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🔥 Manage, format and translate phrases easily
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t8on is a JavaScript library for managing sets of locales and both basic and customizable phrases in the application.

It's lightweight and useful enough at the same time, being able to run in various environments due to the power of UMD.

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Quick example

  en: { welcome: 'Welcome, %0!', greeting_q: 'How do you do?' },
  ru: { welcome: 'Добро пожаловать!' }

t.translate('welcome', 'ru');
// => 'Добро пожаловать!'

t.format('welcome', 'en', 'John');
// => 'Hello, John!'

const toEnglish = t.translateTo('en');
// => 'How do you do?'

Although the library is simple, some details and convenient methods are missing in the example above. So it's recommended to read the following "Usage" section to learn how to configure and to use the library properly.


t8on provides a storage to serve locales and phrases/translations pairs.

Load the storage

The storage is available as a singleton:

import t from 't8on';

It also can be instantiated from Translation class manually.

import { Translation } from 't8on';

const t: Translation = new Translation();

Get storage's current dictionary

You can get the link to the existing dictionary via Translation#dictionary() method. In our case it's empty:

// {}

Load the dictionary or particular locales

The storage accepts dictionaries of the following type:

type Translations = {
  [phrase: string]: string // translation

type Dictionary = {
  [locale: string]: Translations

const initialDictionary: Dictionary = {
  en: { greeting: 'Hello' }

const dictionary: Dictionary = {
  en: { welcome: 'Welcome' },
  ru: { welcome: 'Добро пожаловать' }

To load the dictionary from root level, use Translation#loadRoot(root: Dictionary): Translation. It extends already present locales and translations. Note the method's (and few others') return value is current instance of Translation:

// => { en: { greeting: 'Hello' } }

/* => {
    en: { greeting: 'Hello', welcome: 'Welcome' },
    ru: { welcome: 'Добро пожаловать' }

To load one locale, use Translation#load(locale: string, pairs: Translations). Note that it extends existing locales, doesn't rewrite them.

const newPhrase = { greeting_q: 'How do you do?' };

  .load('en', newPhrase)
/* => {
    en: {
      greeting: 'Hello',
      welcome: 'Welcome',
      greeting_q: 'How do you do?'
    ru: { welcome: 'Добро пожаловать' }

However, if you'd like to set the locale from scratch, deleting all the translations presented there, use Translation#setLocale(locale: string, pairs: Translations):

const nextLocale = { welcome: 'Hello there!' };

  .setLocale('en', nextLocale);
/* => {
    en: { welcome: 'Hello there!' },
    ru: { welcome: 'Добро пожаловать' }

Get the translation

There are two types of phrases/translations:

  • simple, such as listed above;
  • parameterized, like 'Hello, %0!'.

Let's start with simple ones.

Simple translations

In order to get a translation of given phrase, you can use several options:

  1. Set default locale name to Translation#defaultLocale: string for the whole instance of Translation and then call Translation#translateCurrent(phrase: string).
t.defaultLocale = 'en';
// => 'Hello there!'

Important: if there's no translation found, all translate* and format* functions translate the phrase to fallback locale if it's set with Translation#fallbackLocale: string. If the dictionary of fallback locale doesn't contain the phrase too, empty string '' is returned.

  1. Create translation function to desired locale with Translation#translateTo(locale: string). Call it with a phrase name to get the translation:
const toRussian: (phrase: string) => string = t.translateTo('ru');
// => 'Добро пожаловать'
  1. Use Translation#translate(phrase: string, locale: string):
t.translate('welcome', 'en');
// => 'Hello there!'

Parameterized translations

Sometimes, there are situations when you can't just translate the given phrase, you need to customize it smartly.

Parameterized translations accept one or more string arguments to manage more complex expressions. The parameters number to translate the phrase to each locale may differ. The numbering is zero based:

const parameterizedDictionary: Dictionary = {
  en: {
    set_default_q: 'Would you like to set %0 your default browser?'
  ru: {
    set_default_q: 'Не желаете ли Вы сделать %0 браузером по умолчанию?'

The same arguments can be included in the translation as many times as you wish.

'I repeat the argument three times: %0! %0! %0!'

They also can be mixed:

'Your name reversed: %1 %0'

Finally, by analogy with translate* methods, you have 3 options in order to insert arguments to the translations. The operation is format based:

  1. "Format" phrases to the default locale with Translation#formatCurrent(phrase: string, ...args: Array<string>):
  .formatCurrent('set_default_q', 'Mozilla Firefox');
// => 'Would you like to set Mozilla Firefox your default browser?'
  1. Create formatting function to the given locale with Translation#formatTo(locale: string) and then use it directly:
const toRussian: (phrase: string, ...args: Array<string>) => string = t.formatTo('ru');
toRussian('set_default_q', 'Google Chrome');
// => 'Не желаете ли Вы сделать Google Chrome браузером по умолчанию?'
  1. Use common Translation#format(phrase: string, locale: string, ...args: Array<string>):
t.format('set_default_q', 'en', 'Vivaldi');
// => 'Would you like to set Vivaldi your default browser?'


t8on is available as the t8on package on npm.

To install the latest stable version, type

npm install --save t8on

You can also access package's files on

The package provides a CommonJS module in the lib directory and a production-ready UMD build in the dist folder.

Although t8on is intended for usage with module bundlers such as Webpack, thanks to UMD, it's possible to use t8on with many other JavaScript module loaders or completely without them.

If it sounds like your case, you can simply connect the UMD build as a <script> tag on the web page. After that, the library will be available via window.t8on.


t8on is MIT licensed.

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