cjs-shim.js

self.setImmediate = cb => Promise.resolve().then(cb)

var fsModule = new Blob([`
module.exports = {
  readdirSync() {
    return []
  },
  readFileSync(file) {
    const xhr = new XMLHttpRequest()

    xhr.open('GET', file, false)
    xhr.send()

    return xhr.response
  }
}
`])

window.require = function commonjs(options = {}) {
  const { root = '/', modules = 'https://unpkg.com/', cache = {} } = options
  const { map = {} } = options

  const base = new URL(root, location.origin)
  const bare = new URL(modules, location.origin)
  const process = { env: {}, versions: { node: 10 }, argv: [], async nextTick(cb) { cb() } }

  load.resolve = function (local) {
    local = map[local] || local

    const dest = new URL(local, local[0] === '.' ? base.href : bare.href)

    return dest.href
  }

  function load(local) {
    const id = load.resolve(local)

    if(cache[id]) return cache[id]

    console.count(id)

    const xhr = new XMLHttpRequest()

    xhr.open('GET', id, false)
    xhr.send()

    const params = ['module', 'exports', 'require', '__dirname', '__filename', 'process', 'global']
    const __filename = xhr.responseURL
    const __dirname = xhr.responseURL.split('/').slice(0, -1).join('/')
    const require = commonjs({ root: __filename, modules, cache, map })
    const exports = cache[id] = {}
    const module = { exports }


    let code = xhr.response

    const [ type ] = (xhr.getResponseHeader('Content-Type')||'').split(';')

    if(type.endsWith('json')) {
      code = `module.exports = ${code}`
    }
    
    const factory = Function(params, code)

    factory(module, exports, require, __dirname, __filename, process, self)

    return cache[id] = module.exports
  }

  return load
}({
  map: {
    'fs': URL.createObjectURL(fsModule),
    'os': 'os-browserify',
    'util/': 'util',
    'crypto': 'crypto-browserify',
    'stream': 'stream-browserify',
    'https': 'https-browserify',
    'http': 'stream-http',
  }
})

window.Buffer = require('buffer').Buffer