i18next-fs-backend

What is i18next-fs-backend?

The i18next-fs-backend package is a file system backend for i18next, a popular internationalization framework for JavaScript. This backend allows you to load translation files from the file system, making it suitable for server-side applications like Node.js.

What are i18next-fs-backend's main functionalities?

Loading translations from the file system

This feature allows you to load translation files from a specified path on the file system. The 'loadPath' option specifies the path pattern where the translation files are located.

const i18next = require('i18next');
const Backend = require('i18next-fs-backend');

i18next.use(Backend).init({
  backend: {
    loadPath: '/locales/{{lng}}/{{ns}}.json'
  },
  lng: 'en',
  fallbackLng: 'en',
  ns: ['translation'],
  defaultNS: 'translation'
}, (err, t) => {
  if (err) return console.error(err);
  console.log(t('key')); // prints the translation for 'key'
});

Custom file system operations

This feature allows you to customize how the backend reads and writes files. You can provide your own 'readFile' and 'writeFile' functions to handle file operations.

const i18next = require('i18next');
const Backend = require('i18next-fs-backend');
const fs = require('fs');

i18next.use(Backend).init({
  backend: {
    loadPath: '/locales/{{lng}}/{{ns}}.json',
    addPath: '/locales/{{lng}}/{{ns}}.missing.json',
    readFile: (file, cb) => {
      fs.readFile(file, 'utf8', cb);
    },
    writeFile: (file, data, cb) => {
      fs.writeFile(file, data, 'utf8', cb);
    }
  },
  lng: 'en',
  fallbackLng: 'en',
  ns: ['translation'],
  defaultNS: 'translation'
}, (err, t) => {
  if (err) return console.error(err);
  console.log(t('key')); // prints the translation for 'key'
});

Other packages similar to i18next-fs-backend

i18next-http-backend

The i18next-http-backend package is another backend for i18next that loads translations via HTTP. It is suitable for client-side applications where translations are fetched from a remote server. Unlike i18next-fs-backend, which reads from the file system, i18next-http-backend makes HTTP requests to load translation files.

i18next-node-fs-backend

The i18next-node-fs-backend package is an older backend for i18next that also loads translations from the file system. It is similar to i18next-fs-backend but may not have the same level of support and updates. It is specifically designed for Node.js environments.

i18next-localstorage-backend

The i18next-localstorage-backend package is a backend for i18next that stores translations in the browser's localStorage. This is useful for client-side applications that want to cache translations locally to reduce the number of HTTP requests. Unlike i18next-fs-backend, it is designed for use in the browser rather than on the server.

README

Introduction

This is an i18next backend to be used in Node.js and Deno. It will load resources from the file system.

It's based on the deprecated i18next-node-fs-backend and can mostly be used as a drop-in replacement.

It will load resources from filesystem. Right now it supports following filetypes:

• .json
• .json5
• .jsonc
• .yml/.yaml
• .js (very limited, checks for exports or export default)

Getting started

# npm package
$ npm install i18next-fs-backend

Wiring up:

import i18next from 'i18next';
import Backend from 'i18next-fs-backend';

i18next.use(Backend).init(i18nextOptions);

for Deno:

import i18next from 'https://deno.land/x/i18next/index.js'
import Backend from 'https://deno.land/x/i18next_fs_backend/index.js'

i18next.use(Backend).init(i18nextOptions);

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

Backend Options

{
  // path where resources get loaded from, or a function
  // returning a path:
  // function(lngs, namespaces) { return customPath; }
  // the returned path will interpolate lng, ns if provided like giving a static path
  loadPath: '/locales/{{lng}}/{{ns}}.json',

  // path to post missing resources
  addPath: '/locales/{{lng}}/{{ns}}.missing.json',

  // if you use i18next-fs-backend as caching layer in combination with i18next-chained-backend, you can optionally set an expiration time
  // an example on how to use it as cache layer can be found here: https://github.com/i18next/i18next-fs-backend/blob/master/example/caching/app.js
  // expirationTime: 60 * 60 * 1000
}

Options can be passed in:

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

import i18next from 'i18next';
import Backend from 'i18next-fs-backend';

i18next.use(Backend).init({
  backend: options,
});

on construction:

import Backend from 'i18next-fs-backend';
const Backend = new Backend(null, options);

via calling init:

import Backend from 'i18next-fs-backend';
const Backend = new Backend();
Backend.init(null, options);

TypeScript

To properly type the backend options, you can import the FsBackendOptions interface and use it as a generic type parameter to the i18next's init method, e.g.:

import i18n from 'i18next'
import FsBackend, { FsBackendOptions } from 'i18next-fs-backend'

i18n
  .use(FsBackend)
  .init<FsBackendOptions>({
    backend: {
      // fs backend options
    },

    // other i18next options
  })

If set i18next initAsync option to false it will load the files synchronously

// i18n.js
const { join } = require('path')
const { readdirSync, lstatSync } = require('fs')
const i18next = require('i18next')
const Backend = require('i18next-fs-backend')
i18next
  .use(Backend)
  .init({
    // debug: true,
    initAsync: false,
    fallbackLng: 'en',
    lng: 'en',
    preload: readdirSync(join(__dirname, '../locales')).filter((fileName) => {
      const joinedPath = join(join(__dirname, '../locales'), fileName)
      const isDirectory = lstatSync(joinedPath).isDirectory()
      return isDirectory
    }),
    ns: 'backend-app',
    defaultNS: 'backend-app',
    backend: {
      loadPath: join(__dirname, '../locales/{{lng}}/{{ns}}.json')
    }
  })

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Changelog

2.6.0

• support initImmediate -> initAsync renaming of i18next v24