Like Co library to execute Generatos and use yield as await

execute.js

function execute(generator, yieldValue) {

  let next = generator.next(yieldValue);

  if (!next.done) {
    next.value.then(
      result => execute(generator, result),
      err => generator.throw(err)
    );
  } else {
    alert(next.value);
  }

}