Best way to determine user's locale within browser

Question

I have a website (Flash) localized into a dozen of languages and I want to auto-define a default value depending on the user\'s browser settings in order to minimize the ste

Answer 1

I used all the answers and created a single line solution:

const getLanguage = () => navigator.userLanguage || (navigator.languages && navigator.languages.length && navigator.languages[0]) || navigator.language || navigator.browserLanguage || navigator.systemLanguage || 'en';

console.log(getLanguage());