messageformat

What is messageformat?

The messageformat npm package is a tool for handling internationalization (i18n) in JavaScript applications. It allows developers to create localized messages using ICU MessageFormat syntax, which supports pluralization, gender, and other complex message formatting needs.

What are messageformat's main functionalities?

Basic Message Formatting

This feature allows you to create and compile basic messages with placeholders that can be replaced with dynamic values.

const MessageFormat = require('messageformat');
const mf = new MessageFormat('en');
const message = mf.compile('Hello, {name}!');
console.log(message({ name: 'Alice' })); // Output: Hello, Alice!

Pluralization

This feature supports pluralization, allowing you to define different message formats based on the quantity of items.

const MessageFormat = require('messageformat');
const mf = new MessageFormat('en');
const message = mf.compile('{count, plural, one {# item} other {# items}}');
console.log(message({ count: 1 })); // Output: 1 item
console.log(message({ count: 5 })); // Output: 5 items

Gender Formatting

This feature allows you to format messages based on gender, providing different message templates for male, female, and other genders.

const MessageFormat = require('messageformat');
const mf = new MessageFormat('en');
const message = mf.compile('{gender, select, male {He} female {She} other {They}} will respond soon.');
console.log(message({ gender: 'male' })); // Output: He will respond soon.
console.log(message({ gender: 'female' })); // Output: She will respond soon.

Other packages similar to messageformat

i18next

i18next is a popular internationalization framework for JavaScript. It provides a comprehensive solution for handling translations, including support for pluralization, context, and interpolation. Compared to messageformat, i18next offers a more extensive ecosystem with plugins and integrations for various frameworks and libraries.

react-intl

react-intl is a library specifically designed for internationalization in React applications. It uses the ICU MessageFormat syntax similar to messageformat but is tightly integrated with React components. It provides components and hooks for formatting dates, numbers, and messages within React applications.

globalize

Globalize is a library for internationalization and localization in JavaScript. It provides support for formatting dates, numbers, and messages, as well as parsing and validating input. Globalize uses CLDR data for localization and offers a more data-driven approach compared to messageformat.

README

This library provides a formatter and other tools for Unicode MessageFormat 2.0 (MF2), the new standard for localization developed by the MessageFormat Working Group.

This includes a formatter that can be used as a polyfill for the proposed ECMA-402 Intl.MessageFormat formatter.

The API provided by this library is current as of the LDML 47 (March 2025) Final version of the MF2 specification.

npm install --save-exact messageformat@next

import { MessageFormat } from 'messageformat';

const msg = 'Today is {$today :datetime dateStyle=medium}';
const mf = new MessageFormat('en', msg);

mf.format({ today: new Date('2022-02-02') });
// 'Today is Feb 2, 2022'

The library also provides a number of other tools and utilities for MF2, such as:

• MF2 data model conversion tools

  import { parseMessage, stringifyMessage } from 'messageformat';
  

• MF2 data model validation and transformation tools

  import { validate, visit } from 'messageformat';
  

• Concreate Syntax Tree (CST) tools for MF2

  import { parseCST, messageFromCST, stringifyCST } from 'messageformat/cst';
  

• Utilities for building custom function handlers for MF2

  import {
    DraftFunctions,
    asPositiveInteger,
    asString
  } from 'messageformat/functions';
  

In addition to supporting MF2 syntax, compilers and formatting function runtimes are also provided for ICU MessageFormat and Fluent messages:

• @messageformat/icu-messageformat-1
• @messageformat/fluent

For more information on the types and functions provided by this package, see the documentation site.

[!IMPORTANT] The v4 release of the messageformat package has an entirely different API compared to its earlier major releases, which were built on top of ICU MessageFormat, aka "MF1". For that, please see @messageformat/core instead.