37Implement Promise.allSettled()

Implement promiseAllSettled(iterable) without using Promise.allSettled. It returns a promise that always fulfils, once every item has settled, with an array of outcome objects in input order:

• { status: "fulfilled", value } for items that fulfilled;
• { status: "rejected", reason } for items that rejected.

const results = await promiseAllSettled([fetchProfile(), fetchFeed(), fetchAds()]);
for (const result of results) {
  if (result.status === "fulfilled") render(result.value);
  else logError(result.reason);
}

Requirements

• Never reject, even if every item rejects.
• Keep the input order.
• Items may be promises, thenables or plain values; accept any iterable.
• An empty input fulfils with [].