The Navigator.languages read-only property returns an array of strings representing the user's preferred languages. The language is described using language tags according to RFC 5646: Tags for Identifying Languages (also known as BCP 47). In the returned array they are ordered by preference with the most preferred language first.

The value of navigator.language is the first element of the returned array.

When its value changes, as the user's preferred languages are changed a languagechange event is fired on the Window object.

The Accept-Language HTTP header in every HTTP request from the user's browser uses the same value for the navigator.languages property except for the extra qvalues (quality values) field (e.g. en-US;q=0.8).

A string.

The array of language identifiers contained in navigator.languages can be passed directly to the Intl constructors to implement preference-based fallback selection of locales, where the first entry in the list that matches a locale supported by Intl is used:

const date = new Date("2012-05-24");

const formattedDate = new Intl.DateTimeFormat(navigator.languages).format(date);

• navigator.language
• navigator
• languagechange event
• Intl