asbundle

A minimalistic CommonJS bundler.

This module is a perfect ascjs companion to create CommonJS bundles.

Passing a single ESM/CJS source file as path name, it will produce a lightweight, optimized, and minifier friendly bundle, to consume right away without needing global require or runtime discovered CommonJS dependencies.

Goals

• be as simple as possible, but not simpler
• make creation of small modules written in ESM a no brainer
• enable .js files as ESM everywhere, following a simple folder convention
• produce files compatible with most common bundlers and tools (Babel, Webpack, UglifyJS, etc)

Example of a basic module based on ascjs and asbundle.

Non-Goals

• replace Babel, Webpack, Rollup, or any other tool. Let them do complicated things when needed
• transpile anything else than ESM import/export declarations

How to

You can use asbundle as binary utility or as module.

npm install -g asbundle

# to see what you can do
asbundle --help

As executable, you can use asbundle to output, or save, a bundle entry point.

asbundle source-file.js           # writes bundle contents to STDOUT
asbundle source-file.js bundle.js # outputs to bundle.js

As module, you can require it and use it to obtain a bundle string.

const asbundle = require('asbundle');

asbundle(sourceFileName);

Features

• extremely lightweight, based on babylon for performance and reliability
• it uses ascjs to automatically transform, when needed, ES2015+ modules into CommonJS code
• understands both relative files and installed packages too (based on require.resolve(...))
• reproduces a modern and minimalistic CommonJS environments ideal for browsers
• compatible with Babel __esModule and .default convention

Constrains

• same constrains of ascjs
• Node core modules are not brought to the bundle, if a module cannot be resolved as file name it throws

Example

This module can transform main.js entry file via asbundle main.js out.js:

// main.js
import func, {a, b} from './module.js';
const val = 123;
export default function test() {
  console.log('asbundle');
};
export {func, val};

// module.js
export const a = 1, b = 2;
export default function () {
  console.log('module');
};

into the following bundle:

// out.js => 266 bytes minified & gzipped
(function (cache, modules) {
  function require(i) { return cache[i] || get(i); }
  function get(i) {
    var exports = {}, module = {exports: exports};
    modules[i].call(exports, window, require, module, exports);
    return (cache[i] = module.exports);
  }
  var main = require(0);
  return main.__esModule ? main.default : main;
}([],[function (global, require, module, exports) {
// main.js
'use strict';
const func = (m => m.__esModule ? m.default : m)(require(1));
const {a, b} = require(1);
const val = 123;
function test() {
  console.log('asbundle');
}
Object.defineProperty(exports, '__esModule', {value: true}).default = test;
exports.func = func;
exports.val = val;
},function (global, require, module, exports) {
// module.js
'use strict';
const a = 1, b = 2;
exports.a = a;
exports.b = b;
Object.defineProperty(exports, '__esModule', {value: true}).default = function () {
  console.log('module');
};
}]));

The main module is returned and executed as default entry so it becomes easy to publish as global variable for Web purposes too.

Add a const myModule = prefix to the bundled code and use it right away.