const promise1 = randomPromise(1);

const promise2 = randomPromise(2);

const promise3 = randomPromise(3);

​

Promise.all([promise1, promise2, promise3]).then(function(values) {

  console.log(values);

});

​

function randomPromise(id) {

  // Each promise can take upto 5 seconds to execute

  const delay = Math.random() * (5000 - 100) + 100;

  return new Promise(resolve =>

    setTimeout(() => {

      console.log(id);

      resolve([id, delay]);

    }, delay)

  );

}