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


Intl.PluralRules.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 plural formatting 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 plural formatting 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 plural formatting, supportedLocalesOf returns the Indonesian and German language tags unchanged, even though pinyin collation is neither relevant to plural 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.PluralRules.supportedLocalesOf(locales, options).join(', '));
// → "id-u-co-pinyin, de-ID"


ECMAScript Internationalization API (ECMA-402)
The definition of 'Intl.PluralRules.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 63Edge Full support 18Firefox Full support 58IE No support NoOpera Full support 50Safari Full support 13WebView Android Full support 63Chrome Android Full support 63Firefox Android Full support 58Opera Android Full support 46Safari iOS Full support 13Samsung Internet Android Full support 8.0nodejs Full support 10.0.0
Full support 10.0.0
Notes Before version 13.0.0, only the locale data for en-US is available by default. See the PluralRules() constructor for more details.


Full support  
Full support
No support  
No support
See implementation notes.
See implementation notes.

See also