Basic ES6 Promise Example

gistfile1.js

function resolve(val) {
  alert('Counted to ' + val);
  return val;
}

function reject(reason) {
  alert('Could not count');
  return reason;
}

function resolver(resolve, reject) {
  setTimeout(function doneCounting() {
    resolve(5);
  }, 5000);
}

var countToFive = new Promise(resolver);
countToFive.then(resolve, reject);