File size: 4,626 Bytes
bc20498 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 |
# sorcery.js
Sourcemaps are great - if you have a JavaScript file, and you minify it, your minifier can generate a map that lets you debug as though you were looking at the original uncompressed code.
But if you have more than one transformation - say you want to transpile your JavaScript, concatenate several files into one, and minify the result - it gets a little trickier. Each intermediate step needs to be able to both *ingest* a sourcemap and *generate* one, all the time pointing back to the original source.
Most compilers don't do that. ([UglifyJS](https://github.com/mishoo/UglifyJS2) is an honourable exception.) So when you fire up devtools, instead of looking at the original source you find yourself looking at the final intermediate step in the chain of transformations.
**Sorcery aims to fix that.** Given an file at the end of a transformation chain (e.g., your minified JavaScript), it will follow the entire chain back to the original source, and generate a new sourcemap that describes the whole process. How? Magic.
This is a work-in-progress - suitable for playing around with, but don't rely on it to debug air traffic control software or medical equipment. Other than that, it can't do much harm.
## Usage
### As a node module
Install sorcery locally:
```bash
npm install sorcery
```
```js
var sorcery = require( 'sorcery' );
sorcery.load( 'some/generated/code.min.js' ).then( function ( chain ) {
// generate a flattened sourcemap
var map = chain.apply(); // { version: 3, file: 'code.min.js', ... }
// get a JSON representation of the sourcemap
map.toString(); // '{"version":3,"file":"code.min.js",...}'
// get a data URI representation
map.toUrl(); // 'data:application/json;charset=utf-8;base64,eyJ2ZXJ...'
// write to a new file - this will create `output.js` and
// `output.js.map`, and will preserve relative paths. It
// returns a Promise
chain.write( 'output.js' );
// write to a new file but use an absolute path for the
// sourceMappingURL
chain.write( 'output.js', { absolutePath: true });
// write to a new file, but append the flattened sourcemap as a data URI
chain.write( 'output.js', { inline: true });
// overwrite the existing file
chain.write();
chain.write({ inline: true });
// find the origin of line x, column y. Returns an object with
// `source`, `line`, `column` and (if applicable) `name` properties.
// Note - for consistency with other tools, line numbers are always
// one-based, column numbers are always zero-based. It's daft, I know.
var loc = chain.trace( x, y );
});
// You can also use sorcery synchronously:
var chain = sorcery.loadSync( 'some/generated/code.min.js' );
var map = chain.apply();
var loc = chain.trace( x, y );
chain.writeSync();
```
#### Advanced options
You can pass an optional second argument to `sorcery.load()` and `sorcery.loadSync()`, with zero or more of the following properties:
* `content` - a map of `filename: contents` pairs. `filename` will be resolved against the current working directory if needs be
* `sourcemaps` - a map of `filename: sourcemap` pairs, where `filename` is the name of the file the sourcemap is related to. This will override any `sourceMappingURL` comments in the file itself.
For example:
```js
sorcery.load( 'some/generated/code.min.js', {
content: {
'some/minified/code.min.js': '...',
'some/transpiled/code.js': '...',
'some/original/code.js': '...'
},
sourcemaps: {
'some/minified/code.min.js': {...},
'some/transpiled/code.js': {...}
}
}).then( chain => {
/* ... */
});
```
Any files not found will be read from the filesystem as normal.
### On the command line
First, install sorcery globally:
```bash
npm install -g sorcery
```
```
Usage:
sorcery [options]
Options:
-h, --help Show help message
-v, --version Show version
-i, --input <file> Input file
-o, --output <file> Output file (if absent, will overwrite input)
-d, --datauri Append map as a data URI, rather than separate file
-x, --excludeContent Don't populate the sourcesContent array
```
Examples:
```bash
# overwrite sourcemap in place (will write map to
# some/generated/code.min.js.map, and update
# sourceMappingURL comment if necessary
sorcery -i some/generated/code.min.js
# append flattened sourcemap as an inline data URI
# (will delete existing .map file, if applicable)
sorcery -d -i some/generated/code.min.js
# write to a new file (will create newfile.js and
# newfile.js.map)
sorcery -i some/generated/code.min.js -o newfile.js
```
## License
MIT
|