multiform

A simple system for writing modules that ship with multiple Babel builds, each optimised for a different V8 version.

Why

This is a stopgap for people who want to write ES6-7 code today, using things like generators and async functions, and build it with Babel – but without simply compiling everything down to ES5.

Ideally you want your users to run real, native generators where supported (because they're faster, they're more debuggable, and they don't require a runtime library) while still providing an ES5-only build for users on older platforms.

Multiform helps organise this kind of setup.

How

• You define your Babel configurations in multiform.json.
• The multiform command (installed as a devDependency, multiform-build, and run on prepublish) builds your src folder into dist-0, dist-1 etc. corresponding with your Babel configurations.
• Your main script automatically selects and loads the best dist for the current V8 version, like this: module.exports = require('multiform').load();

See multiform-template for an example setup.

multiform.json reference

• builds – array of objects with these properties:
  • version (optional) – the minimum version of V8 that can run this build.
  • options – the Babel options.
• defaults (optional) – base options shared by all your builds. (Each build config will be deep-merged into this.)

Example:

{
  "builds": [
    {
      "version": "4.1.0.27",
      "options": {
        "blacklist": [
          "regenerator",
          "es6.forOf",
          "es6.templateLiterals",
          "es6.constants"
        ],
        "optional": [
          "bluebirdCoroutines"
        ]
      }
    },
    {
      "options": {
        "optional": [
          "runtime",
          "es7.asyncFunctions"
        ]
      }
    }
  ],

  "defaults": {
    "loose": true
  }
}