Caching

Browser caching with local storage

With i18next you can configure a 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.

import i18next from "i18next";
import ChainedBackend from "i18next-chained-backend";
import HttpBackend from "i18next-http-backend";
import LocalStorageBackend from "i18next-localstorage-backend";

i18next
  .use(ChainedBackend)
  .init({
    fallbackLng: "en",
    // ... your i18next config
    backend: {
      backends: [
        LocalStorageBackend,
        HttpBackend
      ],
      backendOptions: [{
        expirationTime: 7 * 24 * 60 * 60 * 1000 // 7 days
      }, {
        loadPath: '/locales/{{lng}}/{{ns}}.json'
      }]
    }
  });

More information can be found here: i18next-chained-backend i18next-localstorage-backend i18next-http-backend

Server side caching with filesystem

With i18next you can configure a cache layer to be used on server side. It will load and cache resources from the filesystem and can be used in combination with the chained backend.

import i18next from "i18next";
import ChainedBackend from "i18next-chained-backend";
import HttpBackend from "i18next-http-backend";
import FsBackend from "i18next-fs-backend";

i18next
  .use(ChainedBackend)
  .init({
    fallbackLng: "en",
    // ... your i18next config
    backend: {
      backends: [
        FsBackend,
        HttpBackend
      ],
      backendOptions: [{
        expirationTime: 7 * 24 * 60 * 60 * 1000, // 7 days
        loadPath: './locales_cache/{{lng}}/{{ns}}.json',
        addPath: './locales_cache/{{lng}}/{{ns}}.json' // make sure the folders "locales_cache/{{lng}}" exists
      }, {
        loadPath: '/locales/{{lng}}/{{ns}}.json'
      }]
    }
  });

More information can be found here: i18next-chained-backend i18next-fs-backend i18next-http-backend

React-native caching with AsyncStorage

With i18next you can configure a cache layer to be used on react-native. It will load and cache resources from the AsyncStorage and can be used in combination with the chained backend.

import i18next from "i18next";
import ChainedBackend from "i18next-chained-backend";
import HttpBackend from "i18next-http-backend";
import AsyncStorageBackend from "i18next-async-storage-backend";

i18next
  .use(ChainedBackend)
  .init({
    fallbackLng: "en",
    // ... your i18next config
    backend: {
      backends: [
        AsyncStorageBackend,
        HttpBackend
      ],
      backendOptions: [{
        expirationTime: 7 * 24 * 60 * 60 * 1000 // 7 days
      }, {
        loadPath: '/locales/{{lng}}/{{ns}}.json'
      }]
    }
  });

More information can be found here: i18next-chained-backend i18next-async-storage-backend i18next-http-backend

Server side Next.js caching with filesystem

Similar to the normal server side caching with filesystem, you can use the same approach in a Next.js app in combination with next-i18next. It will load and cache resources from the filesystem and can be used in combination with the chained backend.

The config file, will probably look similar to this, but for a more complete example have a look at this example by locize.

// next-i18next.config.js
const ChainedBackend = require('i18next-chained-backend')
const FSBackend = require('i18next-fs-backend/cjs')
const HttpBackend = require('i18next-http-backend/cjs')

module.exports = {
  i18n: {
    defaultLocale: 'en',
    locales: ['en', 'de'],
  },
  backend: {
    backends: [
      FSBackend,
      HttpBackend
    ],
    backendOptions: [{ // make sure public/locales_cache/en and public/locales_cache/de exists
      loadPath: './public/locales_cache/{{lng}}/{{ns}}.json',
      addPath: './public/locales_cache/{{lng}}/{{ns}}.json',
      expirationTime: 7 * 24 * 60 * 60 * 1000 // 7 days
    }, {
      loadPath: '/locales/{{lng}}/{{ns}}.json'
    }]
  },
  use: [ChainedBackend],
  ns: ['common', 'footer', 'second-page'], // the namespaces needs to be listed here, to make sure they got preloaded
  serializeConfig: false, // because of the custom use i18next plugin
  // debug: true,
}

More information can be found here: next-i18next-locize example i18next-chained-backend i18next-fs-backend i18next-http-backend

We suggest not to use multiple backends with the i18next-chained-backend in combination with saveMissing or updateMissing, because it may happen, that the trigger for this is based on stale data.