generator.js

function flow (generator) {
  var iterator = generator(next);
  next();

  function next (err, result) {
    if (err) {
      iterator.throw(err);
    }
    var item = iterator.next(result);
    if (item.done) {
      return;
    }
    if (typeof item.value === 'function') {
      item.value(next);
    }
  }
}

function get (resume) {
  setTimeout(function () {
    resume(null, ['bacon', 'lettuce', 'crispy bacon']);
  }, 1000);
}

flow(function* (resume) {
  console.log('fetching food types...');
  var types = yield get;
  console.log('waiting around...');
  yield setTimeout(resume, 2000);
  console.log(types.join(' '));
});