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

messageformat.js

The experience and subtlety of your program's text can be important. MessageFormat is a mechanism for handling both pluralization and gender in your applications. It can also lead to much better translations, as it's designed to support all the languages included in the Unicode CLDR.

The ICU has an official guide for the format. Messageformat.js supports and extends all parts of the standard, with the exception of the deprecated ChoiceFormat.

There is a good slide-deck on Plural and Gender in Translated Messages by Markus Scherer and Mark Davis. But, again, remember that many of these problems apply even if you're only outputting english.

Please see messageformat.github.io for a guide to MessageFormat, more information on on the build-time use of messageformat.js, and the code documentation.

What problems does it solve?

Using messageformat.js, you can separate your code from your text formatting, while enabling much more humane expressions. In other words, you won't need to see this anymore in your output:

There are 1 results.
There are 1 result(s).
Number of results: 5.

What does it look like?

With this message:

> var msg =
  '{GENDER, select, male{He} female{She} other{They} }' +
  ' found ' +
  '{RES, plural, =0{no results} one{1 result} other{# results} }' +
  ' in the ' +
  '{CAT, selectordinal, one{#st} two{#nd} few{#rd} other{#th} }' +
  ' category.';

You'll get these results:

> var mfunc = new MessageFormat('en').compile(msg);

> mfunc({ GENDER: 'male', RES: 1, CAT: 2 })
'He found 1 result in the 2nd category.'

> mfunc({ GENDER: 'female', RES: 1, CAT: 2 })
'She found 1 result in the 2nd category.'

> mfunc({ GENDER: 'male', RES: 2, CAT: 1 })
'He found 2 results in the 1st category.'

> mfunc({ RES: 2, CAT: 2 })
'They found 2 results in the 2nd category.'

Features

• Handles arbitrary nesting of pluralization and select rules
• Supports all ~466 languages included in the Unicode CLDR
• Works on the server and the client
• Remarkably useful even for single-language use
• Speed & efficiency: Can pre-compile messages to JavaScript code
  • Great for speed: message formatting is just string concatenation
• Compatible with other MessageFormat implementations
• Extendable with custom formatting functions
• Very whitespace tolerant
• Supports Unicode

Installation

Node

npm install messageformat

var MessageFormat = require('messageformat');
var mf = new MessageFormat('en');

Bower

bower install messageformat

<script src="path/to/bower_components/messageformat/messageformat.js"></script>
<script>
  var mf = new MessageFormat('en');
</script>

License

You may use this software under the MIT License.

You may contribute to this software under the Dojo CLA.

Original author

• Alex Sexton - @SlexAxton - http://alexsexton.com/

Major contributor

• Eemeli Aro - @eemeli - https://github.com/eemeli

Credits

Thanks to:

• Bazaarvoice - my employer - for letting me do cool stuff like this.
• Google has an implementation that is similar in Google Closure, I tried to vet my code against many of their tests.
• Norbert Lindenberg for showing me how good it can be.

Implementations in other languages

Jeff Hansen (@jeffijoe) has written an implementation for .NET - it's a Portable Class Library, making it possible to use on iOS, Android, Windows Phone, and pretty much any other .NET target.

Additional tools

icu-converter is a NodeJS tool for converting message files in the ICU Resource Bundle format into JSON or .property files.