Introduction

This is an i18next language detection plugin used to detect user language in the browser, with support for:

cookie (set cookie i18next=LANGUAGE)
sessionStorage (set key i18nextLng=LANGUAGE)
localStorage (set key i18nextLng=LANGUAGE)
navigator (set browser language)
querystring (append ?lng=LANGUAGE to URL)
htmlTag (add html language tag <html lang="LANGUAGE" ...)
path (http://my.site.com/LANGUAGE/...)
subdomain (http://LANGUAGE.site.com/...)

Getting started

Source can be loaded via npm, bower or downloaded from this repo.

# npm package
$ npm install i18next-browser-languagedetector

# bower
$ bower install i18next-browser-languagedetector

If you don't use a module loader it will be added to window.i18nextBrowserLanguageDetector

Wiring up:

import i18next from 'i18next';
import LanguageDetector from 'i18next-browser-languagedetector';

i18next.use(LanguageDetector).init({
  supportedLngs: ['de', 'en', 'fr'],
  ...i18nextOptions
});

As with all modules you can either pass the constructor function (class) to the i18next.use or to a concrete instance.

supportedLngs is optional, but allows i18next to pick the best match from the list of detected languages. If it's not set then language will be set to the first detected language, regardless of whether your application has translations for that language or not.

Detector Options

The default options can be found here.

{
  // order and from where user language should be detected
  order: ['querystring', 'cookie', 'localStorage', 'sessionStorage', 'navigator', 'htmlTag', 'path', 'subdomain'],

  // keys or params to lookup language from
  lookupQuerystring: 'lng',
  lookupCookie: 'i18next',
  lookupLocalStorage: 'i18nextLng',
  lookupSessionStorage: 'i18nextLng',
  lookupFromPathIndex: 0,
  lookupFromSubdomainIndex: 0,

  // cache user language on
  caches: ['localStorage', 'cookie'],
  excludeCacheFor: ['cimode'], // languages to not persist (cookie, localStorage)

  // optional expiry and domain for set cookie
  cookieMinutes: 10,
  cookieDomain: 'myDomain',

  // optional htmlTag with lang attribute, the default is:
  htmlTag: document.documentElement,

  // optional set cookie options, reference:[MDN Set-Cookie docs](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie)
  cookieOptions: { path: '/', sameSite: 'strict' },

  // optional conversion function used to modify the detected language code
  convertDetectedLanguage: 'Iso15897',
  convertDetectedLanguage: (lng) => lng.replace('-', '_')
}

Options can be passed in:

preferred - by setting options.detection in i18next.init:

import i18next from 'i18next';
import LanguageDetector from 'i18next-browser-languagedetector';

i18next.use(LanguageDetector).init({
  detection: options,
});

on construction:

import LanguageDetector from 'i18next-browser-languagedetector';
const languageDetector = new LanguageDetector(null, options);

via calling init:

import LanguageDetector from 'i18next-browser-languagedetector';
const languageDetector = new LanguageDetector();
languageDetector.init(options);

Adding own detection functionality

interface

export default {
  name: 'myDetectorsName',

  lookup(options) {
    // options -> are passed in options
    return 'en';
  },

  cacheUserLanguage(lng, options) {
    // options -> are passed in options
    // lng -> current language, will be called after init and on changeLanguage
    // store it
  },
};

adding it

import LanguageDetector from 'i18next-browser-languagedetector';
const languageDetector = new LanguageDetector();
languageDetector.addDetector(myDetector);

i18next.use(languageDetector).init({
  detection: options,
});

Don't forget: You have to add the name of your detector (myDetectorsName in this case) to the order array in your options object. Without that, your detector won't be used. See the Detector Options section for more.

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