i18next-localstorage-backend

Introduction

This is a i18next cache layer to be used in the browser. It will load and cache resources from localStorage and can be used in combination with the chained backend.

Getting started

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

• If you don't use a module loader it will be added to window.i18nextLocalStorageBackend

# npm package
$ npm install i18next-localstorage-backend

Wiring up with the chained backend:

import i18next from 'i18next';
import Backend from 'i18next-chained-backend';
import LocalStorageBackend from 'i18next-localstorage-backend'; // primary use cache
import HttpApi from 'i18next-http-backend'; // fallback http load

i18next
  .use(Backend)
  .init({
    backend: {
      backends: [
        LocalStorageBackend,  // primary backend
        HttpApi               // fallback backend
      ],
      backendOptions: [{
        /* options for primary backend */
      }, {
        /* options for secondary backend */
        loadPath: '/locales/{{lng}}/{{ns}}.json' // http load path for my own fallback
      }]
    }
  });

Cache Backend Options

{
  // prefix for stored languages
  prefix: 'i18next_res_',

  // expiration
  expirationTime: 7*24*60*60*1000,

  // Version applied to all languages, can be overriden using the option `versions`
  defaultVersion: '',

  // language versions
  versions: {},

  // can be either window.localStorage or window.sessionStorage. Default: window.localStorage
  store: typeof window !== 'undefined' ? window.localStorage : null
};

• Contrary to cookies behavior, the cache will respect updates to expirationTime. If you set 7 days and later update to 10 days, the cache will persist for 10 days

• Passing in a versions object (ex.: versions: { en: 'v1.2', fr: 'v1.1' }) will give you control over the cache based on translations version. This setting works along expirationTime, so a cached translation will still expire even though the version did not change. You can still set expirationTime far into the future to avoid this

• Passing in a defaultVersion string (ex.: version: 'v1.2') will act as if you applied a version to all languages using versions option.

• The test on window makes this package available for SSR environments like NextJS

IMPORTANT ADVICE for the usage in combination with saveMissing/updateMissing

We suggest not to use a caching layer in combination with saveMissing or updateMissing, because it may happen, that the trigger for this is based on stale data.

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