Localization library for expressive translations.

  • fluent

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fluent is a JavaScript implementation of Project Fluent, a localization framework designed to unleash the expressive power of the natural language.


fluent can be used both on the client-side and the server-side. You can install it from the npm registry or use it as a standalone script (as the Fluent global).
npm install fluent

How to use

The FluentBundle constructor provides the core functionality of formatting translations from FTL files.
import { FluentBundle, ftl } from 'fluent';

const bundle = new FluentBundle('en-US');

const errors = bundle.addMessages(ftl`
    -brand-name = Foo 3000
    welcome = Welcome, { $name }, to { -brand-name }!

if (errors.length) {
  // syntax errors are per-message and don't break the whole resource

const welcome = bundle.getMessage('welcome');

bundle.format(welcome, { name: 'Anna' });
// → 'Welcome, Anna, to Foo 3000!'

The API reference is available at http://projectfluent.org/fluent.js/fluent.


fluent requires the following Intl formatters:
- Intl.DateTimeFormat (standard, well-supported) - Intl.NumberFormat (standard, well-supported) - Intl.PluralRules (standard, new in ECMAScript 2018)
Intl.PluralRules may already be available in some engines. In most cases, however, a polyfill will be required. We recommend intl-pluralrules.
import 'intl-pluralrules';
import { FluentBundle } from 'fluent';

For legacy browsers, the compat build has been transpiled using Babel's env preset. It requires the regenerator runtime provided by babel-polyfill.
import { FluentBundle } from 'fluent/compat';

Learn more

Find out more about Project Fluent at projectfluent.org, including documentation of the Fluent file format (FTL), links to other packages and implementations, and information about how to get involved.