xgettext-js

xgettext-js is a utility for extracting translatable strings, written in and capable of parsing JavaScript files. It is similar to the GNU xgettext program, but returns strings as a JavaScript array. It makes use of @babel/parser and estree-walker to parse JavaScript code, which facilitates the use of custom logic for string extraction. Because of this, xgettext-js is quite flexible, allowing you to define your own logic for extracting strings from any number of function keywords.

Installation

xgettext-js is a Node.js package available through npm. You must first install Node.js if it is not already installed, which will also install the npm package manager. Once installed, use your terminal to execute the following command from your project directory:

$ npm install xgettext-js

Usage

An instance of xgettext-js exposes a getMatches method which, when passed a JavaScript source string, will return an array of translatable strings. Each item in the array is an object which includes a string property, the line of the matched string, and any optionally included translator comments as the comments property. By default, xgettext-js will search for any occurrence of a _ function within your JavaScript code and assume that a translatable string exists as the first parameter. Translator comments can exist on the same or previous code line, formatted as translators: [insert comment here] by default.

Below is an example of this simple use case in a Node.js application:

var XGettext = require( 'xgettext-js' ),
	source = '_( "Hello World!" ); /* translators: greeting */',
	parser = new XGettext();

console.log( parser.getMatches( source ) );
// Will output: [ { "string": "Hello World!", "comment": "greeting", "line": 1, "column": 0 } ]

Options

To override the default behavior, you can pass an options object when creating an instance of xgettext-js, using one or more of the following options:

• keywords : An object which defines keywords to be searched (the key) and a function or number (the value). If passed a function, it is expected to return either a string replacement for the string value of the getMatches array return value, or a replacement for the object itself. The function is passed a match including up to four keys: keyword (the matched keyword), arguments (a CallExpression arguments array, see parser documentation), line (the line of the matched string), and comment if one exists. If passed a number, it is expected that the translatable string exists at the corresponding argument position on a 1-based index.
• commentPrefix: The comment prefix string to match translator comments to be included with translatable strings. A comment will be matched if it is prefixed by this option. If undesired, setting the value to undefined will omit comments from the getMatches return value.

License

Copyright 2016 Automattic

This package is made available under the GPLv2 or later license