JavaScript for detecting browser language preferen

Question

This question already has an answer here:

• Get visitors language & country code with javascript (client-side) [duplicate] 3 answers
• Best way to determine user's locale within browser 6 answers

I have been trying to detect the browser language preference using JavaScript.

If I set the browser language in IE in Tools>Internet Options>General>Languages, how do I read this value using JavaScript?

Same problem for Firefox. I'm not able to detect the setting for tools>options>content>languages using navigator.language.

Using navigator.userLanguage , it detects the setting done thru Start>ControlPanel>RegionalandLanguageOptions>Regional Options tab.

I have tested with navigator.browserLanguage and navigator.systemLanguage but neither returns the value for the first setting(Tools>InternetOptions>General>Languages)

I found a link which discusses this in detail, but the question remains unanswered :(

Answer 1

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 2

Based on the answer here Accessing the web page's HTTP Headers in JavaScript I built the following script to get the browser language:

var req = new XMLHttpRequest();
req.open('GET', document.location, false);
req.send(null);
var headers = req.getAllResponseHeaders().toLowerCase();
var contentLanguage = headers.match( /^content-language\:(.*)$/gm );
if(contentLanguage[0]) {
    return contentLanguage[0].split(":")[1].trim().toUpperCase();
}

Answer 3

I have a hack that I think uses very little code and is quite reliable.

Put your site's files in a subdirectory. SSL into your server and create symlinks to that subdirectory where your files are stored that indicate your languages.

Something like this:

ln -s /var/www/yourhtml /var/www/en
ln -s /var/www/yourhtml /var/www/sp
ln -s /var/www/yourhtml /var/www/it

Use your web server to read HTTP_ACCEPT_LANGUAGE and redirect to these "different subdirectories" according to the language value it provides.

Now you can use Javascript's window.location.href to get your url and use it in conditionals to reliably identify the preferred language.

url_string = window.location.href;
if (url_string = "http://yoursite.com/it/index.html") {
    document.getElementById("page-wrapper").className = "italian";
}

Answer 4

For what it's worth, Wikimedia's Universal Language Selector library has hooks for doing this: https://www.mediawiki.org/wiki/Extension:UniversalLanguageSelector

See the function getFrequentLanguageList in resources/js/ext.uls.init.js . Direct link: https://gerrit.wikimedia.org/r/gitweb?p=mediawiki/extensions/UniversalLanguageSelector.git;a=blob;f=resources/js/ext.uls.init.js;hb=HEAD

It still depends on the server, or more specifically, the MediaWiki API. The reason I'm showing it is that it may provide a good example of getting all the useful information about the user's language: browser language, Accept-Language, geolocation (with getting country/language info from the CLDR), and of course, user's own site preferences.

Answer 5

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 6

var language = navigator.languages && navigator.languages[0] || // Chrome / Firefox
               navigator.language ||   // All browsers
               navigator.userLanguage; // IE <= 10

console.log(language);

• https://developer.mozilla.org/en-US/docs/Web/API/NavigatorLanguage/languages
• https://developer.mozilla.org/en-US/docs/Web/API/NavigatorLanguage/language

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