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BabelFish - human friendly i18n for JS

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Internationalization with easy syntax for node.js and browser.

Classic solutions use multiple phrases for plurals. Babelfish defines plurals inline instead - that's more compact, and easy for programmers. Also, phrases are grouped into nested scopes, like in Ruby.

BabelFish supports all plural rules from unicode CLDR (via plurals-cldr).



$ npm install babelfish


$ bower install babelfish

Use es5-shim for old browsers compatibility.

Phrases Syntax

  • #{varname} Echoes value of variable
  • ((Singular|Plural1|Plural2)):count Plural form


  • А у меня в кармане #{nails_count} ((гвоздь|гвоздя|гвоздей)):nails_count

You can also omit anchor variable for plurals, by default it will be count. Thus following variants are equal:

  • I have #{count} ((nail|nails))
  • I have #{count} ((nail|nails)):count

Also you can use variables in plural parts:

  • I have ((#{count} nail|#{count} nails))

Need special zero form or overwrite any specific value? No problems:

  • I have ((=0 no nails|#{count} nail|#{count} nails))
Escape chars

If you need #{, ((, | or )) somewhere in text, where it can be considered as markup part - just escape them with \.

Example with YAML

As BabelFish flatten scopes, it's really fun and nice to store translations in YAML files:

  profile: Профиль
  forums: Форумы
      new_topic: Новая тема
        title : Последнее сообщение
        by : от
    apples: "На столе лежит #{count} ((яблоко|яблока|яблок))"


// Create new instance of BabelFish with default language/locale: 'en-GB'
var BabelFish = require('babelfish');
var i18n = new BabelFish('en-GB');

// Fill in some phrases
i18n.addPhrase('en-GB', 'demo.hello',         'Hello, #{}.');
i18n.addPhrase('en-GB', 'demo.conv.wazup',    'Whats up?');
i18n.addPhrase('en-GB', 'demo.conv.alright',  'Alright, man!');
i18n.addPhrase('en-GB', 'demo.coerce',        'Total: #{count}.');

i18n.addPhrase('ru-RU', 'demo.hello',         'Привет, #{}.');
i18n.addPhrase('ru-RU', 'demo.conv.wazup',    'Как дела?');

i18n.addPhrase('uk-UA', 'demo.hello',         'Здоровенькі були, #{}.');

// Set locale fallback to use the most appropriate translation when possible
i18n.setFallback('uk-UA', 'ru-RU');

// Translate
var params = {user: {name: 'ixti'}};

i18n.t('ru-RU', 'demo.hello', params);  // -> 'Привет, ixti.'
i18n.t('ru-RU', 'demo.conv.wazup');     // -> 'Как дела?'
i18n.t('ru-RU', 'demo.conv.alright');   // -> 'Alright, man!'

i18n.t('uk-UA', 'demo.hello', params);  // -> 'Здоровенькі були, ixti.'
i18n.t('uk-UA', 'demo.conv.wazup');     // -> 'Как дела?'
i18n.t('uk-UA', 'demo.conv.alright');   // -> 'Alright, man!'

// When params is number or strings, it will be coerced to
// `{ count: XXX, value: XXX }` - use any of those in phrase.
i18n.t('en-GB', 'demo.coerce', 5);      // -> 'Total: 5.'

// You may wish to "dump" translations to load in browser later
// Dump will include all fallback translations and fallback rules
var locale_dump = i18n.stringify('ru-RU');

var i18n_new = require('babelfish')('en-GB'); // init without `new` also works

// Use objects instead of strings (object/array/number/boolean) - can be
// useful to prepare bulk data for external libraries.
// Note, only JSON-supported types are ok (no date & regex)
i18n.addPhrase('en-GB', 'demo.boolean',  true);
i18n.addPhrase('en-GB', 'demo.number',   123);
i18n.addPhrase('en-GB', 'demo.array',    [1, 2, 3]);
// fourth param required for hashes (objects) to disable flattening,
// other types are autodetected
i18n.addPhrase('en-GB', 'demo.array',    { foo:1, bar:"2" }, false);

Implementations in other languages


View the LICENSE file (MIT).



Internalization and localization library that makes i18n and l10n fun again.

var BabelFish = require('babelfish'),
    i18n = new BabelFish();


var babelfish = require('babelfish'),
    i18n = babelfish();


    • new BabelFish([defaultLocale = "en"])

Initiates new instance of BabelFish.

Note! you can omit new for convenience, direct call will return new instance too.


    • BabelFish#addPhrase(locale, phrase, translation[, flattenLevel])
    • locale
      • String
    • Locale of translation

    • phrase
      • String
      • Null
    • Phrase ID, e.g.

    • translation
      • String
      • Object
      • Array
      • Number
      • Boolean
    • Translation or an object with nested phrases, or a pure object.

    • flattenLevel
      • Number
      • Boolean
    • Optional, 0..infinity. Infinity by default. Define "flatten" deepness for loaded object. You can also use true as 0 or false as Infinity.

Flatten & using JS objects

By default all nested properties are normalized to strings like "", and if value is string, it will be compiled with babelfish notation. If deepness is above flattenLevel OR value is not object and not string, it will be used "as is". Note, only JSON stringifiable data should be used.

In short: you can safely pass Array, Number or Boolean. For objects you should define flatten level or disable it compleetely, to work with pure data.

Pure objects can be useful to prepare bulk data for external libraries, like calendars, time/date generators and so on.

  '#{count} %{ответ|ответа|ответов}:count в теме');

// equals to:
  { replies_count: '#{count} %{ответ|ответа|ответов}:count в теме' });


    • BabelFish#getLocale(locale, phrase)
      • String
      • null
    • locale
      • String
    • Locale of translation

    • phrase
      • String
    • Phrase ID, e.g. app.forums.replies_count

    • noFallback
      • Boolean
    • Disable search in fallbacks

Similar to BabelFish#hasPhrase, but returns real locale of requested phrase, or null if nothing found. Can be useful for dynamic dependencies init. For example, when you fetch i10n config as single object and create phrases from it's content.


    • BabelFish#hasPhrase(locale, phrase)
      • Boolean
    • locale
      • String
    • Locale of translation

    • phrase
      • String
    • Phrase ID, e.g. app.forums.replies_count

    • noFallback
      • Boolean
    • Disable search in fallbacks

Returns whenever or not there's a translation of a phrase.


    • data
      • Object
      • String
    • data from stringify() method, as object or string.

Batch load phrases data, prepared with stringify() method. Useful at browser side.


    • BabelFish#setFallback(locale, fallbacks)
    • locale
      • String
    • Target locale

    • fallbacks
      • Array
    • List of fallback locales

Set fallbacks for given locale.

When locale has no translation for the phrase, fallbacks[0] will be tried, if translation still not found, then fallbacks[1] will be tried and so on. If none of fallbacks have translation, default locale will be tried as last resort.

  • throws Error, when locale equals default locale
i18n.setFallback('ua-UK', ['ua', 'ru']);


    • BabelFish#stringify(locale)
      • String
    • locale
      • String
    • Locale of translation

Returns serialized locale data, including fallbacks. It can be loaded back via load() method.


    • BabelFish#t(locale, phrase[, params])
      • String


    • BabelFish#translate(locale, phrase[, params])
      • String
    • locale
      • String
    • Locale of translation

    • phrase
      • String
    • Phrase ID, e.g. app.forums.replies_count

    • params
      • Object
      • Number
      • String
    • Params for translation. Number & String will be coerced to { count: X, value: X }

   '#{count} ((ответ|ответа|ответов)) в теме');

// ...

i18n.translate('ru-RU', 'app.forums.replies_count', { count: 1 });
i18n.translate('ru-RU', 'app.forums.replies_count', 1});
// -> '1 ответ'

i18n.translate('ru-RU', 'app.forums.replies_count', { count: 2 });
i18n.translate('ru-RU', 'app.forums.replies_count', 2);
// -> '2 ответa'
Aliased as: