navigator-languages (tiny & dependency free)

Retrieves the language information saved in window.navigator.languages in a backwards compatible way.

Install

npm i navigator-languages

Usage

const navigatorLanguages = require('navigator-languages');
console.log(navigatorLanguages());
/* CONSOLE:
["de-DE", "en-US", "nl"]
*/

If the browser is really old and there is no chance to get any information, you'll get undefined.

Why is this needed

IE 6 & 7 & 8: Only .systemLanguage, .userLanguage (.language & .languages missing)
IE 9 & 10: Only .systemLanguage, .userLanguage, .browserLanguage (.language & .languages missing)
IE 11 & Safri 8 & HTC One M8 & Google Nexus 5, etc.: doesn't support .languages, only .language
In some Chrome versions: .languages[0] !== .language (.language doesn't support the country and probably the other additional BCP 47 Language Tag information)

There are probably many more issues like that.

The Code

(about 260 bytes)

var getNavigatorLanguages = function() {
  if (typeof navigator === 'object') {
    var t = 'anguage', n = navigator, f;
    f = n['l' + t + 's'];
    return f && f.length ? f : (t = n['l' + t] ||
      n['browserL' + t] ||
      n['userL' + t]) ? [ t ] : t;
  }
};

Minified: (about 180 bytes)

var getNavigatorLanguages=function(){if('object'==typeof navigator){var c,a='anguage',b=navigator;return c=b['l'+a+'s'],c&&c.length?c:(a=b['l'+a]||b['browserL'+a]||b['userL'+a])?[a]:a}};

The umd module is about 370 bytes.

How does it work?

It checks for different entries in window.navigator, in this order:

.languages (if ! empty array)
.language
.browserLanguage
.userLanguage

.systemLanguage is being ignored, because .userLanguage is always available, when also .systemLanguage is available and .userLanguage is definitely the better choice.

v1.0.0 did also some lowercase/uppercase formatting & validating, which was removed in version 2, because it's normally not needed. Use the format-bcp-47 package, if you need to ensure client-side / server-side consistency