message-format-inline

message-format-inline

Write default messages inline. Optionally transpile translations.

This is still a work-in-progress. Here be dragons.

Quick Start

npm install message-format-inline --save adds the library to node_modules. You can then use it as follows:

var format = require('message-format-inline');

var message = format('Hello { place }!', { place:'World' });

Your source code does not need to be transpiled in order to work properly, so you can use format in server-side code, and transpile your source for better performance in repeated use on the client.

message-format-inline relies on Intl.NumberFormat and Intl.DateTimeFormat for formatting number, date, and time arguments. If you are in an environment missing these (like node <= 0.10, IE < 11, or Safari) you'll need to use a polyfill.

Overview

The ICU Message Format is a great format for user-visible strings, and includes simple placeholders, number and date placeholders, and selecting among submessages for gender and plural arguments. The format is used in apis in C++, PHP, and Java.

message-format-inline provides a way to write your default (often English) messages as literals in your source, and then scrape out the default patterns and transpile your source with fast inline code for formatting the translated message patterns.

This relies on message-format for parsing and formatting ICU messages, and recast for transpiling the source code.

Quoting escaping rules

See the ICU site and message-format for details on how to escape special characters in your messages.

Loading locale data

message-format-inline supports plurals for all CLDR languages. Locale-aware formatting of number, date, and time are delegated to the Intl objects, and select is the same across all locales. You don't need to load any extra files for particular locales for message-format-inline.

Unsupported ICU Formats

ordinal, duration, and spellout arguments are supported by the parser, but will just toString(). These are not supported by Intl.NumberFormat. They require a lot of language-specific code, and would make the library undesireably large. For now, if you need these kinds of formats, you can pass them into the message pre-formatted, and refence them in the message pattern with a simple string placeholder ({ arg }).

API

format

var format = require('message-format-inline')
// or
import format from 'message-format-inline'

format(pattern[, args[, locales]])

Translate and format the message with the given pattern and arguments.

Parameters

• pattern is a properly formatted ICU Message Format pattern. A poorly formatted pattern will cause an Error to be thrown.
  • The pattern is used as a key into the translate function you provide in configuration, and is also used as the fallback if no translation is returned, or translate has not been configured
  • If pattern is not a string literal, the function cannot be transpiled at build time.
• args is an object containing the values to replace placeholders with. Required if the pattern contains placeholders.
• locales is an optional string with a BCP 47 language tag, or an array of such strings.
  • The locales are also passed into the translate function and indicate the desired destination language.
  • If locales is not a string literal, the function cannot be transpiled at build time.

format.setup

format.setup(options)

Configure format behavior for subsequent calls. This should be called before any code that uses format.

Parameters

• options is an object containing the following config values:
  • cache is whether message, number, and date formatters are cached. Defaults to true
  • locale is the default locale to use when no locale is passed to format. Defaults to "en".
  • translate(pattern, locales) is a function to translate messages. It should return the pattern translated for the specified locale.
    • pattern is the message pattern to translate.
    • locale is a string with a BCP 47 language tag, or an array of such strings.

internal apis

format.number, format.date, format.time, format.plural, and format.select are used internally and are not intended for external use. Because these appear in the transpiled code, transpiling does not remove the need to properly define format through require or import.

Example Messages

The examples provide sample transpiler output. This output is not meant to be 100% exact, but to give a general idea of what the transpiler does.

Simple messages with no placeholders

format('My Collections')

// transpiles to translated literal
"Minhas Coleções"

Simple string placeholders

format('Welcome, {name}!', { name:'Bob' });

// non-trivial messages transpile to self-invoking function
(function(locale, args) {
  return "Bem Vindo, " +
    args["name"] +
    "!";
})("pt-BR", { name:'Bob' });

number, date, and time placeholders

format('You took {n,number} pictures since {d,date} {d,time}', { n:4000, d:new Date() });
// en-US: "You took 4,000 pictures since Jan 1, 2015 9:33:04 AM"

format('{ n, number, percent }', { n:0.1 });
// en-US: "10%"

format('{ shorty, date, short }', { shorty:new Date() });
// en-US: "1/1/15"

Complex string with select and plural in ES6

import format from 'message-format-inline'

// using a template string for multiline, no interpolation
let format(`On { date, date, short } {name} ate {
  numBananas, plural,
       =0 {no bananas}
       =1 {a banana}
       =2 {a pair of bananas}
    other {# bananas}
  } {
  gender, select,
      male {at his house.}
    female {at her house.}
     other {at their house.}
  }`, {
  date: new Date(),
  name: 'Curious George',
  gender: 'male',
  numBananas: 27
})
// en-US: "On 1/1/15 Curious George ate 27 bananas at his house."

License

This software is free to use under the MIT license. See the LICENSE-MIT file for license text and copyright information.