co/q

gistfile1.txt

const co = require('q').spawn;
// const co = require('co');

function wait (ms, value) {
  return new Promise((resolve, reject) => {
    if (typeof ms !== 'number') {
      return reject(new Error('arg must be a number'));
    }
    setTimeout(() => {
      resolve(value);
    }, ms);
  });
}

co(function* () {
  let x = wait(3000, 3);
  let y = wait(3000, 5);
  let z = wait('foo', 4);

  let xv,xy;

  try {
   xv = yield x;
   yv = yield y;
  } catch (e) {
    console.log('Error unexpected', e);
  }

  try {
    xz = yield z;
  } catch (e) {
    console.log('Error expected', e);
  }

  console.log(xv + yv);
});