38Implement Promise.race()

Implement promiseRace(iterable) without using Promise.race. It returns a promise that settles the same way as the first item to settle: it fulfils with that value or rejects with that reason.

const result = await promiseRace([
  fetch("/api/search?q=js"),
  new Promise((_, reject) => setTimeout(() => reject(new Error("Timed out")), 3000)),
]);

Requirements

• Fulfilment and rejection both count: whichever comes first wins.
• Plain values count as already settled, so promiseRace([slowPromise, 42]) fulfils with 42.
• With equal timing, the earlier item in the input wins.
• An empty input returns a promise that never settles, like the built-in.
• Accept any iterable.