Implement Promise.allSettled()

Question

Accepted Answer

**Approach:** Map each to `Promise.resolve(p).then(value=>({status:"fulfilled", value}), reason=>({status:"rejected", reason}))` then `Promise.all`.

```javascript
function promiseAllSettled(iterable) {
  const promises = [...iterable];
  if (promises.length === 0) return Promise.resolve([]);
  return Promise.all(promises.map(p =>
    Promise.resolve(p).then(
      value => ({ status: 'fulfilled', value }),
      reason => ({ status: 'rejected', reason })
    )
  ));
}

// Demo
promiseAllSettled([Promise.resolve(1), Promise.reject('err'), 3])
  .then(r => console.log(r));
// [
//   { status: 'fulfilled', value: 1 },
//   { status: 'rejected', reason: 'err' },
//   { status: 'fulfilled', value: 3 }
// ]
promiseAllSettled([]).then(r => console.log('empty', r)); // []
```
Use for batch where partial failure is okay (e.g. fetch multiple resources).

Implement Promise.allSettled()

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Understand the problem

Attempt it yourself

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Solution ready — 2 min read

Join the discussion

Discussion (0)

KEEP THESTREAK ALIVE.

KEEP THE
STREAK ALIVE.