putoutjsBundler 
Install
npm i @putout/bundle
API
import {bundle} from '@putout/bundler';
console.log(bundle(CWD, entry, filesystem));
Internals
Convert ESM to CommonJS
To Simplify things up all files converted to CommonJS first. Let's suppose none of them use top-level await to get things simpler.
Parse filenames
Traverse all files starting from entry and get all filenames.
Bundle all files to object
Traverse filesystem and create object that contains filename and file content:
const __filesystem = {
'/entry.js': () => {
const client = require('/client.js');
console.log(client);
},
'/client.js': (exports, require, module) => {
module.exports = 'hello';
},
};
IIFE
Most likely we need IIFE so couple bundles can be loaded on page simultaneously.
Result Example
const __modules = {};
const __filesystem = {
'/entry.js': () => {
const client = require('/client.js');
console.log(client);
},
'/client.js': (exports, require, module) => {
module.exports = 'hello';
},
};
const require = (name) => {
const exports = {};
const module = {
exports,
};
if (__modules[name])
return __modules[name];
__filesystem[name](exports, require, module);
__modules[name] = module.exports;
return module.exports;
};
require('/entry.js');
License
MIT