promise3.js

promise = v => (new Promise(r => setTimeout(x => r(v), ((Math.random() * (10 - 1)) + 1 | 0) * 1000)));

//execs all promises in parallel but prints numbers randomly
[promise(1),promise(2),promise(3),promise(4),promise(5),promise(6)].forEach(function(p) {
  return p.then(v => console.log(v));
}, Promise.resolve());

//still execs promises in parallel and uses a sequence to print numbers in order
[promise(1),promise(2),promise(3),promise(4),promise(5),promise(6)].reduce(function(sequence, p) {
  // Add these actions to the end of the sequence
  var waitForPromise = sequence.then(x => p);
  return waitForPromise.then(v => console.log(v));
}, Promise.resolve());

//using a map is simple!:
[1,2,3,4,5,6].map(promise).reduce(function(sequence, p) {
  // Add these actions to the end of the sequence
  var waitForPromise = sequence.then(x => p);
  return waitForPromise.then(v => console.log(v));
}, Promise.resolve());

//variant (waits till all promises are resolved)
Promise.all([1,2,3,4,5,6].map(promise)).then(i => i.forEach(v => console.log(v)))

//or if order not matter:
[1,2,3,4,5,6].map(promise).forEach(p => p.then(v => console.log(v)));

inspired by: http://www.html5rocks.com/en/tutorials/es6/promises/#toc-parallelism-sequencing