Promise.race

Requirements

• Export a named function promiseRace from the entry file. Do not replace or mutate the global Promise constructor.
• Return a new native Promise. Adopt the first observed settlement, whether fulfilled or rejected, without waiting for every input.
• Preserve fulfillment values and original rejection reasons. Once settled, later inputs must not change the result.
• An empty iterable, or inputs that all remain pending, must leave the result pending.
• Accept synchronous iterables such as arrays, Sets, strings, and generators. Normalize plain values and nested thenables using native Promise.resolve.
• Consume the iterable synchronously and attach both settlement handlers to every input. An invalid iterable or a thrown iterator error must reject the returned Promise with the original error; it must not throw from the function call.
• Do not mutate the input. Promise handlers must run asynchronously, as native Promise handlers do.
• Use the native Promise constructor, Promise.resolve, and then/catch if useful. Do not call Promise.all, Promise.allSettled, Promise.any, or Promise.race to implement the function.
• Promise subclass constructors, custom species, and full variadic tuple type inference are outside scope. The TypeScript signature may use one common generic value type.

Examples

Input: await promiseRace([Promise.resolve("first"), Promise.resolve("second")])
Output: "first"

Input: await promiseRace([new Promise(() => {}), "ready"])
Output: "ready"

Input: promiseRace([Promise.reject("failed"), Promise.resolve("ready")]).catch((reason) => reason)
Output: "failed"

Input: promiseRace([])
Output: A Promise that stays pending