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7.1.0 • Public • Published

grunt locales

Update, build, import and export locales using grunt.

Table of contents

Getting Started

This plugin requires Grunt 0.4.x

If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-locales --save-dev

Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:


The locales task


The goal of this grunt task is to automate the localization of HTML templates and JavaScript source files.

grunt-locales parses localize attributes in HTML files as well as localize method calls in JS files and collects the parsed locale strings in JSON files for translation.
The translated JSON locale files are then compiled into JavaScript files containing an object with translation mappings.

The JSON locale files can also be exported and imported to and from CSV locale files to ease the translation process.

To support translation features like pluralization and gender selection, this project relies on Alex Sexton's MessageFormat library to parse the locale strings and compile the dynamic translation functions.

Usage Examples


In your project's Gruntfile, add a section named locales to the data object passed into grunt.initConfig():

    locales: {
        options: {
            locales: ['en_US', 'de_DE']
        update: {
            src: [
            dest: 'js/locales/{locale}/i18n.json'
        build: {
            src: 'js/locales/**/i18n.json',
            dest: 'js/locales/{locale}/i18n.js'
        'export': {
            src: 'js/locales/**/i18n.json',
            dest: 'js/locales/{locale}/i18n.csv'
        'import': {
            src: 'js/locales/**/i18n.csv',
            dest: 'js/locales/{locale}/i18n.json'

Edit the src and dest paths according to the paths in your application.

Locales update

Parse the HTML template files and JS source files and update the JSON locale files:

grunt locales:update

Locales build

Parse the JSON locale files and build the JS locale files:

grunt locales:build

Locales export

Export the JSON locale files into CSV export files:

grunt locales:export

Locales import

Create (and overwrite) the JSON locale files from the CSV locale files:

grunt locales:import

Watch tasks

Install grunt-contrib-watch to automatically update and build locales on file changes.

In your project's Gruntfile, add the following to your watch task configuration:

    // ...
    watch: {
        templates: {
            files: [
            tasks: ['locales:update'],
            options: {
                spawn: false
        locales: {
            files: 'js/locales/**/i18n.json',
            tasks: ['locales:build']

Add the following section to only parse updated HTML templates and JS source files:

grunt.event.on('watch', function (action, file) {
    grunt.config('locales.update.options.purgeLocales', false);
    grunt.config('locales.update.src', file);



Type: Array
Default value: ['en_US']

The list of locales you are using for your translation framework.


Type: Array
Default value: ['localize']

A list of attributes that are parsed for locale strings in the HTML templates.
All attributes in this list will also match with attributes of the same name with data- prefix.

If the attribute value is empty and the attribute key matches the default localize attribute (which is the first item in the list of localizeAttributes) or the equivalent with data- prefix, the parser takes the element HTML content as locale string:

<p localize><strong>Bananas</strong></p>

The above example will match <strong>Bananas</strong> as locale string.


Type: Array
Default value: ['localize']

A list of method identifiers to identify the locale strings of localization calls in the JS source files. The default setting will match Bananas as locale string in the following code snippet:

var localizedText = localize('Bananas');


Type RegExp
Default value: /\.html$/

Source files matching this expression will be parsed as HTML files for localize attributes.


Type RegExp
Default value: /\.js$/

Source files matching this expression will be parsed as JS files for localize method calls.


Type RegExp
Default value: /\w+(?=\/[^\/]+$)/

Matches the locale name in a file path, e.g. en_US in js/locale/en_US/i18n.json.
This is used to automatically extract the locale name for the build and export tasks.


Type: String
Default value: '{locale}'

The placeholder for the locale name used to create the destination file paths.


Type: String
Default value: 'i18n'

The name of the variable added to the window object in the created locale scripts.
This variable holds the object of translation mappings.


Type: Boolean
Default value: false

If enabled, wraps static translation strings with a function.
By default, the translation keys are mapped to static strings, unless the translation changes depending on user data, in which case the key maps to a dynamic translation function.
This option ensures that the translation mappings all use functions as values.


Type: Boolean
Default value: true

If enabled, removes obsolete locale strings from the JSON files.
This excludes strings parsed from the HTML templates, JS source files and the default messages.


Type: String|Array
Default value: undefined

The source filepath(s) to the JSON file(s) with default locale strings not found in the HTML templates or JS source files.
Supports filename expansion via globbing patterns.


Type: String
Default value: __dirname + '/../node_modules/messageformat/locale/{locale}.js'

The location of the MessageFormat locale file.
This locale specific file will be included in the build output.


Type: String
Default value: __dirname + '/../node_modules/messageformat/lib/messageformat.include.js'

The location of the MessageFormat shared file.
This file will be included in the build output.


Type: String
Default value: __dirname + '/../i18n.js.tmpl'

The location of the template file used to render the JS locale files.


Type RegExp
Default value: /^((ftp|https?):\/\/|mailto:|#|\{\w+\})/

The allowed URL formats for sanitized HTML output.


Type: Object
Default value: {removeComments: true, collapseWhitespace: true}

Minifies locale strings containing HTML with html-minifier, using the given options object.
Set to false to disable HTML minification.


Type: Boolean
Default value: false

If enabled, also minifies the parsed keys containing HTML markup.
This option can be useful if the locales are parsed from the unminified templates, but the templates are later minified e.g. using grunt-contrib-htmlmin.


Type: Integer
Default value: 2

The space parameter to JSON.stringify used to render the JSON locale files.


Type: function|Array
Default value: undefined

The replacer parameter to JSON.stringify used to render the JSON locale files.


Type: String
Default value: '"'

The string encapsulator character(s) used for the CSV export.


Type: String
Default value: ','

The table cell delimiter character(s) used for the CSV export.


Type: String
Default value: '\r\n'

The line end character(s) used for the CSV export.


Type: Function
Default value:

function (str) {
  return str.replace(/"/g, '""');

The string escape function used for the CSV export.


Type: String
Default value: 'ID'

The label for the header cell for the locale keys created in the CSV export.


Type: Array
Default value: ['files']

Extra fields from the JSON translation objects which are added to each CSV export row as additional information.

HTML templates format

The templates should contain HTML content which can be parsed by node-htmlparser.

By default, the locales:update task parses all elements with localize attributes, as well as the same attributes with -data prefix. So elements with data-localize attribute will also be parsed, which allows strict HTML conformity.

The localization string is taken from the attribute value. For the attributes localize and data-localize, the string will be taken from the content of the element if the attribute value is empty.

HTML template examples

<div data-name="Grunt" data-localize>Hello {name}!</div>
<div data-num="{{results.length}}" localize>There {num, plural, one{is <strong>one</strong> result} other{are <strong>#</strong> results}}.</div>

JavaScript source files format

The JavaScript source files should contain JavaScript code which can be parsed by Esprima.

The parser will match all localize function calls with a String as first argument.
The String must be static and cannot be passed as a variable or concatenation expression.
The localize function can be invoked as an object method, but has to be written in dot notation and cannot be accessed as a String literal.

JavaScript source file examples

By default, the parser will match the following example method calls:

var result = localize(
    'Hello {name}!',
var result = obj.localize('Save the Orangutans!');

It will not match the following:

var result = localize(
    'Hello ' + '{name}!', // Concatenation expression
var result = obj.localize(str); // String passed as variable
var result = obj['localize']('Save the Orangutans!'); // not written in dot notation.

Translation mappings

The compiled translation mappings can be used the following way:

function localize(key, data) {
    var translation = window.i18n[key];
    if (translation) {
        if (! {
            // Translation is not a function, assume a static string:
            return translation;
        return translation(data);
    // No mapping found, the translation value is the translation key:
    return key;
var result = localize('Hello {name}!', {name: 'Grunt'});

DOM replacement

An example replacing the content of all HTML nodes of the current document with data-localize attribute with their translation result:

[]'[data-localize]'), function (node) {
    var dataset = node.dataset,
        data = {},
        attr = dataset.localize,
        translation = window.i18n[attr || node.innerHTML],
    if (translation) {
        if (attr) {
            node.textContent = ( && translation(dataset)) || translation;
        } else {
            if ( {
                for (key in dataset) {
                    if (dataset.hasOwnProperty(key) && key !== 'localize') {
                        data[key] = escapeHTML(dataset[key]);
                node.innerHTML = translation(data);
            } else {
                node.innerHTML = translation;
    } else if (attr) {
        node.textContent = attr;

Please note that when you are dynamically updating HTML content, you have to safeguard against Cross-site scripting attacks.

A safe way is to filter all arguments passed to the translation functions, based on the context where the translation result will be inserted.

Arguments for translation functions which will be inserted as HTML element content can be safely escaped by replacing unsafe characters with their HTML entity equivalents, e.g. with the following function:

function escapeHTML(str) {
    return str.replace(/[<>&"]/g, function (c) {
        return {
            '<' : '&lt;',
            '>' : '&gt;',
            '&' : '&amp;',
            '"' : '&quot;'

AngularJS directive

angular-localize is a localize module for AngularJS, which uses the translation mappings generated by grunt-locales.


In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.


npm i grunt-locales

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