When You Need Everything at Once

Often you need to wait for multiple async operations to complete, not just one. The Promise API provides powerful methods for this.

1. Promise.all([p1, p2, p3])

Runs all promises in parallel and waits for all of them to succeed.

• ✅ Success: Returns an array of all results, in the same order as the input.
• ❌ If ANY ONE fails: Immediately rejects with that error (all other results are discarded).

const [user, products, settings] = await Promise.all([
  fetch('/api/user').then(r => r.json()),
  fetch('/api/products').then(r => r.json()),
  fetch('/api/settings').then(r => r.json())
]);

2. Promise.allSettled([p1, p2, p3])

Waits for all promises to finish, regardless of whether they succeed or fail. Returns an array of result objects.

const results = await Promise.allSettled([p1, p2, p3]);
results.forEach(result => {
  if (result.status === 'fulfilled') console.log(result.value);
  if (result.status === 'rejected') console.error(result.reason);
});

3. Promise.race([p1, p2])

Returns the result of the first promise to settle (success or failure).

4. Promise.any([p1, p2])

Returns the result of the first promise to succeed. Only rejects if ALL promises fail.