Implement Promise.any() with AggregateError

Question

Accepted Answer

**Approach:** Track rejections; on first fulfillment resolve; if all reject, reject with `AggregateError`.

```javascript
function promiseAny(iterable) {
  const promises = [...iterable];
  if (promises.length === 0) return Promise.reject(new AggregateError([], 'All promises were rejected'));
  return new Promise((resolve, reject) => {
    const errors = new Array(promises.length);
    let rejectedCount = 0;
    promises.forEach((p, i) => {
      Promise.resolve(p).then(resolve, err => {
        errors[i] = err;
        rejectedCount++;
        if (rejectedCount === promises.length) reject(new AggregateError(errors, 'All promises were rejected'));
      });
    });
  });
}

// Demo
promiseAny([Promise.reject(1), Promise.reject(2), Promise.resolve(3)])
  .then(v => console.log(v)); // 3
promiseAny([Promise.reject('a'), Promise.reject('b')])
  .catch(e => { console.log(e instanceof AggregateError); console.log(e.errors); });
promiseAny([]).catch(e => console.log(e instanceof AggregateErr

Implement Promise.any() with AggregateError

Understand the problem

Attempt it yourself

Study the solution

Solution ready — 2 min read

Join the discussion

Discussion (0)

KEEP THE
STREAK ALIVE.

Understand the problem

Attempt it yourself

Study the solution

Solution ready — 2 min read

Join the discussion

Discussion (0)

KEEP THESTREAK ALIVE.

KEEP THE
STREAK ALIVE.