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This library provides Ember Handlebar helpers and a localization service. The service, and helpers, provide a way to format dates, numbers, strings messages, including pluralization.

Notable Features

  • Addon support (addons can provide translations up to the project application)
  • Built on top of native standards (Intl API and ICU message syntax)
  • Translations are able to be lazily loaded (not bundled with the app code)
  • Formatting for relative time, datetime, and numbers
  • Handlebar helpers and service API



Documentation is now a series of markdown files hosted within the repository. Read more


Translations are defined in /translations, outside of app in either JSON or YAML format. Example of /translations/en-us.yaml:

# en-us 
  info: '{product} will cost {price, number, USD} if ordered by {deadline, date, time}'
  title: 'Hello world!'
    info: '<strong>{product}</strong> will cost <em>{price, number, USD}</em> if ordered by {deadline, date, time}'

If you wish, you can organize your translations into subdirectories such as /translations/login-page/en-us.yaml and translations/purchase-page/en-us.yaml.

Translation keys containing periods, i.e.,, conflicts with internal accessors -- which assumes nested objects and therefore triggers errors like: Error: Property set failed: object in path "foo" could not be found or was destroyed. However, this is supported as of 2.5.x and to enable run ember g ember-intl-dot-notation.

Translation Compilation

At build time, ember-intl walks all of the translations within the project and attempts to locate missing translation keys. This is done through the baseLocale config property. If translations keys are found on the base but not on other locales, a warning is written to the console and ember-intl will automatically use the value from the base locale as a filler.

// config/ember-intl.js 
module.exports = function(environment) {
  return {
    baseLocale: 'en-us' // default build-time locale 

Setting runtime locale

Open, or create, app/routes/application.js and within beforeModel invoke intl.setLocale. Example:

  // app/routes/application.js 
  export default Ember.Route.extend({
    intl: Ember.inject.service(),
    beforeModel() {
      // define the app's runtime locale 
      // For example, here you would maybe do an API lookup to resolver 
      // which locale the user should be targeted and perhaps lazily 
      // load translations using XHR and calling intl's `addTranslation`/`addTranslations` 
      // method with the results of the XHR request 
      return this.get('intl').setLocale('en-us');
      // OR for those that sideload, an array is accepted to handle fallback lookups 
      // en-ca is the primary locale, en-us is the fallback. 
      // this is optional, and likely unnecessary if you define baseLocale (see above) 
      // The primary usecase is if you side load all translations 
      // return this.get('intl').setLocale(['en-ca', 'en-us']); 

Helper Examples

Format Number

Formats numbers using Intl.NumberFormat, and returns the formatted string value.

{{format-number num}}
{{format-number num format='EUR'}}
{{format-number num style='currency' currency='USD'}}
{{format-number undefined fallback='nothing'}}

Or programmatically convert a number within any Ember Object.

export default Ember.Component.extend({
  intl: Ember.inject.service(),
  computedNumber: Ember.computed('intl.locale', 'cost', function() {
    return this.get('intl').formatNumber(this.get('cost')/*, optional options hash */);

Format Number Options

List of supported format number options

Format Date

Formats dates using Intl.DateTimeFormat, and returns the formatted string value.

{{format-date now weekday='long' timeZone='UTC'}}
{{format-date now hour='numeric' minute='numeric' hour12=false}}
{{format-date undefined fallback='nothing'}

Or programmatically convert a date within any Ember Object.

export default Ember.Component.extend({
  intl: Ember.inject.service(),
  computedNow: Ember.computed('intl.locale', function() {
    return this.get('intl').formatDate(new Date()/*, optional options hash */);

Format Date Options

List of supported format date options

Format Time

This is just like the {{format-date}} helper, except it will reference any string-named format from formats.time.

{{format-time now format='hhmmss'}}
{{format-time now hour='numeric' minute='numeric' hour12=false}}
{{format-time undefined fallback='nothing'}}

Or programmatically convert a time within any Ember Object.

// example 
export default Ember.Component.extend({
  intl: Ember.inject.service(),
  computedNow: Ember.computed('intl.locale', function() {
    return this.get('intl').formatTime(new Date()/*, optional options hash */);

Format Time Options

List of supported format date options

Format Relative

Formats dates relative to "now" using IntlRelativeFormat, and returns the formatted string value.

export default Ember.Component.extend({
  timestamp: Ember.computed(function() {
    var date = new Date();
    date.setDate(date.getDate() - 3);
    return date;
{{format-relative timestamp}} -> 3 days ago
{{format-relative undefined fallback='unknown'}} -> unknown

Or programmatically convert a relative time within any Ember Object.

export default Ember.Component.extend({
  intl: Ember.inject.service(),
  yesterday: Ember.computed('intl.locale', function() {
    var date = new Date();
    return this.get('intl').formatRelative(date.setDate(date.getDate() - 1)/*, optional options hash */);

Live Relative Timestamp

Recompute the relative timestamp on an interval by passing an interval argument (in milliseconds).

{{format-relative now interval=1000}} -> now, 1 second ago, 2 seconds ago, etc. (will recompute every 1s)

Format Relative Options

List of supported format date options

Format Message

Formats ICU Message strings with the given values supplied as the hash arguments.

You have {numPhotos, plural,
  =0 {no photos.}
  =1 {one photo.}
  other {# photos.}}
{{t ''
  product='Apple watch'
{{t boundProperty

Or programmatically convert a message within any Ember Object.

export default Ember.Component.extend({
  intl: Ember.inject.service(),
  yesterday: Ember.computed('intl.locale', function() {
    return this.get('intl').formatMessage('Hello {name}', { name: 'Jason' });

Passing a string literal to Format Message

This is done by using the {{l}} (lowercase L) helper as a subexpression. This is useful for computed properties where you are programmatically constructing a translation string.

{{format-message (l '{name} took {numPhotos, plural,\n  =0 {no photos}\n  =1 {one photo}\n  other {# photos}\n} on {takenDate, date, long}')

Format HTML Message

Escapes all hash arguments and returns as an htmlSafe String which renders an ElementNode. To enable rendering HTML within translations, pass an htmlSafe attribute to the t helper.

{{t ''
  product='Apple watch'
{{format-html-message (l '<strong>{numPhotos}</strong>') numPhotos=(format-number num)}}

Named Formats

Specifying format options (e.g.: style="currency" currency="USD") in every use of format helper can become a problem in large code bases, and isn't DRY. Instead, you can provide named formats through the use of exporting a POJO from app/formats. All helpers accept a format property which accepts a key that maps to the format option under its respected type (time, date, number, relative).

For example:

// app/formats.js 
export default {
  date: {
    hhmmss: {
      hour:   'numeric',
      minute: 'numeric',
      second: 'numeric'
{{format-date 'Thu Jan 23 2014 13:00:44' format='hhmmss'}}
this.get('intl').formatDate('Thu Jan 23 2014 13:00:44', {
  format: 'hhmmss'

Output of both the helper and the programmatic example:

1:00:44 PM


There are two options on how to load the Intl.js polyfill, either through the polyfill which ships with ember-intl or through Both of which are documented:

Helper Options

  • All helpers accept optional arguments:
    • locale argument to explicitly pass/override the application locale
    • format argument which you pass in a key corresponding to a format configuration in app/formats.js

Writing Unit Tests

Phantom does support the Intl API, so in order for ember-intl to work in a browser which does not support the Intl API, it needs to be polyfilled.

To resolve this, add the following above all script tags in tests/index.html:

<script src="{{rootURL}}assets/intl/intl.complete.js"></script>

Asynchronously loading translations

Asynchronously loading translations instead of bundling translations within app.js are fully-supported as of 2.x.

Testing with ember-intl

Common Errors

date value is not finite in DateTimeFormat.format()

Browser vendors implement date/time parsing differently. For example, the following will parse correctly in Chrome but fail in Firefox: new Intl.DateTimeFormat().format('2015-04-21 20:47:31 GMT');

The solution is the ensure that the value you are passing in is in a format which is valid for the Date constructor. This library currently does not try and normalize date strings outside of what the browser already implements.


Running Tests

  • ember test
  • ember test --server