Intl.DisplayNames.prototype.of()

The of() method of DisplayNames instances receives a code and returns a string based on the locale and options provided when instantiating this Intl.DisplayNames object.

const regionNamesInEnglish = new Intl.DisplayNames(["en"], { type: "region" });
const regionNamesInTraditionalChinese = new Intl.DisplayNames(["zh-Hant"], {
  type: "region",
});

console.log(regionNamesInEnglish.of("US"));
// Expected output: "United States"

console.log(regionNamesInTraditionalChinese.of("US"));
// Expected output: "美國"

Syntax

of(code)

Parameters

• code
  • : The code to provide depends on the type:
    • If the type is “region”, code should be either a two-letter ISO 3166 region code, or a three-digit UN M49 geographic region. It is required to follow the unicode_region_subtag grammar. Use uppercase codes (e.g., "US"), because lowercase ones (e.g., "us") may not work reliably everywhere.
    • If the type is “script”, code should be a four-letter ISO 15924 script code. It is required to follow the unicode_script_subtag grammar.
    • If the type is “language”, code should be matched by the unicode_language_id nonterminal.
    • If the type is “currency”, code should be a three-letter ISO 4217 currency code. It is required to have exactly three alphabetic characters.
    • If the type is “dateTimeField”, code should be one of: "era", "year", "quarter", "month", "weekOfYear", "weekday", "day", "dayPeriod", "hour", "minute", "second", "timeZoneName".
    • If the type is “calendar”, code should be a calendar key. It is required to follow the type grammar of a Unicode locale identifier.

Return value

A language-specific formatted string, or undefined if there’s no data for the input and fallback is "none".

[!NOTE] fallback is only used if code is structurally valid. See using fallback.

Exceptions

• RangeError
  • : Thrown if code is not structurally valid for the given type.

Examples

Using the of method

const regionNames = new Intl.DisplayNames("en", { type: "region" });
regionNames.of("419"); // "Latin America"

const languageNames = new Intl.DisplayNames("en", { type: "language" });
languageNames.of("fr"); // "French"

const currencyNames = new Intl.DisplayNames("en", { type: "currency" });
currencyNames.of("EUR"); // "Euro"

const languageNamesStandard = new Intl.DisplayNames("fr", {
  type: "language",
  languageDisplay: "standard",
});
languageNamesStandard.of("fr-CA"); // "français (Canada)"

const languageNamesDialect = new Intl.DisplayNames("fr", {
  type: "language",
  languageDisplay: "dialect",
});
languageNamesDialect.of("fr-CA"); // "français canadien"

Using fallback

When the Intl.DisplayNames is constructed with fallback: "code", the of() method will return the code if the input looks structurally valid but there’s no data for the input. If fallback is "none", undefined is returned.

console.log(
  new Intl.DisplayNames("en", { type: "region", fallback: "code" }).of("ZL"),
); // "ZL"

console.log(
  new Intl.DisplayNames("en", { type: "region", fallback: "none" }).of("ZL"),
); // undefined

However, this only applies if the code is structurally valid. For example, if type is "region" but code does not follow the unicode_region_subtag grammar (2 alphabetic characters or 3 numeric characters), a RangeError is directly thrown instead of using the fallback.

console.log(
  new Intl.DisplayNames("en", { type: "region", fallback: "code" }).of("ZLC"),
); // throws RangeError: invalid value "ZLC" for option region

Specifications

Browser compatibility

See also

• DisplayNames