NODE

function main () {
  return Promise.all([1,2,3,4].map((value) => asyncThing(value)))
}

function asyncThing(n) {
    console.log(n);
    return n;
}

main()
  .then(values => values.map((value) => value * 2))
  .then(v => console.log(v))
  .catch(err => console.error(err))