Intl.DateTimeFormat.supportedLocalesOf()

The Intl.DateTimeFormat.supportedLocalesOf() method returns an array containing those of the provided locales that are supported in date and time formatting without having to fall back to the runtime's default locale.

Syntax

Intl.DateTimeFormat.supportedLocalesOf(locales[, options])

Parameters

locales
A string with a BCP 47 language tag, or an array of such strings. For the general form of the locales argument, see the Intl page.
options

Optional. An object that may have the following property:

localeMatcher
The locale matching algorithm to use. Possible values are "lookup" and "best fit"; the default is "best fit". For information about this option, see the Intl page.

Return value

An array of strings representing a subset of the given locale tags that are supported in date and time formatting without having to fall back to the runtime's default locale.

Description

Returns an array with a subset of the language tags provided in locales. The language tags returned are those for which the runtime supports a locale in date and time formatting that the locale matching algorithm used considers a match, so that it wouldn't have to fall back to the default locale.

Examples

Using supportedLocalesOf

Assuming a runtime that supports Indonesian and German but not Balinese in date and time formatting, supportedLocalesOf returns the Indonesian and German language tags unchanged, even though pinyin collation is neither relevant to date and time formatting nor used with Indonesian, and a specialized German for Indonesia is unlikely to be supported. Note the specification of the "lookup" algorithm here — a "best fit" matcher might decide that Indonesian is an adequate match for Balinese since most Balinese speakers also understand Indonesian, and therefore return the Balinese language tag as well.

var locales = ['ban', 'id-u-co-pinyin', 'de-ID'];
var options = { localeMatcher: 'lookup' };
console.log(Intl.DateTimeFormat.supportedLocalesOf(locales, options).join(', '));
// → "id-u-co-pinyin, de-ID"

Specifications

Specification Status Comment
ECMAScript Internationalization API 1.0 (ECMA-402)
The definition of 'Intl.DateTimeFormat.supportedLocalesOf' in that specification.
Standard Initial definition.
ECMAScript Internationalization API 2.0 (ECMA-402)
The definition of 'Intl.DateTimeFormat.supportedLocalesOf' in that specification.
Standard  
ECMAScript Internationalization API 4.0 (ECMA-402)
The definition of 'Intl.DateTimeFormat.supportedLocalesOf' in that specification.
Draft  

Browser compatibility

Update compatibility data on GitHub
Desktop Mobile Server
Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet Node.js
supportedLocalesOf Chrome Full support 24 Edge Full support 12 Firefox Full support 29 IE Full support 11 Opera Full support 15 Safari Full support 10 WebView Android No support No Chrome Android Full support 26 Firefox Android Full support 56 Opera Android ? Safari iOS Full support 10 Samsung Internet Android Full support 1.5 nodejs ?

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown

See also