Combining the multiple ways browsers are using to store the user's language, you get this function :
const getNavigatorLanguage = () => {
if (navigator.languages && navigator.languages.length) {
return navigator.languages[0];
} else {
return navigator.userLanguage || navigator.language || navigator.browserLanguage || 'en';
}
}
We first check the navigator.languages array for its first element.
Then we get either navigator.userLanguage or navigator.language.
If this fails we get navigator.browserLanguage.
Finally, we set it to 'en' if everything else failed.
And here's the sexy one-liner :
const getNavigatorLanguage = () => (navigator.languages && navigator.languages.length) ? navigator.languages[0] : navigator.userLanguage || navigator.language || navigator.browserLanguage || 'en';