Re-implement Promise.all from Scratch
hardAsync & PromisesHigh freq+300 XPFrontend AlgoArena
Implement promiseAll(promises) without using built-in Promise.all.
What it has to do
- Resolve with an array of values in original input order.
- Reject immediately if any input promise rejects.
- Handle non-promise values seamlessly.
Where it's been asked
- Meta
- Amazon
- Microsoft
- Uber
From public interview reports — a problem very like this one has shown up in a round at these companies. Not an exhaustive list.
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Need a nudge?
Reveal a conceptual hint or the reference solution. Both were written and reviewed with the problem — no runtime magic.
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