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How do you implement a custom Promise.all polyfill?

Q: How do you implement a custom Promise.all polyfill?

**Intuition.** Promise.all returns a promise that resolves with an array of values only when all inputs settle, or rejects immediately on the first rejection. Promise.all accumulates results or fails immediately PENDING <t

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Write an implementation of Promise.all from scratch, showing how you track counts, handle non-promises, and reject immediately on the first error.

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