JavaScript for detecting browser language preference [duplicate]

Answer 1

If you only need to support certain modern browsers then you can now use:

navigator.languages

which returns an array of the user's language preferences in the order specified by the user.

As of now (Sep 2014) this works on: Chrome (v37), Firefox (v32) and Opera (v24)

But not on: IE (v11)

Answer 2

I've just come up with this. It combines newer JS destructuring syntax with a few standard operations to retrieve the language and locale.

var [lang, locale] = (
    (
        (
            navigator.userLanguage || navigator.language
        ).replace(
            '-', '_'
        )
    ).toLowerCase()
).split('_');

Hope it helps someone

Answer 3

Update of year 2014.

Now there is a way to get Accept-Languages in Firefox and Chrome using navigator.languages (works in Chrome >= 32 and Firefox >= 32)

Also, navigator.language in Firefox these years reflects most preferred language of content, not language of UI. But since this notion is yet to be supported by other browsers, it is not very useful.

So, to get most preferred content language when possible, and use UI language as fallback:

navigator.languages
    ? navigator.languages[0]
    : (navigator.language || navigator.userLanguage)

Answer 4

If you are developing a Chrome App / Extension use the chrome.i18n API.

chrome.i18n.getAcceptLanguages(function(languages) {
  console.log(languages);
  // ["en-AU", "en", "en-US"]
});

Answer 5

First of all, excuse me for my English. I would like to share my code, because it works and it is different than the others given anwers. In this exemple,if you speak French (France, Belgium or other french language) you are redirected on the french page, otherwise on the english page, depending on the browser configuration :

<script type="text/javascript">
        $(document).ready(function () {
            var userLang = navigator.language || navigator.userLanguage;
            if (userLang.startsWith("fr")) {
                    window.location.href = '../fr/index.html';
                }
            else {
                    window.location.href = '../en/index.html';
                }
            });
    </script>

Answer 6

I think the main problem here is that the browser settings don't actually affect the navigator.language property that is obtained via javascript.

What they do affect is the HTTP 'Accept-Language' header, but it appears this value is not available through javascript at all. (Probably why @anddoutoi states he can't find a reference for it that doesn't involve server side.)

I have coded a workaround: I've knocked up a google app engine script at http://ajaxhttpheaders.appspot.com that will return you the HTTP request headers via JSONP.

(Note: this is a hack only to be used if you do not have a back end available that can do this for you. In general you should not be making calls to third party hosted javascript files in your pages unless you have a very high level of trust in the host.)

I intend to leave it there in perpetuity so feel free to use it in your code.

Here's some example code (in jQuery) for how you might use it

$.ajax({ 
    url: "http://ajaxhttpheaders.appspot.com", 
    dataType: 'jsonp', 
    success: function(headers) {
        language = headers['Accept-Language'];
        nowDoSomethingWithIt(language);
    }
});

Hope someone finds this useful.

Edit: I have written a small jQuery plugin on github that wraps this functionality: https://github.com/dansingerman/jQuery-Browser-Language

Edit 2: As requested here is the code that is running on AppEngine (super trivial really):

class MainPage(webapp.RequestHandler):
    def get(self):
        headers = self.request.headers
        callback = self.request.get('callback')

        if callback:
          self.response.headers['Content-Type'] = 'application/javascript'
          self.response.out.write(callback + "(")
          self.response.out.write(headers)
          self.response.out.write(")")
        else:
          self.response.headers['Content-Type'] = 'text/plain'
          self.response.out.write("I need a callback=")

application = webapp.WSGIApplication(
                                     [('/', MainPage)],
                                     debug=False)

def main():
    run_wsgi_app(application)

if __name__ == "__main__":
    main()

Edit3: Have open sourced the app engine code here: https://github.com/dansingerman/app-engine-headers