main.js

import 'magic-script-polyfills';

import lumin from 'lumin';
import uv from 'uv';
import ssl from 'ssl';
import egl from 'egl';
import gl from 'gl';
import png from 'png';
import jpeg from 'jpeg';

function require(name) {
  switch(name) {
    case 'lumin': return lumin;
    case 'uv': return uv;
    case 'ssl': return ssl;
    case 'egl': return egl;
    case 'gl': return gl;
    case 'png': return png;
    case 'jpeg': return jpeg;
  }
  throw new Error(`No such supported builtin module: ${name}`);
}

let url;
try {
  url = uv.osGetenv("APP_URL");
} catch (err) {
  if (!url) throw new Error("Please set APP_URL variable.  For example, use v flag in mldb launch `-v APP_URL=http://192.168.0.50:8000/app.js`")
}

console.log(`Downloading ${url}...`);
fetch(url)
  .then(res => {
    if (res.status !== 200) throw new Error(`Expected 200 status code, but got ${res.status}`);
    return res.text();
  })
  .then(body => {
    console.log(`Evaluating downloaded body ${body.length} as cjs module...`)
    const exports = {}
    const module = {exports}
    eval(`(module, exports, require) => { ${body} }`)(module, exports, require);
  })
  .catch(err => {
    console.log(err.stack)
  });

rollup-serve.js

const rollup = require('rollup');
const resolve = require('rollup-plugin-node-resolve');
const commonjs = require('rollup-plugin-commonjs');
var os = require('os');

const http = require('http');
const urlParse = require('url').parse
const pathJoin = require('path').join

const server = http.createServer((req, res) =>
  handleRequest(req, res).catch((err) => {
    res.statusCode = 500;
    res.end(err.stack + "\n")
  })
);
server.on('clientError', (err, socket) => {
  socket.end('HTTP/1.1 400 Bad Request\r\n\r\n');
});
server.listen(8000, "0.0.0.0", () => {
  const port = server.address().port
  console.log(`Rollup IIFE server listening on the following external interfaces:`)
  const ifaces = os.networkInterfaces();
  for (const name in ifaces) {
    for (const { internal, family, address } of ifaces[name]) {
      if (internal || family !== 'IPv4') continue;
      console.log(`  ${name}:\n    http://${address}:${port}/`)
    }
  }
});

async function handleRequest(req, res) {
  const { pathname } = urlParse(req.url);
  if (!/\.js$/.test(pathname)) {
    res.statusCode = 400;
    return res.end("Not a JavaScript module\n");
  }
  const input = pathJoin(__dirname, "src", pathname)
  console.log(`Creating bundle for ${pathname}...`)

  const bundle = await rollup.rollup({
    input,
    external: ['uv', 'lumin', 'egl', 'png', 'gl', 'jpeg', 'ssl'],
    plugins: [resolve(), commonjs()],
  });
  console.log(`Generating bundle for eval...`)
  const { output } = await bundle.generate({
    format: "cjs",
  });
  const [{ code }] = output
  const body = Buffer.from(code);
  console.log(`Sending ${body.length} bytes of JavaScript...`)
  res.setHeader('Content-Type', 'application/javascript')
  res.end(body);

}

To use this, first make sure you have the dependencies npm i rollup rollup-plugin-node-resolve rollup-plugin-commonjs and run it with node rollup-serve.js in the root of your project. It serves src/**.js files as single-file CJS module strings that are ready to pass to eval. It resolves both ES6 module imports as well as node.js style requires.