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This is fork of original Intl.js polyfill, modified for needs.

In December 2012, ECMA International published the first edition of Standard ECMA-402, better known as the ECMAScript Internationalization API. This specification provides the framework to bring long overdue localisation methods to ECMAScript implementations.

Google have an implementation of this API that is available in recent versions of V8 and Chrome/Chromium 24 and later. Mozilla also have a working implementation in the current Firefox nightly builds.

Intl.js fills the void of availability for this API. It will provide the framework as described by the specification, so that developers can take advantage of the native API in environments that support it, or Intl.js for legacy or unsupporting environments.

Getting started

For Node.js applications, you can install Intl.js using NPM:

npm install szn-intl-polyfill

Intl.js is also available as a Bower component for the front-end:

bower install szn-intl-polyfill

For other setups, just clone the repo for the pre-built scripts and locale datafiles.

In browser environments, the library will try to patch the browser by defining the global Intl is not defined. An example of usage might look like this:

var nf = new Intl.NumberFormat(undefined, {style:'currency', currency:'GBP'});
document.getElementById('price').textContent = nf.format(100);


Current progress is as follows:


  • All internal methods except for some that are implementation dependent
  • Checking structural validity of language tags
  • Canonicalizing the case and order of language subtags
  • Intl.NumberFormat
    • The Intl.NumberFormat constructor (11.1)
    • Properties of the Intl.NumberFormat Constructor (11.2)
    • Properties of the Intl.NumberFormat Prototype Object (11.3)
    • Properties of Intl.NumberFormat Instances(11.4)
  • Intl.DateTimeFormat
    • The Intl.DateTimeFormat constructor (12.1)
    • Properties of the Intl.DateTimeFormat Constructor (12.2)
    • Properties of the Intl.DateTimeFormat Prototype Object (12.3)
    • Properties of Intl.DateTimeFormat Instances(12.4)
  • Locale Sensitive Functions of the ECMAScript Language Specification
    • Properties of the Number Prototype Object (13.2)
    • Properties of the Date prototype object (13.3)

Not Implemented

  • BestFitSupportedLocales internal function
  • Implementation-dependent numbering system mappings
  • Calendars other than Gregorian
  • Support for time zones
  • Collator objects (Intl.Collator) (see below)
  • Properties of the String prototype object

A few of the implemented functions may currently be non-conforming and/or incomplete.
Most of those functions have comments marked as 'TODO' in the source code.

The test suite is run with Intl.Collator tests removed, and the Collator constructor removed from most other tests in the suite. Also some parts of tests that cannot be passed by a JavaScript implementation have been disabled, as well as a small part of the same tests that fail due to this bug in v8.

What about Intl.Collator?

Providing an Intl.Collator implementation is no longer a goal of this project. There are several reasons, including:

  • The CLDR convertor does not automatically convert collation data to JSON
  • The Unicode Collation Algorithm is more complicated that originally anticipated, and would increase the code size of Intl.js too much.
  • The Default Unicode Collation Element Table is huge, even after compression, and converting to a native JavaScript object would probably make it slightly larger. Server-side JavaScript environments will (hopefully) soon support Intl.Collator, and we can't really expect client environments to download this data.


Intl.js is designed to be compatible with ECMAScript 3.1 environments in order to follow the specification as closely as possible. However, some consideration is given to legacy (ES3) environments, and the goal of this project is to at least provide a working, albeit non-compliant implementation where ES5 methods are unavailable.

A subset of the tests in the test suite are run in IE 8. Tests that are not passable are skipped, but these tests are mostly about ensuring built-in function behaviour.

Locale Data

Intl.js uses the Unicode CLDR locale data, as recommended by the specification. The data is available in JSON format, or JSONP format in the locale-data folder. This has been converted from CLDR version 24 using the script and config file in the tools folder.

The main Intl.js file contains no locale data itself. In browser environments, the data should be provided, parsed into a JavaScript object, using the Intl.__addLocaleData() method. In Node.js, or when using require('intl'), the data is automatically added to the runtime and does not need to be provided.

Contents of the locale-data directory are a modified form of the Unicode CLDR data found at See the LICENSE.txt file accompanying this software for terms of use.


See the CONTRIBUTING file for info.


Copyright (c) 2013 Andy Earnshaw

This software is licensed under the MIT license. See the LICENSE.txt file accompanying this software for terms of use.

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