Example of Generators using the "co" lib

co.js

var co = require('co');

var i = 0

function getPromiseTime() {
  var t = ++i;

  return new Promise(function (resolve, reject) {
    setTimeout(function() {
      console.log(t + ' released');
      resolve(t);
    }, t * 500);
  });
}

function onerror(err) {
  // log any uncaught errors
  // co will not throw any errors you do not handle!!!
  // HANDLE ALL YOUR ERRORS!!!
  console.error(err.stack);
}

co(function *(){
  // resolve multiple promises in parallel
  var a = getPromiseTime();
  var b = getPromiseTime();
  var c = getPromiseTime();

  console.log('START');

  var res = yield [a, b, c];
  console.log(res);
  // => [1, 2, 3]
}).catch(onerror);