ui/node_modules/string-width/index.js

import stripAnsi from 'strip-ansi';
import eastAsianWidth from 'eastasianwidth';
import emojiRegex from 'emoji-regex';

export default function stringWidth(string, options = {}) {
	if (typeof string !== 'string' || string.length === 0) {
		return 0;
	}

	options = {
		ambiguousIsNarrow: true,
		...options
	};

	string = stripAnsi(string);

	if (string.length === 0) {
		return 0;
	}

	string = string.replace(emojiRegex(), '  ');

	const ambiguousCharacterWidth = options.ambiguousIsNarrow ? 1 : 2;
	let width = 0;

	for (const character of string) {
		const codePoint = character.codePointAt(0);

		// Ignore control characters
		if (codePoint <= 0x1F || (codePoint >= 0x7F && codePoint <= 0x9F)) {
			continue;
		}

		// Ignore combining characters
		if (codePoint >= 0x300 && codePoint <= 0x36F) {
			continue;
		}

		const code = eastAsianWidth.eastAsianWidth(character);
		switch (code) {
			case 'F':
			case 'W':
				width += 2;
				break;
			case 'A':
				width += ambiguousCharacterWidth;
				break;
			default:
				width += 1;
		}
	}

	return width;
}