async.js

'use strict'

const async = makeGenerator => function () {
  const generator = makeGenerator.apply(this, arguments);

  const handle = result =>
    result.done
      ? Promise.resolve(result.value)
      : Promise.resolve(result.value)
          .then(res => handle(generator.next(res)))
          .catch(err => handle(generator.throw(err)))

  try {
    return handle(generator.next());
  } catch (err) {
    return Promise.reject(err);
  }
}

module.exports = async