localizify is very light and performant library for translation and localization in Node.js and the browser.

Goals and features

• ❗️ Written on TypeScript
• 🚀 No dependencies (only 2KB gziped)
• 👯 Translation and localization
• 🎁 Interpolation of values to translations
• 🐧 Detection user language in browser and in server requests
• 📣 Events when locale was changed or translation isn't found
• 🗿 Easy scope system (nested-object translations)
• 🎰 A lot of examples

Examples

• react: you can use react-localizify, which provide high order component and hook, or write it yourself by example (see it in ./docs/usage-with-react)
• ./docs/usage-with-express
• ./docs/usage-with-hapijs

Installation

You can install library from npm:

npm install localizify --save
# or using yarn
yarn add localizify

or download file (full version or minify bundle) from dist folder and add the script to the page (only for browsers):

<script src="/path/to/localizify.min.js"></script>

Usage

Open in CodeSandbox.

Quick start

localizify returns instance of Localizify, so it's singelton. You can add translations in one module and use it in another (but you can get Localizify from localizify.Instance).

First of all you need add locales with translations and set locale by default:

const localizify = require('localizify');

const en = require('../messages/en.json');
const fr = require('../messages/fr.json');

localizify
  .add('en', en)
  .add('fr', fr)
  .setLocale('en');
  

# en.json
{
  "hello world": "Hello world!",
  "how are you, {name}?": "How are you, {name}?"
}

# fr.json
{
  "hello world": "Bonjour tout le monde!",
  "how are you, {name}?": "Сomment êtes-vous, {name}?"
}

You can't set unknown locale (without translations):

const localizify = require('localizify');

localizify.setLocale('es');
localizify.getLocale(); // en, because 'es' is unknown locale
  
  
// to check that it's available locale
localizify.isLocale('es'); // false
localizify.isLocale('en'); // true

Now for get translation by key you can use localizify.translate(key) or localizify.t(key) methods:

const { t } = require('localizify');

t('hello world'); // Hello world!
t('hello, {username}', { username: 'Alexander Morgunov' }); // hello, Alexander Morgunov
t('how are you, {name}', { name: 'Sasha' }); // How are you, Sasha?

localizify.setLocale('fr');

// if we haven't translition, return default message
t('hello, {username}', { username: 'Alexander Morgunov' });  // hello, Alexander Morgunov

// if have
t('hello world'); // Bonjour tout le monde!
t('how are you, {name}?', { name: 'Sasha' }); // Сomment êtes-vous, Sasha?

If locale don't contain appropriate translation, return source interpolated key (key may be equal message) and emit event.

Addition features

Translation as nested object

Translation data is organized as a nested object using the top-level key as namespace (scope or context):

{
  "bot" : {
    "startagain": "reset system",
    "turn_off": "Bot was turned off by {name}.",
    "turn_on": "Bot was turn on!",
    "statuses": {
      "active": "Active",
      "remote": "Remote"
    }
  },
  "web": {
    "go_to_messenger": "Go to messenger",
    "sign_up": "Registration"
  }
}

The key argument can be a dot-separated key. See examples below:

t('bot.turn_off', { name: 'Alex' }); // Bot was turned off by Alex.
t('bot.statuses.active'); // Active

t('web.sign_up'); // Registration

The scope (namespace) option can be either a single key or a dot-separated key. You can combinate keys and scopes as you wish:

t('turn_off', { name: 'Alex', scope: 'bot' }); // Bot was turned off by Alex.

t('statuses.active', { scope: 'bot' }); // Active
t('active', { scope: 'bot.statuses' }); // Active

Available events

When translation is missing, localizify emit an event about it. You can listen it:

localizify.onTranslationNotFound((locale, key, scope) => {});

The setLocale method emits an event you can listen to:

localizify.onLocaleChange((locale, previous) => {});

Register default scope and interpolations

You can set scope for your module by default:

localizify.setDefaultScope('web');

t('go_to_messenger'); // Go to messenger
t('sign_up'); // Registration

localizify.clearDefaultScope(); // clear default scope

You can add translations for certain scope:

localizify.add('en', 'bot', { 'hello': "hello, bot" });

---

You can register default interpolations using the registerInterpolations method. Interpolations you give as options to the translate method take precedence over registered interpolations.

localizify.add('en', {
  my_awesome_namespace: {
    greeting: 'Hello {name} in {app_name}!'
  }
});

localizify.registerInterpolations({ app_name: 'My Awesome App' });

t('my_awesome_namespace.greeting', { name: 'Alex' }); // Hello Alex in My Awesome App!
t('my_awesome_namespace.greeting', { name: 'Alex', app_name: 'The Bar App' }); // Hello Alex in The Bar App!

API

See library API in index.d.ts.