
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L2)
```
type MinHeap[A: Comparable[A] #read] is
BinaryHeap[A, MinHeapPriority[A] val] ref
```
#### Type Alias For
* [BinaryHeap](collections-binaryheap)[A, [MinHeapPriority](collections-minheappriority)[A] val] ref
pony TCPListenNotify TCPListenNotify
===============
[[Source]](https://stdlib.ponylang.io/src/net/tcp_listen_notify/#L1)
Notifications for TCP listeners.
For an example of using this class, please see the documentation for the `TCPListener` actor.
```
interface ref TCPListenNotify
```
Public Functions
----------------
### listening
[[Source]](https://stdlib.ponylang.io/src/net/tcp_listen_notify/#L8)
Called when the listener has been bound to an address.
```
fun ref listening(
listen: TCPListener ref)
: None val
```
#### Parameters
* listen: [TCPListener](net-tcplistener) ref
#### Returns
* [None](builtin-none) val
### not\_listening
[[Source]](https://stdlib.ponylang.io/src/net/tcp_listen_notify/#L14)
Called if it wasn't possible to bind the listener to an address.
It is expected to implement proper error handling. You need to opt in to ignoring errors, which can be implemented like this:
```
fun ref not_listening(listen: TCPListener ref) =>
None
```
```
fun ref not_listening(
listen: TCPListener ref)
: None val
```
#### Parameters
* listen: [TCPListener](net-tcplistener) ref
#### Returns
* [None](builtin-none) val
### closed
[[Source]](https://stdlib.ponylang.io/src/net/tcp_listen_notify/#L27)
Called when the listener is closed.
```
fun ref closed(
listen: TCPListener ref)
: None val
```
#### Parameters
* listen: [TCPListener](net-tcplistener) ref
#### Returns
* [None](builtin-none) val
### connected
[[Source]](https://stdlib.ponylang.io/src/net/tcp_listen_notify/#L33)
Create a new TCPConnectionNotify to attach to a new TCPConnection for a newly established connection to the server.
```
fun ref connected(
listen: TCPListener ref)
: TCPConnectionNotify iso^ ?
```
#### Parameters
* listen: [TCPListener](net-tcplistener) ref
#### Returns
* [TCPConnectionNotify](net-tcpconnectionnotify) iso^ ?
pony Compare Compare
=======
[[Source]](https://stdlib.ponylang.io/src/builtin/compare/#L13)
```
type Compare is
(Less val | Equal val | Greater val)
```
#### Type Alias For
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
pony ListNode[A: A] ListNode[A: A]
==============
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L1)
A node in a doubly linked list.
(See Ponylang [collections.List](collections-list) class for usage examples.)
Each node contains four fields: two link fields (references to the previous and to the next node in the sequence of nodes), one data field, and the reference to the in which it resides.
As you would expect functions are provided to create a ListNode, update a ListNode's contained item, and pop the item from the ListNode.
Additional functions are provided to operate on a ListNode as part of a Linked List. These provide for prepending, appending, removal, and safe traversal in both directions. The Ponylang [collections.List](collections-list) class is the correct way to create these. *Do not attempt to create a Linked List using only ListNodes.*
Example program
---------------
The functions which are illustrated below are only those which operate on an individual ListNode.
It outputs:
My node has the item value: My Node item My node has the updated item value: My updated Node item Popped the item from the ListNode The ListNode has no (None) item.
```
use "collections"
actor Main
new create(env:Env) =>
// Create a new ListNode of type String
let my_list_node = ListNode[String]("My Node item")
try
env.out.print("My node has the item value: "
+ my_list_node.apply()?) // My Node item
end
// Update the item contained in the ListNode
try
my_list_node.update("My updated Node item")?
env.out.print("My node has the updated item value: "
+ my_list_node.apply()?) // My updated Node item
end
// Pop the item from the ListNode
try
my_list_node.pop()?
env.out.print("Popped the item from the ListNode")
my_list_node.apply()? // This will error as the item is now None
else
env.out.print("The ListNode has no (None) item.")
end
...
```pony
class ref ListNode[A: A]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L66)
Create a node. Initially, it is not in any list.
```
new ref create(
item: (A | None val) = reference)
: ListNode[A] ref^
```
#### Parameters
* item: (A | [None](builtin-none) val) = reference
#### Returns
* [ListNode](index)[A] ref^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L72)
Return the item, if we have one, otherwise raise an error.
```
fun box apply()
: this->A ?
```
#### Returns
* this->A ?
### update
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L78)
Replace the item and return the previous one. Raise an error if we have no previous value.
```
fun ref update(
value: (A | None val))
: A^ ?
```
#### Parameters
* value: (A | [None](builtin-none) val)
#### Returns
* A^ ?
### pop
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L85)
Remove the item from the node, if we have one, otherwise raise an error.
```
fun ref pop()
: A^ ?
```
#### Returns
* A^ ?
### prepend
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L91)
Prepend a node to this one. If `that` is already in a list, it is removed before it is prepended. Returns true if `that` was removed from another list. If the ListNode is not contained within a List the prepend will fail.
```
fun ref prepend(
that: ListNode[A] ref)
: Bool val
```
#### Parameters
* that: [ListNode](index)[A] ref
#### Returns
* [Bool](builtin-bool) val
### append
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L124)
Append a node to this one. If `that` is already in a list, it is removed before it is appended. Returns true if `that` was removed from another list.
If the ListNode is not contained within a List the append will fail.
```
fun ref append(
that: ListNode[A] ref)
: Bool val
```
#### Parameters
* that: [ListNode](index)[A] ref
#### Returns
* [Bool](builtin-bool) val
### remove
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L158)
Remove a node from a list.
The ListNode must be contained within a List for this to succeed.
```
fun ref remove()
: None val
```
#### Returns
* [None](builtin-none) val
### has\_prev
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L193)
Return true if there is a previous node.
```
fun box has_prev()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L199)
Return true if there is a next node.
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### prev
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L205)
Return the previous node.
```
fun box prev()
: (this->ListNode[A] ref | None val)
```
#### Returns
* (this->[ListNode](index)[A] ref | [None](builtin-none) val)
### next
[[Source]](https://stdlib.ponylang.io/src/collections/list_node/#L211)
Return the next node.
```
fun box next()
: (this->ListNode[A] ref | None val)
```
#### Returns
* (this->[ListNode](index)[A] ref | [None](builtin-none) val)
| programming_docs |
pony ParseError ParseError
==========
[[Source]](https://stdlib.ponylang.io/src/options/options/#L98)
```
interface ref ParseError
```
Public Functions
----------------
### reason
[[Source]](https://stdlib.ponylang.io/src/options/options/#L99)
```
fun box reason()
: (UnrecognisedOption val | MissingArgument val | InvalidArgument val |
AmbiguousMatch val)
```
#### Returns
* ([UnrecognisedOption](options-unrecognisedoption) val | [MissingArgument](options-missingargument) val | [InvalidArgument](options-invalidargument) val | [AmbiguousMatch](options-ambiguousmatch) val)
### report
[[Source]](https://stdlib.ponylang.io/src/options/options/#L100)
```
fun box report(
out: OutStream tag)
: None val
```
#### Parameters
* out: [OutStream](builtin-outstream) tag
#### Returns
* [None](builtin-none) val
pony Net package Net package
===========
The Net package provides support for creating UDP and TCP clients and servers, reading and writing network data, and establishing UDP and TCP connections.
Public Types
------------
* [type UDPSocketAuth](net-udpsocketauth)
* [actor UDPSocket](net-udpsocket)
* [interface UDPNotify](net-udpnotify)
* [type TCPListenerAuth](net-tcplistenerauth)
* [actor TCPListener](net-tcplistener)
* [interface TCPListenNotify](net-tcplistennotify)
* [interface TCPConnectionNotify](net-tcpconnectionnotify)
* [type TCPConnectionAuth](net-tcpconnectionauth)
* [actor TCPConnection](net-tcpconnection)
* [interface Proxy](net-proxy)
* [class NoProxy](net-noproxy)
* [primitive OSSockOpt](net-ossockopt)
* [class NetAddress](net-netaddress)
* [type DNSLookupAuth](net-dnslookupauth)
* [primitive DNS](net-dns)
* [primitive NetAuth](net-netauth)
* [primitive DNSAuth](net-dnsauth)
* [primitive UDPAuth](net-udpauth)
* [primitive TCPAuth](net-tcpauth)
* [primitive TCPListenAuth](net-tcplistenauth)
* [primitive TCPConnectAuth](net-tcpconnectauth)
pony VecPairs[A: Any #share] VecPairs[A: [Any](builtin-any) #share]
======================================
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/vec/#L280)
```
class ref VecPairs[A: Any #share]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/vec/#L285)
```
new ref create(
v: Vec[A] val)
: VecPairs[A] ref^
```
#### Parameters
* v: [Vec](collections-persistent-vec)[A] val
#### Returns
* [VecPairs](index)[A] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/vec/#L288)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/vec/#L291)
```
fun ref next()
: (USize val , A) ?
```
#### Returns
* ([USize](builtin-usize) val , A) ?
pony FormatFixLarge FormatFixLarge
==============
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L30)
```
primitive val FormatFixLarge is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L30)
```
new val create()
: FormatFixLarge val^
```
#### Returns
* [FormatFixLarge](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L31)
```
fun box eq(
that: FormatFixLarge val)
: Bool val
```
#### Parameters
* that: [FormatFixLarge](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L31)
```
fun box ne(
that: FormatFixLarge val)
: Bool val
```
#### Parameters
* that: [FormatFixLarge](index) val
#### Returns
* [Bool](builtin-bool) val
pony FileStat FileStat
========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L33)
```
primitive val FileStat
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L33)
```
new val create()
: FileStat val^
```
#### Returns
* [FileStat](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L34)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L34)
```
fun box eq(
that: FileStat val)
: Bool val
```
#### Parameters
* that: [FileStat](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L34)
```
fun box ne(
that: FileStat val)
: Bool val
```
#### Parameters
* that: [FileStat](index) val
#### Returns
* [Bool](builtin-bool) val
pony OpenFile OpenFile
========
[[Source]](https://stdlib.ponylang.io/src/files/file/#L64)
Open a File for read only.
```
primitive val OpenFile
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file/#L64)
```
new val create()
: OpenFile val^
```
#### Returns
* [OpenFile](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/files/file/#L68)
```
fun box apply(
from: FilePath val)
: (File ref | FileOK val | FileError val |
FileEOF val | FileBadFileNumber val | FileExists val |
FilePermissionDenied val)
```
#### Parameters
* from: [FilePath](files-filepath) val
#### Returns
* ([File](files-file) ref | [FileOK](files-fileok) val | [FileError](files-fileerror) val | [FileEOF](files-fileeof) val | [FileBadFileNumber](files-filebadfilenumber) val | [FileExists](files-fileexists) val | [FilePermissionDenied](files-filepermissiondenied) val)
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file/#L68)
```
fun box eq(
that: OpenFile val)
: Bool val
```
#### Parameters
* that: [OpenFile](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file/#L68)
```
fun box ne(
that: OpenFile val)
: Bool val
```
#### Parameters
* that: [OpenFile](index) val
#### Returns
* [Bool](builtin-bool) val
pony FileLines FileLines
=========
[[Source]](https://stdlib.ponylang.io/src/files/file_lines/#L3)
Iterate over the lines in a file.
Returns lines without trailing line breaks. Advances the file cursor to the end of each line returned from `next`.
This class buffers the file contents to accumulate full lines. If the file does not contain linebreaks, the whole file content is read and buffered, which might exceed memory resources. Take care.
```
class ref FileLines is
Iterator[String iso^] ref
```
#### Implements
* [Iterator](builtin-iterator)[[String](builtin-string) iso^] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_lines/#L24)
Create a FileLines instance on a given file.
This instance returns lines from the position of the given `file` at the time this constructor is called. Later manipulation of the file position is not accounted for. As a result iterating with this class will always return the full file content without gaps or repeated lines.
`min_read_size` determines the minimum amount of bytes to read from the file in one go. This class keeps track of the line lengths in the current file and uses the length of the last line as amount of bytes to read next, but it will never read less than `min_read_size`.
```
new ref create(
file: File ref,
min_read_size: USize val = 256)
: FileLines ref^
```
#### Parameters
* file: [File](files-file) ref
* min\_read\_size: [USize](builtin-usize) val = 256
#### Returns
* [FileLines](index) ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/files/file_lines/#L45)
```
fun ref has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/files/file_lines/#L48)
Returns the next line in the file.
```
fun ref next()
: String iso^ ?
```
#### Returns
* [String](builtin-string) iso^ ?
pony SplitMix64 SplitMix64
==========
[[Source]](https://stdlib.ponylang.io/src/random/splitmix64/#L1)
Very fast Pseudo-Random-Number-Generator using only 64 bit of state, as detailed at:
http://xoshiro.di.unimi.it/ and http://gee.cs.oswego.edu/dl/papers/oopsla14.pdf
Using [XorOshiro128StarStar](random-xoroshiro128starstar) or [XorOshiro128Plus](random-xoroshiro128plus) should be prefered unless using only 64 bit of state is a requirement.
```
class ref SplitMix64 is
Random ref
```
#### Implements
* [Random](random-random) ref
Constructors
------------
### from\_u64
[[Source]](https://stdlib.ponylang.io/src/random/splitmix64/#L14)
```
new ref from_u64(
x: U64 val = 5489)
: SplitMix64 ref^
```
#### Parameters
* x: [U64](builtin-u64) val = 5489
#### Returns
* [SplitMix64](index) ref^
### create
[[Source]](https://stdlib.ponylang.io/src/random/splitmix64/#L17)
Only x is used, y is discarded.
```
new ref create(
x: U64 val = 5489,
y: U64 val = 0)
: SplitMix64 ref^
```
#### Parameters
* x: [U64](builtin-u64) val = 5489
* y: [U64](builtin-u64) val = 0
#### Returns
* [SplitMix64](index) ref^
Public Functions
----------------
### next
[[Source]](https://stdlib.ponylang.io/src/random/splitmix64/#L23)
```
fun ref next()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### has\_next
```
fun tag has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### u8
```
fun ref u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
```
fun ref u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
```
fun ref u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun ref u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
```
fun ref u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun ref ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun ref usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### i8
```
fun ref i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
```
fun ref i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
```
fun ref i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun ref i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun ref i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun ref ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
```
fun ref isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### int\_fp\_mult[optional N: (([U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val) & [Real](builtin-real)[N] val)]
```
fun ref int_fp_mult[optional N: ((U8 val | U16 val | U32 val |
U64 val | U128 val | ULong val |
USize val) & Real[N] val)](
n: N)
: N
```
#### Parameters
* n: N
#### Returns
* N
### int[optional N: (([U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val) & [Real](builtin-real)[N] val)]
```
fun ref int[optional N: ((U8 val | U16 val | U32 val |
U64 val | U128 val | ULong val |
USize val) & Real[N] val)](
n: N)
: N
```
#### Parameters
* n: N
#### Returns
* N
### int\_unbiased[optional N: (([U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val) & [Real](builtin-real)[N] val)]
```
fun ref int_unbiased[optional N: ((U8 val | U16 val | U32 val |
U64 val | U128 val | ULong val |
USize val) & Real[N] val)](
n: N)
: N
```
#### Parameters
* n: N
#### Returns
* N
### real
```
fun ref real()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### shuffle[A: A]
```
fun ref shuffle[A: A](
array: Array[A] ref)
: None val
```
#### Parameters
* array: [Array](builtin-array)[A] ref
#### Returns
* [None](builtin-none) val
pony MicroBenchmark MicroBenchmark
==============
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L9)
Synchronous benchmarks must provide this trait. The `apply` method defines a single iteration in a sample. Setup and Teardown are defined by the `before` and `after` methods respectively. The `before` method runs before a sample of benchmarks and `after` runs after the all iterations in the sample have completed. If your benchmark requires setup and/or teardown to occur beween each iteration of the benchmark, then you can use `before_iteration` and `after_iteration` methods respectively that run before/after each iteration.
```
trait iso MicroBenchmark
```
Public Functions
----------------
### name
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L19)
```
fun box name()
: String val
```
#### Returns
* [String](builtin-string) val
### config
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L20)
```
fun box config()
: BenchConfig val
```
#### Returns
* [BenchConfig](ponybench-benchconfig) val
### overhead
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L21)
```
fun box overhead()
: MicroBenchmark iso^
```
#### Returns
* [MicroBenchmark](index) iso^
### before
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L22)
```
fun ref before()
: None val ?
```
#### Returns
* [None](builtin-none) val ?
### before\_iteration
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L23)
```
fun ref before_iteration()
: None val ?
```
#### Returns
* [None](builtin-none) val ?
### apply
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L24)
```
fun ref apply()
: None val ?
```
#### Returns
* [None](builtin-none) val ?
### after
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L25)
```
fun ref after()
: None val ?
```
#### Returns
* [None](builtin-none) val ?
### after\_iteration
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L26)
```
fun ref after_iteration()
: None val ?
```
#### Returns
* [None](builtin-none) val ?
pony Arg Arg
===
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L122)
Arg contains a spec and an effective value for a given arg.
```
class val Arg
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L129)
```
new val create(
spec': ArgSpec val,
value': (Bool val | String val | I64 val |
U64 val | F64 val | _StringSeq val))
: Arg val^
```
#### Parameters
* spec': [ArgSpec](cli-argspec) val
* value': ([Bool](builtin-bool) val | [String](builtin-string) val | [I64](builtin-i64) val | [U64](builtin-u64) val | [F64](builtin-f64) val | \_StringSeq val)
#### Returns
* [Arg](index) val^
Public Functions
----------------
### spec
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L136)
```
fun box spec()
: ArgSpec val
```
#### Returns
* [ArgSpec](cli-argspec) val
### bool
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L138)
Returns the arg value as a Bool, defaulting to false.
```
fun box bool()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### string
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L144)
Returns the arg value as a String, defaulting to empty.
```
fun box string()
: String val
```
#### Returns
* [String](builtin-string) val
### i64
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L150)
Returns the arg value as an I64, defaulting to 0.
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### u64
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L156)
Returns the arg value as an U64, defaulting to 0.
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### f64
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L162)
Returns the arg value as an F64, defaulting to 0.0.
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### string\_seq
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L168)
Returns the arg value as a ReadSeq[String], defaulting to empty.
```
fun box string_seq()
: ReadSeq[String val] val
```
#### Returns
* [ReadSeq](builtin-readseq)[[String](builtin-string) val] val
### deb\_string
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L178)
```
fun box deb_string()
: String val
```
#### Returns
* [String](builtin-string) val
pony Help Help
====
[[Source]](https://stdlib.ponylang.io/src/cli/command_help/#L3)
```
primitive val Help
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/cli/command_help/#L3)
```
new val create()
: Help val^
```
#### Returns
* [Help](index) val^
Public Functions
----------------
### general
[[Source]](https://stdlib.ponylang.io/src/cli/command_help/#L4)
Creates a command help that can print a general program help message.
```
fun box general(
cs: CommandSpec box)
: CommandHelp box
```
#### Parameters
* cs: [CommandSpec](cli-commandspec) box
#### Returns
* [CommandHelp](cli-commandhelp) box
### for\_command
[[Source]](https://stdlib.ponylang.io/src/cli/command_help/#L10)
Creates a command help for a specific command that can print a detailed help message.
```
fun box for_command(
cs: CommandSpec box,
argv: Array[String val] box)
: (CommandHelp box | SyntaxError val)
```
#### Parameters
* cs: [CommandSpec](cli-commandspec) box
* argv: [Array](builtin-array)[[String](builtin-string) val] box
#### Returns
* ([CommandHelp](cli-commandhelp) box | [SyntaxError](cli-syntaxerror) val)
### eq
[[Source]](https://stdlib.ponylang.io/src/cli/command_help/#L4)
```
fun box eq(
that: Help val)
: Bool val
```
#### Parameters
* that: [Help](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/cli/command_help/#L4)
```
fun box ne(
that: Help val)
: Bool val
```
#### Parameters
* that: [Help](index) val
#### Returns
* [Bool](builtin-bool) val
pony CollisionHash CollisionHash
=============
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/_test/#L341)
```
primitive val CollisionHash is
HashFunction[U64 val] val
```
#### Implements
* [HashFunction](collections-hashfunction)[[U64](builtin-u64) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/_test/#L341)
```
new val create()
: CollisionHash val^
```
#### Returns
* [CollisionHash](index) val^
Public Functions
----------------
### hash
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/_test/#L342)
```
fun box hash(
x: U64 val)
: USize val
```
#### Parameters
* x: [U64](builtin-u64) val
#### Returns
* [USize](builtin-usize) val
### eq
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/_test/#L343)
```
fun box eq(
x: U64 val,
y: U64 val)
: Bool val
```
#### Parameters
* x: [U64](builtin-u64) val
* y: [U64](builtin-u64) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/_test/#L342)
```
fun box ne(
that: CollisionHash val)
: Bool val
```
#### Parameters
* that: [CollisionHash](index) val
#### Returns
* [Bool](builtin-bool) val
pony IniMap IniMap
======
[[Source]](https://stdlib.ponylang.io/src/ini/ini_map/#L3)
```
type IniMap is
HashMap[String val, HashMap[String val, String val, HashEq[String val] val] ref, HashEq[String val] val] ref
```
#### Type Alias For
* [HashMap](collections-hashmap)[[String](builtin-string) val, [HashMap](collections-hashmap)[[String](builtin-string) val, [String](builtin-string) val, [HashEq](collections-hasheq)[[String](builtin-string) val] val] ref, [HashEq](collections-hasheq)[[String](builtin-string) val] val] ref
| programming_docs |
pony FileTime FileTime
========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L39)
```
primitive val FileTime
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L39)
```
new val create()
: FileTime val^
```
#### Returns
* [FileTime](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L40)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L40)
```
fun box eq(
that: FileTime val)
: Bool val
```
#### Parameters
* that: [FileTime](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L40)
```
fun box ne(
that: FileTime val)
: Bool val
```
#### Parameters
* that: [FileTime](index) val
#### Returns
* [Bool](builtin-bool) val
pony HashMap[K: Any #share, V: Any #share, H: HashFunction[K] val] HashMap[K: [Any](builtin-any) #share, V: [Any](builtin-any) #share, H: [HashFunction](collections-hashfunction)[K] val]
=======================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L14)
A persistent map based on the Compressed Hash Array Mapped Prefix-tree from 'Optimizing Hash-Array Mapped Tries for Fast and Lean Immutable JVM Collections' by Michael J. Steindorfer and Jurgen J. Vinju
Usage
-----
```
use "collections/persistent"
actor Main
new create(env: Env) =>
try
let m1 = Map[String, U32] // {}
// Update returns a new map with the provided key set
// to the provided value. The old map is unchanged.
let m2 = m1("a") = 5 // {a: 5}
let m3 = m2("b") = 10 // {a: 5, b: 10}
let m4 = m3.remove("a")? // {b: 10}
// You can create a new map from key value pairs.
let m5 = Map[String, U32].concat([("a", 2); ("b", 3)].values()) // {a: 2, b: 3}
end
```
```
class val HashMap[K: Any #share, V: Any #share, H: HashFunction[K] val]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L41)
```
new val create()
: HashMap[K, V, H] val^
```
#### Returns
* [HashMap](index)[K, V, H] val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L49)
Attempt to get the value corresponding to k.
```
fun val apply(
k: K)
: val->V ?
```
#### Parameters
* k: K
#### Returns
* val->V ?
### size
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L55)
Return the amount of key-value pairs in the Map.
```
fun val size()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### update
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L61)
Update the value associated with the provided key.
```
fun val update(
key: K,
value: val->V)
: HashMap[K, V, H] val
```
#### Parameters
* key: K
* value: val->V
#### Returns
* [HashMap](index)[K, V, H] val
### remove
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L74)
Try to remove the provided key from the Map.
```
fun val remove(
k: K)
: HashMap[K, V, H] val ?
```
#### Parameters
* k: K
#### Returns
* [HashMap](index)[K, V, H] val ?
### get\_or\_else
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L80)
Get the value associated with provided key if present. Otherwise, return the provided alternate value.
```
fun val get_or_else(
k: K,
alt: val->V)
: val->V
```
#### Parameters
* k: K
* alt: val->V
#### Returns
* val->V
### contains
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L94)
Check whether the node contains the provided key.
```
fun val contains(
k: K)
: Bool val
```
#### Parameters
* k: K
#### Returns
* [Bool](builtin-bool) val
### concat
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L102)
Add the K, V pairs from the given iterator to the map.
```
fun val concat(
iter: Iterator[(val->K , val->V)] ref)
: HashMap[K, V, H] val
```
#### Parameters
* iter: [Iterator](builtin-iterator)[(val->K , val->V)] ref
#### Returns
* [HashMap](index)[K, V, H] val
### add
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L112)
Return this Map with the given (key, value) mapping.
```
fun val add(
key: K,
value: val->V)
: HashMap[K, V, H] val
```
#### Parameters
* key: K
* value: val->V
#### Returns
* [HashMap](index)[K, V, H] val
### sub
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L118)
Return this Map without the given key.
```
fun val sub(
key: K)
: HashMap[K, V, H] val
```
#### Parameters
* key: K
#### Returns
* [HashMap](index)[K, V, H] val
### keys
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L128)
```
fun val keys()
: MapKeys[K, V, H] ref
```
#### Returns
* [MapKeys](collections-persistent-mapkeys)[K, V, H] ref
### values
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L130)
```
fun val values()
: MapValues[K, V, H] ref
```
#### Returns
* [MapValues](collections-persistent-mapvalues)[K, V, H] ref
### pairs
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L132)
```
fun val pairs()
: MapPairs[K, V, H] ref
```
#### Returns
* [MapPairs](collections-persistent-mappairs)[K, V, H] ref
pony MapKeys[K: Any #share, V: Any #share, H: HashFunction[K] val] MapKeys[K: [Any](builtin-any) #share, V: [Any](builtin-any) #share, H: [HashFunction](collections-hashfunction)[K] val]
=======================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L136)
```
class ref MapKeys[K: Any #share, V: Any #share, H: HashFunction[K] val]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L139)
```
new ref create(
m: HashMap[K, V, H] val)
: MapKeys[K, V, H] ref^
```
#### Parameters
* m: [HashMap](collections-persistent-hashmap)[K, V, H] val
#### Returns
* [MapKeys](index)[K, V, H] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L141)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L143)
```
fun ref next()
: K ?
```
#### Returns
* K ?
pony Align Align
=====
[[Source]](https://stdlib.ponylang.io/src/format/align/#L5)
```
type Align is
(AlignLeft val | AlignRight val | AlignCenter val)
```
#### Type Alias For
* ([AlignLeft](format-alignleft) val | [AlignRight](format-alignright) val | [AlignCenter](format-aligncenter) val)
pony Pointer[A: A] Pointer[A: A]
=============
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L1)
A Pointer[A] is a raw memory pointer. It has no descriptor and thus can't be included in a union or intersection, or be a subtype of any interface. Most functions on a Pointer[A] are private to maintain memory safety.
```
struct ref Pointer[A: A]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L7)
A null pointer.
```
new ref create()
: Pointer[A] ref^
```
#### Returns
* [Pointer](index)[A] ref^
Public Functions
----------------
### offset
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L55)
Return a tag pointer to the n-th element.
```
fun tag offset(
n: USize val)
: Pointer[A] tag
```
#### Parameters
* n: [USize](builtin-usize) val
#### Returns
* [Pointer](index)[A] tag
### usize
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L89)
Convert the pointer into an integer.
```
fun tag usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### is\_null
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L95)
Return true for a null pointer, false for anything else.
```
fun tag is_null()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L101)
Return true if this address is that address.
```
fun tag eq(
that: Pointer[A] tag)
: Bool val
```
#### Parameters
* that: [Pointer](index)[A] tag
#### Returns
* [Bool](builtin-bool) val
### lt
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L107)
Return true if this address is less than that address.
```
fun tag lt(
that: Pointer[A] tag)
: Bool val
```
#### Parameters
* that: [Pointer](index)[A] tag
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L113)
```
fun tag ne(
that: Pointer[A] tag)
: Bool val
```
#### Parameters
* that: [Pointer](index)[A] tag
#### Returns
* [Bool](builtin-bool) val
### le
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L114)
```
fun tag le(
that: Pointer[A] tag)
: Bool val
```
#### Parameters
* that: [Pointer](index)[A] tag
#### Returns
* [Bool](builtin-bool) val
### ge
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L115)
```
fun tag ge(
that: Pointer[A] tag)
: Bool val
```
#### Parameters
* that: [Pointer](index)[A] tag
#### Returns
* [Bool](builtin-bool) val
### gt
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L116)
```
fun tag gt(
that: Pointer[A] tag)
: Bool val
```
#### Parameters
* that: [Pointer](index)[A] tag
#### Returns
* [Bool](builtin-bool) val
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L118)
Returns a hash of the address.
```
fun tag hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
[[Source]](https://stdlib.ponylang.io/src/builtin/pointer/#L124)
Returns a 64-bit hash of the address.
```
fun tag hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
pony Map[K: (Hashable #read & Equatable[K] #read), V: V] Map[K: ([Hashable](collections-hashable) #read & [Equatable](builtin-equatable)[K] #read), V: V]
================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L4)
This is a map that uses structural equality on the key.
```
type Map[K: (Hashable #read & Equatable[K] #read), V: V] is
HashMap[K, V, HashEq[K] val] ref
```
#### Type Alias For
* [HashMap](collections-hashmap)[K, V, [HashEq](collections-hasheq)[K] val] ref
pony Cap Cap
===
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L1)
The Capsicum rights.
```
primitive val Cap
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L1)
```
new val create()
: Cap val^
```
#### Returns
* [Cap](index) val^
Public Functions
----------------
### enter
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L5)
This places the current process into capability mode, a mode of execution in which processes may only issue system calls operating on file descriptors or reading limited global system state. Access to global name spaces, such as file system or IPC name spaces, is prevented.
```
fun box enter()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### read
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L18)
```
fun box read()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### write
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L19)
```
fun box write()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### seek\_tell
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L20)
```
fun box seek_tell()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### seek
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L21)
```
fun box seek()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### pread
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L22)
```
fun box pread()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### pwrite
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L23)
```
fun box pwrite()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mmap
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L25)
```
fun box mmap()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mmap\_r
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L26)
```
fun box mmap_r()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mmap\_w
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L27)
```
fun box mmap_w()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mmap\_x
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L28)
```
fun box mmap_x()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mmap\_rw
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L29)
```
fun box mmap_rw()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mmap\_rx
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L30)
```
fun box mmap_rx()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mmap\_wx
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L31)
```
fun box mmap_wx()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mmap\_rwx
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L32)
```
fun box mmap_rwx()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### creat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L34)
```
fun box creat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fexecve
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L35)
```
fun box fexecve()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fsync
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L36)
```
fun box fsync()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### ftruncate
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L37)
```
fun box ftruncate()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### lookup
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L38)
```
fun box lookup()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fchdir
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L39)
```
fun box fchdir()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fchflags
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L40)
```
fun box fchflags()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### chflagsat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L41)
```
fun box chflagsat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fchmod
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L42)
```
fun box fchmod()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fchmodat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L43)
```
fun box fchmodat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fchown
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L44)
```
fun box fchown()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fchownat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L45)
```
fun box fchownat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fcntl
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L46)
```
fun box fcntl()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### flock
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L47)
```
fun box flock()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fpathconf
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L48)
```
fun box fpathconf()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fsck
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L49)
```
fun box fsck()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fstat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L50)
```
fun box fstat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fstatat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L51)
```
fun box fstatat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### fstatfs
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L52)
```
fun box fstatfs()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### futimes
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L53)
```
fun box futimes()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### futimesat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L54)
```
fun box futimesat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### linkat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L56)
```
fun box linkat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mkdirat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L57)
```
fun box mkdirat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mkfifoat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L58)
```
fun box mkfifoat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mknodat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L59)
```
fun box mknodat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### renameat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L60)
```
fun box renameat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### symlinkat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L61)
```
fun box symlinkat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### unlinkat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L62)
```
fun box unlinkat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### accept
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L64)
```
fun box accept()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### bind
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L65)
```
fun box bind()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### connect
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L66)
```
fun box connect()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### getpeername
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L67)
```
fun box getpeername()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### getsockname
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L68)
```
fun box getsockname()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### getsockopt
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L69)
```
fun box getsockopt()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### listen
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L70)
```
fun box listen()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### peeloff
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L71)
```
fun box peeloff()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### recv
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L72)
```
fun box recv()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### send
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L73)
```
fun box send()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### setsockopt
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L74)
```
fun box setsockopt()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### shutdown
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L75)
```
fun box shutdown()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### bindat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L76)
```
fun box bindat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### connectat
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L77)
```
fun box connectat()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### sock\_client
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L79)
```
fun box sock_client()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### sock\_server
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L83)
```
fun box sock_server()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mac\_get
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L87)
```
fun box mac_get()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### mac\_set
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L88)
```
fun box mac_set()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### sem\_getvalue
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L90)
```
fun box sem_getvalue()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### sem\_post
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L91)
```
fun box sem_post()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### sem\_wait
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L92)
```
fun box sem_wait()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### event
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L94)
```
fun box event()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### kqueue\_event
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L95)
```
fun box kqueue_event()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### ioctl
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L96)
```
fun box ioctl()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### ttyhook
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L97)
```
fun box ttyhook()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### pdgetpid
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L99)
```
fun box pdgetpid()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### pdwait
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L100)
```
fun box pdwait()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### pdkill
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L101)
```
fun box pdkill()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### exattr\_delete
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L103)
```
fun box exattr_delete()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### exattr\_get
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L104)
```
fun box exattr_get()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### exattr\_list
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L105)
```
fun box exattr_list()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### exattr\_set
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L106)
```
fun box exattr_set()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### acl\_check
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L108)
```
fun box acl_check()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### acl\_delete
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L109)
```
fun box acl_delete()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### acl\_get
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L110)
```
fun box acl_get()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### acl\_set
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L111)
```
fun box acl_set()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### kqueue\_change
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L113)
```
fun box kqueue_change()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### kqueue
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L114)
```
fun box kqueue()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### eq
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L5)
```
fun box eq(
that: Cap val)
: Bool val
```
#### Parameters
* that: [Cap](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap/#L5)
```
fun box ne(
that: Cap val)
: Bool val
```
#### Parameters
* that: [Cap](index) val
#### Returns
* [Bool](builtin-bool) val
| programming_docs |
pony ErrorReason ErrorReason
===========
[[Source]](https://stdlib.ponylang.io/src/options/options/#L89)
```
type ErrorReason is
(UnrecognisedOption val | MissingArgument val | InvalidArgument val | AmbiguousMatch val)
```
#### Type Alias For
* ([UnrecognisedOption](options-unrecognisedoption) val | [MissingArgument](options-missingargument) val | [InvalidArgument](options-invalidargument) val | [AmbiguousMatch](options-ambiguousmatch) val)
pony Base64 package Base64 package
==============
The Base64 package contains support for doing Base64 binary-to-text encodings. We currently have support 3 encodings: PEM, MIME and URL.
To learn more about Base64, we suggest you check out the [wikipedia entry](https://en.wikipedia.org/wiki/Base64).
Example code
------------
```
use "encode/base64"
actor Main
new create(env: Env) =>
env.out.print(Base64.encode("foobar"))
try
env.out.print(Base64.decode[String iso]("Zm9vYmFy")?)
end
```
Public Types
------------
* [primitive Base64](encode-base64-base64)
pony Serialise package Serialise package
=================
This package provides support for serialising and deserialising arbitrary data structures.
The API is designed to require capability tokens, as otherwise serialising would leak the bit patterns of all private information in a type (since the resulting Array[U8] could be examined.
Deserialisation is fundamentally unsafe currently: there isn't yet a verification pass to check that the resulting object graph maintains a well-formed heap or that individual objects maintain any expected local invariants. However, if only "trusted" data (i.e. data produced by Pony serialisation from the same binary) is deserialised, it will always maintain a well-formed heap and all object invariants.
Note that serialised data is not usable between different Pony binaries. This is due to the use of type identifiers rather than a heavy-weight self-describing serialisation schema. This also means it isn't safe to deserialise something serialised by the same program compiled for a different platform.
The Serialise.signature method is provided for the purposes of comparing communicating Pony binaries to determine if they are the same. Confirming this before deserialising data can help mitigate the risk of accidental serialisation across different Pony binaries, but does not on its own address the security issues of accepting data from untrusted sources.
Public Types
------------
* [primitive Serialise](serialise-serialise)
* [primitive SerialiseAuth](serialise-serialiseauth)
* [primitive DeserialiseAuth](serialise-deserialiseauth)
* [primitive OutputSerialisedAuth](serialise-outputserialisedauth)
* [primitive InputSerialisedAuth](serialise-inputserialisedauth)
* [class Serialised](serialise-serialised)
pony Integer[A: Integer[A] val] Integer[A: [Integer](index)[A] val]
===================================
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L213)
```
trait val Integer[A: Integer[A] val] is
Real[A] val
```
#### Implements
* [Real](builtin-real)[A] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L135)
```
new val create(
value: A)
: Real[A] val^
```
#### Parameters
* value: A
#### Returns
* [Real](builtin-real)[A] val^
### from[B: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[B] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L137)
```
new val from[B: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[B] val)](
a: B)
: Real[A] val^
```
#### Parameters
* a: B
#### Returns
* [Real](builtin-real)[A] val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L138)
```
new val min_value()
: Real[A] val^
```
#### Returns
* [Real](builtin-real)[A] val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L139)
```
new val max_value()
: Real[A] val^
```
#### Returns
* [Real](builtin-real)[A] val^
Public Functions
----------------
### add\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L214)
Unsafe operation. If the operation overflows, the result is undefined.
```
fun box add_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### sub\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L221)
Unsafe operation. If the operation overflows, the result is undefined.
```
fun box sub_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mul\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L228)
Unsafe operation. If the operation overflows, the result is undefined.
```
fun box mul_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### div\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L235)
Integer division, rounded towards zero.
Unsafe operation. If y is 0, the result is undefined. If the operation overflows, the result is undefined.
```
fun box div_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### divrem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L245)
Calculates the quotient of this number and `y` and the remainder.
Unsafe operation. If y is 0, the result is undefined. If the operation overflows, the result is undefined.
```
fun box divrem_unsafe(
y: A)
: (A , A)
```
#### Parameters
* y: A
#### Returns
* (A , A)
### rem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L255)
Calculates the remainder of this number divided by `y`.
Unsafe operation. If y is 0, the result is undefined. If the operation overflows, the result is undefined.
```
fun box rem_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L265)
Floored division, rounded towards negative infinity, as opposed to `div` which rounds towards zero.
*Unsafe Operation*
If y is 0, the result is undefined. If the operation overflows, the result is undefined.
```
fun box fld_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L276)
Calculates the modulo of this number after floored division by `y`.
*Unsafe Operation.*
If y is 0, the result is undefined. If the operation overflows, the result is undefined.
```
fun box mod_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L286)
Add y to this number.
If the operation overflows this function errors.
```
fun box add_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L293)
Subtract y from this number.
If the operation overflows/underflows this function errors.
```
fun box sub_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L300)
Multiply y with this number.
If the operation overflows this function errors.
```
fun box mul_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L307)
Divides this number by `y`, rounds the result towards zero.
If y is `0` or the operation overflows, this function errors.
```
fun box div_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L314)
Calculates the remainder of this number divided by y. The result has the sign of the dividend.
If y is `0` or the operation overflows, this function errors.
```
fun box rem_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L322)
Divides this number by y and calculates the remainder of the operation.
If y is `0` or the operation overflows, this function errors.
```
fun box divrem_partial(
y: A)
: (A , A) ?
```
#### Parameters
* y: A
#### Returns
* (A , A) ?
### fld\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L329)
Floored integer division, rounded towards negative infinity.
If y is `0` or the operation overflows, this function errors
```
fun box fld_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### mod\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L336)
Calculates the modulo of this number and `y` after floored division (`fld`). The result has the sign of the divisor.
If y is `0` or the operation overflows, this function errors.
```
fun box mod_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### neg\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L344)
Unsafe operation. If the operation overflows, the result is undefined.
```
fun box neg_unsafe()
: A
```
#### Returns
* A
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L351)
Add `y` to this integer and return the result and a flag indicating overflow.
```
fun box addc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L355)
Subtract `y` from this integer and return the result and a flag indicating overflow.
```
fun box subc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L359)
Multiply `y` with this integer and return the result and a flag indicating overflow.
```
fun box mulc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L363)
Divide this integer by `y` and return the result and a flag indicating overflow or division by zero.
```
fun box divc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L367)
Calculate the remainder of this number divided by `y` and return the result and a flag indicating division by zero or overflow.
The result will have the sign of the dividend.
```
fun box remc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### fldc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L373)
Divide this integer by `y` and return the result, rounded towards negative infinity and a flag indicating overflow or division by zero.
```
fun box fldc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### modc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L377)
Calculate the modulo of this number after floored division by `y` and return the result and a flag indicating division by zero or overflow.
The result will have the sign of the divisor.
```
fun box modc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### op\_and
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L384)
```
fun box op_and(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### op\_or
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L385)
```
fun box op_or(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### op\_xor
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L386)
```
fun box op_xor(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### op\_not
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L387)
```
fun box op_not()
: A
```
#### Returns
* A
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L389)
Reverse the order of the bits within the integer. For example, 0b11101101 (237) would return 0b10110111 (183).
```
fun box bit_reverse()
: A
```
#### Returns
* A
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L395)
```
fun box bswap()
: A
```
#### Returns
* A
### add
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L141)
```
fun box add(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### sub
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L142)
```
fun box sub(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mul
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L143)
```
fun box mul(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### div
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L144)
```
fun box div(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### divrem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L150)
```
fun box divrem(
y: A)
: (A , A)
```
#### Parameters
* y: A
#### Returns
* (A , A)
### rem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L151)
```
fun box rem(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### neg
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L159)
```
fun box neg()
: A
```
#### Returns
* A
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L161)
```
fun box fld(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L165)
```
fun box mod(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L172)
```
fun box eq(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L173)
```
fun box ne(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### lt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L174)
```
fun box lt(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### le
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L175)
```
fun box le(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ge
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L176)
```
fun box ge(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### gt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L177)
```
fun box gt(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L179)
```
fun box min(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L180)
```
fun box max(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L182)
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L198)
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/stringable/#L5)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### i8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L2)
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L3)
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L4)
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L5)
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L6)
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L7)
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L8)
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L10)
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L11)
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L12)
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L13)
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L14)
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L15)
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L16)
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L18)
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L19)
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L21)
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L28)
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L35)
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L42)
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L49)
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L56)
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L63)
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L70)
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L77)
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L84)
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L91)
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L98)
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L105)
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L112)
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L119)
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L126)
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: box->A)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: box->A
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony Signaled Signaled
========
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L103)
Process exit status: Process was terminated by a signal.
```
class val Signaled is
Stringable box,
Equatable[(Exited val | Signaled val)] ref
```
#### Implements
* [Stringable](builtin-stringable) box
* [Equatable](builtin-equatable)[([Exited](process-exited) val | [Signaled](index) val)] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L109)
```
new val create(
sig: U32 val)
: Signaled val^
```
#### Parameters
* sig: [U32](builtin-u32) val
#### Returns
* [Signaled](index) val^
Public Functions
----------------
### signal
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L112)
Retrieve the signal number that exited the process.
```
fun box signal()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### string
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L118)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L126)
```
fun box eq(
other: (Exited val | Signaled val))
: Bool val
```
#### Parameters
* other: ([Exited](process-exited) val | [Signaled](index) val)
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/compare/#L20)
```
fun box ne(
that: (Exited val | Signaled val))
: Bool val
```
#### Parameters
* that: ([Exited](process-exited) val | [Signaled](index) val)
#### Returns
* [Bool](builtin-bool) val
pony WalkHandler WalkHandler
===========
[[Source]](https://stdlib.ponylang.io/src/files/file_path/#L3)
A handler for `FilePath.walk`.
```
interface ref WalkHandler
```
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/files/file_path/#L7)
```
fun ref apply(
dir_path: FilePath val,
dir_entries: Array[String val] ref)
: None val
```
#### Parameters
* dir\_path: [FilePath](files-filepath) val
* dir\_entries: [Array](builtin-array)[[String](builtin-string) val] ref
#### Returns
* [None](builtin-none) val
pony FileRemove FileRemove
==========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L24)
```
primitive val FileRemove
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L24)
```
new val create()
: FileRemove val^
```
#### Returns
* [FileRemove](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L25)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L25)
```
fun box eq(
that: FileRemove val)
: Bool val
```
#### Parameters
* that: [FileRemove](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L25)
```
fun box ne(
that: FileRemove val)
: Bool val
```
#### Parameters
* that: [FileRemove](index) val
#### Returns
* [Bool](builtin-bool) val
pony Writer Writer
======
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L1)
A buffer for building messages.
`Writer` provides an way to create byte sequences using common data encodings. The `Writer` manages the underlying arrays and sizes. It is useful for encoding data to send over a network or store in a file. Once a message has been built you can call `done()` to get the message's `ByteSeq`s, and you can then reuse the `Writer` for creating a new message.
For example, suppose we have a TCP-based network data protocol where messages consist of the following:
* `message_length` - the number of bytes in the message as a big-endian 32-bit integer
* `list_size` - the number of items in the following list of items as a big-endian 32-bit integer
* zero or more items of the following data:
* a big-endian 64-bit floating point number
* a string that starts with a big-endian 32-bit integer that specifies the length of the string, followed by a number of bytes that represent the string
A message would be something like this:
```
[message_length][list_size][float1][string1][float2][string2]...
```
The following program uses a write buffer to encode an array of tuples as a message of this type:
```
use "buffered"
actor Main
new create(env: Env) =>
let wb = Writer
let messages = [[(F32(3597.82), "Anderson"); (F32(-7979.3), "Graham")]
[(F32(3.14159), "Hopper"); (F32(-83.83), "Jones")]]
for items in messages.values() do
wb.i32_be((items.size() / 2).i32())
for (f, s) in items.values() do
wb.f32_be(f)
wb.i32_be(s.size().i32())
wb.write(s.array())
end
let wb_msg = Writer
wb_msg.i32_be(wb.size().i32())
wb_msg.writev(wb.done())
env.out.writev(wb_msg.done())
end
```
```
class ref Writer
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L1)
```
new iso create()
: Writer iso^
```
#### Returns
* [Writer](index) iso^
Public Functions
----------------
### reserve\_chunks
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L60)
Reserve space for size' chunks.
This needs to be recalled after every call to `done` as `done` resets the chunks.
```
fun ref reserve_chunks(
size': USize val)
: None val
```
#### Parameters
* size': [USize](builtin-usize) val
#### Returns
* [None](builtin-none) val
### reserve\_current
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L69)
Reserve space for size bytes in `_current`.
```
fun ref reserve_current(
size': USize val)
: None val
```
#### Parameters
* size': [USize](builtin-usize) val
#### Returns
* [None](builtin-none) val
### size
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L75)
```
fun box size()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### u8
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L78)
Write a byte to the buffer.
```
fun ref u8(
data: U8 val)
: None val
```
#### Parameters
* data: [U8](builtin-u8) val
#### Returns
* [None](builtin-none) val
### u16\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L86)
Write a U16 to the buffer in little-endian byte order.
```
fun ref u16_le(
data: U16 val)
: None val
```
#### Parameters
* data: [U16](builtin-u16) val
#### Returns
* [None](builtin-none) val
### u16\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L98)
Write a U16 to the buffer in big-endian byte order.
```
fun ref u16_be(
data: U16 val)
: None val
```
#### Parameters
* data: [U16](builtin-u16) val
#### Returns
* [None](builtin-none) val
### i16\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L110)
Write an I16 to the buffer in little-endian byte order.
```
fun ref i16_le(
data: I16 val)
: None val
```
#### Parameters
* data: [I16](builtin-i16) val
#### Returns
* [None](builtin-none) val
### i16\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L116)
Write an I16 to the buffer in big-endian byte order.
```
fun ref i16_be(
data: I16 val)
: None val
```
#### Parameters
* data: [I16](builtin-i16) val
#### Returns
* [None](builtin-none) val
### u32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L122)
Write a U32 to the buffer in little-endian byte order.
```
fun ref u32_le(
data: U32 val)
: None val
```
#### Parameters
* data: [U32](builtin-u32) val
#### Returns
* [None](builtin-none) val
### u32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L134)
Write a U32 to the buffer in big-endian byte order.
```
fun ref u32_be(
data: U32 val)
: None val
```
#### Parameters
* data: [U32](builtin-u32) val
#### Returns
* [None](builtin-none) val
### i32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L146)
Write an I32 to the buffer in little-endian byte order.
```
fun ref i32_le(
data: I32 val)
: None val
```
#### Parameters
* data: [I32](builtin-i32) val
#### Returns
* [None](builtin-none) val
### i32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L152)
Write an I32 to the buffer in big-endian byte order.
```
fun ref i32_be(
data: I32 val)
: None val
```
#### Parameters
* data: [I32](builtin-i32) val
#### Returns
* [None](builtin-none) val
### f32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L158)
Write an F32 to the buffer in little-endian byte order.
```
fun ref f32_le(
data: F32 val)
: None val
```
#### Parameters
* data: [F32](builtin-f32) val
#### Returns
* [None](builtin-none) val
### f32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L164)
Write an F32 to the buffer in big-endian byte order.
```
fun ref f32_be(
data: F32 val)
: None val
```
#### Parameters
* data: [F32](builtin-f32) val
#### Returns
* [None](builtin-none) val
### u64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L170)
Write a U64 to the buffer in little-endian byte order.
```
fun ref u64_le(
data: U64 val)
: None val
```
#### Parameters
* data: [U64](builtin-u64) val
#### Returns
* [None](builtin-none) val
### u64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L182)
Write a U64 to the buffer in big-endian byte order.
```
fun ref u64_be(
data: U64 val)
: None val
```
#### Parameters
* data: [U64](builtin-u64) val
#### Returns
* [None](builtin-none) val
### i64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L194)
Write an I64 to the buffer in little-endian byte order.
```
fun ref i64_le(
data: I64 val)
: None val
```
#### Parameters
* data: [I64](builtin-i64) val
#### Returns
* [None](builtin-none) val
### i64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L200)
Write an I64 to the buffer in big-endian byte order.
```
fun ref i64_be(
data: I64 val)
: None val
```
#### Parameters
* data: [I64](builtin-i64) val
#### Returns
* [None](builtin-none) val
### f64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L206)
Write an F64 to the buffer in little-endian byte order.
```
fun ref f64_le(
data: F64 val)
: None val
```
#### Parameters
* data: [F64](builtin-f64) val
#### Returns
* [None](builtin-none) val
### f64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L212)
Write an F64 to the buffer in big-endian byte order.
```
fun ref f64_be(
data: F64 val)
: None val
```
#### Parameters
* data: [F64](builtin-f64) val
#### Returns
* [None](builtin-none) val
### u128\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L218)
Write a U128 to the buffer in little-endian byte order.
```
fun ref u128_le(
data: U128 val)
: None val
```
#### Parameters
* data: [U128](builtin-u128) val
#### Returns
* [None](builtin-none) val
### u128\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L230)
Write a U128 to the buffer in big-endian byte order.
```
fun ref u128_be(
data: U128 val)
: None val
```
#### Parameters
* data: [U128](builtin-u128) val
#### Returns
* [None](builtin-none) val
### i128\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L242)
Write an I128 to the buffer in little-endian byte order.
```
fun ref i128_le(
data: I128 val)
: None val
```
#### Parameters
* data: [I128](builtin-i128) val
#### Returns
* [None](builtin-none) val
### i128\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L248)
Write an I128 to the buffer in big-endian byte order.
```
fun ref i128_be(
data: I128 val)
: None val
```
#### Parameters
* data: [I128](builtin-i128) val
#### Returns
* [None](builtin-none) val
### write
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L254)
Write a ByteSeq to the buffer.
```
fun ref write(
data: (String val | Array[U8 val] val))
: None val
```
#### Parameters
* data: ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
#### Returns
* [None](builtin-none) val
### writev
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L277)
Write ByteSeqs to the buffer.
```
fun ref writev(
data: ByteSeqIter val)
: None val
```
#### Parameters
* data: [ByteSeqIter](builtin-byteseqiter) val
#### Returns
* [None](builtin-none) val
### done
[[Source]](https://stdlib.ponylang.io/src/buffered/writer/#L285)
Return an array of buffered ByteSeqs and reset the Writer's buffer.
```
fun ref done()
: Array[(String val | Array[U8 val] val)] iso^
```
#### Returns
* [Array](builtin-array)[([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)] iso^
pony OptionSpec OptionSpec
==========
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L159)
OptionSpec describes the specification of a named Option. They have a name, descr(iption), a short-name, a typ(e), and a default value when they are not required.
Options can be placed anywhere before or after commands, and can be thought of as named arguments.
```
class val OptionSpec
```
Constructors
------------
### bool
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L183)
Creates an Option with a Bool typed value that can be used like `--opt` or `-O` or `--opt=true` or `-O=true` to yield an option value like `cmd.option("opt").bool() == true`.
```
new val bool(
name': String val,
descr': String val = "",
short': (U8 val | None val) = reference,
default': (Bool val | None val) = reference)
: OptionSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* short': ([U8](builtin-u8) val | [None](builtin-none) val) = reference
* default': ([Bool](builtin-bool) val | [None](builtin-none) val) = reference
#### Returns
* [OptionSpec](index) val^
### string
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L200)
Creates an Option with a String typed value that can be used like `--file=dir/filename` or `-F=dir/filename` or `-Fdir/filename` to yield an option value like `cmd.option("file").string() == "dir/filename"`.
```
new val string(
name': String val,
descr': String val = "",
short': (U8 val | None val) = reference,
default': (String val | None val) = reference)
: OptionSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* short': ([U8](builtin-u8) val | [None](builtin-none) val) = reference
* default': ([String](builtin-string) val | [None](builtin-none) val) = reference
#### Returns
* [OptionSpec](index) val^
### i64
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L217)
Creates an Option with an I64 typed value that can be used like `--count=42 -C=42` to yield an option value like `cmd.option("count").i64() == I64(42)`.
```
new val i64(
name': String val,
descr': String val = "",
short': (U8 val | None val) = reference,
default': (I64 val | None val) = reference)
: OptionSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* short': ([U8](builtin-u8) val | [None](builtin-none) val) = reference
* default': ([I64](builtin-i64) val | [None](builtin-none) val) = reference
#### Returns
* [OptionSpec](index) val^
### u64
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L233)
Creates an Option with an U64 typed value that can be used like `--count=47 -C=47` to yield an option value like `cmd.option("count").u64() == U64(47)`.
```
new val u64(
name': String val,
descr': String val = "",
short': (U8 val | None val) = reference,
default': (U64 val | None val) = reference)
: OptionSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* short': ([U8](builtin-u8) val | [None](builtin-none) val) = reference
* default': ([U64](builtin-u64) val | [None](builtin-none) val) = reference
#### Returns
* [OptionSpec](index) val^
### f64
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L249)
Creates an Option with a F64 typed value that can be used like `--ratio=1.039` or `-R=1.039` to yield an option value like `cmd.option("ratio").f64() == F64(1.039)`.
```
new val f64(
name': String val,
descr': String val = "",
short': (U8 val | None val) = reference,
default': (F64 val | None val) = reference)
: OptionSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* short': ([U8](builtin-u8) val | [None](builtin-none) val) = reference
* default': ([F64](builtin-f64) val | [None](builtin-none) val) = reference
#### Returns
* [OptionSpec](index) val^
### string\_seq
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L265)
Creates an Option with a ReadSeq[String] typed value that can be used like `--files=file1 --files=files2 --files=files2` to yield a sequence of three strings equivalent to `cmd.option("ratio").string_seq() (equiv) ["file1"; "file2"; "file3"]`.
```
new val string_seq(
name': String val,
descr': String val = "",
short': (U8 val | None val) = reference)
: OptionSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* short': ([U8](builtin-u8) val | [None](builtin-none) val) = reference
#### Returns
* [OptionSpec](index) val^
Public Functions
----------------
### name
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L281)
Returns the name of this option.
```
fun box name()
: String val
```
#### Returns
* [String](builtin-string) val
### descr
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L287)
Returns the description for this option.
```
fun box descr()
: String val
```
#### Returns
* [String](builtin-string) val
### required
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L297)
Returns true iff this option is required to be present in the command line.
```
fun box required()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### help\_string
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L326)
Returns a formated help string for this option.
```
fun box help_string()
: String val
```
#### Returns
* [String](builtin-string) val
### deb\_string
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L339)
```
fun box deb_string()
: String val
```
#### Returns
* [String](builtin-string) val
pony CommandSpec CommandSpec
===========
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L9)
CommandSpec describes the specification of a parent or leaf command. Each command has the following attributes:
* a name: a simple string token that identifies the command.
* a description: used in the syntax message.
* a map of options: the valid options for this command.
* an optional help option+command name for help parsing
* one of:
* a Map of child commands.
* an Array of arguments.
```
class ref CommandSpec
```
Constructors
------------
### parent
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L33)
Creates a command spec that can accept options and child commands, but not arguments.
```
new ref parent(
name': String val,
descr': String val = "",
options': Array[OptionSpec val] box = call,
commands': Array[CommandSpec ref] box = call)
: CommandSpec ref^ ?
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* options': [Array](builtin-array)[[OptionSpec](cli-optionspec) val] box = call
* commands': [Array](builtin-array)[[CommandSpec](index) ref] box = call
#### Returns
* [CommandSpec](index) ref^ ?
### leaf
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L53)
Creates a command spec that can accept options and arguments, but not child commands.
```
new ref leaf(
name': String val,
descr': String val = "",
options': Array[OptionSpec val] box = call,
args': Array[ArgSpec val] box = call)
: CommandSpec ref^ ?
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* options': [Array](builtin-array)[[OptionSpec](cli-optionspec) val] box = call
* args': [Array](builtin-array)[[ArgSpec](cli-argspec) val] box = call
#### Returns
* [CommandSpec](index) ref^ ?
Public Functions
----------------
### add\_command
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L84)
Adds an additional child command to this parent command.
```
fun ref add_command(
cmd: CommandSpec box)
: None val ?
```
#### Parameters
* cmd: [CommandSpec](index) box
#### Returns
* [None](builtin-none) val ?
### add\_help
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L91)
Adds a standard help option and, optionally command, to a root command.
```
fun ref add_help(
hname: String val = "help",
descr': String val = "")
: None val ?
```
#### Parameters
* hname: [String](builtin-string) val = "help"
* descr': [String](builtin-string) val = ""
#### Returns
* [None](builtin-none) val ?
### name
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L106)
Returns the name of this command.
```
fun box name()
: String val
```
#### Returns
* [String](builtin-string) val
### descr
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L112)
Returns the description for this command.
```
fun box descr()
: String val
```
#### Returns
* [String](builtin-string) val
### options
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L118)
Returns a map by name of the named options of this command.
```
fun box options()
: HashMap[String val, OptionSpec val, HashEq[String val] val] box
```
#### Returns
* [HashMap](collections-hashmap)[[String](builtin-string) val, [OptionSpec](cli-optionspec) val, [HashEq](collections-hasheq)[[String](builtin-string) val] val] box
### commands
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L124)
Returns a map by name of the child commands of this command.
```
fun box commands()
: HashMap[String val, CommandSpec box, HashEq[String val] val] box
```
#### Returns
* [HashMap](collections-hashmap)[[String](builtin-string) val, [CommandSpec](index) box, [HashEq](collections-hasheq)[[String](builtin-string) val] val] box
### args
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L130)
Returns an array of the positional arguments of this command.
```
fun box args()
: Array[ArgSpec val] box
```
#### Returns
* [Array](builtin-array)[[ArgSpec](cli-argspec) val] box
### is\_leaf
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L136)
```
fun box is_leaf()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### is\_parent
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L138)
```
fun box is_parent()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### help\_name
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L140)
Returns the name of the help command, which defaults to "help".
```
fun box help_name()
: String val
```
#### Returns
* [String](builtin-string) val
### help\_string
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L146)
Returns a formated help string for this command and all of its arguments.
```
fun box help_string()
: String val
```
#### Returns
* [String](builtin-string) val
| programming_docs |
pony Backpressure Package Backpressure Package
====================
The Backpressure package allows Pony programmers to participate in Pony's runtime backpressure system. The goal of the backpressure system is to prevent an actor's mailbox from growing at an unbounded rate.
At a high level, the runtime backpressure system works by adjusting the scheduling of actors. When an actor becomes overloaded, the Pony runtime will deprioritize scheduling the actors that are sending to it. This change in scheduling allows the overloaded actor to catch up.
The Pony runtime can detect overloading based on message queue size. However, the overloading of some types of actors is harder to detect. Let's take the case of actors like `TCPConnection`.
`TCPConnection` manages a socket for sending data to and receiving data from another process. TCP connections can experience backpressure from outside our Pony program that prevents them from sending. There's no way for the Pony runtime to detect this, so intervention by the programmer is needed.
`TCPConnection` is a single example. This Backpressure package exists to allow a programmer to indicate to the runtime that a given actor is experiencing pressure and sending messages to it should be adjusted accordingly.
Any actor that needs to be able to tell the runtime to "send me messages slower" due to external conditions can do so via this package. Additionally, actors that maintain their own internal queues of any sort, say for buffering, are also prime candidates for using this package. If an actor's internal queue grows too large, it can call `Backpressure.apply` to let the runtime know it is under pressure.
Example program
---------------
```
// Here we have a TCPConnectionNotify that upon construction
// is given a BackpressureAuth token. This allows the notifier
// to inform the Pony runtime when to apply and release backpressure
// as the connection experiences it.
// Note the calls to
//
// Backpressure.apply(_auth)
// Backpressure.release(_auth)
//
// that apply and release backpressure as needed
use "backpressure"
use "collections"
use "net"
class SlowDown is TCPConnectionNotify
let _auth: BackpressureAuth
let _out: StdStream
new iso create(auth: BackpressureAuth, out: StdStream) =>
_auth = auth
_out = out
fun ref throttled(connection: TCPConnection ref) =>
_out.print("Experiencing backpressure!")
Backpressure.apply(_auth)
fun ref unthrottled(connection: TCPConnection ref) =>
_out.print("Releasing backpressure!")
Backpressure.release(_auth)
fun ref connect_failed(conn: TCPConnection ref) =>
None
actor Main
new create(env: Env) =>
try
let auth = env.root as AmbientAuth
let socket = TCPConnection(auth, recover SlowDown(auth, env.out) end,
"", "7669")
end
```
Caveat
------
The runtime backpressure is a powerful system. By intervening, programmers can create deadlocks. Any call to `Backpressure.apply` should be matched by a corresponding call to `Backpressure.release`. Authorization via the `ApplyReleaseBackpressureAuth` capability is required to apply or release backpressure. By requiring that the caller have a token to apply or release a backpressure, rouge 3rd party library code can't run wild and unknowingly interfere with the runtime.
Public Types
------------
* [type BackpressureAuth](backpressure-backpressureauth)
* [primitive Backpressure](backpressure-backpressure)
* [primitive ApplyReleaseBackpressureAuth](backpressure-applyreleasebackpressureauth)
pony Timer Timer
=====
[[Source]](https://stdlib.ponylang.io/src/time/timer/#L3)
The `Timer` class represents a timer that fires after an expiration time, and then fires at an interval. When a `Timer` fires, it calls the `apply` method of the `TimerNotify` object that was passed to it when it was created.
The following example waits 5 seconds and then fires every 2 seconds, and when it fires the `TimerNotify` object prints how many times it has been called:
```
use "time"
actor Main
new create(env: Env) =>
let timers = Timers
let timer = Timer(Notify(env), 5_000_000_000, 2_000_000_000)
timers(consume timer)
class Notify is TimerNotify
let _env: Env
var _counter: U32 = 0
new iso create(env: Env) =>
_env = env
fun ref apply(timer: Timer, count: U64): Bool =>
_env.out.print(_counter.string())
_counter = _counter + 1
true
```
```
class ref Timer
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/time/timer/#L39)
Create a new timer. The expiration time should be a nanosecond count until the first expiration. The interval should also be in nanoseconds.
```
new iso create(
notify: TimerNotify iso,
expiration: U64 val,
interval: U64 val = 0)
: Timer iso^
```
#### Parameters
* notify: [TimerNotify](time-timernotify) iso
* expiration: [U64](builtin-u64) val
* interval: [U64](builtin-u64) val = 0
#### Returns
* [Timer](index) iso^
### abs
[[Source]](https://stdlib.ponylang.io/src/time/timer/#L54)
Creates a new timer with an absolute expiration time rather than a relative time. The expiration time is wall-clock adjusted system time.
```
new ref abs(
notify: TimerNotify ref,
expiration: (I64 val , I64 val),
interval: U64 val = 0)
: Timer ref^
```
#### Parameters
* notify: [TimerNotify](time-timernotify) ref
* expiration: ([I64](builtin-i64) val , [I64](builtin-i64) val)
* interval: [U64](builtin-u64) val = 0
#### Returns
* [Timer](index) ref^
pony Base64 Base64
======
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L26)
```
primitive val Base64
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L26)
```
new val create()
: Base64 val^
```
#### Returns
* [Base64](index) val^
Public Functions
----------------
### encode\_pem
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L27)
Encode for PEM (RFC 1421).
```
fun box encode_pem(
data: ReadSeq[U8 val] box)
: String iso^
```
#### Parameters
* data: [ReadSeq](builtin-readseq)[[U8](builtin-u8) val] box
#### Returns
* [String](builtin-string) iso^
### encode\_mime
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L33)
Encode for MIME (RFC 2045).
```
fun box encode_mime(
data: ReadSeq[U8 val] box)
: String iso^
```
#### Parameters
* data: [ReadSeq](builtin-readseq)[[U8](builtin-u8) val] box
#### Returns
* [String](builtin-string) iso^
### encode\_url[optional A: [Seq](builtin-seq)[[U8](builtin-u8) val] iso]
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L39)
Encode for URLs (RFC 4648). Padding characters are stripped by default.
```
fun box encode_url[optional A: Seq[U8 val] iso](
data: ReadSeq[U8 val] box,
pad: Bool val = false)
: A^
```
#### Parameters
* data: [ReadSeq](builtin-readseq)[[U8](builtin-u8) val] box
* pad: [Bool](builtin-bool) val = false
#### Returns
* A^
### encode[optional A: [Seq](builtin-seq)[[U8](builtin-u8) val] iso]
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L50)
Configurable encoding. The defaults are for RFC 4648.
```
fun box encode[optional A: Seq[U8 val] iso](
data: ReadSeq[U8 val] box,
at62: U8 val = 43,
at63: U8 val = 47,
pad: U8 val = 61,
linelen: USize val = 0,
linesep: String val = "
")
: A^
```
#### Parameters
* data: [ReadSeq](builtin-readseq)[[U8](builtin-u8) val] box
* at62: [U8](builtin-u8) val = 43
* at63: [U8](builtin-u8) val = 47
* pad: [U8](builtin-u8) val = 61
* linelen: [USize](builtin-usize) val = 0
* linesep: [String](builtin-string) val = " "
#### Returns
* A^
### decode\_url[optional A: [Seq](builtin-seq)[[U8](builtin-u8) val] iso]
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L125)
Decode for URLs (RFC 4648).
```
fun box decode_url[optional A: Seq[U8 val] iso](
data: ReadSeq[U8 val] box)
: A^ ?
```
#### Parameters
* data: [ReadSeq](builtin-readseq)[[U8](builtin-u8) val] box
#### Returns
* A^ ?
### decode[optional A: [Seq](builtin-seq)[[U8](builtin-u8) val] iso]
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L131)
Configurable decoding. The defaults are for RFC 4648. Missing padding is not an error. Non-base64 data, other than whitespace (which can appear at any time), is an error.
```
fun box decode[optional A: Seq[U8 val] iso](
data: ReadSeq[U8 val] box,
at62: U8 val = 43,
at63: U8 val = 47,
pad: U8 val = 61)
: A^ ?
```
#### Parameters
* data: [ReadSeq](builtin-readseq)[[U8](builtin-u8) val] box
* at62: [U8](builtin-u8) val = 43
* at63: [U8](builtin-u8) val = 47
* pad: [U8](builtin-u8) val = 61
#### Returns
* A^ ?
### eq
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L27)
```
fun box eq(
that: Base64 val)
: Bool val
```
#### Parameters
* that: [Base64](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/encode-base64/base64/#L27)
```
fun box ne(
that: Base64 val)
: Bool val
```
#### Parameters
* that: [Base64](index) val
#### Returns
* [Bool](builtin-bool) val
pony MapKeys[K: K, V: V, H: HashFunction[K] val, M: HashMap[K, V, H] #read] MapKeys[K: K, V: V, H: [HashFunction](collections-hashfunction)[K] val, M: [HashMap](collections-hashmap)[K, V, H] #read]
=========================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L388)
An iterator over the keys in a map.
```
class ref MapKeys[K: K, V: V, H: HashFunction[K] val, M: HashMap[K, V, H] #read] is
Iterator[M->K] ref
```
#### Implements
* [Iterator](builtin-iterator)[M->K] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L397)
Creates an iterator for the given map.
```
new ref create(
map: M)
: MapKeys[K, V, H, M] ref^
```
#### Parameters
* map: M
#### Returns
* [MapKeys](index)[K, V, H, M] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L403)
True if it believes there are remaining entries. May not be right if values were added or removed from the map.
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L410)
Returns the next key, or raises an error if there isn't one. If keys are added during iteration, this may not return all keys.
```
fun ref next()
: M->K ?
```
#### Returns
* M->K ?
pony HashMap[K: K, V: V, H: HashFunction[K] val] HashMap[K: K, V: V, H: [HashFunction](collections-hashfunction)[K] val]
=======================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L15)
A quadratic probing hash map. Resize occurs at a load factor of 0.75. A resized map has 2 times the space. The hash function can be plugged in to the type to create different kinds of maps.
```
class ref HashMap[K: K, V: V, H: HashFunction[K] val]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L24)
Create an array with space for prealloc elements without triggering a resize. Defaults to 6.
```
new ref create(
prealloc: USize val = 6)
: HashMap[K, V, H] ref^
```
#### Parameters
* prealloc: [USize](builtin-usize) val = 6
#### Returns
* [HashMap](index)[K, V, H] ref^
Public Functions
----------------
### size
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L33)
The number of items in the map.
```
fun box size()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### space
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L39)
The available space in the map. Resize will happen when size / space >= 0.75.
```
fun box space()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### apply
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L46)
Gets a value from the map. Raises an error if no such item exists.
```
fun box apply(
key: box->K!)
: this->V ?
```
#### Parameters
* key: box->K!
#### Returns
* this->V ?
### update
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L58)
Sets a value in the map. Returns the old value if there was one, otherwise returns None. If there was no previous value, this may trigger a resize.
```
fun ref update(
key: K,
value: V)
: (V^ | None val)
```
#### Parameters
* key: K
* value: V
#### Returns
* (V^ | [None](builtin-none) val)
### upsert
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L78)
Combines a provided value with the current value for the provided key using the provided function. If the provided key has not been added to the map yet, it sets its value to the provided value and ignores the provided function.
As a simple example, say we had a map with I64 values and we wanted to add 4 to the current value for key "test", which let's say is currently 2. We call
m.upsert("test", 4, {(current, provided) => current + provided })
This changes the value associated with "test" to 6.
If we have not yet added the key "new-key" to the map and we call
m.upsert("new-key", 4, {(current, provided) => current + provided })
then "new-key" is added to the map with a value of 4.
Returns the value that we set the key to
```
fun ref upsert(
key: K,
value: V,
f: {(V, V): V^}[K, V, H] box)
: V
```
#### Parameters
* key: K
* value: V
* f: {(V, V): V^}[K, V, H] box
#### Returns
* V
### insert
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L132)
Set a value in the map. Returns the new value, allowing reuse.
```
fun ref insert(
key: K,
value: V)
: V!
```
#### Parameters
* key: K
* value: V
#### Returns
* V!
### insert\_if\_absent
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L156)
Set a value in the map if the key doesn't already exist in the Map. Saves an extra lookup when doing a pattern like:
```
if not my_map.contains(my_key) then
my_map(my_key) = my_value
end
```
Returns the value, the same as `insert`, allowing 'insert\_if\_absent' to be used as a drop-in replacement for `insert`.
```
fun ref insert_if_absent(
key: K,
value: V)
: V
```
#### Parameters
* key: K
* value: V
#### Returns
* V
### remove
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L192)
Delete a value from the map and return it. Raises an error if there was no value for the given key.
```
fun ref remove(
key: box->K!)
: (K^ , V^) ?
```
#### Parameters
* key: box->K!
#### Returns
* (K^ , V^) ?
### get\_or\_else
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L211)
Get the value associated with provided key if present. Otherwise, return the provided alternate value.
```
fun box get_or_else(
key: box->K!,
alt: this->V)
: this->V
```
#### Parameters
* key: box->K!
* alt: this->V
#### Returns
* this->V
### contains
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L230)
Checks whether the map contains the key k
```
fun box contains(
k: box->K!)
: Bool val
```
#### Parameters
* k: box->K!
#### Returns
* [Bool](builtin-bool) val
### concat
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L237)
Add K, V pairs from the iterator to the map.
```
fun ref concat(
iter: Iterator[(K^ , V^)] ref)
: None val
```
#### Parameters
* iter: [Iterator](builtin-iterator)[(K^ , V^)] ref
#### Returns
* [None](builtin-none) val
### add[optional H2: [HashFunction](collections-hashfunction)[this->K!] val]
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L245)
This with the new (key, value) mapping.
```
fun box add[optional H2: HashFunction[this->K!] val](
key: this->K!,
value: this->V!)
: HashMap[this->K!, this->V!, H2] ref^
```
#### Parameters
* key: this->K!
* value: this->V!
#### Returns
* [HashMap](index)[this->K!, this->V!, H2] ref^
### sub[optional H2: [HashFunction](collections-hashfunction)[this->K!] val]
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L257)
This without the given key.
```
fun box sub[optional H2: HashFunction[this->K!] val](
key: this->K!)
: HashMap[this->K!, this->V!, H2] ref^
```
#### Parameters
* key: this->K!
#### Returns
* [HashMap](index)[this->K!, this->V!, H2] ref^
### next\_index
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L267)
Given an index, return the next index that has a populated key and value. Raise an error if there is no next populated index.
```
fun box next_index(
prev: USize val = call)
: USize val ?
```
#### Parameters
* prev: [USize](builtin-usize) val = call
#### Returns
* [USize](builtin-usize) val ?
### index
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L279)
Returns the key and value at a given index. Raise an error if the index is not populated.
```
fun box index(
i: USize val)
: (this->K , this->V) ?
```
#### Parameters
* i: [USize](builtin-usize) val
#### Returns
* (this->K , this->V) ?
### compact
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L286)
Minimise the memory used for the map.
```
fun ref compact()
: None val
```
#### Returns
* [None](builtin-none) val
### clone[optional H2: [HashFunction](collections-hashfunction)[this->K!] val]
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L292)
Create a clone. The key and value types may be different due to aliasing and viewpoint adaptation.
```
fun box clone[optional H2: HashFunction[this->K!] val]()
: HashMap[this->K!, this->V!, H2] ref^
```
#### Returns
* [HashMap](index)[this->K!, this->V!, H2] ref^
### clear
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L306)
Remove all entries.
```
fun ref clear()
: None val
```
#### Returns
* [None](builtin-none) val
### keys
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L370)
Return an iterator over the keys.
```
fun box keys()
: MapKeys[K, V, H, this->HashMap[K, V, H] ref] ref^
```
#### Returns
* [MapKeys](collections-mapkeys)[K, V, H, this->[HashMap](index)[K, V, H] ref] ref^
### values
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L376)
Return an iterator over the values.
```
fun box values()
: MapValues[K, V, H, this->HashMap[K, V, H] ref] ref^
```
#### Returns
* [MapValues](collections-mapvalues)[K, V, H, this->[HashMap](index)[K, V, H] ref] ref^
### pairs
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L382)
Return an iterator over the keys and values.
```
fun box pairs()
: MapPairs[K, V, H, this->HashMap[K, V, H] ref] ref^
```
#### Returns
* [MapPairs](collections-mappairs)[K, V, H, this->[HashMap](index)[K, V, H] ref] ref^
pony ParsedOption ParsedOption
============
[[Source]](https://stdlib.ponylang.io/src/options/options/#L96)
```
type ParsedOption is
(String val , (None val | String val | I64 val | U64 val | F64 val))
```
#### Type Alias For
* ([String](builtin-string) val , ([None](builtin-none) val | [String](builtin-string) val | [I64](builtin-i64) val | [U64](builtin-u64) val | [F64](builtin-f64) val))
pony FileInfo FileInfo
========
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L1)
This contains file system metadata for a path.
A symlink will report information about itself, other than the size which will be the size of the target. A broken symlink will report as much as it can and will set the broken flag.
```
class val FileInfo
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L86)
This will raise an error if the FileStat capability isn't available or the path doesn't exist.
```
new val create(
from: FilePath val)
: FileInfo val^ ?
```
#### Parameters
* from: [FilePath](files-filepath) val
#### Returns
* [FileInfo](index) val^ ?
Public fields
-------------
### let filepath: [FilePath](files-filepath) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L9)
### let mode: [FileMode](files-filemode) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L11)
UNIX-style file mode.
### let hard\_links: [U32](builtin-u32) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L14)
Number of hardlinks to this `filepath`.
### let device: [U64](builtin-u64) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L17)
OS id of the device containing this `filepath`. Device IDs consist of a major and minor device id, denoting the type of device and the instance of this type on the system.
### let inode: [U64](builtin-u64) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L24)
UNIX specific INODE number of `filepath`. Is 0 on Windows.
### let uid: [U32](builtin-u32) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L27)
UNIX-style user ID of the owner of `filepath`.
### let gid: [U32](builtin-u32) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L30)
UNIX-style user ID of the owning group of `filepath`.
### let size: [USize](builtin-usize) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L33)
Total size of `filepath` in bytes.
In case of a symlink this is the size of the target, not the symlink itself.
### let access\_time: ([I64](builtin-i64) val , [I64](builtin-i64) val)
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L40)
Time of last access as a tuple of seconds and nanoseconds since the epoch:
```
(let a_secs: I64, let a_nanos: I64) = file_info.access_time
```
### let modified\_time: ([I64](builtin-i64) val , [I64](builtin-i64) val)
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L49)
Time of last modification as tuple of seconds and nanoseconds since the epoch:
```
(let m_secs: I64, let m_nanos: I64) = file_info.modified_time
```
### let change\_time: ([I64](builtin-i64) val , [I64](builtin-i64) val)
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L58)
Time of the last change either the attributes (number of links, owner, group, file mode, ...) or the content of `filepath` as a tuple of seconds and nanoseconds since the epoch:
```
(let c_secs: I64, let c_nanos: I64) = file_info.change_time
```
On Windows this will be the file creation time.
### let file: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L71)
`true` if `filepath` points to an a regular file.
### let directory: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L74)
`true` if `filepath` points to a directory.
### let pipe: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L77)
`true` if `filepath` points to a named pipe.
### let symlink: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L80)
`true` if `filepath` points to a symbolic link.
### let broken: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_info/#L83)
`true` if `filepath` points to a broken symlink.
| programming_docs |
pony Reader Reader
======
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L3)
Store network data and provide a parsing interface.
`Reader` provides a way to extract typed data from a sequence of bytes. The `Reader` manages the underlying data structures to provide a read cursor over a contiguous sequence of bytes. It is useful for decoding data that is received over a network or stored in a file. Chunk of bytes are added to the `Reader` using the `append` method, and typed data is extracted using the getter methods.
For example, suppose we have a UDP-based network data protocol where messages consist of the following:
* `list_size` - the number of items in the following list of items as a big-endian 32-bit integer
* zero or more items of the following data:
* a big-endian 64-bit floating point number
* a string that starts with a big-endian 32-bit integer that specifies the length of the string, followed by a number of bytes that represent the string
A message would be something like this:
```
[message_length][list_size][float1][string1][float2][string2]...
```
The following program uses a `Reader` to decode a message of this type and print them:
```
use "buffered"
use "collections"
class Notify is InputNotify
let _env: Env
new create(env: Env) =>
_env = env
fun ref apply(data: Array[U8] iso) =>
let rb = Reader
rb.append(consume data)
try
while true do
let len = rb.i32_be()?
let items = rb.i32_be()?.usize()
for range in Range(0, items) do
let f = rb.f32_be()?
let str_len = rb.i32_be()?.usize()
let str = String.from_array(rb.block(str_len)?)
_env.out.print("[(" + f.string() + "), (" + str + ")]")
end
end
end
actor Main
new create(env: Env) =>
env.input(recover Notify(env) end, 1024)
```
```
class ref Reader
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L3)
```
new iso create()
: Reader iso^
```
#### Returns
* [Reader](index) iso^
Public Functions
----------------
### size
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L67)
Return the number of available bytes.
```
fun box size()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### clear
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L73)
Discard all pending data.
```
fun ref clear()
: None val
```
#### Returns
* [None](builtin-none) val
### append
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L80)
Add a chunk of data.
```
fun ref append(
data: (String val | Array[U8 val] val))
: None val
```
#### Parameters
* data: ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
#### Returns
* [None](builtin-none) val
### skip
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L93)
Skip n bytes.
```
fun ref skip(
n: USize val)
: None val ?
```
#### Parameters
* n: [USize](builtin-usize) val
#### Returns
* [None](builtin-none) val ?
### block
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L119)
Return a block as a contiguous chunk of memory. Will throw an error if you request a block larger than what is currently stored in the `Reader`.
```
fun ref block(
len: USize val)
: Array[U8 val] iso^ ?
```
#### Parameters
* len: [USize](builtin-usize) val
#### Returns
* [Array](builtin-array)[[U8](builtin-u8) val] iso^ ?
### read\_until
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L159)
Find the first occurrence of the separator and return the block of bytes before its position. The separator is not included in the returned array, but it is removed from the buffer. To read a line of text, prefer line() that handles \n and \r\n.
```
fun ref read_until(
separator: U8 val)
: Array[U8 val] iso^ ?
```
#### Parameters
* separator: [U8](builtin-u8) val
#### Returns
* [Array](builtin-array)[[U8](builtin-u8) val] iso^ ?
### line
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L170)
Return a \n or \r\n terminated line as a string. By default the newline is not included in the returned string, but it is removed from the buffer. Set `keep_line_breaks` to `true` to keep the line breaks in the returned line.
```
fun ref line(
keep_line_breaks: Bool val = false)
: String iso^ ?
```
#### Parameters
* keep\_line\_breaks: [Bool](builtin-bool) val = false
#### Returns
* [String](builtin-string) iso^ ?
### u8
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L213)
Get a U8. Raise an error if there isn't enough data.
```
fun ref u8()
: U8 val ?
```
#### Returns
* [U8](builtin-u8) val ?
### i8
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L223)
Get an I8.
```
fun ref i8()
: I8 val ?
```
#### Returns
* [I8](builtin-i8) val ?
### u16\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L229)
Get a big-endian U16.
```
fun ref u16_be()
: U16 val ?
```
#### Returns
* [U16](builtin-u16) val ?
### u16\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L262)
Get a little-endian U16.
```
fun ref u16_le()
: U16 val ?
```
#### Returns
* [U16](builtin-u16) val ?
### i16\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L295)
Get a big-endian I16.
```
fun ref i16_be()
: I16 val ?
```
#### Returns
* [I16](builtin-i16) val ?
### i16\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L301)
Get a little-endian I16.
```
fun ref i16_le()
: I16 val ?
```
#### Returns
* [I16](builtin-i16) val ?
### u32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L307)
Get a big-endian U32.
```
fun ref u32_be()
: U32 val ?
```
#### Returns
* [U32](builtin-u32) val ?
### u32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L341)
Get a little-endian U32.
```
fun ref u32_le()
: U32 val ?
```
#### Returns
* [U32](builtin-u32) val ?
### i32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L375)
Get a big-endian I32.
```
fun ref i32_be()
: I32 val ?
```
#### Returns
* [I32](builtin-i32) val ?
### i32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L381)
Get a little-endian I32.
```
fun ref i32_le()
: I32 val ?
```
#### Returns
* [I32](builtin-i32) val ?
### u64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L387)
Get a big-endian U64.
```
fun ref u64_be()
: U64 val ?
```
#### Returns
* [U64](builtin-u64) val ?
### u64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L423)
Get a little-endian U64.
```
fun ref u64_le()
: U64 val ?
```
#### Returns
* [U64](builtin-u64) val ?
### i64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L459)
Get a big-endian I64.
```
fun ref i64_be()
: I64 val ?
```
#### Returns
* [I64](builtin-i64) val ?
### i64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L465)
Get a little-endian I64.
```
fun ref i64_le()
: I64 val ?
```
#### Returns
* [I64](builtin-i64) val ?
### u128\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L471)
Get a big-endian U128.
```
fun ref u128_be()
: U128 val ?
```
#### Returns
* [U128](builtin-u128) val ?
### u128\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L511)
Get a little-endian U128.
```
fun ref u128_le()
: U128 val ?
```
#### Returns
* [U128](builtin-u128) val ?
### i128\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L551)
Get a big-endian I129.
```
fun ref i128_be()
: I128 val ?
```
#### Returns
* [I128](builtin-i128) val ?
### i128\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L557)
Get a little-endian I128.
```
fun ref i128_le()
: I128 val ?
```
#### Returns
* [I128](builtin-i128) val ?
### f32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L563)
Get a big-endian F32.
```
fun ref f32_be()
: F32 val ?
```
#### Returns
* [F32](builtin-f32) val ?
### f32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L569)
Get a little-endian F32.
```
fun ref f32_le()
: F32 val ?
```
#### Returns
* [F32](builtin-f32) val ?
### f64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L575)
Get a big-endian F64.
```
fun ref f64_be()
: F64 val ?
```
#### Returns
* [F64](builtin-f64) val ?
### f64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L581)
Get a little-endian F64.
```
fun ref f64_le()
: F64 val ?
```
#### Returns
* [F64](builtin-f64) val ?
### peek\_u8
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L605)
Peek at a U8 at the given offset. Raise an error if there isn't enough data.
```
fun box peek_u8(
offset: USize val = 0)
: U8 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U8](builtin-u8) val ?
### peek\_i8
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L612)
Peek at an I8.
```
fun box peek_i8(
offset: USize val = 0)
: I8 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I8](builtin-i8) val ?
### peek\_u16\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L618)
Peek at a big-endian U16.
```
fun box peek_u16_be(
offset: USize val = 0)
: U16 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U16](builtin-u16) val ?
### peek\_u16\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L624)
Peek at a little-endian U16.
```
fun box peek_u16_le(
offset: USize val = 0)
: U16 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U16](builtin-u16) val ?
### peek\_i16\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L630)
Peek at a big-endian I16.
```
fun box peek_i16_be(
offset: USize val = 0)
: I16 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I16](builtin-i16) val ?
### peek\_i16\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L636)
Peek at a little-endian I16.
```
fun box peek_i16_le(
offset: USize val = 0)
: I16 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I16](builtin-i16) val ?
### peek\_u32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L642)
Peek at a big-endian U32.
```
fun box peek_u32_be(
offset: USize val = 0)
: U32 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U32](builtin-u32) val ?
### peek\_u32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L648)
Peek at a little-endian U32.
```
fun box peek_u32_le(
offset: USize val = 0)
: U32 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U32](builtin-u32) val ?
### peek\_i32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L654)
Peek at a big-endian I32.
```
fun box peek_i32_be(
offset: USize val = 0)
: I32 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I32](builtin-i32) val ?
### peek\_i32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L660)
Peek at a little-endian I32.
```
fun box peek_i32_le(
offset: USize val = 0)
: I32 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I32](builtin-i32) val ?
### peek\_u64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L666)
Peek at a big-endian U64.
```
fun box peek_u64_be(
offset: USize val = 0)
: U64 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U64](builtin-u64) val ?
### peek\_u64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L672)
Peek at a little-endian U64.
```
fun box peek_u64_le(
offset: USize val = 0)
: U64 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U64](builtin-u64) val ?
### peek\_i64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L678)
Peek at a big-endian I64.
```
fun box peek_i64_be(
offset: USize val = 0)
: I64 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I64](builtin-i64) val ?
### peek\_i64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L684)
Peek at a little-endian I64.
```
fun box peek_i64_le(
offset: USize val = 0)
: I64 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I64](builtin-i64) val ?
### peek\_u128\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L690)
Peek at a big-endian U128.
```
fun box peek_u128_be(
offset: USize val = 0)
: U128 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U128](builtin-u128) val ?
### peek\_u128\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L696)
Peek at a little-endian U128.
```
fun box peek_u128_le(
offset: USize val = 0)
: U128 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [U128](builtin-u128) val ?
### peek\_i128\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L702)
Peek at a big-endian I129.
```
fun box peek_i128_be(
offset: USize val = 0)
: I128 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I128](builtin-i128) val ?
### peek\_i128\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L708)
Peek at a little-endian I128.
```
fun box peek_i128_le(
offset: USize val = 0)
: I128 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [I128](builtin-i128) val ?
### peek\_f32\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L714)
Peek at a big-endian F32.
```
fun box peek_f32_be(
offset: USize val = 0)
: F32 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [F32](builtin-f32) val ?
### peek\_f32\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L720)
Peek at a little-endian F32.
```
fun box peek_f32_le(
offset: USize val = 0)
: F32 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [F32](builtin-f32) val ?
### peek\_f64\_be
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L726)
Peek at a big-endian F64.
```
fun box peek_f64_be(
offset: USize val = 0)
: F64 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [F64](builtin-f64) val ?
### peek\_f64\_le
[[Source]](https://stdlib.ponylang.io/src/buffered/reader/#L732)
Peek at a little-endian F64.
```
fun box peek_f64_le(
offset: USize val = 0)
: F64 val ?
```
#### Parameters
* offset: [USize](builtin-usize) val = 0
#### Returns
* [F64](builtin-f64) val ?
pony Real[A: Real[A] val] Real[A: [Real](index)[A] val]
=============================
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L133)
```
trait val Real[A: Real[A] val] is
Stringable box,
_ArithmeticConvertible val,
Comparable[A] ref
```
#### Implements
* [Stringable](builtin-stringable) box
* \_ArithmeticConvertible val
* [Comparable](builtin-comparable)[A] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L135)
```
new val create(
value: A)
: Real[A] val^
```
#### Parameters
* value: A
#### Returns
* [Real](index)[A] val^
### from[B: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](index)[B] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L137)
```
new val from[B: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[B] val)](
a: B)
: Real[A] val^
```
#### Parameters
* a: B
#### Returns
* [Real](index)[A] val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L138)
```
new val min_value()
: Real[A] val^
```
#### Returns
* [Real](index)[A] val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L139)
```
new val max_value()
: Real[A] val^
```
#### Returns
* [Real](index)[A] val^
Public Functions
----------------
### add
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L141)
```
fun box add(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### sub
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L142)
```
fun box sub(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mul
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L143)
```
fun box mul(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### div
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L144)
Integer division, rounded towards zero.
```
fun box div(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### divrem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L150)
```
fun box divrem(
y: A)
: (A , A)
```
#### Parameters
* y: A
#### Returns
* (A , A)
### rem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L151)
Calculate the remainder after integer division, rounded towards zero (`div`).
The result has the sign of the dividend.
```
fun box rem(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### neg
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L159)
```
fun box neg()
: A
```
#### Returns
* A
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L161)
Floored integer division, rounded towards negative infinity.
```
fun box fld(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L165)
Calculate the modulo after floored integer division, rounded towards negative infinity (`fld`).
The result has the sign of the divisor.
```
fun box mod(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L172)
```
fun box eq(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L173)
```
fun box ne(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### lt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L174)
```
fun box lt(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### le
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L175)
```
fun box le(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ge
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L176)
```
fun box ge(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### gt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L177)
```
fun box gt(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L179)
```
fun box min(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L180)
```
fun box max(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L182)
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L198)
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/stringable/#L5)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### i8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L2)
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L3)
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L4)
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L5)
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L6)
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L7)
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L8)
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L10)
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L11)
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L12)
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L13)
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L14)
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L15)
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L16)
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L18)
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L19)
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L21)
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L28)
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L35)
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L42)
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L49)
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L56)
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L63)
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L70)
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L77)
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L84)
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L91)
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L98)
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L105)
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L112)
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L119)
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L126)
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: box->A)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: box->A
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony ISize ISize
=====
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L519)
```
primitive val ISize is
SignedInteger[ISize val, USize val] val
```
#### Implements
* [SignedInteger](builtin-signedinteger)[[ISize](index) val, [USize](builtin-usize) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L520)
```
new val create(
value: ISize val)
: ISize val^
```
#### Parameters
* value: [ISize](index) val
#### Returns
* [ISize](index) val^
### from[A: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](index) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[A] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L521)
```
new val from[A: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[A] val)](
a: A)
: ISize val^
```
#### Parameters
* a: A
#### Returns
* [ISize](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L523)
```
new val min_value()
: ISize val^
```
#### Returns
* [ISize](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L530)
```
new val max_value()
: ISize val^
```
#### Returns
* [ISize](index) val^
Public Functions
----------------
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L537)
```
fun box abs()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L539)
```
fun box bit_reverse()
: ISize val
```
#### Returns
* [ISize](index) val
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L546)
```
fun box bswap()
: ISize val
```
#### Returns
* [ISize](index) val
### popcount
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L553)
```
fun box popcount()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### clz
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L560)
```
fun box clz()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### ctz
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L567)
```
fun box ctz()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### clz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L574)
```
fun box clz_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### ctz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L581)
```
fun box ctz_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### bitwidth
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L588)
```
fun box bitwidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### bytewidth
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L590)
```
fun box bytewidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L592)
```
fun box min(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L593)
```
fun box max(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L595)
```
fun box fld(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L598)
```
fun box fld_unsafe(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L601)
```
fun box mod(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L604)
```
fun box mod_unsafe(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L607)
```
fun box addc(
y: ISize val)
: (ISize val , Bool val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L614)
```
fun box subc(
y: ISize val)
: (ISize val , Bool val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L621)
```
fun box mulc(
y: ISize val)
: (ISize val , Bool val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L628)
```
fun box divc(
y: ISize val)
: (ISize val , Bool val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L631)
```
fun box remc(
y: ISize val)
: (ISize val , Bool val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [Bool](builtin-bool) val)
### fldc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L634)
```
fun box fldc(
y: ISize val)
: (ISize val , Bool val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [Bool](builtin-bool) val)
### modc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L637)
```
fun box modc(
y: ISize val)
: (ISize val , Bool val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [Bool](builtin-bool) val)
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L640)
```
fun box add_partial(
y: ISize val)
: ISize val ?
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L643)
```
fun box sub_partial(
y: ISize val)
: ISize val ?
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L646)
```
fun box mul_partial(
y: ISize val)
: ISize val ?
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L649)
```
fun box div_partial(
y: ISize val)
: ISize val ?
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L652)
```
fun box rem_partial(
y: ISize val)
: ISize val ?
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L655)
```
fun box divrem_partial(
y: ISize val)
: (ISize val , ISize val) ?
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [ISize](index) val) ?
### fld\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L658)
```
fun box fld_partial(
y: ISize val)
: ISize val ?
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val ?
### mod\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L661)
```
fun box mod_partial(
y: ISize val)
: ISize val ?
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val ?
### shl
```
fun box shl(
y: USize val)
: ISize val
```
#### Parameters
* y: [USize](builtin-usize) val
#### Returns
* [ISize](index) val
### shr
```
fun box shr(
y: USize val)
: ISize val
```
#### Parameters
* y: [USize](builtin-usize) val
#### Returns
* [ISize](index) val
### shl\_unsafe
```
fun box shl_unsafe(
y: USize val)
: ISize val
```
#### Parameters
* y: [USize](builtin-usize) val
#### Returns
* [ISize](index) val
### shr\_unsafe
```
fun box shr_unsafe(
y: USize val)
: ISize val
```
#### Parameters
* y: [USize](builtin-usize) val
#### Returns
* [ISize](index) val
### string
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add\_unsafe
```
fun box add_unsafe(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### sub\_unsafe
```
fun box sub_unsafe(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### mul\_unsafe
```
fun box mul_unsafe(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### div\_unsafe
```
fun box div_unsafe(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### divrem\_unsafe
```
fun box divrem_unsafe(
y: ISize val)
: (ISize val , ISize val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [ISize](index) val)
### rem\_unsafe
```
fun box rem_unsafe(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### neg\_unsafe
```
fun box neg_unsafe()
: ISize val
```
#### Returns
* [ISize](index) val
### op\_and
```
fun box op_and(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### op\_or
```
fun box op_or(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### op\_xor
```
fun box op_xor(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### op\_not
```
fun box op_not()
: ISize val
```
#### Returns
* [ISize](index) val
### add
```
fun box add(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### sub
```
fun box sub(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### mul
```
fun box mul(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### div
```
fun box div(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### divrem
```
fun box divrem(
y: ISize val)
: (ISize val , ISize val)
```
#### Parameters
* y: [ISize](index) val
#### Returns
* ([ISize](index) val , [ISize](index) val)
### rem
```
fun box rem(
y: ISize val)
: ISize val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [ISize](index) val
### neg
```
fun box neg()
: ISize val
```
#### Returns
* [ISize](index) val
### eq
```
fun box eq(
y: ISize val)
: Bool val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
```
fun box ne(
y: ISize val)
: Bool val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
```
fun box lt(
y: ISize val)
: Bool val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [Bool](builtin-bool) val
### le
```
fun box le(
y: ISize val)
: Bool val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
```
fun box ge(
y: ISize val)
: Bool val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
```
fun box gt(
y: ISize val)
: Bool val
```
#### Parameters
* y: [ISize](index) val
#### Returns
* [Bool](builtin-bool) val
### hash
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i8
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](index) val
### u8
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](index) val
### u8\_unsafe
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: ISize val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [ISize](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
pony InputSerialisedAuth InputSerialisedAuth
===================
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L68)
This is a capability token that allows the holder to treat data arbitrary bytes as serialised data. This is the most dangerous capability, as currently it is possible for a malformed chunk of data to crash your program if it is deserialised.
```
primitive val InputSerialisedAuth
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L75)
```
new val create(
auth: AmbientAuth val)
: InputSerialisedAuth val^
```
#### Parameters
* auth: [AmbientAuth](builtin-ambientauth) val
#### Returns
* [InputSerialisedAuth](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L75)
```
fun box eq(
that: InputSerialisedAuth val)
: Bool val
```
#### Parameters
* that: [InputSerialisedAuth](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L75)
```
fun box ne(
that: InputSerialisedAuth val)
: Bool val
```
#### Parameters
* that: [InputSerialisedAuth](index) val
#### Returns
* [Bool](builtin-bool) val
pony Logger package Logger package
==============
Provides basic logging facilities. For most use cases, the `StringLogger` class will be used. On construction, it takes 2 parameters and a 3rd optional parameter:
* LogLevel below which no output will be logged
* OutStream to log to
* Optional LogFormatter
If you need to log arbitrary objects, take a look at `ObjectLogger[A]` which can log arbitrary objects so long as you provide it a lambda to covert from A to String.
API Philosophy
--------------
The API for using Logger is an attempt to abide by the Pony philosophy of first, be correct and secondly, aim for performance. One of the ways that logging can slow your system down is by having to evaluate expressions to be logged whether they will be logged or not (based on the level of logging). For example:
`logger.log(Warn, name + ": " + reason)`
will construct a new String regardless of whether we will end up logging the message or not.
The Logger API uses boolean short circuiting to avoid this.
`logger(Warn) and logger.log(name + ": " + reason)`
will not evaluate the expression to be logged unless the log level Warn is at or above the overall log level for our logging. This is as close as we can get to zero cost for items that aren't going to end up being logged.
Example programs
----------------
### String Logger
The following program will output 'my warn message' and 'my error message' to STDOUT in the standard default log format.
```
use "logger"
actor Main
new create(env: Env) =>
let logger = StringLogger(
Warn,
env.out)
logger(Fine) and logger.log("my fine message")
logger(Info) and logger.log("my info message")
logger(Warn) and logger.log("my warn message")
logger(Error) and logger.log("my error message")
```
### Logger[A]
The following program will output '42' to STDOUT in the standard default log format.
```
use "logger"
actor Main
new create(env: Env) =>
let logger = Logger[U64](Fine, env.out, {(a) => a.string() })
logger(Error) and logger.log(U64(42))
```
Custom formatting your logs
---------------------------
The Logger package provides an interface for formatting logs. If you wish to override the standard formatting, you can create an object that implements:
```
interface val LogFormatter
fun apply(
msg: String,
file_name: String,
file_linenum: String,
file_linepos: String): String
```
This can either be a class or because the interface only has a single apply method, can also be a lambda.
Public Types
------------
* [type LogLevel](logger-loglevel)
* [primitive Fine](logger-fine)
* [primitive Info](logger-info)
* [primitive Warn](logger-warn)
* [primitive Error](logger-error)
* [class Logger](logger-logger)
* [primitive StringLogger](logger-stringlogger)
* [interface LogFormatter](logger-logformatter)
* [primitive DefaultLogFormatter](logger-defaultlogformatter)
| programming_docs |
pony FormatBinary FormatBinary
============
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L6)
```
primitive val FormatBinary is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L6)
```
new val create()
: FormatBinary val^
```
#### Returns
* [FormatBinary](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L7)
```
fun box eq(
that: FormatBinary val)
: Bool val
```
#### Parameters
* that: [FormatBinary](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L7)
```
fun box ne(
that: FormatBinary val)
: Bool val
```
#### Parameters
* that: [FormatBinary](index) val
#### Returns
* [Bool](builtin-bool) val
pony stdlib stdlib
======
Packages
* [stdlib](https://stdlib.ponylang.io/stdlib--index/)
* [assert](assert--index)
* [backpressure](backpressure--index)
* [buffered](buffered--index)
* [builtin](builtin--index)
* [bureaucracy](bureaucracy--index)
* [capsicum](capsicum--index)
* [cli](cli--index)
* [collections](collections--index)
* [collections/persistent](collections-persistent--index)
* [debug](debug--index)
* [encode/base64](encode-base64--index)
* [files](files--index)
* [format](format--index)
* [ini](ini--index)
* [itertools](itertools--index)
* [json](json--index)
* [logger](logger--index)
* [math](math--index)
* [net](net--index)
* [options](options--index)
* [ponybench](ponybench--index)
* [ponytest](ponytest--index)
* [process](process--index)
* [promises](promises--index)
* [random](random--index)
* [serialise](serialise--index)
* [signals](signals--index)
* [strings](strings--index)
* [term](term--index)
* [time](time--index)
pony FileCreate FileCreate
==========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L3)
```
primitive val FileCreate
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L3)
```
new val create()
: FileCreate val^
```
#### Returns
* [FileCreate](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L4)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L4)
```
fun box eq(
that: FileCreate val)
: Bool val
```
#### Parameters
* that: [FileCreate](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L4)
```
fun box ne(
that: FileCreate val)
: Bool val
```
#### Parameters
* that: [FileCreate](index) val
#### Returns
* [Bool](builtin-bool) val
pony PosixDate PosixDate
=========
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L1)
Represents a proleptic Gregorian date and time, without specifying a time zone. The day of month, month, day of week, and day of year are all indexed from 1, i.e. January is 1, Monday is 1.
```
class ref PosixDate
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L17)
Create a date from a POSIX time. Negative arguments will be changed to zero.
```
new ref create(
seconds: I64 val = 0,
nanoseconds: I64 val = 0)
: PosixDate ref^
```
#### Parameters
* seconds: [I64](builtin-i64) val = 0
* nanoseconds: [I64](builtin-i64) val = 0
#### Returns
* [PosixDate](index) ref^
Public fields
-------------
### var nsec: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L7)
### var sec: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L8)
### var min: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L9)
### var hour: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L10)
### var day\_of\_month: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L11)
### var month: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L12)
### var year: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L13)
### var day\_of\_week: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L14)
### var day\_of\_year: [I32](builtin-i32) val
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L15)
Public Functions
----------------
### time
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L25)
Return a POSIX time. Treats the date as UTC.
```
fun box time()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### normal
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L31)
Normalise all the fields of the date. For example, if the hour is 24, it is set to 0 and the day is advanced. This allows fields to be changed naively, eg. adding 1000 to hours to advance the time by 1000 hours, and then normalising the date.
```
fun ref normal()
: None val
```
#### Returns
* [None](builtin-none) val
### format
[[Source]](https://stdlib.ponylang.io/src/time/posix_date/#L40)
Format the time as for strftime.
```
fun box format(
fmt: String val)
: String val ?
```
#### Parameters
* fmt: [String](builtin-string) val
#### Returns
* [String](builtin-string) val ?
pony ReadElement[A: A] ReadElement[A: A]
=================
[[Source]](https://stdlib.ponylang.io/src/builtin/read_seq/#L22)
Used to show that a ReadSeq can return an element of a specific unmodified type.
```
interface box ReadElement[A: A]
```
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/builtin/read_seq/#L27)
```
fun box apply(
i: USize val)
: A ?
```
#### Parameters
* i: [USize](builtin-usize) val
#### Returns
* A ?
pony Warn Warn
====
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L104)
```
primitive val Warn
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L104)
```
new val create()
: Warn val^
```
#### Returns
* [Warn](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L105)
```
fun box apply()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L105)
```
fun box eq(
that: Warn val)
: Bool val
```
#### Parameters
* that: [Warn](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L105)
```
fun box ne(
that: Warn val)
: Bool val
```
#### Parameters
* that: [Warn](index) val
#### Returns
* [Bool](builtin-bool) val
pony AmbientAuth AmbientAuth
===========
[[Source]](https://stdlib.ponylang.io/src/builtin/ambient_auth/#L1)
This type represents the root capability. When a Pony program starts, the Env passed to the Main actor contains an instance of the root capability.
Ambient access to the root capability is denied outside of the builtin package. Inside the builtin package, only Env creates a Root.
The root capability can be used by any package that wants to establish a principle of least authority. A typical usage is to have a parameter on a constructor for some resource that expects a limiting capability specific to the package, but will also accept the root capability as representing unlimited access.
```
primitive val AmbientAuth
```
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/ambient_auth/#L15)
```
fun box eq(
that: AmbientAuth val)
: Bool val
```
#### Parameters
* that: [AmbientAuth](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/ambient_auth/#L15)
```
fun box ne(
that: AmbientAuth val)
: Bool val
```
#### Parameters
* that: [AmbientAuth](index) val
#### Returns
* [Bool](builtin-bool) val
pony ProcessExitStatus ProcessExitStatus
=================
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L135)
Representing possible exit states of processes. A process either exited with an exit code or, only on posix systems, has been terminated by a signal.
```
type ProcessExitStatus is
(Exited val | Signaled val)
```
#### Type Alias For
* ([Exited](process-exited) val | [Signaled](process-signaled) val)
pony CapError CapError
========
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L56)
```
primitive val CapError
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L56)
```
new val create()
: CapError val^
```
#### Returns
* [CapError](index) val^
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L57)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L57)
```
fun box eq(
that: CapError val)
: Bool val
```
#### Parameters
* that: [CapError](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L57)
```
fun box ne(
that: CapError val)
: Bool val
```
#### Parameters
* that: [CapError](index) val
#### Returns
* [Bool](builtin-bool) val
pony MapIs[K: K, V: V] MapIs[K: K, V: V]
=================
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L10)
This is a map that uses identity comparison on the key.
```
type MapIs[K: K, V: V] is
HashMap[K, V, HashIs[K] val] ref
```
#### Type Alias For
* [HashMap](collections-hashmap)[K, V, [HashIs](collections-hashis)[K] val] ref
pony FileMode FileMode
========
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L1)
This stores a UNIX-style mode broken out into a Bool for each bit. For other operating systems, the mapping will be approximate. For example, on Windows, if the file is readable all the read Bools will be set, and if the file is writeable, all the write Bools will be set.
The default mode is read/write for the owner, read-only for everyone else.
```
class ref FileMode
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L1)
```
new iso create()
: FileMode iso^
```
#### Returns
* [FileMode](index) iso^
Public fields
-------------
### var setuid: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L10)
`true` if the SETUID bit is set.
### var setgid: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L13)
`true` if the SETGID bit is set.
### var sticky: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L16)
`true` if the sticky bit is set.
### var owner\_read: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L19)
`true` if the owning user can read the file.
### var owner\_write: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L22)
`true` if the owning user can write to the file.
### var owner\_exec: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L25)
`true` if the owning user can execute the file.
### var group\_read: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L28)
`true` if members of the owning group can read the file.
### var group\_write: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L31)
`true` if members of the owning group can write to the file.
### var group\_exec: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L34)
`true` if members of the owning group can execute the file.
### var any\_read: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L37)
`true` if every user can read the file.
### var any\_write: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L40)
`true` if every user can write to the file.
### var any\_exec: [Bool](builtin-bool) val
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L43)
`true if every user can execute the file.
Public Functions
----------------
### exec
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L46)
Set the executable flag for everyone.
```
fun ref exec()
: None val
```
#### Returns
* [None](builtin-none) val
### shared
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L54)
Set the write flag for everyone to the same as owner\_write.
```
fun ref shared()
: None val
```
#### Returns
* [None](builtin-none) val
### group
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L61)
Clear all of the any-user flags.
```
fun ref group()
: None val
```
#### Returns
* [None](builtin-none) val
### private
[[Source]](https://stdlib.ponylang.io/src/files/file_mode/#L69)
Clear all of the group and any-user flags.
```
fun ref private()
: None val
```
#### Returns
* [None](builtin-none) val
pony Directory Directory
=========
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L15)
Operations on a directory.
The directory-relative functions (open, etc) use the \*at interface on FreeBSD and Linux. This isn't available on OS X prior to 10.10, so it is not used. On FreeBSD, this allows the directory-relative functions to take advantage of Capsicum.
```
class ref Directory
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L37)
This will raise an error if the path doesn't exist or it is not a directory, or if FileRead or FileStat permission isn't available.
```
new ref create(
from: FilePath val)
: Directory ref^ ?
```
#### Parameters
* from: [FilePath](files-filepath) val
#### Returns
* [Directory](index) ref^ ?
Public fields
-------------
### let path: [FilePath](files-filepath) val
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L24)
This is the filesystem path locating this directory on the file system and an object capability granting access to operate on this directory.
Public Functions
----------------
### entries
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L77)
The entries will include everything in the directory, but it is not recursive. The path for the entry will be relative to the directory, so it will contain no directory separators. The entries will not include "." or "..".
```
fun box entries()
: Array[String val] iso^ ?
```
#### Returns
* [Array](builtin-array)[[String](builtin-string) val] iso^ ?
### open
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L149)
Open a directory relative to this one. Raises an error if the path is not within this directory hierarchy.
```
fun box open(
target: String val)
: Directory iso^ ?
```
#### Parameters
* target: [String](builtin-string) val
#### Returns
* [Directory](index) iso^ ?
### mkdir
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L171)
Creates a directory relative to this one. Returns false if the path is not within this directory hierarchy or if FileMkdir permission is missing.
```
fun box mkdir(
target: String val)
: Bool val
```
#### Parameters
* target: [String](builtin-string) val
#### Returns
* [Bool](builtin-bool) val
### create\_file
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L210)
Open for read/write, creating if it doesn't exist, preserving the contents if it does exist.
```
fun box create_file(
target: String val)
: File iso^ ?
```
#### Parameters
* target: [String](builtin-string) val
#### Returns
* [File](files-file) iso^ ?
### open\_file
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L238)
Open for read only, failing if it doesn't exist.
```
fun box open_file(
target: String val)
: File iso^ ?
```
#### Parameters
* target: [String](builtin-string) val
#### Returns
* [File](files-file) iso^ ?
### info
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L261)
Return a FileInfo for this directory. Raise an error if the fd is invalid or if we don't have FileStat permission.
```
fun box info()
: FileInfo val ?
```
#### Returns
* [FileInfo](files-fileinfo) val ?
### chmod
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L268)
Set the FileMode for this directory.
```
fun box chmod(
mode: FileMode box)
: Bool val
```
#### Parameters
* mode: [FileMode](files-filemode) box
#### Returns
* [Bool](builtin-bool) val
### chown
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L274)
Set the owner and group for this directory. Does nothing on Windows.
```
fun box chown(
uid: U32 val,
gid: U32 val)
: Bool val
```
#### Parameters
* uid: [U32](builtin-u32) val
* gid: [U32](builtin-u32) val
#### Returns
* [Bool](builtin-bool) val
### touch
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L280)
Set the last access and modification times of the directory to now.
```
fun box touch()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### set\_time
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L286)
Set the last access and modification times of the directory to the given values.
```
fun box set_time(
atime: (I64 val , I64 val),
mtime: (I64 val , I64 val))
: Bool val
```
#### Parameters
* atime: ([I64](builtin-i64) val , [I64](builtin-i64) val)
* mtime: ([I64](builtin-i64) val , [I64](builtin-i64) val)
#### Returns
* [Bool](builtin-bool) val
### infoat
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L293)
Return a FileInfo for some path relative to this directory.
```
fun box infoat(
target: String val)
: FileInfo val ?
```
#### Parameters
* target: [String](builtin-string) val
#### Returns
* [FileInfo](files-fileinfo) val ?
### chmodat
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L313)
Set the FileMode for some path relative to this directory.
```
fun box chmodat(
target: String val,
mode: FileMode box)
: Bool val
```
#### Parameters
* target: [String](builtin-string) val
* mode: [FileMode](files-filemode) box
#### Returns
* [Bool](builtin-bool) val
### chownat
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L337)
Set the FileMode for some path relative to this directory.
```
fun box chownat(
target: String val,
uid: U32 val,
gid: U32 val)
: Bool val
```
#### Parameters
* target: [String](builtin-string) val
* uid: [U32](builtin-u32) val
* gid: [U32](builtin-u32) val
#### Returns
* [Bool](builtin-bool) val
### touchat
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L361)
Set the last access and modification times of the directory to now.
```
fun box touchat(
target: String val)
: Bool val
```
#### Parameters
* target: [String](builtin-string) val
#### Returns
* [Bool](builtin-bool) val
### set\_time\_at
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L367)
Set the last access and modification times of the directory to the given values.
```
fun box set_time_at(
target: String val,
atime: (I64 val , I64 val),
mtime: (I64 val , I64 val))
: Bool val
```
#### Parameters
* target: [String](builtin-string) val
* atime: ([I64](builtin-i64) val , [I64](builtin-i64) val)
* mtime: ([I64](builtin-i64) val , [I64](builtin-i64) val)
#### Returns
* [Bool](builtin-bool) val
### symlink
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L401)
Link the source path to the link\_name, where the link\_name is relative to this directory.
```
fun box symlink(
source: FilePath val,
link_name: String val)
: Bool val
```
#### Parameters
* source: [FilePath](files-filepath) val
* link\_name: [String](builtin-string) val
#### Returns
* [Bool](builtin-bool) val
### remove
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L428)
Remove the file or directory. The directory contents will be removed as well, recursively. Symlinks will be removed but not traversed.
```
fun box remove(
target: String val)
: Bool val
```
#### Parameters
* target: [String](builtin-string) val
#### Returns
* [Bool](builtin-bool) val
### rename
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L467)
Rename source (which is relative to this directory) to target (which is relative to the `to` directory).
```
fun box rename(
source: String val,
to: Directory box,
target: String val)
: Bool val
```
#### Parameters
* source: [String](builtin-string) val
* to: [Directory](index) box
* target: [String](builtin-string) val
#### Returns
* [Bool](builtin-bool) val
### dispose
[[Source]](https://stdlib.ponylang.io/src/files/directory/#L496)
Close the directory.
```
fun ref dispose()
: None val
```
#### Returns
* [None](builtin-none) val
| programming_docs |
pony InputStream InputStream
===========
[[Source]](https://stdlib.ponylang.io/src/builtin/stdin/#L27)
Asynchronous access to some input stream.
```
interface tag InputStream
```
Public Behaviours
-----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/builtin/stdin/#L31)
Set the notifier. Optionally, also sets the chunk size, dictating the maximum number of bytes of each chunk that will be passed to the notifier.
```
be apply(
notify: (InputNotify iso | None val),
chunk_size: USize val = 32)
```
#### Parameters
* notify: ([InputNotify](builtin-inputnotify) iso | [None](builtin-none) val)
* chunk\_size: [USize](builtin-usize) val = 32
### dispose
[[Source]](https://stdlib.ponylang.io/src/builtin/stdin/#L37)
Clear the notifier in order to shut down input.
```
be dispose()
```
pony IniIncompleteSection IniIncompleteSection
====================
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L31)
```
primitive val IniIncompleteSection
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L31)
```
new val create()
: IniIncompleteSection val^
```
#### Returns
* [IniIncompleteSection](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L32)
```
fun box eq(
that: IniIncompleteSection val)
: Bool val
```
#### Parameters
* that: [IniIncompleteSection](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L32)
```
fun box ne(
that: IniIncompleteSection val)
: Bool val
```
#### Parameters
* that: [IniIncompleteSection](index) val
#### Returns
* [Bool](builtin-bool) val
pony Ini Ini
===
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L63)
A streaming parser for INI formatted lines of test.
```
primitive val Ini
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L63)
```
new val create()
: Ini val^
```
#### Returns
* [Ini](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L67)
This accepts a string iterator and calls the IniNotify for each new entry. If any errors are encountered, this will return false. Otherwise, it returns true.
```
fun box apply(
lines: Iterator[String box] ref,
f: IniNotify ref)
: Bool val
```
#### Parameters
* lines: [Iterator](builtin-iterator)[[String](builtin-string) box] ref
* f: [IniNotify](ini-ininotify) ref
#### Returns
* [Bool](builtin-bool) val
### eq
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L67)
```
fun box eq(
that: Ini val)
: Bool val
```
#### Parameters
* that: [Ini](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/ini/ini/#L67)
```
fun box ne(
that: Ini val)
: Bool val
```
#### Parameters
* that: [Ini](index) val
#### Returns
* [Bool](builtin-bool) val
pony MapPairs[K: Any #share, V: Any #share, H: HashFunction[K] val] MapPairs[K: [Any](builtin-any) #share, V: [Any](builtin-any) #share, H: [HashFunction](collections-hashfunction)[K] val]
========================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L157)
```
class ref MapPairs[K: Any #share, V: Any #share, H: HashFunction[K] val]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L160)
```
new ref create(
m: HashMap[K, V, H] val)
: MapPairs[K, V, H] ref^
```
#### Parameters
* m: [HashMap](collections-persistent-hashmap)[K, V, H] val
#### Returns
* [MapPairs](index)[K, V, H] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L163)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L166)
```
fun ref next()
: (K , V) ?
```
#### Returns
* (K , V) ?
pony MapPairs[K: K, V: V, H: HashFunction[K] val, M: HashMap[K, V, H] #read] MapPairs[K: K, V: V, H: [HashFunction](collections-hashfunction)[K] val, M: [HashMap](collections-hashmap)[K, V, H] #read]
==========================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L450)
An iterator over the keys and values in a map.
```
class ref MapPairs[K: K, V: V, H: HashFunction[K] val, M: HashMap[K, V, H] #read] is
Iterator[(M->K , M->V)] ref
```
#### Implements
* [Iterator](builtin-iterator)[(M->K , M->V)] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L459)
Creates an iterator for the given map.
```
new ref create(
map: M)
: MapPairs[K, V, H, M] ref^
```
#### Parameters
* map: M
#### Returns
* [MapPairs](index)[K, V, H, M] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L465)
True if it believes there are remaining entries. May not be right if values were added or removed from the map.
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L472)
Returns the next entry, or raises an error if there isn't one. If entries are added during iteration, this may not return all entries.
```
fun ref next()
: (M->K , M->V) ?
```
#### Returns
* (M->K , M->V) ?
pony Assert package Assert package
==============
Contains runtime assertions. If you are looking for assertion that only run when your code was compiled with the `debug` flag, check out `Assert`. For assertions that are always enabled, check out `Fact`.
Public Types
------------
* [primitive Assert](assert-assert)
* [primitive Fact](assert-fact)
pony U16 U16
===
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L73)
```
primitive val U16 is
UnsignedInteger[U16 val] val
```
#### Implements
* [UnsignedInteger](builtin-unsignedinteger)[[U16](index) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L74)
```
new val create(
value: U16 val)
: U16 val^
```
#### Parameters
* value: [U16](index) val
#### Returns
* [U16](index) val^
### from[A: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](index) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[A] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L75)
```
new val from[A: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[A] val)](
a: A)
: U16 val^
```
#### Parameters
* a: A
#### Returns
* [U16](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L77)
```
new val min_value()
: U16 val^
```
#### Returns
* [U16](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L78)
```
new val max_value()
: U16 val^
```
#### Returns
* [U16](index) val^
Public Functions
----------------
### next\_pow2
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L80)
```
fun box next_pow2()
: U16 val
```
#### Returns
* [U16](index) val
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L84)
```
fun box abs()
: U16 val
```
#### Returns
* [U16](index) val
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L85)
```
fun box bit_reverse()
: U16 val
```
#### Returns
* [U16](index) val
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L86)
```
fun box bswap()
: U16 val
```
#### Returns
* [U16](index) val
### popcount
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L87)
```
fun box popcount()
: U16 val
```
#### Returns
* [U16](index) val
### clz
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L88)
```
fun box clz()
: U16 val
```
#### Returns
* [U16](index) val
### ctz
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L89)
```
fun box ctz()
: U16 val
```
#### Returns
* [U16](index) val
### clz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L91)
Unsafe operation. If this is 0, the result is undefined.
```
fun box clz_unsafe()
: U16 val
```
#### Returns
* [U16](index) val
### ctz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L98)
Unsafe operation. If this is 0, the result is undefined.
```
fun box ctz_unsafe()
: U16 val
```
#### Returns
* [U16](index) val
### bitwidth
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L105)
```
fun box bitwidth()
: U16 val
```
#### Returns
* [U16](index) val
### bytewidth
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L107)
```
fun box bytewidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L109)
```
fun box min(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L110)
```
fun box max(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L112)
```
fun box addc(
y: U16 val)
: (U16 val , Bool val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L115)
```
fun box subc(
y: U16 val)
: (U16 val , Bool val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L118)
```
fun box mulc(
y: U16 val)
: (U16 val , Bool val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L121)
```
fun box divc(
y: U16 val)
: (U16 val , Bool val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L124)
```
fun box remc(
y: U16 val)
: (U16 val , Bool val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [Bool](builtin-bool) val)
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L127)
```
fun box add_partial(
y: U16 val)
: U16 val ?
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L130)
```
fun box sub_partial(
y: U16 val)
: U16 val ?
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L133)
```
fun box mul_partial(
y: U16 val)
: U16 val ?
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L136)
```
fun box div_partial(
y: U16 val)
: U16 val ?
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L139)
```
fun box rem_partial(
y: U16 val)
: U16 val ?
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L142)
```
fun box divrem_partial(
y: U16 val)
: (U16 val , U16 val) ?
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [U16](index) val) ?
### shl
```
fun box shl(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### shr
```
fun box shr(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### fld
```
fun box fld(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### fldc
```
fun box fldc(
y: U16 val)
: (U16 val , Bool val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [Bool](builtin-bool) val)
### fld\_partial
```
fun box fld_partial(
y: U16 val)
: U16 val ?
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val ?
### fld\_unsafe
```
fun box fld_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### mod
```
fun box mod(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### modc
```
fun box modc(
y: U16 val)
: (U16 val , Bool val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [Bool](builtin-bool) val)
### mod\_partial
```
fun box mod_partial(
y: U16 val)
: U16 val ?
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val ?
### mod\_unsafe
```
fun box mod_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### shl\_unsafe
```
fun box shl_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### shr\_unsafe
```
fun box shr_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### rotl
```
fun box rotl(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### rotr
```
fun box rotr(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### string
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add\_unsafe
```
fun box add_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### sub\_unsafe
```
fun box sub_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### mul\_unsafe
```
fun box mul_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### div\_unsafe
```
fun box div_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### divrem\_unsafe
```
fun box divrem_unsafe(
y: U16 val)
: (U16 val , U16 val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [U16](index) val)
### rem\_unsafe
```
fun box rem_unsafe(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### neg\_unsafe
```
fun box neg_unsafe()
: U16 val
```
#### Returns
* [U16](index) val
### op\_and
```
fun box op_and(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### op\_or
```
fun box op_or(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### op\_xor
```
fun box op_xor(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### op\_not
```
fun box op_not()
: U16 val
```
#### Returns
* [U16](index) val
### add
```
fun box add(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### sub
```
fun box sub(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### mul
```
fun box mul(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### div
```
fun box div(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### divrem
```
fun box divrem(
y: U16 val)
: (U16 val , U16 val)
```
#### Parameters
* y: [U16](index) val
#### Returns
* ([U16](index) val , [U16](index) val)
### rem
```
fun box rem(
y: U16 val)
: U16 val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [U16](index) val
### neg
```
fun box neg()
: U16 val
```
#### Returns
* [U16](index) val
### eq
```
fun box eq(
y: U16 val)
: Bool val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
```
fun box ne(
y: U16 val)
: Bool val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
```
fun box lt(
y: U16 val)
: Bool val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [Bool](builtin-bool) val
### le
```
fun box le(
y: U16 val)
: Bool val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
```
fun box ge(
y: U16 val)
: Bool val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
```
fun box gt(
y: U16 val)
: Bool val
```
#### Parameters
* y: [U16](index) val
#### Returns
* [Bool](builtin-bool) val
### hash
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i8
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
```
fun box u16()
: U16 val
```
#### Returns
* [U16](index) val
### u32
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](index) val
### u32\_unsafe
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: U16 val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [U16](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony Stringable Stringable
==========
[[Source]](https://stdlib.ponylang.io/src/builtin/stringable/#L1)
Things that can be turned into a String.
```
interface box Stringable
```
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/stringable/#L5)
Generate a string representation of this object.
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
pony FloatingPoint[A: FloatingPoint[A] val] FloatingPoint[A: [FloatingPoint](index)[A] val]
===============================================
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L516)
```
trait val FloatingPoint[A: FloatingPoint[A] val] is
Real[A] val
```
#### Implements
* [Real](builtin-real)[A] val
Constructors
------------
### min\_normalised
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L517)
```
new val min_normalised()
: FloatingPoint[A] val^
```
#### Returns
* [FloatingPoint](index)[A] val^
### epsilon
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L518)
```
new val epsilon()
: FloatingPoint[A] val^
```
#### Returns
* [FloatingPoint](index)[A] val^
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L135)
```
new val create(
value: A)
: Real[A] val^
```
#### Parameters
* value: A
#### Returns
* [Real](builtin-real)[A] val^
### from[B: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[B] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L137)
```
new val from[B: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[B] val)](
a: B)
: Real[A] val^
```
#### Parameters
* a: B
#### Returns
* [Real](builtin-real)[A] val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L138)
```
new val min_value()
: Real[A] val^
```
#### Returns
* [Real](builtin-real)[A] val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L139)
```
new val max_value()
: Real[A] val^
```
#### Returns
* [Real](builtin-real)[A] val^
Public Functions
----------------
### radix
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L519)
```
fun tag radix()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### precision2
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L520)
```
fun tag precision2()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### precision10
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L521)
```
fun tag precision10()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### min\_exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L522)
```
fun tag min_exp2()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### min\_exp10
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L523)
```
fun tag min_exp10()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### max\_exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L524)
```
fun tag max_exp2()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### max\_exp10
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L525)
```
fun tag max_exp10()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### add\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L527)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box add_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### sub\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L536)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box sub_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mul\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L545)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box mul_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### div\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L554)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box div_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L563)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box fld_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### divrem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L571)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box divrem_unsafe(
y: A)
: (A , A)
```
#### Parameters
* y: A
#### Returns
* (A , A)
### rem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L580)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box rem_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L589)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box mod_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### neg\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L597)
Unsafe operation. If any input or output of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box neg_unsafe()
: A
```
#### Returns
* A
### eq\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L606)
Unsafe operation. If any input of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box eq_unsafe(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ne\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L615)
Unsafe operation. If any input of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box ne_unsafe(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### lt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L624)
Unsafe operation. If any input of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box lt_unsafe(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### le\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L633)
Unsafe operation. If any input of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box le_unsafe(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ge\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L642)
Unsafe operation. If any input of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box ge_unsafe(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### gt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L651)
Unsafe operation. If any input of the operation is +/- infinity or NaN, the result is undefined. The operation isn't required to fully comply to IEEE 754 semantics.
```
fun box gt_unsafe(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L660)
```
fun box abs()
: A
```
#### Returns
* A
### ceil
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L661)
```
fun box ceil()
: A
```
#### Returns
* A
### floor
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L662)
```
fun box floor()
: A
```
#### Returns
* A
### round
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L663)
```
fun box round()
: A
```
#### Returns
* A
### trunc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L664)
```
fun box trunc()
: A
```
#### Returns
* A
### finite
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L666)
```
fun box finite()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### infinite
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L667)
```
fun box infinite()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### nan
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L668)
```
fun box nan()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### ldexp
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L670)
```
fun box ldexp(
x: A,
exponent: I32 val)
: A
```
#### Parameters
* x: A
* exponent: [I32](builtin-i32) val
#### Returns
* A
### frexp
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L671)
```
fun box frexp()
: (A , U32 val)
```
#### Returns
* (A , [U32](builtin-u32) val)
### log
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L672)
```
fun box log()
: A
```
#### Returns
* A
### log2
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L673)
```
fun box log2()
: A
```
#### Returns
* A
### log10
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L674)
```
fun box log10()
: A
```
#### Returns
* A
### logb
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L675)
```
fun box logb()
: A
```
#### Returns
* A
### pow
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L677)
```
fun box pow(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### powi
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L678)
```
fun box powi(
y: I32 val)
: A
```
#### Parameters
* y: [I32](builtin-i32) val
#### Returns
* A
### sqrt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L680)
```
fun box sqrt()
: A
```
#### Returns
* A
### sqrt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L682)
Unsafe operation. If this is negative, the result is undefined.
```
fun box sqrt_unsafe()
: A
```
#### Returns
* A
### cbrt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L688)
```
fun box cbrt()
: A
```
#### Returns
* A
### exp
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L689)
```
fun box exp()
: A
```
#### Returns
* A
### exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L690)
```
fun box exp2()
: A
```
#### Returns
* A
### cos
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L692)
```
fun box cos()
: A
```
#### Returns
* A
### sin
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L693)
```
fun box sin()
: A
```
#### Returns
* A
### tan
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L694)
```
fun box tan()
: A
```
#### Returns
* A
### cosh
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L696)
```
fun box cosh()
: A
```
#### Returns
* A
### sinh
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L697)
```
fun box sinh()
: A
```
#### Returns
* A
### tanh
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L698)
```
fun box tanh()
: A
```
#### Returns
* A
### acos
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L700)
```
fun box acos()
: A
```
#### Returns
* A
### asin
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L701)
```
fun box asin()
: A
```
#### Returns
* A
### atan
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L702)
```
fun box atan()
: A
```
#### Returns
* A
### atan2
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L703)
```
fun box atan2(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### acosh
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L705)
```
fun box acosh()
: A
```
#### Returns
* A
### asinh
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L706)
```
fun box asinh()
: A
```
#### Returns
* A
### atanh
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L707)
```
fun box atanh()
: A
```
#### Returns
* A
### copysign
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L709)
```
fun box copysign(
sign: A)
: A
```
#### Parameters
* sign: A
#### Returns
* A
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L711)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L141)
```
fun box add(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### sub
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L142)
```
fun box sub(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mul
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L143)
```
fun box mul(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### div
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L144)
```
fun box div(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### divrem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L150)
```
fun box divrem(
y: A)
: (A , A)
```
#### Parameters
* y: A
#### Returns
* (A , A)
### rem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L151)
```
fun box rem(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### neg
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L159)
```
fun box neg()
: A
```
#### Returns
* A
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L161)
```
fun box fld(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L165)
```
fun box mod(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L172)
```
fun box eq(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L173)
```
fun box ne(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### lt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L174)
```
fun box lt(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### le
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L175)
```
fun box le(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ge
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L176)
```
fun box ge(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### gt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L177)
```
fun box gt(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L179)
```
fun box min(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L180)
```
fun box max(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L182)
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L198)
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L2)
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L3)
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L4)
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L5)
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L6)
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L7)
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L8)
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L10)
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L11)
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L12)
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L13)
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L14)
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L15)
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L16)
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L18)
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L19)
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L21)
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L28)
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L35)
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L42)
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L49)
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L56)
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L63)
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L70)
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L77)
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L84)
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L91)
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L98)
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L105)
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L112)
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L119)
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L126)
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: box->A)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: box->A
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony AsyncBenchContinue AsyncBenchContinue
==================
[[Source]](https://stdlib.ponylang.io/src/ponybench/_runner/#L145)
```
class val AsyncBenchContinue
```
Public Functions
----------------
### complete
[[Source]](https://stdlib.ponylang.io/src/ponybench/_runner/#L153)
```
fun box complete()
: None val
```
#### Returns
* [None](builtin-none) val
### fail
[[Source]](https://stdlib.ponylang.io/src/ponybench/_runner/#L157)
```
fun box fail()
: None val
```
#### Returns
* [None](builtin-none) val
pony ExecveError ExecveError
===========
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L38)
```
primitive val ExecveError
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L38)
```
new val create()
: ExecveError val^
```
#### Returns
* [ExecveError](index) val^
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L39)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L39)
```
fun box eq(
that: ExecveError val)
: Bool val
```
#### Parameters
* that: [ExecveError](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L39)
```
fun box ne(
that: ExecveError val)
: Bool val
```
#### Parameters
* that: [ExecveError](index) val
#### Returns
* [Bool](builtin-bool) val
pony UnknownError UnknownError
============
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L62)
```
primitive val UnknownError
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L62)
```
new val create()
: UnknownError val^
```
#### Returns
* [UnknownError](index) val^
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L63)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L63)
```
fun box eq(
that: UnknownError val)
: Bool val
```
#### Parameters
* that: [UnknownError](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L63)
```
fun box ne(
that: UnknownError val)
: Bool val
```
#### Parameters
* that: [UnknownError](index) val
#### Returns
* [Bool](builtin-bool) val
pony CLI Package CLI Package
===========
The CLI package provides enhanced Posix+GNU command line parsing with the feature of commands that can be specified in a hierarchy.
See [RFC-0038](https://github.com/ponylang/rfcs/blob/master/text/0038-cli-format.md) for more background.
The general EBNF of a command line is:
```
command_line ::= root_command (option | command)* (option | arg)*
command ::= alphanum_word
alphanum_word ::= alphachar(alphachar | numchar | '_' | '-')*
option ::= longoption | shortoptionset
longoption ::= '--'alphanum_word['='arg | ' 'arg]
shortoptionset := '-'alphachar[alphachar]...['='arg | ' 'arg]
arg := boolarg | intarg | floatarg | stringarg
boolarg := 'true' | 'false'
intarg> := ['-'] numchar...
floatarg ::= ['-'] numchar... ['.' numchar...]
stringarg ::= anychar
```
Some examples:
```
usage: ls [<options>] [<args> ...]
usage: make [<options>] <command> [<options>] [<args> ...]
usage: chat [<options>] <command> <subcommand> [<options>] [<args> ...]
```
Usage
-----
The types in the cli package are broken down into three groups:
### Specs
Pony programs use constructors to create the spec objects to specify their command line syntax. Many aspects of the spec are checked for correctness at compile time, and the result represents everything the parser needs to know when parsing a command line or forming syntax help messages.
#### Option and Arg value types
Options and Args parse values from the command line as one of four Pony types: `Bool`, `String`, `I64` and `F64`. Values of each of these types can then be retrieved using the corresponding accessor funtions.
In addition, there is a string\_seq type that accepts string values from the command line and collects them into a sequence which can then be retrieved as a `ReadSeq[String]` using the `string_seq()` accessor function.
Some specific details:
* bool Options: have a default value of 'true' if no value is given. That is, `-f` is equivalent to `-f=true`.
* string\_seq Options: the option prefix has to be used each time, like: `--file=f1 --file=f2 --file=f3` with the results being collected into a single sequence.
* string\_seq Args: there is no way to indicate termination, so a string\_seq Arg should be the last arg for a command, and will consume all remaining command line arguments.
### Parser
Programs then use the CommandSpec they've built to instantiate a parser to parse any given command line. This is often env.args(), but could also be commands from files or other input sources. The result of a parse is either a parsed command, a command help, or a syntax error object.
### Commands
Programs then match the object returned by the parser to determine what kind it is. Errors and help requests typically print messages and exit. For commands, the fullname can be matched and the effective values for the command's options and arguments can be retrieved.
Example program
===============
This program echos its command line arguments with the option of uppercasing them.
```
use "cli"
actor Main
new create(env: Env) =>
let cs =
try
CommandSpec.leaf("echo", "A sample echo program", [
OptionSpec.bool("upper", "Uppercase words"
where short' = 'U', default' = false)
], [
ArgSpec.string_seq("words", "The words to echo")
])? .> add_help()?
else
env.exitcode(-1) // some kind of coding error
return
end
let cmd =
match CommandParser(cs).parse(env.args, env.vars)
| let c: Command => c
| let ch: CommandHelp =>
ch.print_help(env.out)
env.exitcode(0)
return
| let se: SyntaxError =>
env.out.print(se.string())
env.exitcode(1)
return
end
let upper = cmd.option("upper").bool()
let words = cmd.arg("words").string_seq()
for word in words.values() do
env.out.write(if upper then word.upper() else word end + " ")
end
env.out.print("")
```
Public Types
------------
* [primitive EnvVars](cli-envvars)
* [class CommandSpec](cli-commandspec)
* [class OptionSpec](cli-optionspec)
* [class ArgSpec](cli-argspec)
* [class CommandParser](cli-commandparser)
* [primitive Help](cli-help)
* [class CommandHelp](cli-commandhelp)
* [class Command](cli-command)
* [class Option](cli-option)
* [class Arg](cli-arg)
* [class SyntaxError](cli-syntaxerror)
pony I8 I8
==
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L1)
```
primitive val I8 is
SignedInteger[I8 val, U8 val] val
```
#### Implements
* [SignedInteger](builtin-signedinteger)[[I8](index) val, [U8](builtin-u8) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L2)
```
new val create(
value: I8 val)
: I8 val^
```
#### Parameters
* value: [I8](index) val
#### Returns
* [I8](index) val^
### from[A: (([I8](index) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[A] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L3)
```
new val from[A: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[A] val)](
a: A)
: I8 val^
```
#### Parameters
* a: A
#### Returns
* [I8](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L5)
```
new val min_value()
: I8 val^
```
#### Returns
* [I8](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L6)
```
new val max_value()
: I8 val^
```
#### Returns
* [I8](index) val^
Public Functions
----------------
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L8)
```
fun box abs()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L9)
```
fun box bit_reverse()
: I8 val
```
#### Returns
* [I8](index) val
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L10)
```
fun box bswap()
: I8 val
```
#### Returns
* [I8](index) val
### popcount
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L11)
```
fun box popcount()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### clz
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L12)
```
fun box clz()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### ctz
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L13)
```
fun box ctz()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### clz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L15)
Unsafe operation. If this is 0, the result is undefined.
```
fun box clz_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### ctz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L22)
Unsafe operation. If this is 0, the result is undefined.
```
fun box ctz_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### bitwidth
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L29)
```
fun box bitwidth()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### bytewidth
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L31)
```
fun box bytewidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L33)
```
fun box min(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L34)
```
fun box max(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L36)
```
fun box fld(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L39)
```
fun box fld_unsafe(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L42)
```
fun box mod(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L45)
```
fun box mod_unsafe(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L48)
```
fun box addc(
y: I8 val)
: (I8 val , Bool val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L51)
```
fun box subc(
y: I8 val)
: (I8 val , Bool val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L54)
```
fun box mulc(
y: I8 val)
: (I8 val , Bool val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L57)
```
fun box divc(
y: I8 val)
: (I8 val , Bool val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L60)
```
fun box remc(
y: I8 val)
: (I8 val , Bool val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [Bool](builtin-bool) val)
### fldc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L63)
```
fun box fldc(
y: I8 val)
: (I8 val , Bool val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [Bool](builtin-bool) val)
### modc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L66)
```
fun box modc(
y: I8 val)
: (I8 val , Bool val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [Bool](builtin-bool) val)
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L69)
```
fun box add_partial(
y: I8 val)
: I8 val ?
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L72)
```
fun box sub_partial(
y: I8 val)
: I8 val ?
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L75)
```
fun box mul_partial(
y: I8 val)
: I8 val ?
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L78)
```
fun box div_partial(
y: I8 val)
: I8 val ?
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L81)
```
fun box rem_partial(
y: I8 val)
: I8 val ?
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L84)
```
fun box divrem_partial(
y: I8 val)
: (I8 val , I8 val) ?
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [I8](index) val) ?
### fld\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L87)
```
fun box fld_partial(
y: I8 val)
: I8 val ?
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val ?
### mod\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L90)
```
fun box mod_partial(
y: I8 val)
: I8 val ?
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val ?
### shl
```
fun box shl(
y: U8 val)
: I8 val
```
#### Parameters
* y: [U8](builtin-u8) val
#### Returns
* [I8](index) val
### shr
```
fun box shr(
y: U8 val)
: I8 val
```
#### Parameters
* y: [U8](builtin-u8) val
#### Returns
* [I8](index) val
### shl\_unsafe
```
fun box shl_unsafe(
y: U8 val)
: I8 val
```
#### Parameters
* y: [U8](builtin-u8) val
#### Returns
* [I8](index) val
### shr\_unsafe
```
fun box shr_unsafe(
y: U8 val)
: I8 val
```
#### Parameters
* y: [U8](builtin-u8) val
#### Returns
* [I8](index) val
### string
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add\_unsafe
```
fun box add_unsafe(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### sub\_unsafe
```
fun box sub_unsafe(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### mul\_unsafe
```
fun box mul_unsafe(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### div\_unsafe
```
fun box div_unsafe(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### divrem\_unsafe
```
fun box divrem_unsafe(
y: I8 val)
: (I8 val , I8 val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [I8](index) val)
### rem\_unsafe
```
fun box rem_unsafe(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### neg\_unsafe
```
fun box neg_unsafe()
: I8 val
```
#### Returns
* [I8](index) val
### op\_and
```
fun box op_and(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### op\_or
```
fun box op_or(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### op\_xor
```
fun box op_xor(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### op\_not
```
fun box op_not()
: I8 val
```
#### Returns
* [I8](index) val
### add
```
fun box add(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### sub
```
fun box sub(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### mul
```
fun box mul(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### div
```
fun box div(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### divrem
```
fun box divrem(
y: I8 val)
: (I8 val , I8 val)
```
#### Parameters
* y: [I8](index) val
#### Returns
* ([I8](index) val , [I8](index) val)
### rem
```
fun box rem(
y: I8 val)
: I8 val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [I8](index) val
### neg
```
fun box neg()
: I8 val
```
#### Returns
* [I8](index) val
### eq
```
fun box eq(
y: I8 val)
: Bool val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
```
fun box ne(
y: I8 val)
: Bool val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
```
fun box lt(
y: I8 val)
: Bool val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [Bool](builtin-bool) val
### le
```
fun box le(
y: I8 val)
: Bool val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
```
fun box ge(
y: I8 val)
: Bool val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
```
fun box gt(
y: I8 val)
: Bool val
```
#### Parameters
* y: [I8](index) val
#### Returns
* [Bool](builtin-bool) val
### hash
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i8
```
fun box i8()
: I8 val
```
#### Returns
* [I8](index) val
### i16
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](index) val
### i16\_unsafe
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: I8 val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [I8](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony FileLink FileLink
========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L12)
```
primitive val FileLink
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L12)
```
new val create()
: FileLink val^
```
#### Returns
* [FileLink](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L13)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L13)
```
fun box eq(
that: FileLink val)
: Bool val
```
#### Parameters
* that: [FileLink](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L13)
```
fun box ne(
that: FileLink val)
: Bool val
```
#### Parameters
* that: [FileLink](index) val
#### Returns
* [Bool](builtin-bool) val
pony Fibonacci[optional A: (Integer[A] val & (U8 val | U16 val | U32 val | U64 val | U128 val | ULong val | USize val))] Fibonacci[optional A: ([Integer](builtin-integer)[A] val & ([U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val))]
===================================================================================================================================================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/math/fibonacci/#L15)
Useful for microbenchmarks to impress your friends. Look y'all, Pony goes fast! We suppose if you are into Agile planning poker that you could also use this in conjunction with `Random` to assign User Story Points.
```
class ref Fibonacci[optional A: (Integer[A] val & (U8 val | U16 val | U32 val |
U64 val | U128 val | ULong val |
USize val))] is
Iterator[A] ref
```
#### Implements
* [Iterator](builtin-iterator)[A] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/math/fibonacci/#L15)
```
new iso create()
: Fibonacci[A] iso^
```
#### Returns
* [Fibonacci](index)[A] iso^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/math/fibonacci/#L25)
```
fun box apply(
n: U8 val)
: A
```
#### Parameters
* n: [U8](builtin-u8) val
#### Returns
* A
### has\_next
[[Source]](https://stdlib.ponylang.io/src/math/fibonacci/#L43)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/math/fibonacci/#L45)
```
fun ref next()
: A
```
#### Returns
* A
pony Reverse[optional A: (Real[A] val & (I8 val | I16 val | I32 val | I64 val | I128 val | ILong val | ISize val | U8 val | U16 val | U32 val | U64 val | U128 val | ULong val | USize val | F32 val | F64 val))] Reverse[optional A: ([Real](builtin-real)[A] val & ([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val))]
====================================================================================================================================================================================================================================================================================================================================================================================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/reverse/#L1)
Produces a decreasing range [max, min] with step `dec`, for any `Number` type. (i.e. the reverse of `Range`)
Example program:
```
use "collections"
actor Main
new create(env: Env) =>
for e in Reverse(10, 2, 2) do
env.out.print(e.string())
end
```
Which outputs:
```
10
8
6
4
2
```
If `dec` is 0, produces an infinite series of `max`.
If `dec` is negative, produces a range with `max` as the only value.
```
class ref Reverse[optional A: (Real[A] val & (I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val))] is
Iterator[A] ref
```
#### Implements
* [Iterator](builtin-iterator)[A] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/reverse/#L36)
```
new ref create(
max: A,
min: A,
dec: A = 1)
: Reverse[A] ref^
```
#### Parameters
* max: A
* min: A
* dec: A = 1
#### Returns
* [Reverse](index)[A] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections/reverse/#L42)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections/reverse/#L45)
```
fun ref next()
: A
```
#### Returns
* A
### rewind
[[Source]](https://stdlib.ponylang.io/src/collections/reverse/#L52)
```
fun ref rewind()
: None val
```
#### Returns
* [None](builtin-none) val
pony Cons[A: A] Cons[A: A]
==========
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L234)
A list with a head and a tail, where the tail can be empty.
```
class val Cons[A: A] is
ReadSeq[val->A] box
```
#### Implements
* [ReadSeq](builtin-readseq)[val->A] box
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L243)
```
new val create(
a: val->A,
t: (Cons[A] val | Nil[A] val))
: Cons[A] val^
```
#### Parameters
* a: val->A
* t: ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
#### Returns
* [Cons](index)[A] val^
Public Functions
----------------
### size
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L248)
Returns the size of the list.
```
fun box size()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### apply
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L254)
Returns the i-th element of the list. Errors if the index is out of bounds.
```
fun box apply(
i: USize val)
: val->A ?
```
#### Parameters
* i: [USize](builtin-usize) val
#### Returns
* val->A ?
### values
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L263)
Returns an iterator over the elements of the list.
```
fun box values()
: Iterator[val->A] ref^
```
#### Returns
* [Iterator](builtin-iterator)[val->A] ref^
### is\_empty
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L273)
Returns a Bool indicating if the list is empty.
```
fun box is_empty()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### is\_non\_empty
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L279)
Returns a Bool indicating if the list is non-empty.
```
fun box is_non_empty()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### head
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L285)
Returns the head of the list.
```
fun box head()
: val->A
```
#### Returns
* val->A
### tail
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L291)
Returns the tail of the list.
```
fun box tail()
: (Cons[A] val | Nil[A] val)
```
#### Returns
* ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
### reverse
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L297)
Builds a new list by reversing the elements in the list.
```
fun val reverse()
: (Cons[A] val | Nil[A] val)
```
#### Returns
* ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
### prepend
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L313)
Builds a new list with an element added to the front of this list.
```
fun val prepend(
a: val->A!)
: Cons[A] val
```
#### Parameters
* a: val->A!
#### Returns
* [Cons](index)[A] val
### concat
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L319)
Builds a new list that is the concatenation of this list and the provided list.
```
fun val concat(
l: (Cons[A] val | Nil[A] val))
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* l: ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
#### Returns
* ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
### map[B: B]
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L336)
Builds a new list by applying a function to every member of the list.
```
fun val map[B: B](
f: {(val->A): val->B}[A, B] box)
: (Cons[B] val | Nil[B] val)
```
#### Parameters
* f: {(val->A): val->B}[A, B] box
#### Returns
* ([Cons](index)[B] val | [Nil](collections-persistent-nil)[B] val)
### flat\_map[B: B]
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L353)
Builds a new list by applying a function to every member of the list and using the elements of the resulting lists.
```
fun val flat_map[B: B](
f: {(val->A): List[B]}[A, B] box)
: (Cons[B] val | Nil[B] val)
```
#### Parameters
* f: {(val->A): List[B]}[A, B] box
#### Returns
* ([Cons](index)[B] val | [Nil](collections-persistent-nil)[B] val)
### for\_each
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L383)
Applies the supplied function to every element of the list in order.
```
fun val for_each(
f: {(val->A)}[A] box)
: None val
```
#### Parameters
* f: {(val->A)}[A] box
#### Returns
* [None](builtin-none) val
### filter
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L399)
Builds a new list with those elements that satisfy a provided predicate.
```
fun val filter(
f: {(val->A): Bool}[A] box)
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
### fold[B: B]
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L421)
Folds the elements of the list using the supplied function.
```
fun val fold[B: B](
f: {(B, val->A): B^}[A, B] box,
acc: B)
: B
```
#### Parameters
* f: {(B, val->A): B^}[A, B] box
* acc: B
#### Returns
* B
### every
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L438)
Returns true if every element satisfies the provided predicate, false otherwise.
```
fun val every(
f: {(val->A): Bool}[A] box)
: Bool val
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* [Bool](builtin-bool) val
### exists
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L462)
Returns true if at least one element satisfies the provided predicate, false otherwise.
```
fun val exists(
f: {(val->A): Bool}[A] box)
: Bool val
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* [Bool](builtin-bool) val
### partition
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L485)
Builds a pair of lists, the first of which is made up of the elements satisfying the supplied predicate and the second of which is made up of those that do not.
```
fun val partition(
f: {(val->A): Bool}[A] box)
: ((Cons[A] val | Nil[A] val) , (Cons[A] val | Nil[A] val))
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* (([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val) , ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val))
### drop
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L510)
Builds a list by dropping the first n elements.
```
fun val drop(
n: USize val)
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* n: [USize](builtin-usize) val
#### Returns
* ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
### drop\_while
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L526)
Builds a list by dropping elements from the front of the list until one fails to satisfy the provided predicate.
```
fun val drop_while(
f: {(val->A): Bool}[A] box)
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
### take
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L542)
Builds a list of the first n elements.
```
fun val take(
n: USize val)
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* n: [USize](builtin-usize) val
#### Returns
* ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
### take\_while
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L562)
Builds a list of elements satisfying the provided predicate until one does not.
```
fun val take_while(
f: {(val->A): Bool}[A] box)
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* ([Cons](index)[A] val | [Nil](collections-persistent-nil)[A] val)
pony ILong ILong
=====
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L372)
```
primitive val ILong is
SignedInteger[ILong val, ULong val] val
```
#### Implements
* [SignedInteger](builtin-signedinteger)[[ILong](index) val, [ULong](builtin-ulong) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L373)
```
new val create(
value: ILong val)
: ILong val^
```
#### Parameters
* value: [ILong](index) val
#### Returns
* [ILong](index) val^
### from[A: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](index) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[A] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L374)
```
new val from[A: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[A] val)](
a: A)
: ILong val^
```
#### Parameters
* a: A
#### Returns
* [ILong](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L376)
```
new val min_value()
: ILong val^
```
#### Returns
* [ILong](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L383)
```
new val max_value()
: ILong val^
```
#### Returns
* [ILong](index) val^
Public Functions
----------------
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L390)
```
fun box abs()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L392)
```
fun box bit_reverse()
: ILong val
```
#### Returns
* [ILong](index) val
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L399)
```
fun box bswap()
: ILong val
```
#### Returns
* [ILong](index) val
### popcount
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L406)
```
fun box popcount()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### clz
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L413)
```
fun box clz()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### ctz
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L420)
```
fun box ctz()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### clz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L427)
```
fun box clz_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### ctz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L434)
```
fun box ctz_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### bitwidth
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L441)
```
fun box bitwidth()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### bytewidth
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L443)
```
fun box bytewidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L445)
```
fun box min(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L446)
```
fun box max(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L448)
```
fun box fld(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L451)
```
fun box fld_unsafe(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L454)
```
fun box mod(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L457)
```
fun box mod_unsafe(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L460)
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L462)
```
fun box addc(
y: ILong val)
: (ILong val , Bool val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L469)
```
fun box subc(
y: ILong val)
: (ILong val , Bool val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L476)
```
fun box mulc(
y: ILong val)
: (ILong val , Bool val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L483)
```
fun box divc(
y: ILong val)
: (ILong val , Bool val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L486)
```
fun box remc(
y: ILong val)
: (ILong val , Bool val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [Bool](builtin-bool) val)
### fldc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L489)
```
fun box fldc(
y: ILong val)
: (ILong val , Bool val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [Bool](builtin-bool) val)
### modc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L492)
```
fun box modc(
y: ILong val)
: (ILong val , Bool val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [Bool](builtin-bool) val)
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L495)
```
fun box add_partial(
y: ILong val)
: ILong val ?
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L498)
```
fun box sub_partial(
y: ILong val)
: ILong val ?
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L501)
```
fun box mul_partial(
y: ILong val)
: ILong val ?
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L504)
```
fun box div_partial(
y: ILong val)
: ILong val ?
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L507)
```
fun box rem_partial(
y: ILong val)
: ILong val ?
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L510)
```
fun box divrem_partial(
y: ILong val)
: (ILong val , ILong val) ?
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [ILong](index) val) ?
### fld\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L513)
```
fun box fld_partial(
y: ILong val)
: ILong val ?
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val ?
### mod\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L516)
```
fun box mod_partial(
y: ILong val)
: ILong val ?
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val ?
### shl
```
fun box shl(
y: ULong val)
: ILong val
```
#### Parameters
* y: [ULong](builtin-ulong) val
#### Returns
* [ILong](index) val
### shr
```
fun box shr(
y: ULong val)
: ILong val
```
#### Parameters
* y: [ULong](builtin-ulong) val
#### Returns
* [ILong](index) val
### shl\_unsafe
```
fun box shl_unsafe(
y: ULong val)
: ILong val
```
#### Parameters
* y: [ULong](builtin-ulong) val
#### Returns
* [ILong](index) val
### shr\_unsafe
```
fun box shr_unsafe(
y: ULong val)
: ILong val
```
#### Parameters
* y: [ULong](builtin-ulong) val
#### Returns
* [ILong](index) val
### string
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add\_unsafe
```
fun box add_unsafe(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### sub\_unsafe
```
fun box sub_unsafe(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### mul\_unsafe
```
fun box mul_unsafe(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### div\_unsafe
```
fun box div_unsafe(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### divrem\_unsafe
```
fun box divrem_unsafe(
y: ILong val)
: (ILong val , ILong val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [ILong](index) val)
### rem\_unsafe
```
fun box rem_unsafe(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### neg\_unsafe
```
fun box neg_unsafe()
: ILong val
```
#### Returns
* [ILong](index) val
### op\_and
```
fun box op_and(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### op\_or
```
fun box op_or(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### op\_xor
```
fun box op_xor(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### op\_not
```
fun box op_not()
: ILong val
```
#### Returns
* [ILong](index) val
### add
```
fun box add(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### sub
```
fun box sub(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### mul
```
fun box mul(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### div
```
fun box div(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### divrem
```
fun box divrem(
y: ILong val)
: (ILong val , ILong val)
```
#### Parameters
* y: [ILong](index) val
#### Returns
* ([ILong](index) val , [ILong](index) val)
### rem
```
fun box rem(
y: ILong val)
: ILong val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [ILong](index) val
### neg
```
fun box neg()
: ILong val
```
#### Returns
* [ILong](index) val
### eq
```
fun box eq(
y: ILong val)
: Bool val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
```
fun box ne(
y: ILong val)
: Bool val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
```
fun box lt(
y: ILong val)
: Bool val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [Bool](builtin-bool) val
### le
```
fun box le(
y: ILong val)
: Bool val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
```
fun box ge(
y: ILong val)
: Bool val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
```
fun box gt(
y: ILong val)
: Bool val
```
#### Parameters
* y: [ILong](index) val
#### Returns
* [Bool](builtin-bool) val
### hash64
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i8
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](index) val
### isize
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](index) val
### isize\_unsafe
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: ILong val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [ILong](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony Int Int
===
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L716)
```
type Int is
(I8 val | I16 val | I32 val | I64 val | I128 val | ILong val | ISize val | U8 val | U16 val | U32 val | U64 val | U128 val | ULong val | USize val)
```
#### Type Alias For
* ([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val)
pony FormatExp FormatExp
=========
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L27)
```
primitive val FormatExp is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L27)
```
new val create()
: FormatExp val^
```
#### Returns
* [FormatExp](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L28)
```
fun box eq(
that: FormatExp val)
: Bool val
```
#### Parameters
* that: [FormatExp](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L28)
```
fun box ne(
that: FormatExp val)
: Bool val
```
#### Parameters
* that: [FormatExp](index) val
#### Returns
* [Bool](builtin-bool) val
pony DefaultLogFormatter DefaultLogFormatter
===================
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L154)
```
primitive val DefaultLogFormatter is
LogFormatter val
```
#### Implements
* [LogFormatter](logger-logformatter) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L154)
```
new val create()
: DefaultLogFormatter val^
```
#### Returns
* [DefaultLogFormatter](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L155)
```
fun box apply(
msg: String val,
loc: SourceLoc val)
: String val
```
#### Parameters
* msg: [String](builtin-string) val
* loc: [SourceLoc](builtin-sourceloc) val
#### Returns
* [String](builtin-string) val
### eq
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L155)
```
fun box eq(
that: DefaultLogFormatter val)
: Bool val
```
#### Parameters
* that: [DefaultLogFormatter](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L155)
```
fun box ne(
that: DefaultLogFormatter val)
: Bool val
```
#### Parameters
* that: [DefaultLogFormatter](index) val
#### Returns
* [Bool](builtin-bool) val
pony FileChmod FileChmod
=========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L6)
```
primitive val FileChmod
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L6)
```
new val create()
: FileChmod val^
```
#### Returns
* [FileChmod](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L7)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L7)
```
fun box eq(
that: FileChmod val)
: Bool val
```
#### Parameters
* that: [FileChmod](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L7)
```
fun box ne(
that: FileChmod val)
: Bool val
```
#### Parameters
* that: [FileChmod](index) val
#### Returns
* [Bool](builtin-bool) val
pony StdStream StdStream
=========
[[Source]](https://stdlib.ponylang.io/src/builtin/std_stream/#L38)
Asynchronous access to stdout and stderr. The constructors are private to ensure that access is provided only via an environment.
```
actor tag StdStream
```
Public Behaviours
-----------------
### print
[[Source]](https://stdlib.ponylang.io/src/builtin/std_stream/#L57)
Print some bytes and insert a newline afterwards.
```
be print(
data: (String val | Array[U8 val] val))
```
#### Parameters
* data: ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
### write
[[Source]](https://stdlib.ponylang.io/src/builtin/std_stream/#L63)
Print some bytes without inserting a newline afterwards.
```
be write(
data: (String val | Array[U8 val] val))
```
#### Parameters
* data: ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
### printv
[[Source]](https://stdlib.ponylang.io/src/builtin/std_stream/#L69)
Print an iterable collection of ByteSeqs.
```
be printv(
data: ByteSeqIter val)
```
#### Parameters
* data: [ByteSeqIter](builtin-byteseqiter) val
### writev
[[Source]](https://stdlib.ponylang.io/src/builtin/std_stream/#L77)
Write an iterable collection of ByteSeqs.
```
be writev(
data: ByteSeqIter val)
```
#### Parameters
* data: [ByteSeqIter](builtin-byteseqiter) val
### flush
[[Source]](https://stdlib.ponylang.io/src/builtin/std_stream/#L85)
Flush any data out to the os (ignoring failures).
```
be flush()
```
pony Timers Timers
======
[[Source]](https://stdlib.ponylang.io/src/time/timers/#L13)
A hierarchical set of timing wheels.
```
actor tag Timers
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/time/timers/#L24)
Create a timer handler with the specified number of slop bits. No slop bits means trying for nanosecond resolution. 10 slop bits is approximately microsecond resolution, 20 slop bits is approximately millisecond resolution.
```
new tag create(
slop: USize val = 20)
: Timers tag^
```
#### Parameters
* slop: [USize](builtin-usize) val = 20
#### Returns
* [Timers](index) tag^
Public Behaviours
-----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/time/timers/#L38)
Sets a timer. Fire it if need be, schedule it on the right timing wheel, then rearm the timer.
```
be apply(
timer: Timer iso)
```
#### Parameters
* timer: [Timer](time-timer) iso
### cancel
[[Source]](https://stdlib.ponylang.io/src/time/timers/#L49)
Cancels a timer.
```
be cancel(
timer: Timer tag)
```
#### Parameters
* timer: [Timer](time-timer) tag
### dispose
[[Source]](https://stdlib.ponylang.io/src/time/timers/#L64)
Dispose of this set of timing wheels.
```
be dispose()
```
pony ProcessError ProcessError
============
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L1)
```
class val ProcessError
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L5)
```
new val create(
error_type': (ExecveError val | PipeError val | ForkError val |
WaitpidError val | WriteError val | KillError val |
CapError val | ChdirError val | UnknownError val),
message': (String val | None val) = reference)
: ProcessError val^
```
#### Parameters
* error\_type': ([ExecveError](process-execveerror) val | [PipeError](process-pipeerror) val | [ForkError](process-forkerror) val | [WaitpidError](process-waitpiderror) val | [WriteError](process-writeerror) val | [KillError](process-killerror) val | [CapError](process-caperror) val | [ChdirError](process-chdirerror) val | [UnknownError](process-unknownerror) val)
* message': ([String](builtin-string) val | [None](builtin-none) val) = reference
#### Returns
* [ProcessError](index) val^
Public fields
-------------
### let error\_type: ([ExecveError](process-execveerror) val | [PipeError](process-pipeerror) val | [ForkError](process-forkerror) val |
```
[WaitpidError](process-WaitpidError.md) val | [WriteError](process-WriteError.md) val | [KillError](process-KillError.md) val |
[CapError](process-CapError.md) val | [ChdirError](process-ChdirError.md) val | [UnknownError](process-UnknownError.md) val)
```
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L2)
### let message: ([String](builtin-string) val | [None](builtin-none) val)
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L3)
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L11)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
pony ANSINotify ANSINotify
==========
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L1)
Receive input from an ANSITerm.
```
interface ref ANSINotify
```
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L5)
```
fun ref apply(
term: ANSITerm ref,
input: U8 val)
: None val
```
#### Parameters
* term: [ANSITerm](term-ansiterm) ref
* input: [U8](builtin-u8) val
#### Returns
* [None](builtin-none) val
### up
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L8)
```
fun ref up(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### down
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L11)
```
fun ref down(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### left
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L14)
```
fun ref left(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### right
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L17)
```
fun ref right(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### delete
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L20)
```
fun ref delete(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### insert
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L23)
```
fun ref insert(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### home
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L26)
```
fun ref home(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### end\_key
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L29)
```
fun ref end_key(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### page\_up
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L32)
```
fun ref page_up(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### page\_down
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L35)
```
fun ref page_down(
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### fn\_key
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L38)
```
fun ref fn_key(
i: U8 val,
ctrl: Bool val,
alt: Bool val,
shift: Bool val)
: None val
```
#### Parameters
* i: [U8](builtin-u8) val
* ctrl: [Bool](builtin-bool) val
* alt: [Bool](builtin-bool) val
* shift: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### prompt
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L41)
```
fun ref prompt(
term: ANSITerm ref,
value: String val)
: None val
```
#### Parameters
* term: [ANSITerm](term-ansiterm) ref
* value: [String](builtin-string) val
#### Returns
* [None](builtin-none) val
### size
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L44)
```
fun ref size(
rows: U16 val,
cols: U16 val)
: None val
```
#### Parameters
* rows: [U16](builtin-u16) val
* cols: [U16](builtin-u16) val
#### Returns
* [None](builtin-none) val
### closed
[[Source]](https://stdlib.ponylang.io/src/term/ansi_notify/#L47)
```
fun ref closed()
: None val
```
#### Returns
* [None](builtin-none) val
pony Time Time
====
[[Source]](https://stdlib.ponylang.io/src/time/time/#L38)
A collection of ways to fetch the current time.
```
primitive val Time
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/time/time/#L38)
```
new val create()
: Time val^
```
#### Returns
* [Time](index) val^
Public Functions
----------------
### now
[[Source]](https://stdlib.ponylang.io/src/time/time/#L42)
The wall-clock adjusted system time with nanoseconds. Return: (seconds, nanoseconds)
```
fun box now()
: (I64 val , I64 val)
```
#### Returns
* ([I64](builtin-i64) val , [I64](builtin-i64) val)
### seconds
[[Source]](https://stdlib.ponylang.io/src/time/time/#L65)
The wall-clock adjusted system time.
```
fun box seconds()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### millis
[[Source]](https://stdlib.ponylang.io/src/time/time/#L71)
Monotonic unadjusted milliseconds.
```
fun box millis()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### micros
[[Source]](https://stdlib.ponylang.io/src/time/time/#L87)
Monotonic unadjusted microseconds.
```
fun box micros()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### nanos
[[Source]](https://stdlib.ponylang.io/src/time/time/#L103)
Monotonic unadjusted nanoseconds.
```
fun box nanos()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### cycles
[[Source]](https://stdlib.ponylang.io/src/time/time/#L119)
Processor cycle count. Don't use this for performance timing, as it does not control for out-of-order execution.
```
fun box cycles()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### perf\_begin
[[Source]](https://stdlib.ponylang.io/src/time/time/#L126)
Get a cycle count for beginning a performance testing block. This will will prevent instructions from before this call leaking into the block and instructions after this call being executed earlier.
```
fun box perf_begin()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### perf\_end
[[Source]](https://stdlib.ponylang.io/src/time/time/#L139)
Get a cycle count for ending a performance testing block. This will will prevent instructions from after this call leaking into the block and instructions before this call being executed later.
```
fun box perf_end()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### eq
[[Source]](https://stdlib.ponylang.io/src/time/time/#L42)
```
fun box eq(
that: Time val)
: Bool val
```
#### Parameters
* that: [Time](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/time/time/#L42)
```
fun box ne(
that: Time val)
: Bool val
```
#### Parameters
* that: [Time](index) val
#### Returns
* [Bool](builtin-bool) val
pony AsyncMicroBenchmark AsyncMicroBenchmark
===================
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L28)
Asynchronous benchmarks must provide this trait. The `apply` method defines a single iteration in a sample. Each phase of the sample completes when the given `AsyncBenchContinue` has its `complete` method invoked. Setup and Teardown are defined by the `before` and `after` methods respectively. The `before` method runs before a sample of benchmarks and `after` runs after the all iterations in the sample have completed. If your benchmark requires setup and/or teardown to occur beween each iteration of the benchmark, then you can use `before_iteration` and `after_iteration` methods respectively that run before/after each iteration.
```
trait iso AsyncMicroBenchmark
```
Public Functions
----------------
### name
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L40)
```
fun box name()
: String val
```
#### Returns
* [String](builtin-string) val
### config
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L41)
```
fun box config()
: BenchConfig val
```
#### Returns
* [BenchConfig](ponybench-benchconfig) val
### overhead
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L42)
```
fun box overhead()
: AsyncMicroBenchmark iso^
```
#### Returns
* [AsyncMicroBenchmark](index) iso^
### before
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L43)
```
fun ref before(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
### before\_iteration
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L44)
```
fun ref before_iteration(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
### apply
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L45)
```
fun ref apply(
c: AsyncBenchContinue val)
: None val ?
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val ?
### after
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L46)
```
fun ref after(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
### after\_iteration
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L47)
```
fun ref after_iteration(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
pony Format package Format package
==============
The Format package provides support for formatting strings. It can be used to set things like width, padding and alignment, as well as controlling the way numbers are displayed (decimal, octal, hexadecimal).
Example program
===============
```
use "format"
actor Main
fun disp(desc: String, v: I32, fmt: FormatInt = FormatDefault): String =>
Format(desc where width = 10)
+ ":"
+ Format.int[I32](v where width = 10, align = AlignRight, fmt = fmt)
new create(env: Env) =>
try
(let x, let y) = (env.args(1)?.i32()?, env.args(2)?.i32()?)
env.out.print(disp("x", x))
env.out.print(disp("y", y))
env.out.print(disp("hex(x)", x, FormatHex))
env.out.print(disp("hex(y)", y, FormatHex))
env.out.print(disp("x * y", x * y))
else
let exe = try env.args(0)? else "fmt_example" end
env.err.print("Usage: " + exe + " NUMBER1 NUMBER2")
end
```
Public Types
------------
* [trait PrefixSpec](format-prefixspec)
* [primitive PrefixDefault](format-prefixdefault)
* [primitive PrefixSpace](format-prefixspace)
* [primitive PrefixSign](format-prefixsign)
* [type PrefixNumber](format-prefixnumber)
* [trait FormatSpec](format-formatspec)
* [primitive FormatDefault](format-formatdefault)
* [primitive FormatUTF32](format-formatutf32)
* [primitive FormatBinary](format-formatbinary)
* [primitive FormatBinaryBare](format-formatbinarybare)
* [primitive FormatOctal](format-formatoctal)
* [primitive FormatOctalBare](format-formatoctalbare)
* [primitive FormatHex](format-formathex)
* [primitive FormatHexBare](format-formathexbare)
* [primitive FormatHexSmall](format-formathexsmall)
* [primitive FormatHexSmallBare](format-formathexsmallbare)
* [type FormatInt](format-formatint)
* [primitive FormatExp](format-formatexp)
* [primitive FormatExpLarge](format-formatexplarge)
* [primitive FormatFix](format-formatfix)
* [primitive FormatFixLarge](format-formatfixlarge)
* [primitive FormatGeneral](format-formatgeneral)
* [primitive FormatGeneralLarge](format-formatgenerallarge)
* [type FormatFloat](format-formatfloat)
* [primitive Format](format-format)
* [primitive AlignLeft](format-alignleft)
* [primitive AlignRight](format-alignright)
* [primitive AlignCenter](format-aligncenter)
* [type Align](format-align)
| programming_docs |
pony XorOshiro128Plus XorOshiro128Plus
================
[[Source]](https://stdlib.ponylang.io/src/random/xoroshiro/#L1)
This is an implementation of xoroshiro128+, as detailed at:
http://xoroshiro.di.unimi.it
This is currently the default Rand implementation.
```
class ref XorOshiro128Plus is
Random ref
```
#### Implements
* [Random](random-random) ref
Constructors
------------
### from\_u64
[[Source]](https://stdlib.ponylang.io/src/random/xoroshiro/#L13)
Use seed x to seed a [SplitMix64](random-splitmix64) and use this to initialize the 128 bits of state.
```
new ref from_u64(
x: U64 val = 5489)
: XorOshiro128Plus ref^
```
#### Parameters
* x: [U64](builtin-u64) val = 5489
#### Returns
* [XorOshiro128Plus](index) ref^
### create
[[Source]](https://stdlib.ponylang.io/src/random/xoroshiro/#L22)
Create with the specified seed. Returned values are deterministic for a given seed.
```
new ref create(
x: U64 val = 5489,
y: U64 val = 0)
: XorOshiro128Plus ref^
```
#### Parameters
* x: [U64](builtin-u64) val = 5489
* y: [U64](builtin-u64) val = 0
#### Returns
* [XorOshiro128Plus](index) ref^
Public Functions
----------------
### next
[[Source]](https://stdlib.ponylang.io/src/random/xoroshiro/#L31)
A random integer in [0, 2^64)
```
fun ref next()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### has\_next
```
fun tag has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### u8
```
fun ref u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
```
fun ref u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
```
fun ref u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun ref u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
```
fun ref u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun ref ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun ref usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### i8
```
fun ref i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
```
fun ref i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
```
fun ref i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun ref i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun ref i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun ref ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
```
fun ref isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### int\_fp\_mult[optional N: (([U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val) & [Real](builtin-real)[N] val)]
```
fun ref int_fp_mult[optional N: ((U8 val | U16 val | U32 val |
U64 val | U128 val | ULong val |
USize val) & Real[N] val)](
n: N)
: N
```
#### Parameters
* n: N
#### Returns
* N
### int[optional N: (([U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val) & [Real](builtin-real)[N] val)]
```
fun ref int[optional N: ((U8 val | U16 val | U32 val |
U64 val | U128 val | ULong val |
USize val) & Real[N] val)](
n: N)
: N
```
#### Parameters
* n: N
#### Returns
* N
### int\_unbiased[optional N: (([U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val) & [Real](builtin-real)[N] val)]
```
fun ref int_unbiased[optional N: ((U8 val | U16 val | U32 val |
U64 val | U128 val | ULong val |
USize val) & Real[N] val)](
n: N)
: N
```
#### Parameters
* n: N
#### Returns
* N
### real
```
fun ref real()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### shuffle[A: A]
```
fun ref shuffle[A: A](
array: Array[A] ref)
: None val
```
#### Parameters
* array: [Array](builtin-array)[A] ref
#### Returns
* [None](builtin-none) val
pony U8 U8
==
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L1)
```
primitive val U8 is
UnsignedInteger[U8 val] val
```
#### Implements
* [UnsignedInteger](builtin-unsignedinteger)[[U8](index) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L2)
```
new val create(
value: U8 val)
: U8 val^
```
#### Parameters
* value: [U8](index) val
#### Returns
* [U8](index) val^
### from[B: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](index) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[B] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L3)
```
new val from[B: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[B] val)](
a: B)
: U8 val^
```
#### Parameters
* a: B
#### Returns
* [U8](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L5)
```
new val min_value()
: U8 val^
```
#### Returns
* [U8](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L6)
```
new val max_value()
: U8 val^
```
#### Returns
* [U8](index) val^
Public Functions
----------------
### next\_pow2
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L8)
```
fun box next_pow2()
: U8 val
```
#### Returns
* [U8](index) val
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L12)
```
fun box abs()
: U8 val
```
#### Returns
* [U8](index) val
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L13)
```
fun box bit_reverse()
: U8 val
```
#### Returns
* [U8](index) val
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L14)
```
fun box bswap()
: U8 val
```
#### Returns
* [U8](index) val
### popcount
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L15)
```
fun box popcount()
: U8 val
```
#### Returns
* [U8](index) val
### clz
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L16)
```
fun box clz()
: U8 val
```
#### Returns
* [U8](index) val
### ctz
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L17)
```
fun box ctz()
: U8 val
```
#### Returns
* [U8](index) val
### clz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L19)
Unsafe operation. If this is 0, the result is undefined.
```
fun box clz_unsafe()
: U8 val
```
#### Returns
* [U8](index) val
### ctz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L26)
Unsafe operation. If this is 0, the result is undefined.
```
fun box ctz_unsafe()
: U8 val
```
#### Returns
* [U8](index) val
### bitwidth
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L33)
```
fun box bitwidth()
: U8 val
```
#### Returns
* [U8](index) val
### bytewidth
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L35)
```
fun box bytewidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L37)
```
fun box min(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L38)
```
fun box max(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L40)
```
fun box addc(
y: U8 val)
: (U8 val , Bool val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L43)
```
fun box subc(
y: U8 val)
: (U8 val , Bool val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L46)
```
fun box mulc(
y: U8 val)
: (U8 val , Bool val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L49)
```
fun box divc(
y: U8 val)
: (U8 val , Bool val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L52)
```
fun box remc(
y: U8 val)
: (U8 val , Bool val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [Bool](builtin-bool) val)
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L55)
```
fun box add_partial(
y: U8 val)
: U8 val ?
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L58)
```
fun box sub_partial(
y: U8 val)
: U8 val ?
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L61)
```
fun box mul_partial(
y: U8 val)
: U8 val ?
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L64)
```
fun box div_partial(
y: U8 val)
: U8 val ?
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L67)
```
fun box rem_partial(
y: U8 val)
: U8 val ?
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L70)
```
fun box divrem_partial(
y: U8 val)
: (U8 val , U8 val) ?
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [U8](index) val) ?
### shl
```
fun box shl(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### shr
```
fun box shr(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### fld
```
fun box fld(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### fldc
```
fun box fldc(
y: U8 val)
: (U8 val , Bool val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [Bool](builtin-bool) val)
### fld\_partial
```
fun box fld_partial(
y: U8 val)
: U8 val ?
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val ?
### fld\_unsafe
```
fun box fld_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### mod
```
fun box mod(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### modc
```
fun box modc(
y: U8 val)
: (U8 val , Bool val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [Bool](builtin-bool) val)
### mod\_partial
```
fun box mod_partial(
y: U8 val)
: U8 val ?
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val ?
### mod\_unsafe
```
fun box mod_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### shl\_unsafe
```
fun box shl_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### shr\_unsafe
```
fun box shr_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### rotl
```
fun box rotl(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### rotr
```
fun box rotr(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### string
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add\_unsafe
```
fun box add_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### sub\_unsafe
```
fun box sub_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### mul\_unsafe
```
fun box mul_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### div\_unsafe
```
fun box div_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### divrem\_unsafe
```
fun box divrem_unsafe(
y: U8 val)
: (U8 val , U8 val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [U8](index) val)
### rem\_unsafe
```
fun box rem_unsafe(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### neg\_unsafe
```
fun box neg_unsafe()
: U8 val
```
#### Returns
* [U8](index) val
### op\_and
```
fun box op_and(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### op\_or
```
fun box op_or(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### op\_xor
```
fun box op_xor(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### op\_not
```
fun box op_not()
: U8 val
```
#### Returns
* [U8](index) val
### add
```
fun box add(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### sub
```
fun box sub(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### mul
```
fun box mul(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### div
```
fun box div(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### divrem
```
fun box divrem(
y: U8 val)
: (U8 val , U8 val)
```
#### Parameters
* y: [U8](index) val
#### Returns
* ([U8](index) val , [U8](index) val)
### rem
```
fun box rem(
y: U8 val)
: U8 val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [U8](index) val
### neg
```
fun box neg()
: U8 val
```
#### Returns
* [U8](index) val
### eq
```
fun box eq(
y: U8 val)
: Bool val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
```
fun box ne(
y: U8 val)
: Bool val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
```
fun box lt(
y: U8 val)
: Bool val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [Bool](builtin-bool) val
### le
```
fun box le(
y: U8 val)
: Bool val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
```
fun box ge(
y: U8 val)
: Bool val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
```
fun box gt(
y: U8 val)
: Bool val
```
#### Parameters
* y: [U8](index) val
#### Returns
* [Bool](builtin-bool) val
### hash
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i8
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
```
fun box u8()
: U8 val
```
#### Returns
* [U8](index) val
### u16
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](index) val
### u16\_unsafe
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: U8 val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [U8](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
pony AsyncOverheadBenchmark AsyncOverheadBenchmark
======================
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L90)
Default benchmark for measuring asynchronous overhead.
```
class iso AsyncOverheadBenchmark is
AsyncMicroBenchmark iso
```
#### Implements
* [AsyncMicroBenchmark](ponybench-asyncmicrobenchmark) iso
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L90)
```
new iso create()
: AsyncOverheadBenchmark iso^
```
#### Returns
* [AsyncOverheadBenchmark](index) iso^
Public Functions
----------------
### name
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L94)
```
fun box name()
: String val
```
#### Returns
* [String](builtin-string) val
### apply
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L97)
```
fun ref apply(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
### config
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L41)
```
fun box config()
: BenchConfig val
```
#### Returns
* [BenchConfig](ponybench-benchconfig) val
### overhead
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L42)
```
fun box overhead()
: AsyncMicroBenchmark iso^
```
#### Returns
* [AsyncMicroBenchmark](ponybench-asyncmicrobenchmark) iso^
### before
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L43)
```
fun ref before(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
### before\_iteration
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L44)
```
fun ref before_iteration(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
### after
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L46)
```
fun ref after(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
### after\_iteration
[[Source]](https://stdlib.ponylang.io/src/ponybench/benchmark/#L47)
```
fun ref after_iteration(
c: AsyncBenchContinue val)
: None val
```
#### Parameters
* c: [AsyncBenchContinue](ponybench-asyncbenchcontinue) val
#### Returns
* [None](builtin-none) val
| programming_docs |
pony AsioEventID AsioEventID
===========
[[Source]](https://stdlib.ponylang.io/src/builtin/asio_event/#L1)
```
type AsioEventID is
Pointer[AsioEvent val] tag
```
#### Type Alias For
* [Pointer](builtin-pointer)[[AsioEvent](builtin-asioevent) val] tag
pony Logger[A: A] Logger[A: A]
============
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L110)
```
class val Logger[A: A]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L116)
```
new val create(
level: (Fine val | Info val | Warn val |
Error val),
out: OutStream tag,
f: {(A): String}[A] val,
formatter: LogFormatter val = reference)
: Logger[A] val^
```
#### Parameters
* level: ([Fine](logger-fine) val | [Info](logger-info) val | [Warn](logger-warn) val | [Error](logger-error) val)
* out: [OutStream](builtin-outstream) tag
* f: {(A): String}[A] val
* formatter: [LogFormatter](logger-logformatter) val = reference
#### Returns
* [Logger](index)[A] val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L127)
```
fun box apply(
level: (Fine val | Info val | Warn val |
Error val))
: Bool val
```
#### Parameters
* level: ([Fine](logger-fine) val | [Info](logger-info) val | [Warn](logger-warn) val | [Error](logger-error) val)
#### Returns
* [Bool](builtin-bool) val
### log
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L130)
```
fun box log(
value: A,
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* value: A
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
pony F64 F64
===
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L218)
```
primitive val F64 is
FloatingPoint[F64 val] val
```
#### Implements
* [FloatingPoint](builtin-floatingpoint)[[F64](index) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L219)
```
new val create(
value: F64 val = 0)
: F64 val^
```
#### Parameters
* value: [F64](index) val = 0
#### Returns
* [F64](index) val^
### pi
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L220)
```
new val pi()
: F64 val^
```
#### Returns
* [F64](index) val^
### e
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L221)
```
new val e()
: F64 val^
```
#### Returns
* [F64](index) val^
### from\_bits
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L226)
```
new val from_bits(
i: U64 val)
: F64 val^
```
#### Parameters
* i: [U64](builtin-u64) val
#### Returns
* [F64](index) val^
### from[B: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](index) val) & [Real](builtin-real)[B] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L228)
```
new val from[B: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[B] val)](
a: B)
: F64 val^
```
#### Parameters
* a: B
#### Returns
* [F64](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L230)
Minimum negative value representable.
```
new val min_value()
: F64 val^
```
#### Returns
* [F64](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L236)
Maximum positive value representable.
```
new val max_value()
: F64 val^
```
#### Returns
* [F64](index) val^
### min\_normalised
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L242)
Minimum positive value representable at full precision (ie a normalised number).
```
new val min_normalised()
: F64 val^
```
#### Returns
* [F64](index) val^
### epsilon
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L249)
Minimum positive value such that (1 + epsilon) != 1.
```
new val epsilon()
: F64 val^
```
#### Returns
* [F64](index) val^
Public Functions
----------------
### bits
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L227)
```
fun box bits()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### radix
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L255)
Exponent radix.
```
fun tag radix()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### precision2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L261)
Mantissa precision in bits.
```
fun tag precision2()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### precision10
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L267)
Mantissa precision in decimal digits.
```
fun tag precision10()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### min\_exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L273)
Minimum exponent value such that (2^exponent) - 1 is representable at full precision (ie a normalised number).
```
fun tag min_exp2()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### min\_exp10
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L280)
Minimum exponent value such that (10^exponent) - 1 is representable at full precision (ie a normalised number).
```
fun tag min_exp10()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### max\_exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L287)
Maximum exponent value such that (2^exponent) - 1 is representable.
```
fun tag max_exp2()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### max\_exp10
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L293)
Maximum exponent value such that (10^exponent) - 1 is representable.
```
fun tag max_exp10()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L299)
```
fun box abs()
: F64 val
```
#### Returns
* [F64](index) val
### ceil
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L300)
```
fun box ceil()
: F64 val
```
#### Returns
* [F64](index) val
### floor
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L301)
```
fun box floor()
: F64 val
```
#### Returns
* [F64](index) val
### round
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L302)
```
fun box round()
: F64 val
```
#### Returns
* [F64](index) val
### trunc
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L303)
```
fun box trunc()
: F64 val
```
#### Returns
* [F64](index) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L305)
```
fun box min(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L306)
```
fun box max(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L308)
```
fun box fld(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L311)
```
fun box fld_unsafe(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L314)
```
fun box mod(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L324)
```
fun box mod_unsafe(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### finite
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L334)
Check whether this number is finite, ie not +/-infinity and not NaN.
```
fun box finite()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### infinite
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L341)
Check whether this number is +/-infinity
```
fun box infinite()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### nan
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L349)
Check whether this number is NaN.
```
fun box nan()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### ldexp
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L357)
```
fun box ldexp(
x: F64 val,
exponent: I32 val)
: F64 val
```
#### Parameters
* x: [F64](index) val
* exponent: [I32](builtin-i32) val
#### Returns
* [F64](index) val
### frexp
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L360)
```
fun box frexp()
: (F64 val , U32 val)
```
#### Returns
* ([F64](index) val , [U32](builtin-u32) val)
### log
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L365)
```
fun box log()
: F64 val
```
#### Returns
* [F64](index) val
### log2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L366)
```
fun box log2()
: F64 val
```
#### Returns
* [F64](index) val
### log10
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L367)
```
fun box log10()
: F64 val
```
#### Returns
* [F64](index) val
### logb
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L368)
```
fun box logb()
: F64 val
```
#### Returns
* [F64](index) val
### pow
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L370)
```
fun box pow(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### powi
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L371)
```
fun box powi(
y: I32 val)
: F64 val
```
#### Parameters
* y: [I32](builtin-i32) val
#### Returns
* [F64](index) val
### sqrt
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L378)
```
fun box sqrt()
: F64 val
```
#### Returns
* [F64](index) val
### sqrt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L385)
Unsafe operation. If this is negative, the result is undefined.
```
fun box sqrt_unsafe()
: F64 val
```
#### Returns
* [F64](index) val
### cbrt
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L392)
```
fun box cbrt()
: F64 val
```
#### Returns
* [F64](index) val
### exp
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L393)
```
fun box exp()
: F64 val
```
#### Returns
* [F64](index) val
### exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L394)
```
fun box exp2()
: F64 val
```
#### Returns
* [F64](index) val
### cos
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L396)
```
fun box cos()
: F64 val
```
#### Returns
* [F64](index) val
### sin
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L397)
```
fun box sin()
: F64 val
```
#### Returns
* [F64](index) val
### tan
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L398)
```
fun box tan()
: F64 val
```
#### Returns
* [F64](index) val
### cosh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L400)
```
fun box cosh()
: F64 val
```
#### Returns
* [F64](index) val
### sinh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L401)
```
fun box sinh()
: F64 val
```
#### Returns
* [F64](index) val
### tanh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L402)
```
fun box tanh()
: F64 val
```
#### Returns
* [F64](index) val
### acos
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L404)
```
fun box acos()
: F64 val
```
#### Returns
* [F64](index) val
### asin
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L405)
```
fun box asin()
: F64 val
```
#### Returns
* [F64](index) val
### atan
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L406)
```
fun box atan()
: F64 val
```
#### Returns
* [F64](index) val
### atan2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L407)
```
fun box atan2(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### acosh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L409)
```
fun box acosh()
: F64 val
```
#### Returns
* [F64](index) val
### asinh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L410)
```
fun box asinh()
: F64 val
```
#### Returns
* [F64](index) val
### atanh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L411)
```
fun box atanh()
: F64 val
```
#### Returns
* [F64](index) val
### copysign
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L413)
```
fun box copysign(
sign: F64 val)
: F64 val
```
#### Parameters
* sign: [F64](index) val
#### Returns
* [F64](index) val
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L415)
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L416)
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i128
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L418)
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### u128
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L445)
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### i128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L471)
Unsafe operation. If the value doesn't fit in the destination type, the result is undefined.
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### u128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L478)
Unsafe operation. If the value doesn't fit in the destination type, the result is undefined.
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### add\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L527)
```
fun box add_unsafe(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### sub\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L536)
```
fun box sub_unsafe(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### mul\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L545)
```
fun box mul_unsafe(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### div\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L554)
```
fun box div_unsafe(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### divrem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L571)
```
fun box divrem_unsafe(
y: F64 val)
: (F64 val , F64 val)
```
#### Parameters
* y: [F64](index) val
#### Returns
* ([F64](index) val , [F64](index) val)
### rem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L580)
```
fun box rem_unsafe(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### neg\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L597)
```
fun box neg_unsafe()
: F64 val
```
#### Returns
* [F64](index) val
### eq\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L606)
```
fun box eq_unsafe(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### ne\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L615)
```
fun box ne_unsafe(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### lt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L624)
```
fun box lt_unsafe(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### le\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L633)
```
fun box le_unsafe(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### ge\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L642)
```
fun box ge_unsafe(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### gt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L651)
```
fun box gt_unsafe(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L711)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L141)
```
fun box add(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### sub
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L142)
```
fun box sub(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### mul
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L143)
```
fun box mul(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### div
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L144)
```
fun box div(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### divrem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L150)
```
fun box divrem(
y: F64 val)
: (F64 val , F64 val)
```
#### Parameters
* y: [F64](index) val
#### Returns
* ([F64](index) val , [F64](index) val)
### rem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L151)
```
fun box rem(
y: F64 val)
: F64 val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [F64](index) val
### neg
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L159)
```
fun box neg()
: F64 val
```
#### Returns
* [F64](index) val
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L172)
```
fun box eq(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L173)
```
fun box ne(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L174)
```
fun box lt(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### le
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L175)
```
fun box le(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L176)
```
fun box ge(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L177)
```
fun box gt(
y: F64 val)
: Bool val
```
#### Parameters
* y: [F64](index) val
#### Returns
* [Bool](builtin-bool) val
### i8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L2)
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L3)
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L4)
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L5)
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### ilong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L7)
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L8)
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L10)
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L11)
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L12)
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L13)
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### ulong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L15)
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L16)
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L18)
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L19)
```
fun box f64()
: F64 val
```
#### Returns
* [F64](index) val
### i8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L21)
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L28)
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L35)
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L42)
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### ilong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L56)
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L63)
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L70)
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L77)
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L84)
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L91)
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### ulong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L105)
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L112)
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L119)
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L126)
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](index) val
### compare
```
fun box compare(
that: F64 val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [F64](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony StringRunes StringRunes
===========
[[Source]](https://stdlib.ponylang.io/src/builtin/string/#L1697)
```
class ref StringRunes is
Iterator[U32 val] ref
```
#### Implements
* [Iterator](builtin-iterator)[[U32](builtin-u32) val] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/string/#L1701)
```
new ref create(
string: String box)
: StringRunes ref^
```
#### Parameters
* string: [String](builtin-string) box
#### Returns
* [StringRunes](index) ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/builtin/string/#L1705)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/builtin/string/#L1708)
```
fun ref next()
: U32 val ?
```
#### Returns
* [U32](builtin-u32) val ?
pony UDPAuth UDPAuth
=======
[[Source]](https://stdlib.ponylang.io/src/net/auth/#L9)
```
primitive val UDPAuth
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/net/auth/#L10)
```
new val create(
from: (AmbientAuth val | NetAuth val))
: UDPAuth val^
```
#### Parameters
* from: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val)
#### Returns
* [UDPAuth](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/net/auth/#L10)
```
fun box eq(
that: UDPAuth val)
: Bool val
```
#### Parameters
* that: [UDPAuth](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/net/auth/#L10)
```
fun box ne(
that: UDPAuth val)
: Bool val
```
#### Parameters
* that: [UDPAuth](index) val
#### Returns
* [Bool](builtin-bool) val
pony Sig Sig
===
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L51)
Define the portable signal numbers. Other signals can be used, but they are not guaranteed to be portable.
```
primitive val Sig
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L51)
```
new val create()
: Sig val^
```
#### Returns
* [Sig](index) val^
Public Functions
----------------
### hup
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L56)
```
fun box hup()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### int
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L57)
```
fun box int()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### quit
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L58)
```
fun box quit()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### ill
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L60)
```
fun box ill()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### trap
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L65)
```
fun box trap()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### abrt
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L70)
```
fun box abrt()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### emt
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L72)
```
fun box emt()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### fpe
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L77)
```
fun box fpe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### kill
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L82)
```
fun box kill()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### bus
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L84)
```
fun box bus()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### segv
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L90)
```
fun box segv()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### sys
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L95)
```
fun box sys()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### pipe
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L101)
```
fun box pipe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### alrm
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L106)
```
fun box alrm()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### term
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L107)
```
fun box term()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### urg
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L109)
```
fun box urg()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### stkflt
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L115)
```
fun box stkflt()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### stop
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L120)
```
fun box stop()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### tstp
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L126)
```
fun box tstp()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### cont
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L132)
```
fun box cont()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### chld
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L138)
```
fun box chld()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### ttin
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L144)
```
fun box ttin()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### ttou
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L149)
```
fun box ttou()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### io
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L154)
```
fun box io()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### xcpu
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L160)
```
fun box xcpu()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### xfsz
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L165)
```
fun box xfsz()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### vtalrm
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L170)
```
fun box vtalrm()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### prof
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L175)
```
fun box prof()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### winch
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L180)
```
fun box winch()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### info
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L185)
```
fun box info()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### pwr
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L190)
```
fun box pwr()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### usr1
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L195)
```
fun box usr1()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### usr2
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L201)
```
fun box usr2()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### rt
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L215)
```
fun box rt(
n: U32 val)
: U32 val ?
```
#### Parameters
* n: [U32](builtin-u32) val
#### Returns
* [U32](builtin-u32) val ?
### eq
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L56)
```
fun box eq(
that: Sig val)
: Bool val
```
#### Parameters
* that: [Sig](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/signals/sig/#L56)
```
fun box ne(
that: Sig val)
: Bool val
```
#### Parameters
* that: [Sig](index) val
#### Returns
* [Bool](builtin-bool) val
pony Package Package
=======
PonyBench provides a microbenchmarking framework. It is designed to measure the runtime of synchronous and asynchronous operations.
Example Program
---------------
The following is a complete program with multiple trivial benchmarks followed by their output.
```
use "time"
actor Main is BenchmarkList
new create(env: Env) =>
PonyBench(env, this)
fun tag benchmarks(bench: PonyBench) =>
bench(_Nothing)
bench(_Fib(5))
bench(_Fib(10))
bench(_Fib(20))
bench(_Timer(10_000))
class iso _Nothing is MicroBenchmark
// Benchmark absolutely nothing.
fun name(): String => "Nothing"
fun apply() =>
// prevent compiler from optimizing out this operation
DoNotOptimise[None](None)
DoNotOptimise.observe()
class iso _Fib is MicroBenchmark
// Benchmark non-tail-recursive fibonacci
let _n: U64
new iso create(n: U64) =>
_n = n
fun name(): String =>
"_Fib(" + _n.string() + ")"
fun apply() =>
DoNotOptimise[U64](_fib(_n))
DoNotOptimise.observe()
fun _fib(n: U64): U64 =>
if n < 2 then 1
else _fib(n - 1) + _fib(n - 2)
end
class iso _Timer is AsyncMicroBenchmark
// Asynchronous benchmark of timer.
let _ts: Timers = Timers
let _ns: U64
new iso create(ns: U64) =>
_ns = ns
fun name(): String =>
"_Timer (" + _ns.string() + " ns)"
fun apply(c: AsyncBenchContinue) =>
_ts(Timer(
object iso is TimerNotify
fun apply(timer: Timer, count: U64 = 0): Bool =>
// signal completion of async benchmark iteration when timer fires
c.complete()
false
end,
_ns))
```
By default, the results are printed to stdout like so:
```
Benchmark results will have their mean and median adjusted for overhead.
You may disable this with --noadjust.
Benchmark mean median deviation iterations
Nothing 1 ns 1 ns ±0.87% 3000000
_Fib(5) 12 ns 12 ns ±1.02% 2000000
_Fib(10) 185 ns 184 ns ±1.03% 1000000
_Fib(20) 23943 ns 23898 ns ±1.11% 10000
_Timer (10000ns) 10360 ns 10238 ns ±3.25% 10000
```
The `--noadjust` option outputs results of the overhead measured prior to each benchmark run followed by the unadjusted benchmark result. An example of the output of this program with `--noadjust` is as follows:
```
Benchmark mean median deviation iterations
Benchmark Overhead 604 ns 603 ns ±0.58% 300000
Nothing 553 ns 553 ns ±0.30% 300000
Benchmark Overhead 555 ns 555 ns ±0.51% 300000
_Fib(5) 574 ns 574 ns ±0.43% 300000
Benchmark Overhead 554 ns 556 ns ±0.48% 300000
_Fib(10) 822 ns 821 ns ±0.39% 200000
Benchmark Overhead 554 ns 553 ns ±0.65% 300000
_Fib(20) 30470 ns 30304 ns ±1.55% 5000
Benchmark Overhead 552 ns 552 ns ±0.39% 300000
_Timer (10000 ns) 10780 ns 10800 ns ±3.60% 10000
```
It is recommended that a PonyBench program is compiled with the `--runtimebc` option, if possible, and run with the `--ponynoyield` option.
Public Types
------------
* [actor PonyBench](ponybench-ponybench)
* [type Benchmark](ponybench-benchmark)
* [trait MicroBenchmark](ponybench-microbenchmark)
* [trait AsyncMicroBenchmark](ponybench-asyncmicrobenchmark)
* [interface BenchmarkList](ponybench-benchmarklist)
* [class BenchConfig](ponybench-benchconfig)
* [class OverheadBenchmark](ponybench-overheadbenchmark)
* [class AsyncOverheadBenchmark](ponybench-asyncoverheadbenchmark)
* [class AsyncBenchContinue](ponybench-asyncbenchcontinue)
pony UnrecognisedOption UnrecognisedOption
==================
[[Source]](https://stdlib.ponylang.io/src/options/options/#L76)
```
primitive val UnrecognisedOption
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/options/options/#L76)
```
new val create()
: UnrecognisedOption val^
```
#### Returns
* [UnrecognisedOption](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/options/options/#L77)
```
fun box eq(
that: UnrecognisedOption val)
: Bool val
```
#### Parameters
* that: [UnrecognisedOption](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/options/options/#L77)
```
fun box ne(
that: UnrecognisedOption val)
: Bool val
```
#### Parameters
* that: [UnrecognisedOption](index) val
#### Returns
* [Bool](builtin-bool) val
pony CommonPrefix CommonPrefix
============
[[Source]](https://stdlib.ponylang.io/src/strings/common_prefix/#L1)
Creates a string that is the common prefix of the supplied strings, possibly empty.
```
primitive val CommonPrefix
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/strings/common_prefix/#L1)
```
new val create()
: CommonPrefix val^
```
#### Returns
* [CommonPrefix](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/strings/common_prefix/#L7)
```
fun box apply(
data: ReadSeq[Stringable box] box)
: String iso^
```
#### Parameters
* data: [ReadSeq](builtin-readseq)[[Stringable](builtin-stringable) box] box
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/strings/common_prefix/#L7)
```
fun box eq(
that: CommonPrefix val)
: Bool val
```
#### Parameters
* that: [CommonPrefix](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/strings/common_prefix/#L7)
```
fun box ne(
that: CommonPrefix val)
: Bool val
```
#### Parameters
* that: [CommonPrefix](index) val
#### Returns
* [Bool](builtin-bool) val
pony Package Package
=======
No package doc string provided for capsicum.
Public Types
------------
* [type CapRights](capsicum-caprights)
* [class CapRights0](capsicum-caprights0)
* [primitive Cap](capsicum-cap)
pony FulfillIdentity[A: Any #share] FulfillIdentity[A: [Any](builtin-any) #share]
=============================================
[[Source]](https://stdlib.ponylang.io/src/promises/fulfill/#L16)
An identity function for fulfilling promises.
```
class iso FulfillIdentity[A: Any #share]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/promises/fulfill/#L16)
```
new iso create()
: FulfillIdentity[A] iso^
```
#### Returns
* [FulfillIdentity](index)[A] iso^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/promises/fulfill/#L20)
```
fun ref apply(
value: A)
: A
```
#### Parameters
* value: A
#### Returns
* A
pony SetIs[A: Any #share] SetIs[A: [Any](builtin-any) #share]
===================================
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/set/#L5)
```
type SetIs[A: Any #share] is
HashSet[A, HashIs[A] val] val
```
#### Type Alias For
* [HashSet](collections-persistent-hashset)[A, [HashIs](collections-hashis)[A] val] val
pony MapValues[K: K, V: V, H: HashFunction[K] val, M: HashMap[K, V, H] #read] MapValues[K: K, V: V, H: [HashFunction](collections-hashfunction)[K] val, M: [HashMap](collections-hashmap)[K, V, H] #read]
===========================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L419)
An iterator over the values in a map.
```
class ref MapValues[K: K, V: V, H: HashFunction[K] val, M: HashMap[K, V, H] #read] is
Iterator[M->V] ref
```
#### Implements
* [Iterator](builtin-iterator)[M->V] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L428)
Creates an iterator for the given map.
```
new ref create(
map: M)
: MapValues[K, V, H, M] ref^
```
#### Parameters
* map: M
#### Returns
* [MapValues](index)[K, V, H, M] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L434)
True if it believes there are remaining entries. May not be right if values were added or removed from the map.
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections/map/#L441)
Returns the next value, or raises an error if there isn't one. If values are added during iteration, this may not return all values.
```
fun ref next()
: M->V ?
```
#### Returns
* M->V ?
pony Seq[A: A] Seq[A: A]
=========
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L1)
A sequence of elements.
```
interface ref Seq[A: A]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L5)
Create a sequence, reserving space for len elements.
```
new ref create(
len: USize val = 0)
: Seq[A] ref^
```
#### Parameters
* len: [USize](builtin-usize) val = 0
#### Returns
* [Seq](index)[A] ref^
Public Functions
----------------
### reserve
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L10)
Reserve space for len elements.
```
fun ref reserve(
len: USize val)
: None val
```
#### Parameters
* len: [USize](builtin-usize) val
#### Returns
* [None](builtin-none) val
### size
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L15)
Returns the number of elements in the sequence.
```
fun box size()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### apply
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L20)
Returns the i-th element of the sequence. Raises an error if the index is out of bounds.
```
fun box apply(
i: USize val)
: this->A ?
```
#### Parameters
* i: [USize](builtin-usize) val
#### Returns
* this->A ?
### update
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L26)
Replaces the i-th element of the sequence. Returns the previous value. Raises an error if the index is out of bounds.
```
fun ref update(
i: USize val,
value: A)
: A^ ?
```
#### Parameters
* i: [USize](builtin-usize) val
* value: A
#### Returns
* A^ ?
### clear
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L32)
Removes all elements from the sequence.
```
fun ref clear()
: None val
```
#### Returns
* [None](builtin-none) val
### push
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L37)
Adds an element to the end of the sequence.
```
fun ref push(
value: A)
: None val
```
#### Parameters
* value: A
#### Returns
* [None](builtin-none) val
### pop
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L42)
Removes an element from the end of the sequence.
```
fun ref pop()
: A^ ?
```
#### Returns
* A^ ?
### unshift
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L47)
Adds an element to the beginning of the sequence.
```
fun ref unshift(
value: A)
: None val
```
#### Parameters
* value: A
#### Returns
* [None](builtin-none) val
### shift
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L52)
Removes an element from the beginning of the sequence.
```
fun ref shift()
: A^ ?
```
#### Returns
* A^ ?
### append
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L57)
Add len elements to the end of the list, starting from the given offset.
```
fun ref append(
seq: (ReadSeq[A] box & ReadElement[A^] box),
offset: USize val = 0,
len: USize val = call)
: None val
```
#### Parameters
* seq: ([ReadSeq](builtin-readseq)[A] box & [ReadElement](builtin-readelement)[A^] box)
* offset: [USize](builtin-usize) val = 0
* len: [USize](builtin-usize) val = call
#### Returns
* [None](builtin-none) val
### concat
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L66)
Add len iterated elements to the end of the list, starting from the given offset.
```
fun ref concat(
iter: Iterator[A^] ref,
offset: USize val = 0,
len: USize val = call)
: None val
```
#### Parameters
* iter: [Iterator](builtin-iterator)[A^] ref
* offset: [USize](builtin-usize) val = 0
* len: [USize](builtin-usize) val = call
#### Returns
* [None](builtin-none) val
### truncate
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L72)
Truncate the sequence to the given length, discarding excess elements. If the sequence is already smaller than len, do nothing.
```
fun ref truncate(
len: USize val)
: None val
```
#### Parameters
* len: [USize](builtin-usize) val
#### Returns
* [None](builtin-none) val
### values
[[Source]](https://stdlib.ponylang.io/src/builtin/seq/#L78)
Returns an iterator over the elements of the sequence.
```
fun box values()
: Iterator[this->A] ref^
```
#### Returns
* [Iterator](builtin-iterator)[this->A] ref^
| programming_docs |
pony PrefixDefault PrefixDefault
=============
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L3)
```
primitive val PrefixDefault is
PrefixSpec val
```
#### Implements
* [PrefixSpec](format-prefixspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L3)
```
new val create()
: PrefixDefault val^
```
#### Returns
* [PrefixDefault](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L5)
```
fun box eq(
that: PrefixDefault val)
: Bool val
```
#### Parameters
* that: [PrefixDefault](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L5)
```
fun box ne(
that: PrefixDefault val)
: Bool val
```
#### Parameters
* that: [PrefixDefault](index) val
#### Returns
* [Bool](builtin-bool) val
pony PonyTest PonyTest
========
[[Source]](https://stdlib.ponylang.io/src/ponytest/pony_test/#L245)
Main test framework actor that organises tests, collates information and prints results.
```
actor tag PonyTest
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/ponytest/pony_test/#L270)
Create a PonyTest object and use it to run the tests from the given TestList
```
new tag create(
env: Env val,
list: TestList tag)
: PonyTest tag^
```
#### Parameters
* env: [Env](builtin-env) val
* list: [TestList](ponytest-testlist) tag
#### Returns
* [PonyTest](index) tag^
Public Behaviours
-----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/ponytest/pony_test/#L282)
Run the given test, subject to our filters and options.
```
be apply(
test: UnitTest iso)
```
#### Parameters
* test: [UnitTest](ponytest-unittest) iso
pony U64Argument U64Argument
===========
[[Source]](https://stdlib.ponylang.io/src/options/options/#L71)
```
primitive val U64Argument
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/options/options/#L71)
```
new val create()
: U64Argument val^
```
#### Returns
* [U64Argument](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/options/options/#L72)
```
fun box eq(
that: U64Argument val)
: Bool val
```
#### Parameters
* that: [U64Argument](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/options/options/#L72)
```
fun box ne(
that: U64Argument val)
: Bool val
```
#### Parameters
* that: [U64Argument](index) val
#### Returns
* [Bool](builtin-bool) val
pony NetAddress NetAddress
==========
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L1)
Represents an IPv4 or IPv6 address. The family field indicates the address type. The addr field is either the IPv4 address or the IPv6 flow info. The addr1-4 fields are the IPv6 address, or invalid for an IPv4 address. The scope field is the IPv6 scope, or invalid for an IPv4 address.
This class is modelled after the C data structure for holding socket addresses for both IPv4 and IPv6 `sockaddr_storage`.
Use the `name` method to obtain address/hostname and port/service as Strings.
```
class val NetAddress is
Equatable[NetAddress val] ref
```
#### Implements
* [Equatable](builtin-equatable)[[NetAddress](index) val] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L1)
```
new iso create()
: NetAddress iso^
```
#### Returns
* [NetAddress](index) iso^
Public Functions
----------------
### ip4
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L55)
Returns true for an IPv4 address.
```
fun box ip4()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### ip6
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L61)
Returns true for an IPv6 address.
```
fun box ip6()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### name
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L67)
Returns the host and service name.
If `reversedns` is an instance of `DNSLookupAuth` a DNS lookup will be executed and the hostname for this address is returned as first element of the result tuple. If no hostname could be found, an error is raised. If `reversedns` is `None` the plain IP address is given and no DNS lookup is executed.
If `servicename` is `false` the numeric port is returned as second element of the result tuple. If it is `true` the port is translated into its corresponding servicename (e.g. port 80 is returned as `"http"`).
Internally this method uses the POSIX C function `getnameinfo`.
```
fun box name(
reversedns: (AmbientAuth val | NetAuth val | DNSAuth val |
None val) = reference,
servicename: Bool val = false)
: (String val , String val) ?
```
#### Parameters
* reversedns: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [DNSAuth](net-dnsauth) val | [None](builtin-none) val) = reference
* servicename: [Bool](builtin-bool) val = false
#### Returns
* ([String](builtin-string) val , [String](builtin-string) val) ?
### eq
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L103)
```
fun box eq(
that: NetAddress box)
: Bool val
```
#### Parameters
* that: [NetAddress](index) box
#### Returns
* [Bool](builtin-bool) val
### host\_eq
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L109)
```
fun box host_eq(
that: NetAddress box)
: Bool val
```
#### Parameters
* that: [NetAddress](index) box
#### Returns
* [Bool](builtin-bool) val
### length
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L119)
For platforms (OSX/FreeBSD) with `length` field as part of its `struct sockaddr` definition, returns the `length`. Else (Linux/Windows) returns the size of `sockaddr_in` or `sockaddr_in6`.
```
fun box length()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### family
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L136)
Returns the `family`.
```
fun box family()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### port
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L155)
Returns port number in host byte order.
```
fun box port()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### scope
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L161)
Returns IPv6 scope identifier: Unicast, Anycast, Multicast and unassigned scopes.
```
fun box scope()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### ipv4\_addr
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L169)
Returns IPV4 address (`_addr` field in the class) if `ip4()` is `True`. If `ip4()` is `False` then the contents are invalid.
```
fun box ipv4_addr()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### ipv6\_addr
[[Source]](https://stdlib.ponylang.io/src/net/net_address/#L176)
Returns IPV6 address as the 4-tuple (say `a`). `a._1 = _addr1` // Bits 0-32 of the IPv6 address in host byte order. `a._2 = _addr2 // Bits 33-64 of the IPv6 address in host byte order.`a.\_3 = \_addr3 // Bits 65-96 of the IPv6 address in host byte order. `a.\_4 = \_addr4 // Bits 97-128 of the IPv6 address in host byte order.
The contents of the 4-tuple returned are valid only if `ip6()` is `True`.
```
fun box ipv6_addr()
: (U32 val , U32 val , U32 val ,
U32 val)
```
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val , [U32](builtin-u32) val , [U32](builtin-u32) val)
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/compare/#L20)
```
fun box ne(
that: NetAddress val)
: Bool val
```
#### Parameters
* that: [NetAddress](index) val
#### Returns
* [Bool](builtin-bool) val
pony Map[K: (Hashable val & Equatable[K]), V: Any #share] Map[K: ([Hashable](collections-hashable) val & [Equatable](builtin-equatable)[K]), V: [Any](builtin-any) #share]
================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/map/#L3)
A map that uses structural equality on the key.
```
type Map[K: (Hashable val & Equatable[K]), V: Any #share] is
HashMap[K, V, HashEq[K] val] val
```
#### Type Alias For
* [HashMap](collections-persistent-hashmap)[K, V, [HashEq](collections-hasheq)[K] val] val
pony Number Number
======
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L714)
```
type Number is
(I8 val | I16 val | I32 val | I64 val | I128 val | ILong val | ISize val | U8 val | U16 val | U32 val | U64 val | U128 val | ULong val | USize val | F32 val | F64 val)
```
#### Type Alias For
* ([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val)
pony ByteSeqIter ByteSeqIter
===========
[[Source]](https://stdlib.ponylang.io/src/builtin/std_stream/#L3)
Accept an iterable collection of String or Array[U8] val.
```
interface val ByteSeqIter
```
Public Functions
----------------
### values
[[Source]](https://stdlib.ponylang.io/src/builtin/std_stream/#L7)
```
fun box values()
: Iterator[(this->String box | this->Array[U8 val] box)] ref
```
#### Returns
* [Iterator](builtin-iterator)[(this->[String](builtin-string) box | this->[Array](builtin-array)[[U8](builtin-u8) val] box)] ref
pony Range[optional A: (Real[A] val & (I8 val | I16 val | I32 val | I64 val | I128 val | ILong val | ISize val | U8 val | U16 val | U32 val | U64 val | U128 val | ULong val | USize val | F32 val | F64 val))] Range[optional A: ([Real](builtin-real)[A] val & ([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val))]
==================================================================================================================================================================================================================================================================================================================================================================================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/range/#L1)
Produces `[min, max)` with a step of `inc` for any `Number` type.
```
// iterating with for-loop
for i in Range(0, 10) do
env.out.print(i.string())
end
// iterating over Range of U8 with while-loop
let range = Range[U8](5, 100, 5)
while range.has_next() do
try
handle_u8(range.next()?)
end
end
```
Supports `min` being smaller than `max` with negative `inc` but only for signed integer types and floats:
```
var previous = 11
for left in Range[I64](10, -5, -1) do
if not (left < previous) then
error
end
previous = left
end
```
If the `step` is not moving `min` towards `max` or if it is `0`, the Range is considered infinite and iterating over it will never terminate:
```
let infinite_range1 = Range(0, 1, 0)
infinite_range1.is_infinite() == true
let infinite_range2 = Range[I8](0, 10, -1)
for _ in infinite_range2 do
env.out.print("will this ever end?")
env.err.print("no, never!")
end
```
When using `Range` with floating point types (`F32` and `F64`) `inc` steps < 1.0 are possible. If any of the arguments contains `NaN`, `+Inf` or `-Inf` the range is considered infinite as operations on any of them won't move `min` towards `max`. The actual values produced by such a `Range` are determined by what IEEE 754 defines as the result of `min` + `inc`:
```
for and_a_half in Range[F64](0.5, 100) do
handle_half(and_a_half)
end
// this Range will produce 0 at first, then infinitely NaN
let nan: F64 = F64(0) / F64(0)
for what_am_i in Range[F64](0, 1000, nan) do
wild_guess(what_am_i)
end
```
```
class ref Range[optional A: (Real[A] val & (I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val))] is
Iterator[A] ref
```
#### Implements
* [Iterator](builtin-iterator)[A] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/range/#L75)
```
new ref create(
min: A,
max: A,
inc: A = 1)
: Range[A] ref^
```
#### Parameters
* min: A
* max: A
* inc: A = 1
#### Returns
* [Range](index)[A] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections/range/#L95)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections/range/#L102)
```
fun ref next()
: A ?
```
#### Returns
* A ?
### rewind
[[Source]](https://stdlib.ponylang.io/src/collections/range/#L109)
```
fun ref rewind()
: None val
```
#### Returns
* [None](builtin-none) val
### is\_infinite
[[Source]](https://stdlib.ponylang.io/src/collections/range/#L112)
```
fun box is_infinite()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
pony FormatSpec FormatSpec
==========
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L1)
```
trait val FormatSpec
```
pony I16 I16
===
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L93)
```
primitive val I16 is
SignedInteger[I16 val, U16 val] val
```
#### Implements
* [SignedInteger](builtin-signedinteger)[[I16](index) val, [U16](builtin-u16) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L94)
```
new val create(
value: I16 val)
: I16 val^
```
#### Parameters
* value: [I16](index) val
#### Returns
* [I16](index) val^
### from[A: (([I8](builtin-i8) val | [I16](index) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[A] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L95)
```
new val from[A: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[A] val)](
a: A)
: I16 val^
```
#### Parameters
* a: A
#### Returns
* [I16](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L97)
```
new val min_value()
: I16 val^
```
#### Returns
* [I16](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L98)
```
new val max_value()
: I16 val^
```
#### Returns
* [I16](index) val^
Public Functions
----------------
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L100)
```
fun box abs()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L101)
```
fun box bit_reverse()
: I16 val
```
#### Returns
* [I16](index) val
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L102)
```
fun box bswap()
: I16 val
```
#### Returns
* [I16](index) val
### popcount
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L103)
```
fun box popcount()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### clz
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L104)
```
fun box clz()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### ctz
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L105)
```
fun box ctz()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### clz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L107)
Unsafe operation. If this is 0, the result is undefined.
```
fun box clz_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### ctz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L114)
Unsafe operation. If this is 0, the result is undefined.
```
fun box ctz_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### bitwidth
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L121)
```
fun box bitwidth()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### bytewidth
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L123)
```
fun box bytewidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L125)
```
fun box min(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L126)
```
fun box max(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L128)
```
fun box fld(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L131)
```
fun box fld_unsafe(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L134)
```
fun box mod(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L137)
```
fun box mod_unsafe(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L140)
```
fun box addc(
y: I16 val)
: (I16 val , Bool val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L143)
```
fun box subc(
y: I16 val)
: (I16 val , Bool val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L146)
```
fun box mulc(
y: I16 val)
: (I16 val , Bool val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L149)
```
fun box divc(
y: I16 val)
: (I16 val , Bool val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L152)
```
fun box remc(
y: I16 val)
: (I16 val , Bool val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [Bool](builtin-bool) val)
### fldc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L155)
```
fun box fldc(
y: I16 val)
: (I16 val , Bool val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [Bool](builtin-bool) val)
### modc
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L158)
```
fun box modc(
y: I16 val)
: (I16 val , Bool val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [Bool](builtin-bool) val)
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L161)
```
fun box add_partial(
y: I16 val)
: I16 val ?
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L164)
```
fun box sub_partial(
y: I16 val)
: I16 val ?
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L167)
```
fun box mul_partial(
y: I16 val)
: I16 val ?
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L170)
```
fun box div_partial(
y: I16 val)
: I16 val ?
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L173)
```
fun box rem_partial(
y: I16 val)
: I16 val ?
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L176)
```
fun box divrem_partial(
y: I16 val)
: (I16 val , I16 val) ?
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [I16](index) val) ?
### fld\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L179)
```
fun box fld_partial(
y: I16 val)
: I16 val ?
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val ?
### mod\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/signed/#L182)
```
fun box mod_partial(
y: I16 val)
: I16 val ?
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val ?
### shl
```
fun box shl(
y: U16 val)
: I16 val
```
#### Parameters
* y: [U16](builtin-u16) val
#### Returns
* [I16](index) val
### shr
```
fun box shr(
y: U16 val)
: I16 val
```
#### Parameters
* y: [U16](builtin-u16) val
#### Returns
* [I16](index) val
### shl\_unsafe
```
fun box shl_unsafe(
y: U16 val)
: I16 val
```
#### Parameters
* y: [U16](builtin-u16) val
#### Returns
* [I16](index) val
### shr\_unsafe
```
fun box shr_unsafe(
y: U16 val)
: I16 val
```
#### Parameters
* y: [U16](builtin-u16) val
#### Returns
* [I16](index) val
### string
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add\_unsafe
```
fun box add_unsafe(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### sub\_unsafe
```
fun box sub_unsafe(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### mul\_unsafe
```
fun box mul_unsafe(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### div\_unsafe
```
fun box div_unsafe(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### divrem\_unsafe
```
fun box divrem_unsafe(
y: I16 val)
: (I16 val , I16 val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [I16](index) val)
### rem\_unsafe
```
fun box rem_unsafe(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### neg\_unsafe
```
fun box neg_unsafe()
: I16 val
```
#### Returns
* [I16](index) val
### op\_and
```
fun box op_and(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### op\_or
```
fun box op_or(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### op\_xor
```
fun box op_xor(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### op\_not
```
fun box op_not()
: I16 val
```
#### Returns
* [I16](index) val
### add
```
fun box add(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### sub
```
fun box sub(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### mul
```
fun box mul(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### div
```
fun box div(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### divrem
```
fun box divrem(
y: I16 val)
: (I16 val , I16 val)
```
#### Parameters
* y: [I16](index) val
#### Returns
* ([I16](index) val , [I16](index) val)
### rem
```
fun box rem(
y: I16 val)
: I16 val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [I16](index) val
### neg
```
fun box neg()
: I16 val
```
#### Returns
* [I16](index) val
### eq
```
fun box eq(
y: I16 val)
: Bool val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
```
fun box ne(
y: I16 val)
: Bool val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
```
fun box lt(
y: I16 val)
: Bool val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [Bool](builtin-bool) val
### le
```
fun box le(
y: I16 val)
: Bool val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
```
fun box ge(
y: I16 val)
: Bool val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
```
fun box gt(
y: I16 val)
: Bool val
```
#### Parameters
* y: [I16](index) val
#### Returns
* [Bool](builtin-bool) val
### hash
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i8
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
```
fun box i16()
: I16 val
```
#### Returns
* [I16](index) val
### i32
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](index) val
### i32\_unsafe
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: I16 val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [I16](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony ArrayPairs[A: A, B: Array[A] #read] ArrayPairs[A: A, B: [Array](builtin-array)[A] #read]
====================================================
[[Source]](https://stdlib.ponylang.io/src/builtin/array/#L972)
```
class ref ArrayPairs[A: A, B: Array[A] #read] is
Iterator[(USize val , B->A)] ref
```
#### Implements
* [Iterator](builtin-iterator)[([USize](builtin-usize) val , B->A)] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/array/#L976)
```
new ref create(
array: B)
: ArrayPairs[A, B] ref^
```
#### Parameters
* array: B
#### Returns
* [ArrayPairs](index)[A, B] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/builtin/array/#L980)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/builtin/array/#L983)
```
fun ref next()
: (USize val , B->A) ?
```
#### Returns
* ([USize](builtin-usize) val , B->A) ?
pony FileExists FileExists
==========
[[Source]](https://stdlib.ponylang.io/src/files/file/#L28)
```
primitive val FileExists
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file/#L28)
```
new val create()
: FileExists val^
```
#### Returns
* [FileExists](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file/#L29)
```
fun box eq(
that: FileExists val)
: Bool val
```
#### Parameters
* that: [FileExists](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file/#L29)
```
fun box ne(
that: FileExists val)
: Bool val
```
#### Parameters
* that: [FileExists](index) val
#### Returns
* [Bool](builtin-bool) val
pony TCPConnection TCPConnection
=============
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L16)
A TCP connection. When connecting, the Happy Eyeballs algorithm is used.
The following code creates a client that connects to port 8989 of the local host, writes "hello world", and listens for a response, which it then prints.
```
use "net"
class MyTCPConnectionNotify is TCPConnectionNotify
let _out: OutStream
new create(out: OutStream) =>
_out = out
fun ref connected(conn: TCPConnection ref) =>
conn.write("hello world")
fun ref received(
conn: TCPConnection ref,
data: Array[U8] iso,
times: USize)
: Bool
=>
_out.print("GOT:" + String.from_array(consume data))
conn.close()
true
fun ref connect_failed(conn: TCPConnection ref) =>
None
actor Main
new create(env: Env) =>
try
TCPConnection(env.root as AmbientAuth,
recover MyTCPConnectionNotify(env.out) end, "", "8989")
end
```
Note: when writing to the connection data will be silently discarded if the connection has not yet been established.
Backpressure support
--------------------
### Write
The TCP protocol has built-in backpressure support. This is generally experienced as the outgoing write buffer becoming full and being unable to write all requested data to the socket. In `TCPConnection`, this is hidden from the programmer. When this occurs, `TCPConnection` will buffer the extra data until such time as it is able to be sent. Left unchecked, this could result in uncontrolled queuing. To address this, `TCPConnectionNotify` implements two methods `throttled` and `unthrottled` that are called when backpressure is applied and released.
Upon receiving a `throttled` notification, your application has two choices on how to handle it. One is to inform the Pony runtime that it can no longer make progress and that runtime backpressure should be applied to any actors sending this one messages. For example, you might construct your application like:
```
// Here we have a TCPConnectionNotify that upon construction
// is given a BackpressureAuth token. This allows the notifier
// to inform the Pony runtime when to apply and release backpressure
// as the connection experiences it.
// Note the calls to
//
// Backpressure.apply(_auth)
// Backpressure.release(_auth)
//
// that apply and release backpressure as needed
use "backpressure"
use "collections"
use "net"
class SlowDown is TCPConnectionNotify
let _auth: BackpressureAuth
let _out: StdStream
new iso create(auth: BackpressureAuth, out: StdStream) =>
_auth = auth
_out = out
fun ref throttled(connection: TCPConnection ref) =>
_out.print("Experiencing backpressure!")
Backpressure.apply(_auth)
fun ref unthrottled(connection: TCPConnection ref) =>
_out.print("Releasing backpressure!")
Backpressure.release(_auth)
fun ref closed(connection: TCPConnection ref) =>
// if backpressure has been applied, make sure we release
// when shutting down
_out.print("Releasing backpressure if applied!")
Backpressure.release(_auth)
fun ref connect_failed(conn: TCPConnection ref) =>
None
actor Main
new create(env: Env) =>
try
let auth = env.root as AmbientAuth
let socket = TCPConnection(auth, recover SlowDown(auth, env.out) end,
"", "7669")
end
```
Or if you want, you could handle backpressure by shedding load, that is, dropping the extra data rather than carrying out the send. This might look like:
```
use "net"
class ThrowItAway is TCPConnectionNotify
var _throttled: Bool = false
fun ref sent(conn: TCPConnection ref, data: ByteSeq): ByteSeq =>
if not _throttled then
data
else
""
end
fun ref sentv(conn: TCPConnection ref, data: ByteSeqIter): ByteSeqIter =>
if not _throttled then
data
else
recover Array[String] end
end
fun ref throttled(connection: TCPConnection ref) =>
_throttled = true
fun ref unthrottled(connection: TCPConnection ref) =>
_throttled = false
fun ref connect_failed(conn: TCPConnection ref) =>
None
actor Main
new create(env: Env) =>
try
TCPConnection(env.root as AmbientAuth,
recover ThrowItAway end, "", "7669")
end
```
In general, unless you have a very specific use case, we strongly advise that you don't implement a load shedding scheme where you drop data.
### Read
If your application is unable to keep up with data being sent to it over a `TCPConnection` you can use the builtin read backpressure support to pause reading the socket which will in turn start to exert backpressure on the corresponding writer on the other end of that socket.
The `mute` behavior allow any other actors in your application to request the cessation of additional reads until such time as `unmute` is called. Please note that this cessation is not guaranteed to happen immediately as it is the result of an asynchronous behavior call and as such will have to wait for existing messages in the `TCPConnection`'s mailbox to be handled.
On non-windows platforms, your `TCPConnection` will not notice if the other end of the connection closes until you unmute it. Unix type systems like FreeBSD, Linux and OSX learn about a closed connection upon read. On these platforms, you **must** call `unmute` on a muted connection to have it close. Without calling `unmute` the `TCPConnection` actor will never exit.
Proxy support
-------------
Using the `proxy_via` callback in a `TCPConnectionNotify` it is possible to implement proxies. The function takes the intended destination host and service as parameters and returns a 2-tuple of the proxy host and service.
The proxy `TCPConnectionNotify` should decorate another implementation of `TCPConnectionNotify` passing relevent data through.
### Example proxy implementation
```
actor Main
new create(env: Env) =>
MyClient.create(
"example.com", // we actually want to connect to this host
"80",
ExampleProxy.create("proxy.example.com", "80")) // we connect via this proxy
actor MyClient
new create(host: String, service: String, proxy: Proxy = NoProxy) =>
let conn: TCPConnection = TCPConnection.create(
env.root as AmbientAuth,
proxy.apply(MyConnectionNotify.create()),
host,
service)
class ExampleProxy is Proxy
let _proxy_host: String
let _proxy_service: String
new create(proxy_host: String, proxy_service: String) =>
_proxy_host = proxy_host
_proxy_service = proxy_service
fun apply(wrap: TCPConnectionNotify iso): TCPConnectionNotify iso^ =>
ExampleProxyNotify.create(consume wrap, _proxy_service, _proxy_service)
class iso ExampleProxyNotify is TCPConnectionNotify
// Fictional proxy implementation that has no error
// conditions, and always forwards the connection.
let _proxy_host: String
let _proxy_service: String
var _destination_host: (None | String) = None
var _destination_service: (None | String) = None
let _wrapped: TCPConnectionNotify iso
new iso create(wrap: TCPConnectionNotify iso, proxy_host: String, proxy_service: String) =>
_wrapped = wrap
_proxy_host = proxy_host
_proxy_service = proxy_service
fun ref proxy_via(host: String, service: String): (String, String) =>
// Stash the original host & service; return the host & service
// for the proxy; indicating that the initial TCP connection should
// be made to the proxy
_destination_host = host
_destination_service = service
(_proxy_host, _proxy_service)
fun ref connected(conn: TCPConnection ref) =>
// conn is the connection to the *proxy* server. We need to ask the
// proxy server to forward this connection to our intended final
// destination.
conn.write((_destination_host + "\n").array())
conn.write((_destination_service + "\n").array())
wrapped.connected(conn)
fun ref received(conn, data, times) => _wrapped.received(conn, data, times)
fun ref connect_failed(conn: TCPConnection ref) => None
```
```
actor tag TCPConnection
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L300)
Connect via IPv4 or IPv6. If `from` is a non-empty string, the connection will be made from the specified interface.
```
new tag create(
auth: (AmbientAuth val | NetAuth val | TCPAuth val |
TCPConnectAuth val),
notify: TCPConnectionNotify iso,
host: String val,
service: String val,
from: String val = "",
read_buffer_size: USize val = 16384,
yield_after_reading: USize val = 16384,
yield_after_writing: USize val = 16384)
: TCPConnection tag^
```
#### Parameters
* auth: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [TCPAuth](net-tcpauth) val | [TCPConnectAuth](net-tcpconnectauth) val)
* notify: [TCPConnectionNotify](net-tcpconnectionnotify) iso
* host: [String](builtin-string) val
* service: [String](builtin-string) val
* from: [String](builtin-string) val = ""
* read\_buffer\_size: [USize](builtin-usize) val = 16384
* yield\_after\_reading: [USize](builtin-usize) val = 16384
* yield\_after\_writing: [USize](builtin-usize) val = 16384
#### Returns
* [TCPConnection](index) tag^
### ip4
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L331)
Connect via IPv4.
```
new tag ip4(
auth: (AmbientAuth val | NetAuth val | TCPAuth val |
TCPConnectAuth val),
notify: TCPConnectionNotify iso,
host: String val,
service: String val,
from: String val = "",
read_buffer_size: USize val = 16384,
yield_after_reading: USize val = 16384,
yield_after_writing: USize val = 16384)
: TCPConnection tag^
```
#### Parameters
* auth: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [TCPAuth](net-tcpauth) val | [TCPConnectAuth](net-tcpconnectauth) val)
* notify: [TCPConnectionNotify](net-tcpconnectionnotify) iso
* host: [String](builtin-string) val
* service: [String](builtin-string) val
* from: [String](builtin-string) val = ""
* read\_buffer\_size: [USize](builtin-usize) val = 16384
* yield\_after\_reading: [USize](builtin-usize) val = 16384
* yield\_after\_writing: [USize](builtin-usize) val = 16384
#### Returns
* [TCPConnection](index) tag^
### ip6
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L361)
Connect via IPv6.
```
new tag ip6(
auth: (AmbientAuth val | NetAuth val | TCPAuth val |
TCPConnectAuth val),
notify: TCPConnectionNotify iso,
host: String val,
service: String val,
from: String val = "",
read_buffer_size: USize val = 16384,
yield_after_reading: USize val = 16384,
yield_after_writing: USize val = 16384)
: TCPConnection tag^
```
#### Parameters
* auth: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [TCPAuth](net-tcpauth) val | [TCPConnectAuth](net-tcpconnectauth) val)
* notify: [TCPConnectionNotify](net-tcpconnectionnotify) iso
* host: [String](builtin-string) val
* service: [String](builtin-string) val
* from: [String](builtin-string) val = ""
* read\_buffer\_size: [USize](builtin-usize) val = 16384
* yield\_after\_reading: [USize](builtin-usize) val = 16384
* yield\_after\_writing: [USize](builtin-usize) val = 16384
#### Returns
* [TCPConnection](index) tag^
Public Behaviours
-----------------
### write
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L429)
Write a single sequence of bytes. Data will be silently discarded if the connection has not yet been established though.
```
be write(
data: (String val | Array[U8 val] val))
```
#### Parameters
* data: ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
### writev
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L440)
Write a sequence of sequences of bytes. Data will be silently discarded if the connection has not yet been established though.
```
be writev(
data: ByteSeqIter val)
```
#### Parameters
* data: [ByteSeqIter](builtin-byteseqiter) val
### mute
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L497)
Temporarily suspend reading off this TCPConnection until such time as `unmute` is called.
```
be mute()
```
### unmute
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L504)
Start reading off this TCPConnection again after having been muted.
```
be unmute()
```
### set\_notify
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L513)
Change the notifier.
```
be set_notify(
notify: TCPConnectionNotify iso)
```
#### Parameters
* notify: [TCPConnectionNotify](net-tcpconnectionnotify) iso
### dispose
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L519)
Close the connection gracefully once all writes are sent.
```
be dispose()
```
Public Functions
----------------
### local\_address
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L525)
Return the local IP address. If this TCPConnection is closed then the address returned is invalid.
```
fun box local_address()
: NetAddress val
```
#### Returns
* [NetAddress](net-netaddress) val
### remote\_address
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L534)
Return the remote IP address. If this TCPConnection is closed then the address returned is invalid.
```
fun box remote_address()
: NetAddress val
```
#### Returns
* [NetAddress](net-netaddress) val
### expect
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L543)
A `received` call on the notifier must contain exactly `qty` bytes. If `qty` is zero, the call can contain any amount of data. This has no effect if called in the `sent` notifier callback.
Errors if `qty` exceeds the max buffer size as indicated by the `read_buffer_size` supplied when the connection was created.
```
fun ref expect(
qty: USize val = 0)
: None val ?
```
#### Parameters
* qty: [USize](builtin-usize) val = 0
#### Returns
* [None](builtin-none) val ?
### set\_nodelay
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L562)
Turn Nagle on/off. Defaults to on. This can only be set on a connected socket.
```
fun ref set_nodelay(
state: Bool val)
: None val
```
#### Parameters
* state: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### set\_keepalive
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L571)
Sets the TCP keepalive timeout to approximately `secs` seconds. Exact timing is OS dependent. If `secs` is zero, TCP keepalive is disabled. TCP keepalive is disabled by default. This can only be set on a connected socket.
```
fun ref set_keepalive(
secs: U32 val)
: None val
```
#### Parameters
* secs: [U32](builtin-u32) val
#### Returns
* [None](builtin-none) val
### write\_final
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L673)
Write as much as possible to the socket. Set `_writeable` to `false` if not everything was written. On an error, close the connection. This is for data that has already been transformed by the notifier. Data will be silently discarded if the connection has not yet been established though.
```
fun ref write_final(
data: (String val | Array[U8 val] val))
: None val
```
#### Parameters
* data: ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
#### Returns
* [None](builtin-none) val
### close
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1017)
Attempt to perform a graceful shutdown. Don't accept new writes. If the connection isn't muted then we won't finish closing until we get a zero length read. If the connection is muted, perform a hard close and shut down immediately.
```
fun ref close()
: None val
```
#### Returns
* [None](builtin-none) val
### hard\_close
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1073)
When an error happens, do a non-graceful close.
```
fun ref hard_close()
: None val
```
#### Returns
* [None](builtin-none) val
### getsockopt
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1139)
General wrapper for TCP sockets to the `getsockopt(2)` system call.
The caller must provide an array that is pre-allocated to be at least as large as the largest data structure that the kernel may return for the requested option.
In case of system call success, this function returns the 2-tuple: 1. The integer `0`. 2. An `Array[U8]` of data returned by the system call's `void *` 4th argument. Its size is specified by the kernel via the system call's `sockopt_len_t *` 5th argument.
In case of system call failure, this function returns the 2-tuple: 1. The value of `errno`. 2. An undefined value that must be ignored.
Usage example:
```
// connected() is a callback function for class TCPConnectionNotify
fun ref connected(conn: TCPConnection ref) =>
match conn.getsockopt(OSSockOpt.sol_socket(), OSSockOpt.so_rcvbuf(), 4)
| (0, let gbytes: Array[U8] iso) =>
try
let br = Reader.create().>append(consume gbytes)
ifdef littleendian then
let buffer_size = br.u32_le()?
else
let buffer_size = br.u32_be()?
end
end
| (let errno: U32, _) =>
// System call failed
end
```
```
fun ref getsockopt(
level: I32 val,
option_name: I32 val,
option_max_size: USize val = 4)
: (U32 val , Array[U8 val] iso^)
```
#### Parameters
* level: [I32](builtin-i32) val
* option\_name: [I32](builtin-i32) val
* option\_max\_size: [USize](builtin-usize) val = 4
#### Returns
* ([U32](builtin-u32) val , [Array](builtin-array)[[U8](builtin-u8) val] iso^)
### getsockopt\_u32
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1180)
Wrapper for TCP sockets to the `getsockopt(2)` system call where the kernel's returned option value is a C `uint32_t` type / Pony type `U32`.
In case of system call success, this function returns the 2-tuple: 1. The integer `0`. 2. The `*option_value` returned by the kernel converted to a Pony `U32`.
In case of system call failure, this function returns the 2-tuple: 1. The value of `errno`. 2. An undefined value that must be ignored.
```
fun ref getsockopt_u32(
level: I32 val,
option_name: I32 val)
: (U32 val , U32 val)
```
#### Parameters
* level: [I32](builtin-i32) val
* option\_name: [I32](builtin-i32) val
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### setsockopt
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1196)
General wrapper for TCP sockets to the `setsockopt(2)` system call.
The caller is responsible for the correct size and byte contents of the `option` array for the requested `level` and `option_name`, including using the appropriate machine endian byte order.
This function returns `0` on success, else the value of `errno` on failure.
Usage example:
```
// connected() is a callback function for class TCPConnectionNotify
fun ref connected(conn: TCPConnection ref) =>
let sb = Writer
sb.u32_le(7744) // Our desired socket buffer size
let sbytes = Array[U8]
for bs in sb.done().values() do
sbytes.append(bs)
end
match conn.setsockopt(OSSockOpt.sol_socket(), OSSockOpt.so_rcvbuf(), sbytes)
| 0 =>
// System call was successful
| let errno: U32 =>
// System call failed
end
```
```
fun ref setsockopt(
level: I32 val,
option_name: I32 val,
option: Array[U8 val] ref)
: U32 val
```
#### Parameters
* level: [I32](builtin-i32) val
* option\_name: [I32](builtin-i32) val
* option: [Array](builtin-array)[[U8](builtin-u8) val] ref
#### Returns
* [U32](builtin-u32) val
### setsockopt\_u32
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1229)
General wrapper for TCP sockets to the `setsockopt(2)` system call where the kernel expects an option value of a C `uint32_t` type / Pony type `U32`.
This function returns `0` on success, else the value of `errno` on failure.
```
fun ref setsockopt_u32(
level: I32 val,
option_name: I32 val,
option: U32 val)
: U32 val
```
#### Parameters
* level: [I32](builtin-i32) val
* option\_name: [I32](builtin-i32) val
* option: [U32](builtin-u32) val
#### Returns
* [U32](builtin-u32) val
### get\_so\_error
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1241)
Wrapper for the FFI call `getsockopt(fd, SOL_SOCKET, SO_ERROR, ...)`
```
fun ref get_so_error()
: (U32 val , U32 val)
```
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### get\_so\_rcvbuf
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1247)
Wrapper for the FFI call `getsockopt(fd, SOL_SOCKET, SO_RCVBUF, ...)`
```
fun ref get_so_rcvbuf()
: (U32 val , U32 val)
```
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### get\_so\_sndbuf
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1253)
Wrapper for the FFI call `getsockopt(fd, SOL_SOCKET, SO_SNDBUF, ...)`
```
fun ref get_so_sndbuf()
: (U32 val , U32 val)
```
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### get\_tcp\_nodelay
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1259)
Wrapper for the FFI call `getsockopt(fd, SOL_SOCKET, TCP_NODELAY, ...)`
```
fun ref get_tcp_nodelay()
: (U32 val , U32 val)
```
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### set\_so\_rcvbuf
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1266)
Wrapper for the FFI call `setsockopt(fd, SOL_SOCKET, SO_RCVBUF, ...)`
```
fun ref set_so_rcvbuf(
bufsize: U32 val)
: U32 val
```
#### Parameters
* bufsize: [U32](builtin-u32) val
#### Returns
* [U32](builtin-u32) val
### set\_so\_sndbuf
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1272)
Wrapper for the FFI call `setsockopt(fd, SOL_SOCKET, SO_SNDBUF, ...)`
```
fun ref set_so_sndbuf(
bufsize: U32 val)
: U32 val
```
#### Parameters
* bufsize: [U32](builtin-u32) val
#### Returns
* [U32](builtin-u32) val
### set\_tcp\_nodelay
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L1278)
Wrapper for the FFI call `setsockopt(fd, SOL_SOCKET, TCP_NODELAY, ...)`
```
fun ref set_tcp_nodelay(
state: Bool val)
: U32 val
```
#### Parameters
* state: [Bool](builtin-bool) val
#### Returns
* [U32](builtin-u32) val
| programming_docs |
pony TCPConnectionAuth TCPConnectionAuth
=================
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection/#L14)
```
type TCPConnectionAuth is
(AmbientAuth val | NetAuth val | TCPAuth val | TCPConnectAuth val)
```
#### Type Alias For
* ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [TCPAuth](net-tcpauth) val | [TCPConnectAuth](net-tcpconnectauth) val)
pony FormatHexBare FormatHexBare
=============
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L11)
```
primitive val FormatHexBare is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L11)
```
new val create()
: FormatHexBare val^
```
#### Returns
* [FormatHexBare](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L12)
```
fun box eq(
that: FormatHexBare val)
: Bool val
```
#### Parameters
* that: [FormatHexBare](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L12)
```
fun box ne(
that: FormatHexBare val)
: Bool val
```
#### Parameters
* that: [FormatHexBare](index) val
#### Returns
* [Bool](builtin-bool) val
pony DisposableActor DisposableActor
===============
[[Source]](https://stdlib.ponylang.io/src/builtin/disposable_actor/#L1)
An interface used to asynchronously dispose of an actor.
```
interface tag DisposableActor
```
Public Behaviours
-----------------
### dispose
[[Source]](https://stdlib.ponylang.io/src/builtin/disposable_actor/#L5)
```
be dispose()
```
pony MissingArgument MissingArgument
===============
[[Source]](https://stdlib.ponylang.io/src/options/options/#L78)
```
primitive val MissingArgument
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/options/options/#L78)
```
new val create()
: MissingArgument val^
```
#### Returns
* [MissingArgument](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/options/options/#L79)
```
fun box eq(
that: MissingArgument val)
: Bool val
```
#### Parameters
* that: [MissingArgument](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/options/options/#L79)
```
fun box ne(
that: MissingArgument val)
: Bool val
```
#### Parameters
* that: [MissingArgument](index) val
#### Returns
* [Bool](builtin-bool) val
pony Option Option
======
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L63)
Option contains a spec and an effective value for a given option.
```
class val Option
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L70)
```
new val create(
spec': OptionSpec val,
value': (Bool val | String val | I64 val |
U64 val | F64 val | _StringSeq val))
: Option val^
```
#### Parameters
* spec': [OptionSpec](cli-optionspec) val
* value': ([Bool](builtin-bool) val | [String](builtin-string) val | [I64](builtin-i64) val | [U64](builtin-u64) val | [F64](builtin-f64) val | \_StringSeq val)
#### Returns
* [Option](index) val^
Public Functions
----------------
### spec
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L77)
```
fun box spec()
: OptionSpec val
```
#### Returns
* [OptionSpec](cli-optionspec) val
### bool
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L79)
Returns the option value as a Bool, defaulting to false.
```
fun box bool()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### string
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L85)
Returns the option value as a String, defaulting to empty.
```
fun box string()
: String val
```
#### Returns
* [String](builtin-string) val
### i64
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L91)
Returns the option value as an I64, defaulting to 0.
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### u64
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L97)
Returns the option value as an U64, defaulting to 0.
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### f64
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L103)
Returns the option value as an F64, defaulting to 0.0.
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### string\_seq
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L109)
Returns the option value as a ReadSeq[String], defaulting to empty.
```
fun box string_seq()
: ReadSeq[String val] val
```
#### Returns
* [ReadSeq](builtin-readseq)[[String](builtin-string) val] val
### deb\_string
[[Source]](https://stdlib.ponylang.io/src/cli/command/#L119)
```
fun box deb_string()
: String val
```
#### Returns
* [String](builtin-string) val
pony JsonType JsonType
========
[[Source]](https://stdlib.ponylang.io/src/json/json_type/#L3)
All JSON data types.
```
type JsonType is
(F64 val | I64 val | Bool val | None val | String val | JsonArray ref | JsonObject ref)
```
#### Type Alias For
* ([F64](builtin-f64) val | [I64](builtin-i64) val | [Bool](builtin-bool) val | [None](builtin-none) val | [String](builtin-string) val | [JsonArray](json-jsonarray) ref | [JsonObject](json-jsonobject) ref)
pony FormatOctal FormatOctal
===========
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L8)
```
primitive val FormatOctal is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L8)
```
new val create()
: FormatOctal val^
```
#### Returns
* [FormatOctal](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L9)
```
fun box eq(
that: FormatOctal val)
: Bool val
```
#### Parameters
* that: [FormatOctal](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L9)
```
fun box ne(
that: FormatOctal val)
: Bool val
```
#### Parameters
* that: [FormatOctal](index) val
#### Returns
* [Bool](builtin-bool) val
pony Bool Bool
====
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L1)
```
primitive val Bool is
Stringable box
```
#### Implements
* [Stringable](builtin-stringable) box
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L2)
```
new val create(
from: Bool val)
: Bool val^
```
#### Parameters
* from: [Bool](index) val
#### Returns
* [Bool](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L4)
```
fun box eq(
y: Bool val)
: Bool val
```
#### Parameters
* y: [Bool](index) val
#### Returns
* [Bool](index) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L5)
```
fun box ne(
y: Bool val)
: Bool val
```
#### Parameters
* y: [Bool](index) val
#### Returns
* [Bool](index) val
### op\_and
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L6)
```
fun box op_and(
y: Bool val)
: Bool val
```
#### Parameters
* y: [Bool](index) val
#### Returns
* [Bool](index) val
### op\_or
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L7)
```
fun box op_or(
y: Bool val)
: Bool val
```
#### Parameters
* y: [Bool](index) val
#### Returns
* [Bool](index) val
### op\_xor
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L8)
```
fun box op_xor(
y: Bool val)
: Bool val
```
#### Parameters
* y: [Bool](index) val
#### Returns
* [Bool](index) val
### op\_not
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L9)
```
fun box op_not()
: Bool val
```
#### Returns
* [Bool](index) val
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/bool/#L11)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
pony Lists[A: A] Lists[A: A]
===========
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L36)
A primitive containing helper functions for constructing and testing Lists.
```
primitive val Lists[A: A]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L36)
```
new val create()
: Lists[A] val^
```
#### Returns
* [Lists](index)[A] val^
Public Functions
----------------
### empty
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L42)
Returns an empty list.
```
fun box empty()
: (Cons[A] val | Nil[A] val)
```
#### Returns
* ([Cons](collections-persistent-cons)[A] val | [Nil](collections-persistent-nil)[A] val)
### cons
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L48)
Returns a list that has h as a head and t as a tail.
```
fun box cons(
h: val->A,
t: (Cons[A] val | Nil[A] val))
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* h: val->A
* t: ([Cons](collections-persistent-cons)[A] val | [Nil](collections-persistent-nil)[A] val)
#### Returns
* ([Cons](collections-persistent-cons)[A] val | [Nil](collections-persistent-nil)[A] val)
### apply
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L54)
Builds a new list from an Array
```
fun box apply(
arr: Array[val->A] ref)
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* arr: [Array](builtin-array)[val->A] ref
#### Returns
* ([Cons](collections-persistent-cons)[A] val | [Nil](collections-persistent-nil)[A] val)
### from
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L60)
Builds a new list from an iterator
```
fun box from(
iter: Iterator[val->A] ref)
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* iter: [Iterator](builtin-iterator)[val->A] ref
#### Returns
* ([Cons](collections-persistent-cons)[A] val | [Nil](collections-persistent-nil)[A] val)
### eq[optional T: [Equatable](builtin-equatable)[T] val]
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L71)
Checks whether two lists are equal.
```
fun box eq[optional T: Equatable[T] val](
l1: (Cons[T] val | Nil[T] val),
l2: (Cons[T] val | Nil[T] val))
: Bool val ?
```
#### Parameters
* l1: ([Cons](collections-persistent-cons)[T] val | [Nil](collections-persistent-nil)[T] val)
* l2: ([Cons](collections-persistent-cons)[T] val | [Nil](collections-persistent-nil)[T] val)
#### Returns
* [Bool](builtin-bool) val ?
### ne
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L42)
```
fun box ne(
that: Lists[A] val)
: Bool val
```
#### Parameters
* that: [Lists](index)[A] val
#### Returns
* [Bool](builtin-bool) val
pony Dice Dice
====
[[Source]](https://stdlib.ponylang.io/src/random/dice/#L1)
A simple dice roller.
```
class ref Dice
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/random/dice/#L7)
Initialise with a random number generator.
```
new ref create(
from: Random ref)
: Dice ref^
```
#### Parameters
* from: [Random](random-random) ref
#### Returns
* [Dice](index) ref^
Public fields
-------------
### var r: [Random](random-random) ref
[[Source]](https://stdlib.ponylang.io/src/random/dice/#L5)
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/random/dice/#L13)
Return the sum of `count` rolls of a die with the given number of `sides`. The die is numbered from 1 to `sides`. For example, count = 2 and sides = 6 will return a value between 2 and 12.
```
fun ref apply(
count: U64 val,
sides: U64 val)
: U64 val
```
#### Parameters
* count: [U64](builtin-u64) val
* sides: [U64](builtin-u64) val
#### Returns
* [U64](builtin-u64) val
pony CommandParser CommandParser
=============
[[Source]](https://stdlib.ponylang.io/src/cli/command_parser/#L3)
```
class ref CommandParser
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/cli/command_parser/#L7)
Creates a new parser for a given command spec.
```
new box create(
spec': CommandSpec box)
: CommandParser box^
```
#### Parameters
* spec': [CommandSpec](cli-commandspec) box
#### Returns
* [CommandParser](index) box^
Public Functions
----------------
### parse
[[Source]](https://stdlib.ponylang.io/src/cli/command_parser/#L18)
Parses all of the command line tokens and env vars and returns a Command, or the first SyntaxError.
```
fun box parse(
argv: Array[String val] box,
envs: (Array[String val] box | None val) = reference)
: (Command box | CommandHelp box | SyntaxError val)
```
#### Parameters
* argv: [Array](builtin-array)[[String](builtin-string) val] box
* envs: ([Array](builtin-array)[[String](builtin-string) val] box | [None](builtin-none) val) = reference
#### Returns
* ([Command](cli-command) box | [CommandHelp](cli-commandhelp) box | [SyntaxError](cli-syntaxerror) val)
pony ListValues[A: A, N: ListNode[A] #read] ListValues[A: A, N: [ListNode](collections-listnode)[A] #read]
==============================================================
[[Source]](https://stdlib.ponylang.io/src/collections/list/#L714)
Iterate over the values in a list.
```
class ref ListValues[A: A, N: ListNode[A] #read] is
Iterator[N->A] ref
```
#### Implements
* [Iterator](builtin-iterator)[N->A] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/list/#L721)
Keep the next list node to be examined.
```
new ref create(
head: (N | None val),
reverse: Bool val = false)
: ListValues[A, N] ref^
```
#### Parameters
* head: (N | [None](builtin-none) val)
* reverse: [Bool](builtin-bool) val = false
#### Returns
* [ListValues](index)[A, N] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections/list/#L728)
If we have a list node, we have more values.
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections/list/#L734)
Get the value of the list node and replace it with the next one.
```
fun ref next()
: N->A ?
```
#### Returns
* N->A ?
pony ReadlineNotify ReadlineNotify
==============
[[Source]](https://stdlib.ponylang.io/src/term/readline_notify/#L3)
Notifier for readline.
```
interface ref ReadlineNotify
```
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/term/readline_notify/#L7)
Receives finished lines. The next prompt is set by fulfilling the promise. If the promise is rejected, readline will stop handling input.
```
fun ref apply(
line: String val,
prompt: Promise[String val] tag)
: None val
```
#### Parameters
* line: [String](builtin-string) val
* prompt: [Promise](promises-promise)[[String](builtin-string) val] tag
#### Returns
* [None](builtin-none) val
### tab
[[Source]](https://stdlib.ponylang.io/src/term/readline_notify/#L14)
Return tab completion possibilities.
```
fun ref tab(
line: String val)
: Seq[String val] box
```
#### Parameters
* line: [String](builtin-string) val
#### Returns
* [Seq](builtin-seq)[[String](builtin-string) val] box
pony Itertools Package Itertools Package
=================
The itertools package provides the `Iter` class for doing useful things with iterators. It is Inspired by Python's itertools library, Rust's Iterator, and Elixir's Enum and Stream.
Iter
----
The Iter class wraps iterators so that additional methods may be applied to it. Some methods, such as fold and collect, run through the underlying iterator in order to return a result. Others, such as map and filter, are lazy. This means that they return another Iter so that the resulting values are computed one by one as needed. Lazy methods return Iter types.
For example, the following code creates an Iter from the values of an array containing the numbers 1 through 5, increments each number by one, filters out any odd numbers, and prints the rest.
```
let xs = Iter[I64]([1; 2; 3; 4; 5].values())
.map[I64]({(x) => x + 1 })
.filter({(x) => (x % 2) == 0 })
.map[None]({(x) => env.out.print(x.string()) })
```
This will result in an iterator that prints the numbers 2, 4, and 6. However, due to the lazy nature of the map and filter, no iteration has actually occurred and nothing will be printed. One solution to this would be to loop over the resulting Iter as so:
```
for x in xs do
None
end
```
This will trigger the iteration and print out the values 2, 4, and 6. This is where the `run` method comes in handy by doing the iteration without the need for a loop. So the final code would be as follows:
```
Iter[I64]([1; 2; 3; 4; 5].values())
.map[I64]({(x) => x + 1 })
.filter({(x) => (x % 2) == 0 })
.map[None]({(x) => env.out.print(x.string()) })
.run()
```
Output:
```
2
4
6
```
Public Types
------------
* [class Iter](itertools-iter)
pony FileRead FileRead
========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L21)
```
primitive val FileRead
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L21)
```
new val create()
: FileRead val^
```
#### Returns
* [FileRead](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L22)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L22)
```
fun box eq(
that: FileRead val)
: Bool val
```
#### Parameters
* that: [FileRead](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L22)
```
fun box ne(
that: FileRead val)
: Bool val
```
#### Parameters
* that: [FileRead](index) val
#### Returns
* [Bool](builtin-bool) val
pony StringBytes StringBytes
===========
[[Source]](https://stdlib.ponylang.io/src/builtin/string/#L1683)
```
class ref StringBytes is
Iterator[U8 val] ref
```
#### Implements
* [Iterator](builtin-iterator)[[U8](builtin-u8) val] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/string/#L1687)
```
new ref create(
string: String box)
: StringBytes ref^
```
#### Parameters
* string: [String](builtin-string) box
#### Returns
* [StringBytes](index) ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/builtin/string/#L1691)
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/builtin/string/#L1694)
```
fun ref next()
: U8 val ?
```
#### Returns
* [U8](builtin-u8) val ?
pony Bureaucracy package Bureaucracy package
===================
It happens to almost every program. It starts small, tiny if you will, like a village where every actor knows every other actor and shutdown is easy. One day you realize your program is no longer a cute seaside hamlet, its a bustling metropolis and you are doing way too much work to keep track of everything. What do you do? Call for a little bureaucracy.
The bureaucracy contains objects designed to ease your bookkeeping burdens. Need to shutdown a number of actors together? Check out `Custodian`. Need to keep track of a lot of stuff and be able to look it up by name? Check out `Registrar`.
Put bureaucracy to use today and before long, your sprawling metropolis of a code base will be manageable again in no time.
Public Types
------------
* [actor Registrar](bureaucracy-registrar)
* [actor Custodian](bureaucracy-custodian)
| programming_docs |
pony ProcessMonitorAuth ProcessMonitorAuth
==================
[[Source]](https://stdlib.ponylang.io/src/process/process_monitor/#L100)
```
type ProcessMonitorAuth is
(AmbientAuth val | StartProcessAuth val)
```
#### Type Alias For
* ([AmbientAuth](builtin-ambientauth) val | [StartProcessAuth](process-startprocessauth) val)
pony HashFunction64[A: A] HashFunction64[A: A]
====================
[[Source]](https://stdlib.ponylang.io/src/collections/hashable/#L35)
A pluggable hash function with 64-bit hashes.
```
interface val HashFunction64[A: A]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/hashable/#L39)
Data structures create instances internally. Use a primitive if possible.
```
new val create()
: HashFunction64[A] val^
```
#### Returns
* [HashFunction64](index)[A] val^
Public Functions
----------------
### hash64
[[Source]](https://stdlib.ponylang.io/src/collections/hashable/#L44)
Calculate the hash of some type. This is an alias of the type parameter to allow data structures to hash things without consuming them.
```
fun box hash64(
x: box->A!)
: U64 val
```
#### Parameters
* x: box->A!
#### Returns
* [U64](builtin-u64) val
### eq
[[Source]](https://stdlib.ponylang.io/src/collections/hashable/#L50)
Determine equality between two keys with the same hash. This is done with viewpoint adapted aliases to allow data structures to determine equality in a box fun without consuming keys.
```
fun box eq(
x: box->A!,
y: box->A!)
: Bool val
```
#### Parameters
* x: box->A!
* y: box->A!
#### Returns
* [Bool](builtin-bool) val
pony None None
====
[[Source]](https://stdlib.ponylang.io/src/builtin/none/#L1)
```
primitive val None is
Stringable box
```
#### Implements
* [Stringable](builtin-stringable) box
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/none/#L1)
```
new val create()
: None val^
```
#### Returns
* [None](index) val^
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/none/#L2)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/none/#L2)
```
fun box eq(
that: None val)
: Bool val
```
#### Parameters
* that: [None](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/none/#L2)
```
fun box ne(
that: None val)
: Bool val
```
#### Parameters
* that: [None](index) val
#### Returns
* [Bool](builtin-bool) val
pony Promises Package Promises Package
================
A `Promise` represents a value that will be available at a later time. `Promise`s can either be fulfilled with a value or rejected. Any number of function handlers can be added to the `Promise`, to be called when the `Promise` is fulfilled or rejected. These handlers themselves are also wrapped in `Promise`s so that they can be chained together in order for the fulfilled value of one `Promise` to be used to compute a value which will be used to fulfill the next `Promise` in the chain, or so that if the `Promise` is rejected then the subsequent reject functions will also be called. The input and output types of a fulfill handler do not have to be the same, so a chain of fulfill handlers can transform the original value into something new.
Fulfill and reject handlers can either be specified as classes that implment the `Fulfill` and `Reject` interfaces, or as functions with the same signatures as the `apply` methods in `Fulfill` and `Reject`.
In the following code, the fulfillment of the `Promise` causes the execution of several fulfillment functions. The output is:
```
fulfilled + foo
fulfilled + bar
fulfilled + baz
```
```
use "promises"
class PrintFulfill is Fulfill[String, String]
let _env: Env
let _msg: String
new create(env: Env, msg: String) =>
_env = env
_msg = msg
fun apply(s: String): String =>
_env.out.print(" + ".join([s; _msg].values()))
s
actor Main
new create(env: Env) =>
let promise = Promise[String]
promise.next[String](recover PrintFulfill(env, "foo") end)
promise.next[String](recover PrintFulfill(env, "bar") end)
promise.next[String](recover PrintFulfill(env, "baz") end)
promise("fulfilled")
```
In the following code, the fulfill functions are chained together so that the fulfilled value of the first one is used to generate a value which fulfills the second one, which in turn is used to compute a value which fulfills the third one, which in turn is used to compute a value which fulfills the fourth one. The output is the average length of the words passed on the command line or `0` if there are no command line arguments.
```
use "promises"
primitive Computation
fun tag string_to_strings(s: String): Array[String] val =>
recover s.split() end
fun tag strings_to_sizes(sa: Array[String] val): Array[USize] val =>
recover
let len = Array[USize]
for s in sa.values() do
len.push(s.size())
end
len
end
fun tag sizes_to_avg(sza: Array[USize] val): USize =>
var acc = USize(0)
for sz in sza.values() do
acc = acc + sz
end
acc / sza.size()
fun tag output(env: Env, sz: USize): None =>
env.out.print(sz.string())
actor Main
new create(env: Env) =>
let promise = Promise[String]
promise.next[Array[String] val](recover Computation~string_to_strings() end)
.next[Array[USize] val](recover Computation~strings_to_sizes() end)
.next[USize](recover Computation~sizes_to_avg() end)
.next[None](recover Computation~output(env) end)
promise(" ".join(env.args.slice(1).values()))
```
Public Types
------------
* [actor Promise](promises-promise)
* [primitive Promises](promises-promises)
* [interface Fulfill](promises-fulfill)
* [interface Reject](promises-reject)
* [class FulfillIdentity](promises-fulfillidentity)
* [class RejectAlways](promises-rejectalways)
pony BackpressureAuth BackpressureAuth
================
[[Source]](https://stdlib.ponylang.io/src/backpressure/backpressure/#L93)
```
type BackpressureAuth is
(AmbientAuth val | ApplyReleaseBackpressureAuth val)
```
#### Type Alias For
* ([AmbientAuth](builtin-ambientauth) val | [ApplyReleaseBackpressureAuth](backpressure-applyreleasebackpressureauth) val)
pony MaxHeap[A: Comparable[A] #read] MaxHeap[A: [Comparable](builtin-comparable)[A] #read]
=====================================================
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L3)
```
type MaxHeap[A: Comparable[A] #read] is
BinaryHeap[A, MaxHeapPriority[A] val] ref
```
#### Type Alias For
* [BinaryHeap](collections-binaryheap)[A, [MaxHeapPriority](collections-maxheappriority)[A] val] ref
pony Assert Assert
======
[[Source]](https://stdlib.ponylang.io/src/assert/assert/#L9)
This is a debug only assertion. If the test is false, it will print any supplied error message to stderr and raise an error.
```
primitive val Assert
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/assert/assert/#L9)
```
new val create()
: Assert val^
```
#### Returns
* [Assert](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/assert/assert/#L14)
```
fun box apply(
test: Bool val,
msg: String val = "")
: None val ?
```
#### Parameters
* test: [Bool](builtin-bool) val
* msg: [String](builtin-string) val = ""
#### Returns
* [None](builtin-none) val ?
### eq
[[Source]](https://stdlib.ponylang.io/src/assert/assert/#L14)
```
fun box eq(
that: Assert val)
: Bool val
```
#### Parameters
* that: [Assert](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/assert/assert/#L14)
```
fun box ne(
that: Assert val)
: Bool val
```
#### Parameters
* that: [Assert](index) val
#### Returns
* [Bool](builtin-bool) val
pony PrefixNumber PrefixNumber
============
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L8)
```
type PrefixNumber is
(PrefixDefault val | PrefixSpace val | PrefixSign val)
```
#### Type Alias For
* ([PrefixDefault](format-prefixdefault) val | [PrefixSpace](format-prefixspace) val | [PrefixSign](format-prefixsign) val)
pony ArgSpec ArgSpec
=======
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L343)
ArgSpec describes the specification of a positional Arg(ument). They have a name, descr(iption), a typ(e), and a default value when they are not required.
Args always come after a leaf command, and are assigned in their positional order.
```
class val ArgSpec
```
Constructors
------------
### bool
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L366)
Creates an Arg with a Bool typed value that can be used like `<cmd> true` to yield an arg value like `cmd.arg("opt").bool() == true`.
```
new val bool(
name': String val,
descr': String val = "",
default': (Bool val | None val) = reference)
: ArgSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* default': ([Bool](builtin-bool) val | [None](builtin-none) val) = reference
#### Returns
* [ArgSpec](index) val^
### string
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L381)
Creates an Arg with a String typed value that can be used like `<cmd> filename` to yield an arg value `cmd.arg("file").string() == "filename"`.
```
new val string(
name': String val,
descr': String val = "",
default': (String val | None val) = reference)
: ArgSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* default': ([String](builtin-string) val | [None](builtin-none) val) = reference
#### Returns
* [ArgSpec](index) val^
### i64
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L396)
Creates an Arg with an I64 typed value that can be used like `<cmd> 42` to yield an arg value like `cmd.arg("count").i64() == I64(42)`.
```
new val i64(
name': String val,
descr': String val = "",
default': (I64 val | None val) = reference)
: ArgSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* default': ([I64](builtin-i64) val | [None](builtin-none) val) = reference
#### Returns
* [ArgSpec](index) val^
### u64
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L410)
Creates an Arg with an U64 typed value that can be used like `<cmd> 47` to yield an arg value like `cmd.arg("count").u64() == U64(47)`.
```
new val u64(
name': String val,
descr': String val = "",
default': (U64 val | None val) = reference)
: ArgSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* default': ([U64](builtin-u64) val | [None](builtin-none) val) = reference
#### Returns
* [ArgSpec](index) val^
### f64
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L424)
Creates an Arg with a F64 typed value that can be used like `<cmd> 1.039` to yield an arg value like `cmd.arg("ratio").f64() == F64(1.039)`.
```
new val f64(
name': String val,
descr': String val = "",
default': (F64 val | None val) = reference)
: ArgSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
* default': ([F64](builtin-f64) val | [None](builtin-none) val) = reference
#### Returns
* [ArgSpec](index) val^
### string\_seq
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L438)
Creates an Arg with a ReadSeq[String] typed value that can be used like `<cmd> file1 file2 file3` to yield a sequence of three strings equivalent to `cmd.arg("file").string_seq() (equiv) ["file1"; "file2"; "file3"]`.
```
new val string_seq(
name': String val,
descr': String val = "")
: ArgSpec val^
```
#### Parameters
* name': [String](builtin-string) val
* descr': [String](builtin-string) val = ""
#### Returns
* [ArgSpec](index) val^
Public Functions
----------------
### name
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L452)
Returns the name of this arg.
```
fun box name()
: String val
```
#### Returns
* [String](builtin-string) val
### descr
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L458)
Returns the description for this arg.
```
fun box descr()
: String val
```
#### Returns
* [String](builtin-string) val
### required
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L468)
Returns true iff this arg is required to be present in the command line.
```
fun box required()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### help\_string
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L474)
Returns a formated help string for this arg.
```
fun box help_string()
: String val
```
#### Returns
* [String](builtin-string) val
### deb\_string
[[Source]](https://stdlib.ponylang.io/src/cli/command_spec/#L480)
```
fun box deb_string()
: String val
```
#### Returns
* [String](builtin-string) val
pony EnvVars EnvVars
=======
[[Source]](https://stdlib.ponylang.io/src/options/env_vars/#L3)
```
primitive val EnvVars
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/options/env_vars/#L3)
```
new val create()
: EnvVars val^
```
#### Returns
* [EnvVars](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/options/env_vars/#L4)
Turns an array of strings that look like environment variables, ie key=value, into a map from string to string.
```
fun box apply(
from: Array[String val] val)
: HashMap[String val, String val, HashEq[String val] val] val
```
#### Parameters
* from: [Array](builtin-array)[[String](builtin-string) val] val
#### Returns
* [HashMap](collections-hashmap)[[String](builtin-string) val, [String](builtin-string) val, [HashEq](collections-hasheq)[[String](builtin-string) val] val] val
### eq
[[Source]](https://stdlib.ponylang.io/src/options/env_vars/#L4)
```
fun box eq(
that: EnvVars val)
: Bool val
```
#### Parameters
* that: [EnvVars](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/options/env_vars/#L4)
```
fun box ne(
that: EnvVars val)
: Bool val
```
#### Parameters
* that: [EnvVars](index) val
#### Returns
* [Bool](builtin-bool) val
pony UnsignedInteger[A: UnsignedInteger[A] val] UnsignedInteger[A: [UnsignedInteger](index)[A] val]
===================================================
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L442)
```
trait val UnsignedInteger[A: UnsignedInteger[A] val] is
Integer[A] val
```
#### Implements
* [Integer](builtin-integer)[A] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L135)
```
new val create(
value: A)
: Real[A] val^
```
#### Parameters
* value: A
#### Returns
* [Real](builtin-real)[A] val^
### from[B: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[B] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L137)
```
new val from[B: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[B] val)](
a: B)
: Real[A] val^
```
#### Parameters
* a: B
#### Returns
* [Real](builtin-real)[A] val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L138)
```
new val min_value()
: Real[A] val^
```
#### Returns
* [Real](builtin-real)[A] val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L139)
```
new val max_value()
: Real[A] val^
```
#### Returns
* [Real](builtin-real)[A] val^
Public Functions
----------------
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L443)
```
fun box abs()
: A
```
#### Returns
* A
### shl
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L445)
```
fun box shl(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### shr
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L446)
```
fun box shr(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L449)
```
fun box fld(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### fldc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L450)
```
fun box fldc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### fld\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L451)
```
fun box fld_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L452)
```
fun box fld_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L454)
```
fun box mod(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### modc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L455)
```
fun box modc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### mod\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L456)
```
fun box mod_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L457)
```
fun box mod_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### shl\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L459)
Unsafe operation. If non-zero bits are shifted-out, the result is undefined.
```
fun box shl_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### shr\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L466)
Unsafe operation. If non-zero bits are shifted-out, the result is undefined.
```
fun box shr_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### rotl
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L473)
```
fun box rotl(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### rotr
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L481)
```
fun box rotr(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### popcount
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L489)
```
fun box popcount()
: A
```
#### Returns
* A
### clz
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L490)
```
fun box clz()
: A
```
#### Returns
* A
### ctz
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L491)
```
fun box ctz()
: A
```
#### Returns
* A
### clz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L493)
Count leading zeroes.
Unsafe operation. If this is 0, the result is undefined.
```
fun box clz_unsafe()
: A
```
#### Returns
* A
### ctz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L501)
Count trailing zeroes.
Unsafe operation. If this is 0, the result is undefined.
```
fun box ctz_unsafe()
: A
```
#### Returns
* A
### bitwidth
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L509)
```
fun box bitwidth()
: A
```
#### Returns
* A
### bytewidth
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L511)
```
fun box bytewidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L513)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L214)
```
fun box add_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### sub\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L221)
```
fun box sub_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mul\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L228)
```
fun box mul_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### div\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L235)
```
fun box div_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### divrem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L245)
```
fun box divrem_unsafe(
y: A)
: (A , A)
```
#### Parameters
* y: A
#### Returns
* (A , A)
### rem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L255)
```
fun box rem_unsafe(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L286)
```
fun box add_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L293)
```
fun box sub_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L300)
```
fun box mul_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L307)
```
fun box div_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L314)
```
fun box rem_partial(
y: A)
: A ?
```
#### Parameters
* y: A
#### Returns
* A ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L322)
```
fun box divrem_partial(
y: A)
: (A , A) ?
```
#### Parameters
* y: A
#### Returns
* (A , A) ?
### neg\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L344)
```
fun box neg_unsafe()
: A
```
#### Returns
* A
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L351)
```
fun box addc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L355)
```
fun box subc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L359)
```
fun box mulc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L363)
```
fun box divc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L367)
```
fun box remc(
y: A)
: (A , Bool val)
```
#### Parameters
* y: A
#### Returns
* (A , [Bool](builtin-bool) val)
### op\_and
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L384)
```
fun box op_and(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### op\_or
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L385)
```
fun box op_or(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### op\_xor
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L386)
```
fun box op_xor(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### op\_not
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L387)
```
fun box op_not()
: A
```
#### Returns
* A
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L389)
```
fun box bit_reverse()
: A
```
#### Returns
* A
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L395)
```
fun box bswap()
: A
```
#### Returns
* A
### add
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L141)
```
fun box add(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### sub
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L142)
```
fun box sub(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### mul
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L143)
```
fun box mul(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### div
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L144)
```
fun box div(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### divrem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L150)
```
fun box divrem(
y: A)
: (A , A)
```
#### Parameters
* y: A
#### Returns
* (A , A)
### rem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L151)
```
fun box rem(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### neg
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L159)
```
fun box neg()
: A
```
#### Returns
* A
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L172)
```
fun box eq(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L173)
```
fun box ne(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### lt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L174)
```
fun box lt(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### le
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L175)
```
fun box le(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### ge
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L176)
```
fun box ge(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### gt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L177)
```
fun box gt(
y: box->A)
: Bool val
```
#### Parameters
* y: box->A
#### Returns
* [Bool](builtin-bool) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L179)
```
fun box min(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L180)
```
fun box max(
y: A)
: A
```
#### Parameters
* y: A
#### Returns
* A
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L182)
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L198)
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L2)
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L3)
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L4)
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L5)
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L6)
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L7)
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L8)
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L10)
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L11)
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L12)
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L13)
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L14)
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L15)
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L16)
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L18)
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L19)
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L21)
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L28)
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L35)
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L42)
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L49)
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L56)
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L63)
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L70)
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L77)
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L84)
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L91)
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### u128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L98)
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L105)
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L112)
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L119)
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L126)
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: box->A)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: box->A
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony TCPConnectionNotify TCPConnectionNotify
===================
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L1)
Notifications for TCP connections.
For an example of using this class please see the documentation for the `TCPConnection` and `TCPListener` actors.
```
interface ref TCPConnectionNotify
```
Public Functions
----------------
### accepted
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L8)
Called when a TCPConnection is accepted by a TCPListener.
```
fun ref accepted(
conn: TCPConnection ref)
: None val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
#### Returns
* [None](builtin-none) val
### proxy\_via
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L14)
Called before before attempting to connect to the destination server In order to connect via proxy, return the host & service for the proxy server.
An implementation of this function might look like:
```
let _proxy_host = "some-proxy.example.com"
let _proxy_service = "80"
var _destination_host: ( None | String )
var _destination_service: ( None | String )
fun ref proxy_via(host: String, service: String): (String, String) =>
_destination_host = host
_destination_service = service
( _proxy_host, _proxy_service )
```
```
fun ref proxy_via(
host: String val,
service: String val)
: (String val , String val)
```
#### Parameters
* host: [String](builtin-string) val
* service: [String](builtin-string) val
#### Returns
* ([String](builtin-string) val , [String](builtin-string) val)
### connecting
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L35)
Called if name resolution succeeded for a TCPConnection and we are now waiting for a connection to the server to succeed. The count is the number of connections we're trying. The notifier will be informed each time the count changes, until a connection is made or connect\_failed() is called.
```
fun ref connecting(
conn: TCPConnection ref,
count: U32 val)
: None val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
* count: [U32](builtin-u32) val
#### Returns
* [None](builtin-none) val
### connected
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L44)
Called when we have successfully connected to the server.
```
fun ref connected(
conn: TCPConnection ref)
: None val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
#### Returns
* [None](builtin-none) val
### connect\_failed
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L50)
Called when we have failed to connect to all possible addresses for the server. At this point, the connection will never be established.
It is expected to implement proper error handling. You need to opt in to ignoring errors, which can be implemented like this:
```
fun ref connect_failed(conn: TCPConnection ref) =>
None
```
```
fun ref connect_failed(
conn: TCPConnection ref)
: None val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
#### Returns
* [None](builtin-none) val
### auth\_failed
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L64)
A raw TCPConnection has no authentication mechanism. However, when protocols are wrapped in other protocols, this can be used to report an authentication failure in a lower level protocol (e.g. SSL).
```
fun ref auth_failed(
conn: TCPConnection ref)
: None val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
#### Returns
* [None](builtin-none) val
### sent
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L72)
Called when data is sent on the connection. This gives the notifier an opportunity to modify sent data before it is written. To swallow data, return an empty string.
```
fun ref sent(
conn: TCPConnection ref,
data: (String val | Array[U8 val] val))
: (String val | Array[U8 val] val)
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
* data: ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
#### Returns
* ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
### sentv
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L80)
Called when multiple chunks of data are sent to the connection in a single call. This gives the notifier an opportunity to modify the sent data chunks before they are written. To swallow the send, return an empty Array[String].
```
fun ref sentv(
conn: TCPConnection ref,
data: ByteSeqIter val)
: ByteSeqIter val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
* data: [ByteSeqIter](builtin-byteseqiter) val
#### Returns
* [ByteSeqIter](builtin-byteseqiter) val
### received
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L89)
Called when new data is received on the connection. Return true if you want to continue receiving messages without yielding until you read max\_size on the TCPConnection. Return false to cause the TCPConnection to yield now.
Includes the number of times during the current behavior, that received has been called. This allows the notifier to end reads on a regular basis.
```
fun ref received(
conn: TCPConnection ref,
data: Array[U8 val] iso,
times: USize val)
: Bool val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
* data: [Array](builtin-array)[[U8](builtin-u8) val] iso
* times: [USize](builtin-usize) val
#### Returns
* [Bool](builtin-bool) val
### expect
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L106)
Called when the connection has been told to expect a certain quantity of bytes. This allows nested notifiers to change the expected quantity, which allows a lower level protocol to handle any framing (e.g. SSL).
```
fun ref expect(
conn: TCPConnection ref,
qty: USize val)
: USize val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
* qty: [USize](builtin-usize) val
#### Returns
* [USize](builtin-usize) val
### closed
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L114)
Called when the connection is closed.
```
fun ref closed(
conn: TCPConnection ref)
: None val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
#### Returns
* [None](builtin-none) val
### throttled
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L120)
Called when the connection starts experiencing TCP backpressure. You should respond to this by pausing additional calls to `write` and `writev` until you are informed that pressure has been released. Failure to respond to the `throttled` notification will result in outgoing data queuing in the connection and increasing memory usage.
```
fun ref throttled(
conn: TCPConnection ref)
: None val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
#### Returns
* [None](builtin-none) val
### unthrottled
[[Source]](https://stdlib.ponylang.io/src/net/tcp_connection_notify/#L130)
Called when the connection stops experiencing TCP backpressure. Upon receiving this notification, you should feel free to start making calls to `write` and `writev` again.
```
fun ref unthrottled(
conn: TCPConnection ref)
: None val
```
#### Parameters
* conn: [TCPConnection](net-tcpconnection) ref
#### Returns
* [None](builtin-none) val
pony Buffered Package Buffered Package
================
The Buffered package provides two classes, `Writer` and `Reader`, for writing and reading messages using common encodings. These classes are useful when dealing with things like network data and binary file formats.
Example program
---------------
```
use "buffered"
actor Main
new create(env: Env) =>
let reader = Reader
let writer = Writer
writer.u32_be(42)
writer.f32_be(3.14)
let b = recover iso Array[U8] end
for chunk in writer.done().values() do
b.append(chunk)
end
reader.append(consume b)
try
env.out.print(reader.u32_be()?.string()) // prints 42
env.out.print(reader.f32_be()?.string()) // prints 3.14
end
```
Public Types
------------
* [class Writer](buffered-writer)
* [class Reader](buffered-reader)
pony Float Float
=====
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L485)
```
type Float is
(F32 val | F64 val)
```
#### Type Alias For
* ([F32](builtin-f32) val | [F64](builtin-f64) val)
pony PrefixSpec PrefixSpec
==========
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L1)
```
trait val PrefixSpec
```
pony Serialise Serialise
=========
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L30)
```
primitive val Serialise
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L30)
```
new val create()
: Serialise val^
```
#### Returns
* [Serialise](index) val^
Public Functions
----------------
### signature
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L31)
Returns a byte array that is unique to this compiled Pony binary, for the purposes of comparing before deserialising any data from that source. It is statistically impossible for two serialisation-incompatible Pony binaries to have the same serialise signature.
```
fun box signature()
: Array[U8 val] val
```
#### Returns
* [Array](builtin-array)[[U8](builtin-u8) val] val
### eq
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L31)
```
fun box eq(
that: Serialise val)
: Bool val
```
#### Parameters
* that: [Serialise](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L31)
```
fun box ne(
that: Serialise val)
: Bool val
```
#### Parameters
* that: [Serialise](index) val
#### Returns
* [Bool](builtin-bool) val
pony Format Format
======
[[Source]](https://stdlib.ponylang.io/src/format/format/#L37)
Provides functions for generating formatted strings.
* fmt. Format to use.
* prefix. Prefix to use.
* prec. Precision to use. The exact meaning of this depends on the type, but is generally the number of characters used for all, or part, of the string. A value of -1 indicates that the default for the type should be used.
* width. The minimum number of characters that will be in the produced string. If necessary the string will be padded with the fill character to make it long enough. *align. Specify whether fill characters should be added at the beginning or end of the generated string, or both.* fill: The character to pad a string with if is is shorter than width.
```
primitive val Format
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format/#L37)
```
new val create()
: Format val^
```
#### Returns
* [Format](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/format/format/#L54)
```
fun box apply(
str: String val,
fmt: FormatDefault val = reference,
prefix: PrefixDefault val = reference,
prec: USize val = call,
width: USize val = 0,
align: (AlignLeft val | AlignRight val | AlignCenter val) = reference,
fill: U32 val = 32)
: String iso^
```
#### Parameters
* str: [String](builtin-string) val
* fmt: [FormatDefault](format-formatdefault) val = reference
* prefix: [PrefixDefault](format-prefixdefault) val = reference
* prec: [USize](builtin-usize) val = call
* width: [USize](builtin-usize) val = 0
* align: ([AlignLeft](format-alignleft) val | [AlignRight](format-alignright) val | [AlignCenter](format-aligncenter) val) = reference
* fill: [U32](builtin-u32) val = 32
#### Returns
* [String](builtin-string) iso^
### int[A: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val) & [Integer](builtin-integer)[A])]
[[Source]](https://stdlib.ponylang.io/src/format/format/#L94)
```
fun box int[A: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val) & Integer[A])](
x: A,
fmt: (FormatDefault val | FormatUTF32 val | FormatBinary val |
FormatBinaryBare val | FormatOctal val | FormatOctalBare val |
FormatHex val | FormatHexBare val | FormatHexSmall val |
FormatHexSmallBare val) = reference,
prefix: (PrefixDefault val | PrefixSpace val | PrefixSign val) = reference,
prec: USize val = call,
width: USize val = 0,
align: (AlignLeft val | AlignRight val | AlignCenter val) = reference,
fill: U32 val = 32)
: String iso^
```
#### Parameters
* x: A
* fmt: ([FormatDefault](format-formatdefault) val | [FormatUTF32](format-formatutf32) val | [FormatBinary](format-formatbinary) val | [FormatBinaryBare](format-formatbinarybare) val | [FormatOctal](format-formatoctal) val | [FormatOctalBare](format-formatoctalbare) val | [FormatHex](format-formathex) val | [FormatHexBare](format-formathexbare) val | [FormatHexSmall](format-formathexsmall) val | [FormatHexSmallBare](format-formathexsmallbare) val) = reference
* prefix: ([PrefixDefault](format-prefixdefault) val | [PrefixSpace](format-prefixspace) val | [PrefixSign](format-prefixsign) val) = reference
* prec: [USize](builtin-usize) val = call
* width: [USize](builtin-usize) val = 0
* align: ([AlignLeft](format-alignleft) val | [AlignRight](format-alignright) val | [AlignCenter](format-aligncenter) val) = reference
* fill: [U32](builtin-u32) val = 32
#### Returns
* [String](builtin-string) iso^
### float[A: (([F32](builtin-f32) val | [F64](builtin-f64) val) & [FloatingPoint](builtin-floatingpoint)[A])]
[[Source]](https://stdlib.ponylang.io/src/format/format/#L135)
```
fun box float[A: ((F32 val | F64 val) & FloatingPoint[A])](
x: A,
fmt: (FormatDefault val | FormatExp val | FormatExpLarge val |
FormatFix val | FormatFixLarge val | FormatGeneral val |
FormatGeneralLarge val) = reference,
prefix: (PrefixDefault val | PrefixSpace val | PrefixSign val) = reference,
prec: USize val = 6,
width: USize val = 0,
align: (AlignLeft val | AlignRight val | AlignCenter val) = reference,
fill: U32 val = 32)
: String iso^
```
#### Parameters
* x: A
* fmt: ([FormatDefault](format-formatdefault) val | [FormatExp](format-formatexp) val | [FormatExpLarge](format-formatexplarge) val | [FormatFix](format-formatfix) val | [FormatFixLarge](format-formatfixlarge) val | [FormatGeneral](format-formatgeneral) val | [FormatGeneralLarge](format-formatgenerallarge) val) = reference
* prefix: ([PrefixDefault](format-prefixdefault) val | [PrefixSpace](format-prefixspace) val | [PrefixSign](format-prefixsign) val) = reference
* prec: [USize](builtin-usize) val = 6
* width: [USize](builtin-usize) val = 0
* align: ([AlignLeft](format-alignleft) val | [AlignRight](format-alignright) val | [AlignCenter](format-aligncenter) val) = reference
* fill: [U32](builtin-u32) val = 32
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format/#L54)
```
fun box eq(
that: Format val)
: Bool val
```
#### Parameters
* that: [Format](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format/#L54)
```
fun box ne(
that: Format val)
: Bool val
```
#### Parameters
* that: [Format](index) val
#### Returns
* [Bool](builtin-bool) val
pony PrefixSpace PrefixSpace
===========
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L5)
```
primitive val PrefixSpace is
PrefixSpec val
```
#### Implements
* [PrefixSpec](format-prefixspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L5)
```
new val create()
: PrefixSpace val^
```
#### Returns
* [PrefixSpace](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L6)
```
fun box eq(
that: PrefixSpace val)
: Bool val
```
#### Parameters
* that: [PrefixSpace](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/prefix_spec/#L6)
```
fun box ne(
that: PrefixSpace val)
: Bool val
```
#### Parameters
* that: [PrefixSpace](index) val
#### Returns
* [Bool](builtin-bool) val
pony F32 F32
===
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L1)
```
primitive val F32 is
FloatingPoint[F32 val] val
```
#### Implements
* [FloatingPoint](builtin-floatingpoint)[[F32](index) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L2)
```
new val create(
value: F32 val = 0)
: F32 val^
```
#### Parameters
* value: [F32](index) val = 0
#### Returns
* [F32](index) val^
### pi
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L3)
```
new val pi()
: F32 val^
```
#### Returns
* [F32](index) val^
### e
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L4)
```
new val e()
: F32 val^
```
#### Returns
* [F32](index) val^
### from\_bits
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L9)
```
new val from_bits(
i: U32 val)
: F32 val^
```
#### Parameters
* i: [U32](builtin-u32) val
#### Returns
* [F32](index) val^
### from[B: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](builtin-u64) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](index) val | [F64](builtin-f64) val) & [Real](builtin-real)[B] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L11)
```
new val from[B: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[B] val)](
a: B)
: F32 val^
```
#### Parameters
* a: B
#### Returns
* [F32](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L13)
Minimum negative value representable.
```
new val min_value()
: F32 val^
```
#### Returns
* [F32](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L19)
Maximum positive value representable.
```
new val max_value()
: F32 val^
```
#### Returns
* [F32](index) val^
### min\_normalised
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L25)
Minimum positive value representable at full precision (ie a normalised number).
```
new val min_normalised()
: F32 val^
```
#### Returns
* [F32](index) val^
### epsilon
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L32)
Minimum positive value such that (1 + epsilon) != 1.
```
new val epsilon()
: F32 val^
```
#### Returns
* [F32](index) val^
Public Functions
----------------
### bits
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L10)
```
fun box bits()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### radix
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L38)
Exponent radix.
```
fun tag radix()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### precision2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L44)
Mantissa precision in bits.
```
fun tag precision2()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### precision10
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L50)
Mantissa precision in decimal digits.
```
fun tag precision10()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### min\_exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L56)
Minimum exponent value such that (2^exponent) - 1 is representable at full precision (ie a normalised number).
```
fun tag min_exp2()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### min\_exp10
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L63)
Minimum exponent value such that (10^exponent) - 1 is representable at full precision (ie a normalised number).
```
fun tag min_exp10()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### max\_exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L70)
Maximum exponent value such that (2^exponent) - 1 is representable.
```
fun tag max_exp2()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### max\_exp10
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L76)
Maximum exponent value such that (10^exponent) - 1 is representable.
```
fun tag max_exp10()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L82)
```
fun box abs()
: F32 val
```
#### Returns
* [F32](index) val
### ceil
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L83)
```
fun box ceil()
: F32 val
```
#### Returns
* [F32](index) val
### floor
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L84)
```
fun box floor()
: F32 val
```
#### Returns
* [F32](index) val
### round
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L85)
```
fun box round()
: F32 val
```
#### Returns
* [F32](index) val
### trunc
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L86)
```
fun box trunc()
: F32 val
```
#### Returns
* [F32](index) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L88)
```
fun box min(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L89)
```
fun box max(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### fld
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L91)
```
fun box fld(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### fld\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L94)
```
fun box fld_unsafe(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### mod
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L97)
```
fun box mod(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### mod\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L107)
```
fun box mod_unsafe(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### finite
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L117)
Check whether this number is finite, ie not +/-infinity and not NaN.
```
fun box finite()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### infinite
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L124)
Check whether this number is +/-infinity
```
fun box infinite()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### nan
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L132)
Check whether this number is NaN.
```
fun box nan()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### ldexp
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L140)
```
fun box ldexp(
x: F32 val,
exponent: I32 val)
: F32 val
```
#### Parameters
* x: [F32](index) val
* exponent: [I32](builtin-i32) val
#### Returns
* [F32](index) val
### frexp
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L143)
```
fun box frexp()
: (F32 val , U32 val)
```
#### Returns
* ([F32](index) val , [U32](builtin-u32) val)
### log
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L148)
```
fun box log()
: F32 val
```
#### Returns
* [F32](index) val
### log2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L149)
```
fun box log2()
: F32 val
```
#### Returns
* [F32](index) val
### log10
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L150)
```
fun box log10()
: F32 val
```
#### Returns
* [F32](index) val
### logb
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L151)
```
fun box logb()
: F32 val
```
#### Returns
* [F32](index) val
### pow
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L153)
```
fun box pow(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### powi
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L154)
```
fun box powi(
y: I32 val)
: F32 val
```
#### Parameters
* y: [I32](builtin-i32) val
#### Returns
* [F32](index) val
### sqrt
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L161)
```
fun box sqrt()
: F32 val
```
#### Returns
* [F32](index) val
### sqrt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L168)
Unsafe operation. If this is negative, the result is undefined.
```
fun box sqrt_unsafe()
: F32 val
```
#### Returns
* [F32](index) val
### cbrt
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L175)
```
fun box cbrt()
: F32 val
```
#### Returns
* [F32](index) val
### exp
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L176)
```
fun box exp()
: F32 val
```
#### Returns
* [F32](index) val
### exp2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L177)
```
fun box exp2()
: F32 val
```
#### Returns
* [F32](index) val
### cos
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L179)
```
fun box cos()
: F32 val
```
#### Returns
* [F32](index) val
### sin
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L180)
```
fun box sin()
: F32 val
```
#### Returns
* [F32](index) val
### tan
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L181)
```
fun box tan()
: F32 val
```
#### Returns
* [F32](index) val
### cosh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L183)
```
fun box cosh()
: F32 val
```
#### Returns
* [F32](index) val
### sinh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L184)
```
fun box sinh()
: F32 val
```
#### Returns
* [F32](index) val
### tanh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L185)
```
fun box tanh()
: F32 val
```
#### Returns
* [F32](index) val
### acos
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L187)
```
fun box acos()
: F32 val
```
#### Returns
* [F32](index) val
### asin
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L188)
```
fun box asin()
: F32 val
```
#### Returns
* [F32](index) val
### atan
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L189)
```
fun box atan()
: F32 val
```
#### Returns
* [F32](index) val
### atan2
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L190)
```
fun box atan2(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### acosh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L192)
```
fun box acosh()
: F32 val
```
#### Returns
* [F32](index) val
### asinh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L193)
```
fun box asinh()
: F32 val
```
#### Returns
* [F32](index) val
### atanh
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L194)
```
fun box atanh()
: F32 val
```
#### Returns
* [F32](index) val
### copysign
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L196)
```
fun box copysign(
sign: F32 val)
: F32 val
```
#### Parameters
* sign: [F32](index) val
#### Returns
* [F32](index) val
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L198)
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### hash64
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L199)
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### i128
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L201)
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### u128
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L202)
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### i128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L204)
Unsafe operation. If the value doesn't fit in the destination type, the result is undefined.
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### u128\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/float/#L211)
Unsafe operation. If the value doesn't fit in the destination type, the result is undefined.
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### add\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L527)
```
fun box add_unsafe(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### sub\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L536)
```
fun box sub_unsafe(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### mul\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L545)
```
fun box mul_unsafe(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### div\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L554)
```
fun box div_unsafe(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### divrem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L571)
```
fun box divrem_unsafe(
y: F32 val)
: (F32 val , F32 val)
```
#### Parameters
* y: [F32](index) val
#### Returns
* ([F32](index) val , [F32](index) val)
### rem\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L580)
```
fun box rem_unsafe(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### neg\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L597)
```
fun box neg_unsafe()
: F32 val
```
#### Returns
* [F32](index) val
### eq\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L606)
```
fun box eq_unsafe(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### ne\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L615)
```
fun box ne_unsafe(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### lt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L624)
```
fun box lt_unsafe(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### le\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L633)
```
fun box le_unsafe(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### ge\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L642)
```
fun box ge_unsafe(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### gt\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L651)
```
fun box gt_unsafe(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### string
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L711)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L141)
```
fun box add(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### sub
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L142)
```
fun box sub(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### mul
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L143)
```
fun box mul(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### div
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L144)
```
fun box div(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### divrem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L150)
```
fun box divrem(
y: F32 val)
: (F32 val , F32 val)
```
#### Parameters
* y: [F32](index) val
#### Returns
* ([F32](index) val , [F32](index) val)
### rem
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L151)
```
fun box rem(
y: F32 val)
: F32 val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [F32](index) val
### neg
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L159)
```
fun box neg()
: F32 val
```
#### Returns
* [F32](index) val
### eq
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L172)
```
fun box eq(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L173)
```
fun box ne(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L174)
```
fun box lt(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### le
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L175)
```
fun box le(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L176)
```
fun box ge(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L177)
```
fun box gt(
y: F32 val)
: Bool val
```
#### Parameters
* y: [F32](index) val
#### Returns
* [Bool](builtin-bool) val
### i8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L2)
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L3)
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L4)
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L5)
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### ilong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L7)
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L8)
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L10)
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L11)
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L12)
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L13)
```
fun box u64()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### ulong
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L15)
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L16)
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L18)
```
fun box f32()
: F32 val
```
#### Returns
* [F32](index) val
### f64
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L19)
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L21)
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L28)
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L35)
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L42)
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### ilong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L56)
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L63)
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L70)
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L77)
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L84)
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L91)
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](builtin-u64) val
### ulong\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L105)
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L112)
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L119)
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](index) val
### f64\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/real/#L126)
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: F32 val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [F32](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
pony FileLookup FileLookup
==========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L15)
```
primitive val FileLookup
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L15)
```
new val create()
: FileLookup val^
```
#### Returns
* [FileLookup](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L16)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L16)
```
fun box eq(
that: FileLookup val)
: Bool val
```
#### Parameters
* that: [FileLookup](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L16)
```
fun box ne(
that: FileLookup val)
: Bool val
```
#### Parameters
* that: [FileLookup](index) val
#### Returns
* [Bool](builtin-bool) val
pony Random package Random package
==============
The Random package provides support generating random numbers. The package provides random number generators you can use in your code, a dice roller and a trait for implementing your own random number generator.
If your application does not require a specific generator, use Rand.
Seed values can contain up to 128 bits of randomness in the form of two U64s. A common non-cryptographically secure way to seed a generator is with `Time.now`.
```
let rand = Rand
let n = rand.next()
```
Public Types
------------
* [class XorShift128Plus](random-xorshift128plus)
* [class XorOshiro128Plus](random-xoroshiro128plus)
* [class XorOshiro128StarStar](random-xoroshiro128starstar)
* [class SplitMix64](random-splitmix64)
* [type Rand](random-rand)
* [trait Random](random-random)
* [class MT](random-mt)
* [class Dice](random-dice)
pony FormatHex FormatHex
=========
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L10)
```
primitive val FormatHex is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L10)
```
new val create()
: FormatHex val^
```
#### Returns
* [FormatHex](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L11)
```
fun box eq(
that: FormatHex val)
: Bool val
```
#### Parameters
* that: [FormatHex](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L11)
```
fun box ne(
that: FormatHex val)
: Bool val
```
#### Parameters
* that: [FormatHex](index) val
#### Returns
* [Bool](builtin-bool) val
pony OutputSerialisedAuth OutputSerialisedAuth
====================
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L56)
This is a capability token that allows the holder to examine serialised data. This should only be provided to types that need to write serialised data to some output stream, such as a file or socket. A type with the SerialiseAuth capability should usually not also have OutputSerialisedAuth, as the combination gives the holder the ability to examine the bitwise contents of any object it has a reference to.
```
primitive val OutputSerialisedAuth
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L65)
```
new val create(
auth: AmbientAuth val)
: OutputSerialisedAuth val^
```
#### Parameters
* auth: [AmbientAuth](builtin-ambientauth) val
#### Returns
* [OutputSerialisedAuth](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L65)
```
fun box eq(
that: OutputSerialisedAuth val)
: Bool val
```
#### Parameters
* that: [OutputSerialisedAuth](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L65)
```
fun box ne(
that: OutputSerialisedAuth val)
: Bool val
```
#### Parameters
* that: [OutputSerialisedAuth](index) val
#### Returns
* [Bool](builtin-bool) val
pony SetValues[A: A, H: HashFunction[A!] val, S: HashSet[A, H] #read] SetValues[A: A, H: [HashFunction](collections-hashfunction)[A!] val, S: [HashSet](collections-hashset)[A, H] #read]
===================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/set/#L286)
An iterator over the values in a set.
```
class ref SetValues[A: A, H: HashFunction[A!] val, S: HashSet[A, H] #read] is
Iterator[S->A] ref
```
#### Implements
* [Iterator](builtin-iterator)[S->A] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/set/#L295)
Creates an iterator for the given set.
```
new ref create(
set: S)
: SetValues[A, H, S] ref^
```
#### Parameters
* set: S
#### Returns
* [SetValues](index)[A, H, S] ref^
Public Functions
----------------
### has\_next
[[Source]](https://stdlib.ponylang.io/src/collections/set/#L301)
True if it believes there are remaining entries. May not be right if values were added or removed from the set.
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/collections/set/#L308)
Returns the next value, or raises an error if there isn't one. If values are added during iteration, this may not return all values.
```
fun ref next()
: S->A ?
```
#### Returns
* S->A ?
pony FormatHexSmall FormatHexSmall
==============
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L12)
```
primitive val FormatHexSmall is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L12)
```
new val create()
: FormatHexSmall val^
```
#### Returns
* [FormatHexSmall](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L13)
```
fun box eq(
that: FormatHexSmall val)
: Bool val
```
#### Parameters
* that: [FormatHexSmall](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L13)
```
fun box ne(
that: FormatHexSmall val)
: Bool val
```
#### Parameters
* that: [FormatHexSmall](index) val
#### Returns
* [Bool](builtin-bool) val
pony FormatInt FormatInt
=========
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L15)
```
type FormatInt is
(FormatDefault val | FormatUTF32 val | FormatBinary val | FormatBinaryBare val | FormatOctal val | FormatOctalBare val | FormatHex val | FormatHexBare val | FormatHexSmall val | FormatHexSmallBare val)
```
#### Type Alias For
* ([FormatDefault](format-formatdefault) val | [FormatUTF32](format-formatutf32) val | [FormatBinary](format-formatbinary) val | [FormatBinaryBare](format-formatbinarybare) val | [FormatOctal](format-formatoctal) val | [FormatOctalBare](format-formatoctalbare) val | [FormatHex](format-formathex) val | [FormatHexBare](format-formathexbare) val | [FormatHexSmall](format-formathexsmall) val | [FormatHexSmallBare](format-formathexsmallbare) val)
pony TestHelper TestHelper
==========
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L4)
Per unit test class that provides control, logging and assertion functions.
Each unit test is given a TestHelper when it is run. This is val and so can be passed between methods and actors within the test without restriction.
The assertion functions check the relevant condition and mark the test as a failure if appropriate. The success or failure of the condition is reported back as a Bool which can be checked if a different code path is needed when that condition fails.
All assert functions take an optional message argument. This is simply a string that is printed as part of the error message when the condition fails. It is intended to aid identifying what failed.
```
class val TestHelper
```
Public fields
-------------
### let env: [Env](builtin-env) val
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L22)
The process environment.
This is useful for getting the [root authority](builtin-ambientauth) in order to access the filesystem (See [files](files--index)) or the network (See [net](net--index)) in your tests.
Public Functions
----------------
### log
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L38)
Log the given message.
The verbose parameter allows messages to be printed only when the --verbose command line option is used. For example, by default assert failures are logged, but passes are not. With --verbose both passes and fails are reported.
Logs are printed one test at a time to avoid interleaving log lines from concurrent tests.
```
fun box log(
msg: String val,
verbose: Bool val = false)
: None val
```
#### Parameters
* msg: [String](builtin-string) val
* verbose: [Bool](builtin-bool) val = false
#### Returns
* [None](builtin-none) val
### fail
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L52)
Flag the test as having failed.
```
fun box fail(
msg: String val = "Test failed")
: None val
```
#### Parameters
* msg: [String](builtin-string) val = "Test failed"
#### Returns
* [None](builtin-none) val
### assert\_true
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L58)
Assert that the given expression is true.
```
fun box assert_true(
actual: Bool val,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* actual: [Bool](builtin-bool) val
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_false
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L71)
Assert that the given expression is false.
```
fun box assert_false(
actual: Bool val,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* actual: [Bool](builtin-bool) val
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_error
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L84)
Assert that the given test function throws an error when run.
```
fun box assert_error(
test: ITest box,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* test: [ITest](ponytest-itest) box
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_no\_error
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L99)
Assert that the gived test function does not throw an error when run.
```
fun box assert_no_error(
test: ITest box,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* test: [ITest](ponytest-itest) box
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_is[A: A]
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L117)
Assert that the 2 given expressions resolve to the same instance
```
fun box assert_is[A: A](
expect: A,
actual: A,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* expect: A
* actual: A
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_eq[A: ([Equatable](builtin-equatable)[A] #read & [Stringable](builtin-stringable) #read)]
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L154)
Assert that the 2 given expressions are equal.
```
fun box assert_eq[A: (Equatable[A] #read & Stringable #read)](
expect: A,
actual: A,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* expect: A
* actual: A
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_isnt[A: A]
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L179)
Assert that the 2 given expressions resolve to different instances.
```
fun box assert_isnt[A: A](
not_expect: A,
actual: A,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* not\_expect: A
* actual: A
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_ne[A: ([Equatable](builtin-equatable)[A] #read & [Stringable](builtin-stringable) #read)]
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L216)
Assert that the 2 given expressions are not equal.
```
fun box assert_ne[A: (Equatable[A] #read & Stringable #read)](
not_expect: A,
actual: A,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* not\_expect: A
* actual: A
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_array\_eq[A: ([Equatable](builtin-equatable)[A] #read & [Stringable](builtin-stringable) #read)]
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L244)
Assert that the contents of the 2 given ReadSeqs are equal.
The type parameter of this function is the type parameter of the elements in both ReadSeqs. For instance, when comparing two `Array[U8]`, you should call this method as follows:
```
fun apply(h: TestHelper) =>
let a: Array[U8] = [1; 2; 3]
let b: Array[U8] = [1; 2; 3]
h.assert_array_eq[U8](a, b)
```
```
fun box assert_array_eq[A: (Equatable[A] #read & Stringable #read)](
expect: ReadSeq[A] box,
actual: ReadSeq[A] box,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* expect: [ReadSeq](builtin-readseq)[A] box
* actual: [ReadSeq](builtin-readseq)[A] box
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### assert\_array\_eq\_unordered[A: ([Equatable](builtin-equatable)[A] #read & [Stringable](builtin-stringable) #read)]
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L297)
Assert that the contents of the 2 given ReadSeqs are equal ignoring order.
The type parameter of this function is the type parameter of the elements in both ReadSeqs. For instance, when comparing two `Array[U8]`, you should call this method as follows:
```
fun apply(h: TestHelper) =>
let a: Array[U8] = [1; 2; 3]
let b: Array[U8] = [1; 3; 2]
h.assert_array_eq_unordered[U8](a, b)
```
```
fun box assert_array_eq_unordered[A: (Equatable[A] #read & Stringable #read)](
expect: ReadSeq[A] box,
actual: ReadSeq[A] box,
msg: String val = "",
loc: SourceLoc val = __loc)
: Bool val
```
#### Parameters
* expect: [ReadSeq](builtin-readseq)[A] box
* actual: [ReadSeq](builtin-readseq)[A] box
* msg: [String](builtin-string) val = ""
* loc: [SourceLoc](builtin-sourceloc) val = \_\_loc
#### Returns
* [Bool](builtin-bool) val
### long\_test
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L375)
Indicate that this is a long running test that may continue after the test function exits. Once this function is called, complete() must be called to finish the test, unless a timeout occurs. The timeout is specified in nanseconds.
```
fun box long_test(
timeout: U64 val)
: None val
```
#### Parameters
* timeout: [U64](builtin-u64) val
#### Returns
* [None](builtin-none) val
### complete
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L385)
MUST be called by each long test to indicate the test has finished, unless a timeout occurs.
The "success" parameter specifies whether the test succeeded. However if any asserts fail the test will be considered a failure, regardless of the value of this parameter.
Once this is called tear\_down() may be called at any time.
```
fun box complete(
success: Bool val)
: None val
```
#### Parameters
* success: [Bool](builtin-bool) val
#### Returns
* [None](builtin-none) val
### expect\_action
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L398)
Can be called in a long test to set up expectations for one or more actions that, when all completed, will complete the test.
This pattern is useful for cases where you have multiple things that need to happen to complete your test, but don't want to have to collect them all yourself into a single actor that calls the complete method.
The order of calls to expect\_action don't matter - the actions may be completed in any other order to complete the test.
```
fun box expect_action(
name: String val)
: None val
```
#### Parameters
* name: [String](builtin-string) val
#### Returns
* [None](builtin-none) val
### complete\_action
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L412)
MUST be called for each action expectation that was set up in a long test to fulfill the expectations. Any expectations that are still outstanding when the long test timeout runs out will be printed by name when it fails.
Completing all outstanding actions is enough to finish the test. There's no need to also call the complete method when the actions are finished.
Calling the complete method will finish the test immediately, without waiting for any outstanding actions to be completed.
```
fun box complete_action(
name: String val)
: None val
```
#### Parameters
* name: [String](builtin-string) val
#### Returns
* [None](builtin-none) val
### fail\_action
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L426)
Call to fail an action, which will also cause the entire test to fail immediately, without waiting the rest of the outstanding actions.
The name of the failed action will be included in the failure output.
Usually the action name should be an expected action set up by a call to expect\_action, but failing unexpected actions will also fail the test.
```
fun box fail_action(
name: String val)
: None val
```
#### Parameters
* name: [String](builtin-string) val
#### Returns
* [None](builtin-none) val
### dispose\_when\_done
[[Source]](https://stdlib.ponylang.io/src/ponytest/test_helper/#L438)
Pass a disposable actor to be disposed of when the test is complete. The actor will be disposed no matter whether the test succeeds or fails.
If the test is already tearing down, the actor will be disposed immediately.
```
fun box dispose_when_done(
disposable: DisposableActor tag)
: None val
```
#### Parameters
* disposable: [DisposableActor](builtin-disposableactor) tag
#### Returns
* [None](builtin-none) val
pony Stdin Stdin
=====
[[Source]](https://stdlib.ponylang.io/src/builtin/stdin/#L43)
Asynchronous access to stdin. The constructor is private to ensure that access is provided only via an environment.
Reading from stdin is done by registering an `InputNotify`:
```
actor Main
new create(env: Env) =>
// do not forget to call `env.input.dispose` at some point
env.input(
object iso is InputNotify
fun ref apply(data: Array[U8] iso) =>
env.out.write(String.from_iso_array(consume data))
fun ref dispose() =>
env.out.print("Done.")
end,
512)
```
**Note:** For reading user input from a terminal, use the [term](term--index) package.
```
actor tag Stdin
```
Public Behaviours
-----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/builtin/stdin/#L78)
Set the notifier. Optionally, also sets the chunk size, dictating the maximum number of bytes of each chunk that will be passed to the notifier.
```
be apply(
notify: (InputNotify iso | None val),
chunk_size: USize val = 32)
```
#### Parameters
* notify: ([InputNotify](builtin-inputnotify) iso | [None](builtin-none) val)
* chunk\_size: [USize](builtin-usize) val = 32
### dispose
[[Source]](https://stdlib.ponylang.io/src/builtin/stdin/#L86)
Clear the notifier in order to shut down input.
```
be dispose()
```
| programming_docs |
pony FormatDefault FormatDefault
=============
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L3)
```
primitive val FormatDefault is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L3)
```
new val create()
: FormatDefault val^
```
#### Returns
* [FormatDefault](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L5)
```
fun box eq(
that: FormatDefault val)
: Bool val
```
#### Parameters
* that: [FormatDefault](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L5)
```
fun box ne(
that: FormatDefault val)
: Bool val
```
#### Parameters
* that: [FormatDefault](index) val
#### Returns
* [Bool](builtin-bool) val
pony ANSITerm ANSITerm
========
[[Source]](https://stdlib.ponylang.io/src/term/ansi_term/#L45)
Handles ANSI escape codes from stdin.
```
actor tag ANSITerm
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/term/ansi_term/#L59)
Create a new ANSI term.
```
new tag create(
notify: ANSINotify iso,
source: DisposableActor tag,
timers: Timers tag = reference)
: ANSITerm tag^
```
#### Parameters
* notify: [ANSINotify](term-ansinotify) iso
* source: [DisposableActor](builtin-disposableactor) tag
* timers: [Timers](time-timers) tag = reference
#### Returns
* [ANSITerm](index) tag^
Public Behaviours
-----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/term/ansi_term/#L77)
Receives input from stdin.
```
be apply(
data: Array[U8 val] iso)
```
#### Parameters
* data: [Array](builtin-array)[[U8](builtin-u8) val] iso
### prompt
[[Source]](https://stdlib.ponylang.io/src/term/ansi_term/#L187)
Pass a prompt along to the notifier.
```
be prompt(
value: String val)
```
#### Parameters
* value: [String](builtin-string) val
### size
[[Source]](https://stdlib.ponylang.io/src/term/ansi_term/#L193)
```
be size()
```
### dispose
[[Source]](https://stdlib.ponylang.io/src/term/ansi_term/#L206)
Stop accepting input, inform the notifier we have closed, and dispose of our source.
```
be dispose()
```
pony ChdirError ChdirError
==========
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L59)
```
primitive val ChdirError
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L59)
```
new val create()
: ChdirError val^
```
#### Returns
* [ChdirError](index) val^
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L60)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L60)
```
fun box eq(
that: ChdirError val)
: Bool val
```
#### Parameters
* that: [ChdirError](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L60)
```
fun box ne(
that: ChdirError val)
: Bool val
```
#### Parameters
* that: [ChdirError](index) val
#### Returns
* [Bool](builtin-bool) val
pony UDPSocket UDPSocket
=========
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L5)
Creates a UDP socket that can be used for sending and receiving UDP messages.
The following examples create: \* an echo server that listens for connections and returns whatever message it receives \* a client that connects to the server, sends a message, and prints the message it receives in response
The server is implemented like this:
```
use "net"
class MyUDPNotify is UDPNotify
fun ref received(
sock: UDPSocket ref,
data: Array[U8] iso,
from: NetAddress)
=>
sock.write(consume data, from)
fun ref not_listening(sock: UDPSocket ref) =>
None
actor Main
new create(env: Env) =>
try
UDPSocket(env.root as AmbientAuth,
MyUDPNotify, "", "8989")
end
```
The client is implemented like this:
```
use "net"
class MyUDPNotify is UDPNotify
let _out: OutStream
let _destination: NetAddress
new create(
out: OutStream,
destination: NetAddress)
=>
_out = out
_destination = destination
fun ref listening(sock: UDPSocket ref) =>
sock.write("hello world", _destination)
fun ref received(
sock: UDPSocket ref,
data: Array[U8] iso,
from: NetAddress)
=>
_out.print("GOT:" + String.from_array(consume data))
sock.dispose()
fun ref not_listening(sock: UDPSocket ref) =>
None
actor Main
new create(env: Env) =>
try
let destination =
DNS.ip4(env.root as AmbientAuth, "localhost", "8989")(0)?
UDPSocket(env.root as AmbientAuth,
recover MyUDPNotify(env.out, consume destination) end)
end
```
```
actor tag UDPSocket
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L89)
Listens for both IPv4 and IPv6 datagrams.
```
new tag create(
auth: (AmbientAuth val | NetAuth val | UDPAuth val),
notify: UDPNotify iso,
host: String val = "",
service: String val = "0",
size: USize val = 1024)
: UDPSocket tag^
```
#### Parameters
* auth: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [UDPAuth](net-udpauth) val)
* notify: [UDPNotify](net-udpnotify) iso
* host: [String](builtin-string) val = ""
* service: [String](builtin-string) val = "0"
* size: [USize](builtin-usize) val = 1024
#### Returns
* [UDPSocket](index) tag^
### ip4
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L110)
Listens for IPv4 datagrams.
```
new tag ip4(
auth: (AmbientAuth val | NetAuth val | UDPAuth val),
notify: UDPNotify iso,
host: String val = "",
service: String val = "0",
size: USize val = 1024)
: UDPSocket tag^
```
#### Parameters
* auth: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [UDPAuth](net-udpauth) val)
* notify: [UDPNotify](net-udpnotify) iso
* host: [String](builtin-string) val = ""
* service: [String](builtin-string) val = "0"
* size: [USize](builtin-usize) val = 1024
#### Returns
* [UDPSocket](index) tag^
### ip6
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L131)
Listens for IPv6 datagrams.
```
new tag ip6(
auth: (AmbientAuth val | NetAuth val | UDPAuth val),
notify: UDPNotify iso,
host: String val = "",
service: String val = "0",
size: USize val = 1024)
: UDPSocket tag^
```
#### Parameters
* auth: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [UDPAuth](net-udpauth) val)
* notify: [UDPNotify](net-udpnotify) iso
* host: [String](builtin-string) val = ""
* service: [String](builtin-string) val = "0"
* size: [USize](builtin-usize) val = 1024
#### Returns
* [UDPSocket](index) tag^
Public Behaviours
-----------------
### write
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L152)
Write a single sequence of bytes.
```
be write(
data: (String val | Array[U8 val] val),
to: NetAddress val)
```
#### Parameters
* data: ([String](builtin-string) val | [Array](builtin-array)[[U8](builtin-u8) val] val)
* to: [NetAddress](net-netaddress) val
### writev
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L158)
Write a sequence of sequences of bytes.
```
be writev(
data: ByteSeqIter val,
to: NetAddress val)
```
#### Parameters
* data: [ByteSeqIter](builtin-byteseqiter) val
* to: [NetAddress](net-netaddress) val
### set\_notify
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L166)
Change the notifier.
```
be set_notify(
notify: UDPNotify iso)
```
#### Parameters
* notify: [UDPNotify](net-udpnotify) iso
### set\_broadcast
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L172)
Enable or disable broadcasting from this socket.
```
be set_broadcast(
state: Bool val)
```
#### Parameters
* state: [Bool](builtin-bool) val
### set\_multicast\_interface
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L184)
By default, the OS will choose which address is used to send packets bound for multicast addresses. This can be used to force a specific interface. To revert to allowing the OS to choose, call with an empty string.
```
be set_multicast_interface(
from: String val = "")
```
#### Parameters
* from: [String](builtin-string) val = ""
### set\_multicast\_loopback
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L194)
By default, packets sent to a multicast address will be received by the sending system if it has subscribed to that address. Disabling loopback prevents this.
```
be set_multicast_loopback(
loopback: Bool val)
```
#### Parameters
* loopback: [Bool](builtin-bool) val
### set\_multicast\_ttl
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L204)
Set the TTL for multicast sends. Defaults to 1.
```
be set_multicast_ttl(
ttl: U8 val)
```
#### Parameters
* ttl: [U8](builtin-u8) val
### multicast\_join
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L212)
Add a multicast group. This can be limited to packets arriving on a specific interface.
```
be multicast_join(
group: String val,
to: String val = "")
```
#### Parameters
* group: [String](builtin-string) val
* to: [String](builtin-string) val = ""
### multicast\_leave
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L221)
Drop a multicast group. This can be limited to packets arriving on a specific interface. No attempt is made to check that this socket has previously added this group.
```
be multicast_leave(
group: String val,
to: String val = "")
```
#### Parameters
* group: [String](builtin-string) val
* to: [String](builtin-string) val = ""
### dispose
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L231)
Stop listening.
```
be dispose()
```
Public Functions
----------------
### local\_address
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L239)
Return the bound IP address.
```
fun box local_address()
: NetAddress val
```
#### Returns
* [NetAddress](net-netaddress) val
### getsockopt
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L410)
General wrapper for UDP sockets to the `getsockopt(2)` system call.
The caller must provide an array that is pre-allocated to be at least as large as the largest data structure that the kernel may return for the requested option.
In case of system call success, this function returns the 2-tuple: 1. The integer `0`. 2. An `Array[U8]` of data returned by the system call's `void *` 4th argument. Its size is specified by the kernel via the system call's `sockopt_len_t *` 5th argument.
In case of system call failure, this function returns the 2-tuple: 1. The value of `errno`. 2. An undefined value that must be ignored.
Usage example:
```
// listening() is a callback function for class UDPNotify
fun ref listening(sock: UDPSocket ref) =>
match sock.getsockopt(OSSockOpt.sol_socket(), OSSockOpt.so_rcvbuf(), 4)
| (0, let gbytes: Array[U8] iso) =>
try
let br = Reader.create().>append(consume gbytes)
ifdef littleendian then
let buffer_size = br.u32_le()?
else
let buffer_size = br.u32_be()?
end
end
| (let errno: U32, _) =>
// System call failed
end
```
```
fun ref getsockopt(
level: I32 val,
option_name: I32 val,
option_max_size: USize val = 4)
: (U32 val , Array[U8 val] iso^)
```
#### Parameters
* level: [I32](builtin-i32) val
* option\_name: [I32](builtin-i32) val
* option\_max\_size: [USize](builtin-usize) val = 4
#### Returns
* ([U32](builtin-u32) val , [Array](builtin-array)[[U8](builtin-u8) val] iso^)
### getsockopt\_u32
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L450)
Wrapper for UDP sockets to the `getsockopt(2)` system call where the kernel's returned option value is a C `uint32_t` type / Pony type `U32`.
In case of system call success, this function returns the 2-tuple: 1. The integer `0`. 2. The `*option_value` returned by the kernel converted to a Pony `U32`.
In case of system call failure, this function returns the 2-tuple: 1. The value of `errno`. 2. An undefined value that must be ignored.
```
fun ref getsockopt_u32(
level: I32 val,
option_name: I32 val)
: (U32 val , U32 val)
```
#### Parameters
* level: [I32](builtin-i32) val
* option\_name: [I32](builtin-i32) val
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### setsockopt
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L466)
General wrapper for UDP sockets to the `setsockopt(2)` system call.
The caller is responsible for the correct size and byte contents of the `option` array for the requested `level` and `option_name`, including using the appropriate CPU endian byte order.
This function returns `0` on success, else the value of `errno` on failure.
Usage example:
```
// listening() is a callback function for class UDPNotify
fun ref listening(sock: UDPSocket ref) =>
let sb = Writer
sb.u32_le(7744) // Our desired socket buffer size
let sbytes = Array[U8]
for bs in sb.done().values() do
sbytes.append(bs)
end
match sock.setsockopt(OSSockOpt.sol_socket(), OSSockOpt.so_rcvbuf(), sbytes)
| 0 =>
// System call was successful
| let errno: U32 =>
// System call failed
end
```
```
fun ref setsockopt(
level: I32 val,
option_name: I32 val,
option: Array[U8 val] ref)
: U32 val
```
#### Parameters
* level: [I32](builtin-i32) val
* option\_name: [I32](builtin-i32) val
* option: [Array](builtin-array)[[U8](builtin-u8) val] ref
#### Returns
* [U32](builtin-u32) val
### setsockopt\_u32
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L499)
Wrapper for UDP sockets to the `setsockopt(2)` system call where the kernel expects an option value of a C `uint32_t` type / Pony type `U32`.
This function returns `0` on success, else the value of `errno` on failure.
```
fun ref setsockopt_u32(
level: I32 val,
option_name: I32 val,
option: U32 val)
: U32 val
```
#### Parameters
* level: [I32](builtin-i32) val
* option\_name: [I32](builtin-i32) val
* option: [U32](builtin-u32) val
#### Returns
* [U32](builtin-u32) val
### get\_so\_error
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L511)
Wrapper for the FFI call `getsockopt(fd, SOL_SOCKET, SO_ERROR, ...)`
```
fun ref get_so_error()
: (U32 val , U32 val)
```
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### get\_so\_rcvbuf
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L517)
Wrapper for the FFI call `getsockopt(fd, SOL_SOCKET, SO_RCVBUF, ...)`
```
fun ref get_so_rcvbuf()
: (U32 val , U32 val)
```
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### get\_so\_sndbuf
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L523)
Wrapper for the FFI call `getsockopt(fd, SOL_SOCKET, SO_SNDBUF, ...)`
```
fun ref get_so_sndbuf()
: (U32 val , U32 val)
```
#### Returns
* ([U32](builtin-u32) val , [U32](builtin-u32) val)
### set\_ip\_multicast\_loop
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L530)
Wrapper for the FFI call `setsockopt(fd, SOL_SOCKET, IP_MULTICAST_LOOP, ...)`
```
fun ref set_ip_multicast_loop(
loopback: Bool val)
: U32 val
```
#### Parameters
* loopback: [Bool](builtin-bool) val
#### Returns
* [U32](builtin-u32) val
### set\_ip\_multicast\_ttl
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L538)
Wrapper for the FFI call `setsockopt(fd, SOL_SOCKET, IP_MULTICAST_TTL, ...)`
```
fun ref set_ip_multicast_ttl(
ttl: U8 val)
: U32 val
```
#### Parameters
* ttl: [U8](builtin-u8) val
#### Returns
* [U32](builtin-u32) val
### set\_so\_broadcast
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L545)
Wrapper for the FFI call `setsockopt(fd, SOL_SOCKET, SO_BROADCAST, ...)`
```
fun ref set_so_broadcast(
state: Bool val)
: U32 val
```
#### Parameters
* state: [Bool](builtin-bool) val
#### Returns
* [U32](builtin-u32) val
### set\_so\_rcvbuf
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L553)
Wrapper for the FFI call `setsockopt(fd, SOL_SOCKET, SO_RCVBUF, ...)`
```
fun ref set_so_rcvbuf(
bufsize: U32 val)
: U32 val
```
#### Parameters
* bufsize: [U32](builtin-u32) val
#### Returns
* [U32](builtin-u32) val
### set\_so\_sndbuf
[[Source]](https://stdlib.ponylang.io/src/net/udp_socket/#L559)
Wrapper for the FFI call `setsockopt(fd, SOL_SOCKET, SO_SNDBUF, ...)`
```
fun ref set_so_sndbuf(
bufsize: U32 val)
: U32 val
```
#### Parameters
* bufsize: [U32](builtin-u32) val
#### Returns
* [U32](builtin-u32) val
pony Exited Exited
======
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L72)
Process exit status: Process exited with an exit code.
```
class val Exited is
Stringable box,
Equatable[(Exited val | Signaled val)] ref
```
#### Implements
* [Stringable](builtin-stringable) box
* [Equatable](builtin-equatable)[([Exited](index) val | [Signaled](process-signaled) val)] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L78)
```
new val create(
code: I32 val)
: Exited val^
```
#### Parameters
* code: [I32](builtin-i32) val
#### Returns
* [Exited](index) val^
Public Functions
----------------
### exit\_code
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L81)
Retrieve the exit code of the exited process.
```
fun box exit_code()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### string
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L87)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/process/_process/#L95)
```
fun box eq(
other: (Exited val | Signaled val))
: Bool val
```
#### Parameters
* other: ([Exited](index) val | [Signaled](process-signaled) val)
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/builtin/compare/#L20)
```
fun box ne(
that: (Exited val | Signaled val))
: Bool val
```
#### Parameters
* that: ([Exited](index) val | [Signaled](process-signaled) val)
#### Returns
* [Bool](builtin-bool) val
pony Serialised Serialised
==========
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L78)
This represents serialised data. How it can be used depends on the other capabilities a caller holds.
```
class val Serialised
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L85)
A caller with SerialiseAuth can create serialised data from any object.
```
new ref create(
auth: SerialiseAuth val,
data: Any box)
: Serialised ref^ ?
```
#### Parameters
* auth: [SerialiseAuth](serialise-serialiseauth) val
* data: [Any](builtin-any) box
#### Returns
* [Serialised](index) ref^ ?
### input
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L99)
A caller with InputSerialisedAuth can create serialised data from any arbitrary set of bytes. It is the caller's responsibility to ensure that the data is in fact well-formed serialised data. This is currently the most dangerous method, as there is currently no way to check validity at runtime.
```
new ref input(
auth: InputSerialisedAuth val,
data: Array[U8 val] val)
: Serialised ref^
```
#### Parameters
* auth: [InputSerialisedAuth](serialise-inputserialisedauth) val
* data: [Array](builtin-array)[[U8](builtin-u8) val] val
#### Returns
* [Serialised](index) ref^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L109)
A caller with DeserialiseAuth can create an object graph from serialised data.
```
fun box apply(
auth: DeserialiseAuth val)
: Any iso^ ?
```
#### Parameters
* auth: [DeserialiseAuth](serialise-deserialiseauth) val
#### Returns
* [Any](builtin-any) iso^ ?
### output
[[Source]](https://stdlib.ponylang.io/src/serialise/serialise/#L126)
A caller with OutputSerialisedAuth can gain access to the underlying bytes that contain the serialised data. This can be used to write those bytes to, for example, a file or socket.
```
fun box output(
auth: OutputSerialisedAuth val)
: Array[U8 val] val
```
#### Parameters
* auth: [OutputSerialisedAuth](serialise-outputserialisedauth) val
#### Returns
* [Array](builtin-array)[[U8](builtin-u8) val] val
| programming_docs |
pony Files package Files package
=============
The Files package provides classes for working with files and directories.
Files are identified by `FilePath` objects, which represent both the path to the file and the capabilites for accessing the file at that path. `FilePath` objects can be used with the `CreateFile` and `OpenFile` primitives and the `File` class to get a reference to a file that can be used to write to and/or read from the file. It can also be used with the `Directory` object to get a reference to a directory object that can be used for directory operations.
The `FileLines` class allows a file to be accessed one line at a time.
The `FileStream` actor provides the ability to asynchronously write to a file.
The `Path` primitive can be used to do path-related operations on strings and characters.
Example program
===============
This program opens the files that are given as command line arguments and prints their contents.
```
use "files"
actor Main
new create(env: Env) =>
try
for file_name in env.args.slice(1).values() do
let path = FilePath(env.root as AmbientAuth, file_name)?
match OpenFile(path)
| let file: File =>
while file.errno() is FileOK do
env.out.write(file.read(1024))
end
else
env.err.print("Error opening file '" + file_name + "'")
end
end
end
```
Public Types
------------
* [primitive Path](files-path)
* [actor FileStream](files-filestream)
* [interface WalkHandler](files-walkhandler)
* [class FilePath](files-filepath)
* [class FileMode](files-filemode)
* [class FileLines](files-filelines)
* [class FileInfo](files-fileinfo)
* [primitive FileCreate](files-filecreate)
* [primitive FileChmod](files-filechmod)
* [primitive FileChown](files-filechown)
* [primitive FileLink](files-filelink)
* [primitive FileLookup](files-filelookup)
* [primitive FileMkdir](files-filemkdir)
* [primitive FileRead](files-fileread)
* [primitive FileRemove](files-fileremove)
* [primitive FileRename](files-filerename)
* [primitive FileSeek](files-fileseek)
* [primitive FileStat](files-filestat)
* [primitive FileSync](files-filesync)
* [primitive FileTime](files-filetime)
* [primitive FileTruncate](files-filetruncate)
* [primitive FileWrite](files-filewrite)
* [primitive FileExec](files-fileexec)
* [type FileCaps](files-filecaps)
* [primitive FileOK](files-fileok)
* [primitive FileError](files-fileerror)
* [primitive FileEOF](files-fileeof)
* [primitive FileBadFileNumber](files-filebadfilenumber)
* [primitive FileExists](files-fileexists)
* [primitive FilePermissionDenied](files-filepermissiondenied)
* [type FileErrNo](files-fileerrno)
* [primitive CreateFile](files-createfile)
* [primitive OpenFile](files-openfile)
* [class File](files-file)
* [class Directory](files-directory)
pony FileChown FileChown
=========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L9)
```
primitive val FileChown
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L9)
```
new val create()
: FileChown val^
```
#### Returns
* [FileChown](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L10)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L10)
```
fun box eq(
that: FileChown val)
: Bool val
```
#### Parameters
* that: [FileChown](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L10)
```
fun box ne(
that: FileChown val)
: Bool val
```
#### Parameters
* that: [FileChown](index) val
#### Returns
* [Bool](builtin-bool) val
pony HashFunction[A: A] HashFunction[A: A]
==================
[[Source]](https://stdlib.ponylang.io/src/collections/hashable/#L13)
A pluggable hash function.
```
interface val HashFunction[A: A]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/hashable/#L17)
Data structures create instances internally. Use a primitive if possible.
```
new val create()
: HashFunction[A] val^
```
#### Returns
* [HashFunction](index)[A] val^
Public Functions
----------------
### hash
[[Source]](https://stdlib.ponylang.io/src/collections/hashable/#L22)
Calculate the hash of some type. This is an alias of the type parameter to allow data structures to hash things without consuming them.
```
fun box hash(
x: box->A!)
: USize val
```
#### Parameters
* x: box->A!
#### Returns
* [USize](builtin-usize) val
### eq
[[Source]](https://stdlib.ponylang.io/src/collections/hashable/#L28)
Determine equality between two keys with the same hash. This is done with viewpoint adapted aliases to allow data structures to determine equality in a box fun without consuming keys.
```
fun box eq(
x: box->A!,
y: box->A!)
: Bool val
```
#### Parameters
* x: box->A!
* y: box->A!
#### Returns
* [Bool](builtin-bool) val
pony FileRename FileRename
==========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L27)
```
primitive val FileRename
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L27)
```
new val create()
: FileRename val^
```
#### Returns
* [FileRename](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L28)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L28)
```
fun box eq(
that: FileRename val)
: Bool val
```
#### Parameters
* that: [FileRename](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L28)
```
fun box ne(
that: FileRename val)
: Bool val
```
#### Parameters
* that: [FileRename](index) val
#### Returns
* [Bool](builtin-bool) val
pony CapRights0 CapRights0
==========
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L5)
Version 0 of the capsicum cap\_rights\_t structure.
```
class ref CapRights0
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L12)
Initialises with no rights.
```
new ref create()
: CapRights0 ref^
```
#### Returns
* [CapRights0](index) ref^
### from
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L18)
Initialises with the rights from a FileCaps.
```
new ref from(
caps: Flags[(FileCreate val | FileChmod val | FileChown val | FileLink val | FileLookup val | FileMkdir val | FileRead val | FileRemove val | FileRename val | FileSeek val | FileStat val | FileSync val | FileTime val | FileTruncate val | FileWrite val | FileExec val), U32 val] box)
: CapRights0 ref^
```
#### Parameters
* caps: [Flags](collections-flags)[([FileCreate](files-filecreate) val | [FileChmod](files-filechmod) val | [FileChown](files-filechown) val | [FileLink](files-filelink) val | [FileLookup](files-filelookup) val | [FileMkdir](files-filemkdir) val | [FileRead](files-fileread) val | [FileRemove](files-fileremove) val | [FileRename](files-filerename) val | [FileSeek](files-fileseek) val | [FileStat](files-filestat) val | [FileSync](files-filesync) val | [FileTime](files-filetime) val | [FileTruncate](files-filetruncate) val | [FileWrite](files-filewrite) val | [FileExec](files-fileexec) val), [U32](builtin-u32) val] box
#### Returns
* [CapRights0](index) ref^
### descriptor
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L52)
Initialises with the rights on the given file descriptor.
```
new ref descriptor(
fd: I32 val)
: CapRights0 ref^
```
#### Parameters
* fd: [I32](builtin-i32) val
#### Returns
* [CapRights0](index) ref^
Public Functions
----------------
### set
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L60)
```
fun ref set(
cap: U64 val)
: None val
```
#### Parameters
* cap: [U64](builtin-u64) val
#### Returns
* [None](builtin-none) val
### unset
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L65)
```
fun ref unset(
cap: U64 val)
: None val
```
#### Parameters
* cap: [U64](builtin-u64) val
#### Returns
* [None](builtin-none) val
### limit
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L70)
Limits the fd to the encoded rights.
```
fun box limit(
fd: I32 val)
: Bool val
```
#### Parameters
* fd: [I32](builtin-i32) val
#### Returns
* [Bool](builtin-bool) val
### merge
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L80)
Merge the rights in that into this.
```
fun ref merge(
that: CapRights0 ref)
: None val
```
#### Parameters
* that: [CapRights0](index) ref
#### Returns
* [None](builtin-none) val
### remove
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L88)
Remove the rights in that from this.
```
fun ref remove(
that: CapRights0 ref)
: None val
```
#### Parameters
* that: [CapRights0](index) ref
#### Returns
* [None](builtin-none) val
### clear
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L96)
Clear all rights.
```
fun ref clear()
: None val
```
#### Returns
* [None](builtin-none) val
### contains
[[Source]](https://stdlib.ponylang.io/src/capsicum/cap_rights/#L104)
Check that this is a superset of the rights in that.
```
fun box contains(
that: CapRights0 ref)
: Bool val
```
#### Parameters
* that: [CapRights0](index) ref
#### Returns
* [Bool](builtin-bool) val
pony Info Info
====
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L101)
```
primitive val Info
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L101)
```
new val create()
: Info val^
```
#### Returns
* [Info](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L102)
```
fun box apply()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L102)
```
fun box eq(
that: Info val)
: Bool val
```
#### Parameters
* that: [Info](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L102)
```
fun box ne(
that: Info val)
: Bool val
```
#### Parameters
* that: [Info](index) val
#### Returns
* [Bool](builtin-bool) val
pony BinaryHeapPriority[A: Comparable[A] #read] BinaryHeapPriority[A: [Comparable](builtin-comparable)[A] #read]
================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L131)
```
type BinaryHeapPriority[A: Comparable[A] #read] is
(_BinaryHeapPriority[A] val & (MinHeapPriority[A] val | MaxHeapPriority[A] val))
```
#### Type Alias For
* (\_BinaryHeapPriority[A] val & ([MinHeapPriority](collections-minheappriority)[A] val | [MaxHeapPriority](collections-maxheappriority)[A] val))
pony DNSLookupAuth DNSLookupAuth
=============
[[Source]](https://stdlib.ponylang.io/src/net/dns/#L1)
```
type DNSLookupAuth is
(AmbientAuth val | NetAuth val | DNSAuth val)
```
#### Type Alias For
* ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val | [DNSAuth](net-dnsauth) val)
pony FileErrNo FileErrNo
=========
[[Source]](https://stdlib.ponylang.io/src/files/file/#L40)
```
type FileErrNo is
(FileOK val | FileError val | FileEOF val | FileBadFileNumber val | FileExists val | FilePermissionDenied val)
```
#### Type Alias For
* ([FileOK](files-fileok) val | [FileError](files-fileerror) val | [FileEOF](files-fileeof) val | [FileBadFileNumber](files-filebadfilenumber) val | [FileExists](files-fileexists) val | [FilePermissionDenied](files-filepermissiondenied) val)
pony FormatHexSmallBare FormatHexSmallBare
==================
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L13)
```
primitive val FormatHexSmallBare is
FormatSpec val
```
#### Implements
* [FormatSpec](format-formatspec) val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L13)
```
new val create()
: FormatHexSmallBare val^
```
#### Returns
* [FormatHexSmallBare](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L15)
```
fun box eq(
that: FormatHexSmallBare val)
: Bool val
```
#### Parameters
* that: [FormatHexSmallBare](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/format/format_spec/#L15)
```
fun box ne(
that: FormatHexSmallBare val)
: Bool val
```
#### Parameters
* that: [FormatHexSmallBare](index) val
#### Returns
* [Bool](builtin-bool) val
pony InvalidArgument InvalidArgument
===============
[[Source]](https://stdlib.ponylang.io/src/options/options/#L79)
```
primitive val InvalidArgument
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/options/options/#L79)
```
new val create()
: InvalidArgument val^
```
#### Returns
* [InvalidArgument](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/options/options/#L81)
```
fun box eq(
that: InvalidArgument val)
: Bool val
```
#### Parameters
* that: [InvalidArgument](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/options/options/#L81)
```
fun box ne(
that: InvalidArgument val)
: Bool val
```
#### Parameters
* that: [InvalidArgument](index) val
#### Returns
* [Bool](builtin-bool) val
pony Math package Math package
============
Given the name `Math` for this package, you'd expect it have a broad and grand scope. Surprise! Not currently. However, we do have the most useful of all programming language math constructs: fibonacci!
People like to make fun of fibonacci but let's face it, no fibonacci, no benchmarks. We hear from some of our engineer friends that math is very important to programming, we call upon that particular class of engineer friends to help us fill out this package with more maths than you can shake a stick at. Btw, in case you are wondering, yes we can shake a stick at a lot of maths.
Public Types
------------
* [class Fibonacci](math-fibonacci)
pony JsonObject JsonObject
==========
[[Source]](https://stdlib.ponylang.io/src/json/json_type/#L77)
```
class ref JsonObject
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/json/json_type/#L84)
Create a map with space for prealloc elements without triggering a resize. Defaults to 6.
```
new ref create(
prealloc: USize val = 6)
: JsonObject ref^
```
#### Parameters
* prealloc: [USize](builtin-usize) val = 6
#### Returns
* [JsonObject](index) ref^
### from\_map
[[Source]](https://stdlib.ponylang.io/src/json/json_type/#L91)
Create a Json object from a map.
```
new ref from_map(
data': HashMap[String val, (F64 val | I64 val | Bool val | None val | String val | JsonArray ref | JsonObject ref), HashEq[String val] val] ref)
: JsonObject ref^
```
#### Parameters
* data': [HashMap](collections-hashmap)[[String](builtin-string) val, ([F64](builtin-f64) val | [I64](builtin-i64) val | [Bool](builtin-bool) val | [None](builtin-none) val | [String](builtin-string) val | [JsonArray](json-jsonarray) ref | [JsonObject](index) ref), [HashEq](collections-hasheq)[[String](builtin-string) val] val] ref
#### Returns
* [JsonObject](index) ref^
Public fields
-------------
### var data: [HashMap](collections-hashmap)[[String](builtin-string) val, ([F64](builtin-f64) val | [I64](builtin-i64) val | [Bool](builtin-bool) val | [None](builtin-none) val | [String](builtin-string) val | [JsonArray](json-jsonarray) ref | [JsonObject](index) ref), [HashEq](collections-hasheq)[[String](builtin-string) val] val] ref
[[Source]](https://stdlib.ponylang.io/src/json/json_type/#L78)
The actual JSON object structure, mapping `String` keys to other JSON structures.
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/json/json_type/#L97)
Generate string representation of this object.
```
fun box string(
indent: String val = "",
pretty_print: Bool val = false)
: String val
```
#### Parameters
* indent: [String](builtin-string) val = ""
* pretty\_print: [Bool](builtin-bool) val = false
#### Returns
* [String](builtin-string) val
pony AsioEventNotify AsioEventNotify
===============
[[Source]](https://stdlib.ponylang.io/src/builtin/asio_event/#L3)
```
interface tag AsioEventNotify
```
pony Fine Fine
====
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L98)
```
primitive val Fine
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L98)
```
new val create()
: Fine val^
```
#### Returns
* [Fine](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L99)
```
fun box apply()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L99)
```
fun box eq(
that: Fine val)
: Bool val
```
#### Parameters
* that: [Fine](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/logger/logger/#L99)
```
fun box ne(
that: Fine val)
: Bool val
```
#### Parameters
* that: [Fine](index) val
#### Returns
* [Bool](builtin-bool) val
pony Nil[A: A] Nil[A: A]
=========
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L87)
The empty list of As.
```
primitive val Nil[A: A] is
ReadSeq[val->A] box
```
#### Implements
* [ReadSeq](builtin-readseq)[val->A] box
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L87)
```
new val create()
: Nil[A] val^
```
#### Returns
* [Nil](index)[A] val^
Public Functions
----------------
### size
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L92)
Returns the size of the list.
```
fun box size()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### apply
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L98)
Returns the i-th element of the sequence. For the empty list this call will always error because any index will be out of bounds.
```
fun box apply(
i: USize val)
: val->A ?
```
#### Parameters
* i: [USize](builtin-usize) val
#### Returns
* val->A ?
### values
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L105)
Returns an empty iterator over the elements of the empty list.
```
fun box values()
: Iterator[val->A] ref^
```
#### Returns
* [Iterator](builtin-iterator)[val->A] ref^
### is\_empty
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L114)
Returns a Bool indicating if the list is empty.
```
fun box is_empty()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### is\_non\_empty
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L120)
Returns a Bool indicating if the list is non-empty.
```
fun box is_non_empty()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### head
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L126)
Returns an error, since Nil has no head.
```
fun box head()
: val->A ?
```
#### Returns
* val->A ?
### tail
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L132)
Returns an error, since Nil has no tail.
```
fun box tail()
: (Cons[A] val | Nil[A] val) ?
```
#### Returns
* ([Cons](collections-persistent-cons)[A] val | [Nil](index)[A] val) ?
### reverse
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L138)
The reverse of the empty list is the empty list.
```
fun box reverse()
: Nil[A] val
```
#### Returns
* [Nil](index)[A] val
### prepend
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L144)
Builds a new list with an element added to the front of this list.
```
fun box prepend(
a: val->A!)
: Cons[A] val
```
#### Parameters
* a: val->A!
#### Returns
* [Cons](collections-persistent-cons)[A] val
### concat
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L150)
The concatenation of any list l with the empty list is l.
```
fun box concat(
l: (Cons[A] val | Nil[A] val))
: (Cons[A] val | Nil[A] val)
```
#### Parameters
* l: ([Cons](collections-persistent-cons)[A] val | [Nil](index)[A] val)
#### Returns
* ([Cons](collections-persistent-cons)[A] val | [Nil](index)[A] val)
### map[B: B]
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L156)
Mapping a function from A to B over the empty list yields the empty list of Bs.
```
fun box map[B: B](
f: {(val->A): val->B}[A, B] box)
: Nil[B] val
```
#### Parameters
* f: {(val->A): val->B}[A, B] box
#### Returns
* [Nil](index)[B] val
### flat\_map[B: B]
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L163)
Flatmapping a function from A to B over the empty list yields the empty list of Bs.
```
fun box flat_map[B: B](
f: {(val->A): List[B]}[A, B] box)
: Nil[B] val
```
#### Parameters
* f: {(val->A): List[B]}[A, B] box
#### Returns
* [Nil](index)[B] val
### for\_each
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L170)
Applying a function to every member of the empty list is a no-op.
```
fun box for_each(
f: {(val->A)}[A] box)
: None val
```
#### Parameters
* f: {(val->A)}[A] box
#### Returns
* [None](builtin-none) val
### filter
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L176)
Filtering the empty list yields the empty list.
```
fun box filter(
f: {(val->A): Bool}[A] box)
: Nil[A] val
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* [Nil](index)[A] val
### fold[B: B]
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L182)
Folding over the empty list yields the initial accumulator.
```
fun box fold[B: B](
f: {(B, val->A): B^}[A, B] box,
acc: B)
: B
```
#### Parameters
* f: {(B, val->A): B^}[A, B] box
* acc: B
#### Returns
* B
### every
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L188)
Any predicate is true of every member of the empty list.
```
fun box every(
f: {(val->A): Bool}[A] box)
: Bool val
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* [Bool](builtin-bool) val
### exists
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L194)
For any predicate, there is no element that satisfies it in the empty list.
```
fun box exists(
f: {(val->A): Bool}[A] box)
: Bool val
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* [Bool](builtin-bool) val
### partition
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L201)
The only partition of the empty list is two empty lists.
```
fun box partition(
f: {(val->A): Bool}[A] box)
: (Nil[A] val , Nil[A] val)
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* ([Nil](index)[A] val , [Nil](index)[A] val)
### drop
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L207)
There are no elements to drop from the empty list.
```
fun box drop(
n: USize val)
: Nil[A] val
```
#### Parameters
* n: [USize](builtin-usize) val
#### Returns
* [Nil](index)[A] val
### drop\_while
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L213)
There are no elements to drop from the empty list.
```
fun box drop_while(
f: {(val->A): Bool}[A] box)
: Nil[A] val
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* [Nil](index)[A] val
### take
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L219)
There are no elements to take from the empty list.
```
fun box take(
n: USize val)
: Nil[A] val
```
#### Parameters
* n: [USize](builtin-usize) val
#### Returns
* [Nil](index)[A] val
### take\_while
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L225)
There are no elements to take from the empty list.
```
fun box take_while(
f: {(val->A): Bool}[A] box)
: Nil[A] val
```
#### Parameters
* f: {(val->A): Bool}[A] box
#### Returns
* [Nil](index)[A] val
### contains[optional T: (A & [HasEq](builtin-haseq)[A!] #read)]
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L231)
```
fun val contains[optional T: (A & HasEq[A!] #read)](
a: val->T)
: Bool val
```
#### Parameters
* a: val->T
#### Returns
* [Bool](builtin-bool) val
### eq
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L92)
```
fun box eq(
that: Nil[A] val)
: Bool val
```
#### Parameters
* that: [Nil](index)[A] val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/collections-persistent/list/#L92)
```
fun box ne(
that: Nil[A] val)
: Bool val
```
#### Parameters
* that: [Nil](index)[A] val
#### Returns
* [Bool](builtin-bool) val
| programming_docs |
pony BinaryHeap[A: Comparable[A] #read, P: (_BinaryHeapPriority[A] val & (MinHeapPriority[A] val | MaxHeapPriority[A] val))] BinaryHeap[A: [Comparable](builtin-comparable)[A] #read, P: (\_BinaryHeapPriority[A] val & ([MinHeapPriority](collections-minheappriority)[A] val | [MaxHeapPriority](collections-maxheappriority)[A] val))]
============================================================================================================================================================================================================
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L5)
A priority queue implemented as a binary heap. The `BinaryHeapPriority` type parameter determines whether this is max-heap or a min-heap.
```
class ref BinaryHeap[A: Comparable[A] #read, P: (_BinaryHeapPriority[A] val & (MinHeapPriority[A] val | MaxHeapPriority[A] val))]
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L12)
Create an empty heap with space for `len` elements.
```
new ref create(
len: USize val)
: BinaryHeap[A, P] ref^
```
#### Parameters
* len: [USize](builtin-usize) val
#### Returns
* [BinaryHeap](index)[A, P] ref^
Public Functions
----------------
### clear
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L18)
Remove all elements from the heap.
```
fun ref clear()
: None val
```
#### Returns
* [None](builtin-none) val
### size
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L24)
Return the number of elements in the heap.
```
fun box size()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### peek
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L30)
Return the highest priority item in the heap. For max-heaps, the greatest item will be returned. For min-heaps, the smallest item will be returned.
```
fun box peek()
: this->A ?
```
#### Returns
* this->A ?
### push
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L37)
Push an item into the heap.
The time complexity of this operation is O(log(n)) with respect to the size of the heap.
```
fun ref push(
value: A)
: None val
```
#### Parameters
* value: A
#### Returns
* [None](builtin-none) val
### pop
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L47)
Remove the highest priority value from the heap and return it. For max-heaps, the greatest item will be returned. For min-heaps, the smallest item will be returned.
The time complexity of this operation is O(log(n)) with respect to the size of the heap.
```
fun ref pop()
: A^ ?
```
#### Returns
* A^ ?
### append
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L61)
Append len elements from a sequence, starting from the given offset.
```
fun ref append(
seq: (ReadSeq[A] box & ReadElement[A^] box),
offset: USize val = 0,
len: USize val = call)
: None val
```
#### Parameters
* seq: ([ReadSeq](builtin-readseq)[A] box & [ReadElement](builtin-readelement)[A^] box)
* offset: [USize](builtin-usize) val = 0
* len: [USize](builtin-usize) val = call
#### Returns
* [None](builtin-none) val
### concat
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L72)
Add len iterated elements, starting from the given offset.
```
fun ref concat(
iter: Iterator[A^] ref,
offset: USize val = 0,
len: USize val = call)
: None val
```
#### Parameters
* iter: [Iterator](builtin-iterator)[A^] ref
* offset: [USize](builtin-usize) val = 0
* len: [USize](builtin-usize) val = call
#### Returns
* [None](builtin-none) val
### values
[[Source]](https://stdlib.ponylang.io/src/collections/heap/#L79)
Return an iterator for the elements in the heap. The order of elements is arbitrary.
```
fun box values()
: ArrayValues[A, this->Array[A] ref] ref^
```
#### Returns
* [ArrayValues](builtin-arrayvalues)[A, this->[Array](builtin-array)[A] ref] ref^
pony SignalRaise SignalRaise
===========
[[Source]](https://stdlib.ponylang.io/src/signals/signal_notify/#L19)
Raise a signal.
```
primitive val SignalRaise
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/signals/signal_notify/#L19)
```
new val create()
: SignalRaise val^
```
#### Returns
* [SignalRaise](index) val^
Public Functions
----------------
### apply
[[Source]](https://stdlib.ponylang.io/src/signals/signal_notify/#L23)
```
fun box apply(
sig: U32 val)
: None val
```
#### Parameters
* sig: [U32](builtin-u32) val
#### Returns
* [None](builtin-none) val
### eq
[[Source]](https://stdlib.ponylang.io/src/signals/signal_notify/#L23)
```
fun box eq(
that: SignalRaise val)
: Bool val
```
#### Parameters
* that: [SignalRaise](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/signals/signal_notify/#L23)
```
fun box ne(
that: SignalRaise val)
: Bool val
```
#### Parameters
* that: [SignalRaise](index) val
#### Returns
* [Bool](builtin-bool) val
pony KillError KillError
=========
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L53)
```
primitive val KillError
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L53)
```
new val create()
: KillError val^
```
#### Returns
* [KillError](index) val^
Public Functions
----------------
### string
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L54)
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### eq
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L54)
```
fun box eq(
that: KillError val)
: Bool val
```
#### Parameters
* that: [KillError](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/process/process_error/#L54)
```
fun box ne(
that: KillError val)
: Bool val
```
#### Parameters
* that: [KillError](index) val
#### Returns
* [Bool](builtin-bool) val
pony Process package Process package
===============
The Process package provides support for handling Unix style processes. For each external process that you want to handle, you need to create a `ProcessMonitor` and a corresponding `ProcessNotify` object. Each ProcessMonitor runs as it own actor and upon receiving data will call its corresponding `ProcessNotify`'s method.
Example program
---------------
The following program will spawn an external program and write to it's STDIN. Output received on STDOUT of the child process is forwarded to the ProcessNotify client and printed.
```
use "process"
use "files"
actor Main
new create(env: Env) =>
// create a notifier
let client = ProcessClient(env)
let notifier: ProcessNotify iso = consume client
// define the binary to run
try
let path = FilePath(env.root as AmbientAuth, "/bin/cat")?
// define the arguments; first arg is always the binary name
let args: Array[String] val = ["cat"]
// define the environment variable for the execution
let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
// create a ProcessMonitor and spawn the child process
let auth = env.root as AmbientAuth
let pm: ProcessMonitor = ProcessMonitor(auth, auth, consume notifier,
path, args, vars)
// write to STDIN of the child process
pm.write("one, two, three")
pm.done_writing() // closing stdin allows cat to terminate
else
env.out.print("Could not create FilePath!")
end
// define a client that implements the ProcessNotify interface
class ProcessClient is ProcessNotify
let _env: Env
new iso create(env: Env) =>
_env = env
fun ref stdout(process: ProcessMonitor ref, data: Array[U8] iso) =>
let out = String.from_array(consume data)
_env.out.print("STDOUT: " + out)
fun ref stderr(process: ProcessMonitor ref, data: Array[U8] iso) =>
let err = String.from_array(consume data)
_env.out.print("STDERR: " + err)
fun ref failed(process: ProcessMonitor ref, err: ProcessError) =>
_env.out.print(err.string())
fun ref dispose(process: ProcessMonitor ref, child_exit_status: ProcessExitStatus) =>
let code: I32 = consume child_exit_code
match child_exit_status
| let exited: Exited =>
_env.out.print("Child exit code: " + exited.exit_code().string())
| let signaled: Signaled =>
_env.out.print("Child terminated by signal: " + signaled.signal().string())
end
```
Process portability
-------------------
The ProcessMonitor supports spawning processes on Linux, FreeBSD, OSX and Windows.
Shutting down ProcessMonitor and external process
-------------------------------------------------
When a process is spawned using ProcessMonitor, and it is not necessary to communicate to it any further using `stdin` and `stdout` or `stderr`, calling [done\_writing()](process-processmonitor#done_writing) will close stdin to the child process. Processes expecting input will be notified of an `EOF` on their `stdin` and can terminate.
If a running program needs to be canceled and the [ProcessMonitor](process-processmonitor) should be shut down, calling [dispose](process-processmonitor#dispose) will terminate the child process and clean up all resources.
Once the child process is detected to be closed, the process exit status is retrieved and [ProcessNotify.dispose](process-processnotify#dispose) is called.
The process exit status can be either an instance of [Exited](process-exited) containing the process exit code in case the program exited on its own, or (only on posix systems like linux, osx or bsd) an instance of [Signaled](process-signaled) containing the signal number that terminated the process.
Public Types
------------
* [interface ProcessNotify](process-processnotify)
* [type ProcessMonitorAuth](process-processmonitorauth)
* [actor ProcessMonitor](process-processmonitor)
* [class ProcessError](process-processerror)
* [type ProcessErrorType](process-processerrortype)
* [primitive ExecveError](process-execveerror)
* [primitive PipeError](process-pipeerror)
* [primitive ForkError](process-forkerror)
* [primitive WaitpidError](process-waitpiderror)
* [primitive WriteError](process-writeerror)
* [primitive KillError](process-killerror)
* [primitive CapError](process-caperror)
* [primitive ChdirError](process-chdirerror)
* [primitive UnknownError](process-unknownerror)
* [primitive StartProcessAuth](process-startprocessauth)
* [class Exited](process-exited)
* [class Signaled](process-signaled)
* [type ProcessExitStatus](process-processexitstatus)
pony TCPAuth TCPAuth
=======
[[Source]](https://stdlib.ponylang.io/src/net/auth/#L13)
```
primitive val TCPAuth
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/net/auth/#L14)
```
new val create(
from: (AmbientAuth val | NetAuth val))
: TCPAuth val^
```
#### Parameters
* from: ([AmbientAuth](builtin-ambientauth) val | [NetAuth](net-netauth) val)
#### Returns
* [TCPAuth](index) val^
Public Functions
----------------
### eq
[[Source]](https://stdlib.ponylang.io/src/net/auth/#L14)
```
fun box eq(
that: TCPAuth val)
: Bool val
```
#### Parameters
* that: [TCPAuth](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/net/auth/#L14)
```
fun box ne(
that: TCPAuth val)
: Bool val
```
#### Parameters
* that: [TCPAuth](index) val
#### Returns
* [Bool](builtin-bool) val
pony Options Options
=======
[[Source]](https://stdlib.ponylang.io/src/options/options/#L102)
```
class ref Options is
Iterator[((String val , (None val | String val | I64 val | U64 val | F64 val)) | ParseError ref | None val)] ref
```
#### Implements
* [Iterator](builtin-iterator)[(([String](builtin-string) val , ([None](builtin-none) val | [String](builtin-string) val | [I64](builtin-i64) val | [U64](builtin-u64) val | [F64](builtin-f64) val)) | [ParseError](options-parseerror) ref | [None](builtin-none) val)] ref
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/options/options/#L109)
```
new ref create(
args: Array[String val] box,
fatal: Bool val = true)
: Options ref^
```
#### Parameters
* args: [Array](builtin-array)[[String](builtin-string) val] box
* fatal: [Bool](builtin-bool) val = true
#### Returns
* [Options](index) ref^
Public Functions
----------------
### add
[[Source]](https://stdlib.ponylang.io/src/options/options/#L117)
Adds a new named option to the parser configuration.
```
fun ref add(
long: String val,
short: (None val | String val) = reference,
arg: (None val | StringArgument val | I64Argument val |
U64Argument val | F64Argument val) = reference,
mode: (Required val | Optional val) = reference)
: Options ref
```
#### Parameters
* long: [String](builtin-string) val
* short: ([None](builtin-none) val | [String](builtin-string) val) = reference
* arg: ([None](builtin-none) val | [StringArgument](options-stringargument) val | [I64Argument](options-i64argument) val | [U64Argument](options-u64argument) val | [F64Argument](options-f64argument) val) = reference
* mode: ([Required](options-required) val | [Optional](options-optional) val) = reference
#### Returns
* [Options](index) ref
### remaining
[[Source]](https://stdlib.ponylang.io/src/options/options/#L130)
Returns all unprocessed command line arguments. After parsing all options, this will only include positional arguments, potentially unrecognised and ambiguous options and invalid arguments.
```
fun ref remaining()
: Array[String ref] ref
```
#### Returns
* [Array](builtin-array)[[String](builtin-string) ref] ref
### has\_next
[[Source]](https://stdlib.ponylang.io/src/options/options/#L250)
Parsing options is done if either an error occurs and fatal error reporting is turned on, or if all command line arguments have been processed.
```
fun box has_next()
: Bool val
```
#### Returns
* [Bool](builtin-bool) val
### next
[[Source]](https://stdlib.ponylang.io/src/options/options/#L257)
Skips all positional arguments and attemps to match named options. Returns a ParsedOption on success, a ParseError on error, or None if no named options are found.
```
fun ref next()
: ((String val , (None val | String val | I64 val |
U64 val | F64 val)) | ParseError ref | None val)
```
#### Returns
* (([String](builtin-string) val , ([None](builtin-none) val | [String](builtin-string) val | [I64](builtin-i64) val | [U64](builtin-u64) val | [F64](builtin-f64) val)) | [ParseError](options-parseerror) ref | [None](builtin-none) val)
pony FileWrite FileWrite
=========
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L45)
```
primitive val FileWrite
```
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L45)
```
new val create()
: FileWrite val^
```
#### Returns
* [FileWrite](index) val^
Public Functions
----------------
### value
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L46)
```
fun box value()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### eq
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L46)
```
fun box eq(
that: FileWrite val)
: Bool val
```
#### Parameters
* that: [FileWrite](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
[[Source]](https://stdlib.ponylang.io/src/files/file_caps/#L46)
```
fun box ne(
that: FileWrite val)
: Bool val
```
#### Parameters
* that: [FileWrite](index) val
#### Returns
* [Bool](builtin-bool) val
pony U64 U64
===
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L217)
```
primitive val U64 is
UnsignedInteger[U64 val] val
```
#### Implements
* [UnsignedInteger](builtin-unsignedinteger)[[U64](index) val] val
Constructors
------------
### create
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L218)
```
new val create(
value: U64 val)
: U64 val^
```
#### Parameters
* value: [U64](index) val
#### Returns
* [U64](index) val^
### from[A: (([I8](builtin-i8) val | [I16](builtin-i16) val | [I32](builtin-i32) val | [I64](builtin-i64) val | [I128](builtin-i128) val | [ILong](builtin-ilong) val | [ISize](builtin-isize) val | [U8](builtin-u8) val | [U16](builtin-u16) val | [U32](builtin-u32) val | [U64](index) val | [U128](builtin-u128) val | [ULong](builtin-ulong) val | [USize](builtin-usize) val | [F32](builtin-f32) val | [F64](builtin-f64) val) & [Real](builtin-real)[A] val)]
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L219)
```
new val from[A: ((I8 val | I16 val | I32 val |
I64 val | I128 val | ILong val |
ISize val | U8 val | U16 val |
U32 val | U64 val | U128 val |
ULong val | USize val | F32 val |
F64 val) & Real[A] val)](
a: A)
: U64 val^
```
#### Parameters
* a: A
#### Returns
* [U64](index) val^
### min\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L221)
```
new val min_value()
: U64 val^
```
#### Returns
* [U64](index) val^
### max\_value
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L222)
```
new val max_value()
: U64 val^
```
#### Returns
* [U64](index) val^
Public Functions
----------------
### next\_pow2
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L224)
```
fun box next_pow2()
: U64 val
```
#### Returns
* [U64](index) val
### abs
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L228)
```
fun box abs()
: U64 val
```
#### Returns
* [U64](index) val
### bit\_reverse
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L229)
```
fun box bit_reverse()
: U64 val
```
#### Returns
* [U64](index) val
### bswap
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L230)
```
fun box bswap()
: U64 val
```
#### Returns
* [U64](index) val
### popcount
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L231)
```
fun box popcount()
: U64 val
```
#### Returns
* [U64](index) val
### clz
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L232)
```
fun box clz()
: U64 val
```
#### Returns
* [U64](index) val
### ctz
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L233)
```
fun box ctz()
: U64 val
```
#### Returns
* [U64](index) val
### clz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L235)
Unsafe operation. If this is 0, the result is undefined.
```
fun box clz_unsafe()
: U64 val
```
#### Returns
* [U64](index) val
### ctz\_unsafe
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L242)
Unsafe operation. If this is 0, the result is undefined.
```
fun box ctz_unsafe()
: U64 val
```
#### Returns
* [U64](index) val
### bitwidth
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L249)
```
fun box bitwidth()
: U64 val
```
#### Returns
* [U64](index) val
### bytewidth
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L251)
```
fun box bytewidth()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### min
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L253)
```
fun box min(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### max
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L254)
```
fun box max(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### hash
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L256)
```
fun box hash()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### addc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L263)
```
fun box addc(
y: U64 val)
: (U64 val , Bool val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [Bool](builtin-bool) val)
### subc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L266)
```
fun box subc(
y: U64 val)
: (U64 val , Bool val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [Bool](builtin-bool) val)
### mulc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L269)
```
fun box mulc(
y: U64 val)
: (U64 val , Bool val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [Bool](builtin-bool) val)
### divc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L272)
```
fun box divc(
y: U64 val)
: (U64 val , Bool val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [Bool](builtin-bool) val)
### remc
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L275)
```
fun box remc(
y: U64 val)
: (U64 val , Bool val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [Bool](builtin-bool) val)
### add\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L278)
```
fun box add_partial(
y: U64 val)
: U64 val ?
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val ?
### sub\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L281)
```
fun box sub_partial(
y: U64 val)
: U64 val ?
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val ?
### mul\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L284)
```
fun box mul_partial(
y: U64 val)
: U64 val ?
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val ?
### div\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L287)
```
fun box div_partial(
y: U64 val)
: U64 val ?
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val ?
### rem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L290)
```
fun box rem_partial(
y: U64 val)
: U64 val ?
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val ?
### divrem\_partial
[[Source]](https://stdlib.ponylang.io/src/builtin/unsigned/#L293)
```
fun box divrem_partial(
y: U64 val)
: (U64 val , U64 val) ?
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [U64](index) val) ?
### shl
```
fun box shl(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### shr
```
fun box shr(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### fld
```
fun box fld(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### fldc
```
fun box fldc(
y: U64 val)
: (U64 val , Bool val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [Bool](builtin-bool) val)
### fld\_partial
```
fun box fld_partial(
y: U64 val)
: U64 val ?
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val ?
### fld\_unsafe
```
fun box fld_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### mod
```
fun box mod(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### modc
```
fun box modc(
y: U64 val)
: (U64 val , Bool val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [Bool](builtin-bool) val)
### mod\_partial
```
fun box mod_partial(
y: U64 val)
: U64 val ?
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val ?
### mod\_unsafe
```
fun box mod_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### shl\_unsafe
```
fun box shl_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### shr\_unsafe
```
fun box shr_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### rotl
```
fun box rotl(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### rotr
```
fun box rotr(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### string
```
fun box string()
: String iso^
```
#### Returns
* [String](builtin-string) iso^
### add\_unsafe
```
fun box add_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### sub\_unsafe
```
fun box sub_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### mul\_unsafe
```
fun box mul_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### div\_unsafe
```
fun box div_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### divrem\_unsafe
```
fun box divrem_unsafe(
y: U64 val)
: (U64 val , U64 val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [U64](index) val)
### rem\_unsafe
```
fun box rem_unsafe(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### neg\_unsafe
```
fun box neg_unsafe()
: U64 val
```
#### Returns
* [U64](index) val
### op\_and
```
fun box op_and(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### op\_or
```
fun box op_or(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### op\_xor
```
fun box op_xor(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### op\_not
```
fun box op_not()
: U64 val
```
#### Returns
* [U64](index) val
### add
```
fun box add(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### sub
```
fun box sub(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### mul
```
fun box mul(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### div
```
fun box div(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### divrem
```
fun box divrem(
y: U64 val)
: (U64 val , U64 val)
```
#### Parameters
* y: [U64](index) val
#### Returns
* ([U64](index) val , [U64](index) val)
### rem
```
fun box rem(
y: U64 val)
: U64 val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [U64](index) val
### neg
```
fun box neg()
: U64 val
```
#### Returns
* [U64](index) val
### eq
```
fun box eq(
y: U64 val)
: Bool val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [Bool](builtin-bool) val
### ne
```
fun box ne(
y: U64 val)
: Bool val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [Bool](builtin-bool) val
### lt
```
fun box lt(
y: U64 val)
: Bool val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [Bool](builtin-bool) val
### le
```
fun box le(
y: U64 val)
: Bool val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [Bool](builtin-bool) val
### ge
```
fun box ge(
y: U64 val)
: Bool val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [Bool](builtin-bool) val
### gt
```
fun box gt(
y: U64 val)
: Bool val
```
#### Parameters
* y: [U64](index) val
#### Returns
* [Bool](builtin-bool) val
### hash64
```
fun box hash64()
: U64 val
```
#### Returns
* [U64](index) val
### i8
```
fun box i8()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16
```
fun box i16()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32
```
fun box i32()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64
```
fun box i64()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128
```
fun box i128()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong
```
fun box ilong()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize
```
fun box isize()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8
```
fun box u8()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16
```
fun box u16()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32
```
fun box u32()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64
```
fun box u64()
: U64 val
```
#### Returns
* [U64](index) val
### u128
```
fun box u128()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong
```
fun box ulong()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize
```
fun box usize()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32
```
fun box f32()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64
```
fun box f64()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### i8\_unsafe
```
fun box i8_unsafe()
: I8 val
```
#### Returns
* [I8](builtin-i8) val
### i16\_unsafe
```
fun box i16_unsafe()
: I16 val
```
#### Returns
* [I16](builtin-i16) val
### i32\_unsafe
```
fun box i32_unsafe()
: I32 val
```
#### Returns
* [I32](builtin-i32) val
### i64\_unsafe
```
fun box i64_unsafe()
: I64 val
```
#### Returns
* [I64](builtin-i64) val
### i128\_unsafe
```
fun box i128_unsafe()
: I128 val
```
#### Returns
* [I128](builtin-i128) val
### ilong\_unsafe
```
fun box ilong_unsafe()
: ILong val
```
#### Returns
* [ILong](builtin-ilong) val
### isize\_unsafe
```
fun box isize_unsafe()
: ISize val
```
#### Returns
* [ISize](builtin-isize) val
### u8\_unsafe
```
fun box u8_unsafe()
: U8 val
```
#### Returns
* [U8](builtin-u8) val
### u16\_unsafe
```
fun box u16_unsafe()
: U16 val
```
#### Returns
* [U16](builtin-u16) val
### u32\_unsafe
```
fun box u32_unsafe()
: U32 val
```
#### Returns
* [U32](builtin-u32) val
### u64\_unsafe
```
fun box u64_unsafe()
: U64 val
```
#### Returns
* [U64](index) val
### u128\_unsafe
```
fun box u128_unsafe()
: U128 val
```
#### Returns
* [U128](builtin-u128) val
### ulong\_unsafe
```
fun box ulong_unsafe()
: ULong val
```
#### Returns
* [ULong](builtin-ulong) val
### usize\_unsafe
```
fun box usize_unsafe()
: USize val
```
#### Returns
* [USize](builtin-usize) val
### f32\_unsafe
```
fun box f32_unsafe()
: F32 val
```
#### Returns
* [F32](builtin-f32) val
### f64\_unsafe
```
fun box f64_unsafe()
: F64 val
```
#### Returns
* [F64](builtin-f64) val
### compare
```
fun box compare(
that: U64 val)
: (Less val | Equal val | Greater val)
```
#### Parameters
* that: [U64](index) val
#### Returns
* ([Less](builtin-less) val | [Equal](builtin-equal) val | [Greater](builtin-greater) val)
| programming_docs |
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