files/en-us/web/api/navigator/language/index.md
{{APIRef("HTML DOM")}}
The language read-only property of the {{domxref("Navigator")}} interface returns a string representing the preferred language of the user, usually the language of the browser UI.
A string representing the language version in {{glossary("BCP 47 language tag")}} format. Examples of valid language tags include en, en-US, fr, fr-FR, es-ES, etc.
Note that in Safari on iOS prior to 10.2, the country code returned is lowercase: "en-us", "fr-fr" etc.
The {{jsxref("Intl")}} constructors allow formatting content to match the rules of a given locale. You can pass navigator.language to them to format content in the locale corresponding to the user's preferred language:
const date = new Date("2012-05-24");
const formattedDate = new Intl.DateTimeFormat(navigator.language).format(date);
{{Specifications}}
{{Compat}}