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Introduction

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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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