Translator helper for Express using PO files system.

const express = require('express');
const app = express();
const Translator = require('express-translator');
const {translate} = new Translator({app});
translate('Foo');

Installation

This is a Node.js module available through the npm registry.

Before installing, download and install Node.js. Node.js 8.0 or higher is required.

Installation is done using the npm install command:

$ npm install express-translator

Features

• Support both server-side and client-side translation
• Focus on high performance
• 100% test coverage
• HTTP helpers (redirection, caching, etc)
• View system supporting 14+ template engines
• Content negotiation
• Executable for generating applications quickly

Usage

Configuration and default options

Constructor

Create and return an instance of Translator

Returns: Object - A Translator instance

Params

• [options]: Object - A set of options
  • app: Object - An instance of Express
  • country: string (Default US) - Code of country following ISO 3166-1 Country Code
  • language: string (Default en) - Code of language following ISO 639-1 Language Code
  • url: string (Default /translate) - Route for exporting translate data in JSON for client-side usage
  • src: string (Default locale) - Relative path to get translation source

Translate

Translate provided string

Returns: string - A translated string if translation found or original string if not

Params:

• source: string - A string to translate
• [options]: Object - A set of options
  • context: string - A context to pick the right translation
  • [params]: Object - keyed list of dynamical value in string

Common Usage

Plain text

locale/fr_FR.po:

msgid "The quick brown fox jumps over the lazy dog"
msgstr "Le renard brun rapide saute par-dessus le chien paresseux"

app.js

const {translate} = new Translator({
  app,
  country: 'FR',
  language: 'fr',
});
translate('The quick brown fox jumps over the lazy dog');
// -> "Le renard brun rapide saute par-dessus le chien paresseux"

Text with a custom context

locale/fr_FR.po:

msgid "The quick brown fox jumps over the lazy dog"
msgstr "Le renard brun rapide saute par-dessus le chien paresseux"

msgctxt "different"
msgid "The quick brown fox jumps over the lazy dog"
msgstr "Le renard saute par-dessus le chien"

app.js

const {translate} = new Translator({
  app,
  country: 'FR',
  language: 'fr',
});
translate('The quick brown fox jumps over the lazy dog', {context: 'different'});
// -> "Le renard saute par-dessus le chien"

Text with a dynamical param:

locale/fr_FR.po:

msgid "You tried @time times"
msgstr "Tu as essayé @time fois"

app.js

const {translate} = new Translator({
  app,
  country: 'FR',
  language: 'fr',
});
translate('You tried @times times', {params: {'@time': 5}});
// -> "Tu as essayé 5 fois"

Custom translation source

public/translation/fr_FR.po:

msgid "The quick brown fox jumps over the lazy dog"
msgstr "Le renard brun rapide saute par-dessus le chien paresseux"

app.js

const {translate} = new Translator({
  app,
  src: 'public/translation',
  country: 'FR',
  language: 'fr',
});
translate('The quick brown fox jumps over the lazy dog');
// -> ""Le renard brun rapide saute par-dessus le chien paresseux""

Custom data endpoint

locale/fr_FR.po:

msgid "The quick brown fox jumps over the lazy dog"
msgstr "Le renard brun rapide saute par-dessus le chien paresseux"

app.js

new Translator({
  app,
  url: '/custom/translation',
  country: 'FR',
  language: 'fr',
});

http://localhost:3000/custom/translation

{
  "translations": {
    "": {
      "The quick brown fox jumps over the lazy dog": {
        "msgid": "The quick brown fox jumps over the lazy dog",
        "msgstr": [
          "Le renard brun rapide saute par-dessus le chien paresseux"
        ]
      }
    }
  }
}

With template engines

nunjucks

app.js

// view engine setup
const nunEnv = nunjucks.configure('views', {
  express: app,
});

// Add translate to be a custom filter.
nunEnv.addFilter('translate', translate);

index.njk

{{ 'The quick brown fox jumps over the lazy dog' | translate }}

EJS

index.ejs

<%- translate('The quick brown fox jumps over the lazy dog') %>

Pug

app.js

options.filters = {
  translate,
};

index.pug

:translate
    The quick brown fox jumps over the lazy dog

Advanced usage

Use translation in web browser

This feature needs Webpack to convert server-side javascript to client-side server.js

new Translator({
  app,
  country: 'FR',
  language: 'fr',
});

client.js

import Translator from 'express-translator/client';

const {translate} = Translator({
    server: 'http://localhost:3000/translate',
    language: 'fr',
    country: 'FR',
  });
translate('The quick brown fox jumps over the lazy dog');
// -> "Le renard brun rapide saute par-dessus le chien paresseux"

Potential Features (Not yet supported)

• Plural translation
• POT auto-generating

License

MIT

See also

• express - Fast, unopinionated, minimalist web framework for node.
• node-gettext - a JavaScript implementation of (a large subset of) gettext, a localization framework originally written in C.
• gettext-parser - Parse and compile gettext po and mo files with node.js, nothing more, nothing less.
• node-fecth - A light-weight module that brings window.fetch to Node.js