medium.allSettled.3.js

// -- simple
function isIterator(obj) {
  return !!obj && !!obj[Symbol.iterator];
}

function allSettled(iterable) {
  if (!isIterator(iterable)) {
    throw new Error('[allSettled] first param must be iterable');
  }

  const onFulfill = v => ({ status: 'fulfilled', value: v });
  const onReject = v => ({ status: 'rejected', reason: v });

  return Promise
    .all(Array.from(iterable).map(p =>
      Promise
        .resolve(p)
        .then(onFulfill)
        .catch(onReject)));
}