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


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


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.

Optional. An object that may have the following property:

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 collation without having to fall back to the runtime's default locale.


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 collation that the locale matching algorithm used considers a match, so that it wouldn't have to fall back to the default locale.


Using supportedLocalesOf

Assuming a runtime that supports Indonesian and German but not Balinese in collation, supportedLocalesOf returns the Indonesian and German language tags unchanged, even though pinyin collation is not 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.Collator.supportedLocalesOf(locales, options).join(', '));
// → "id-u-co-pinyin, de-ID"


ECMAScript Internationalization API (ECMA-402)
The definition of 'Intl.Collator.supportedLocalesOf' in that specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
supportedLocalesOfChrome Full support 24Edge Full support 12Firefox Full support 29IE Full support 11Opera Full support 15Safari Full support 10WebView Android Full support 4.4Chrome Android Full support 25Firefox Android Full support 56Opera Android Full support 14Safari iOS Full support 10Samsung Internet Android Full support 1.5nodejs Full support 13.0.0
Full support 13.0.0
Partial support 0.12
Notes Before version 13.0.0, only the locale data for en-US is available by default. To make full ICU (locale) data available for versions prior to 13, see Node.js documentation on the --with-intl option and how to provide the data.


Full support  
Full support
See implementation notes.
See implementation notes.

See also