Intl.DisplayNames.prototype.of()

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

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

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

of(code)

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"); // "franais (Canada)"

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

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

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