Promise.any - async/await vs then()

async-await.ts

async function any<T>(promises: Promise<T>[]): Promise<T> {
	const rejections: any[] = [];

	for (const promise of promises) {
		try {
			return await promise;
		}
		catch (reason) {
			rejections.push(reason);
		}
	}

	throw rejections;
}

perverse.ts

function any<T>(promises: Promise<T>[]): Promise<T> {
	return new Promise<T>((resolve, reject) =>
		Promise.all<any>(promises.map(promise => promise.then(resolve, reason => reason))).then(reject));
}

then-all.ts

function any<T>(promises: Promise<T>[]): Promise<T> {
	const rejections: any[] = [];

	return new Promise<T>((resolve, reject) => {
		Promise.all<void>(promises.map((promise, index) =>
			promise.then(resolve).catch(reason => {
				rejections[index] = reason;
			}))).then(() => {
				reject(rejections);
			});
	});
}

then.ts

function any<T>(promises: Promise<T>[]): Promise<T> {
	let numLeft = promises.length;
	const rejections: any[] = [];

	return new Promise<T>((resolve, reject) => {
		promises.forEach((promise, index) => {
			promise.then(resolve).catch(reason => {
				rejections[index] = reason;
			}).then(() => {
				numLeft--;

				if (numLeft == 0) {
					reject(rejections);
				}
			});
		});
	});
}