async cb w/ promises in es2015!

asyncCB_es2015.js

//the most basic async cb
sleep = function(ms) {
  let promise = new Promise(function(resolve, reject) {
    setTimeout(function() {
      resolve("the result");
    }, ms);
  });

  return promise;
};

sleep(1000)
  .then((result) => sleep(1000)) //1st execution after 1 second
  .then((result) => console.log("2: " + result)); //2nd execution after another 1 second
  .catch((err) => console.log("error: " + err));

//wait for everything to complete
Promise.all([sleep(1000), sleep(2000)])
  .then(() => console.log("all done")); //printed 2nd

//wait for the 1st promise to complete, then, call the then callback
Promise.race([sleep(1000), sleep(2000)])
  .then(() => console.log("race")); //printed 1st