Retry a flaky async call

advanced Promises Challenge 14 of 18

Write retry(fn, attempts, delayMs = 0). fn is an async function that sometimes fails, such as an API call to create test data in a slow environment.

Requirements

Call fn up to attempts times in total, and resolve with the first successful result.
Do not call fn again after it succeeds.
If every attempt fails, reject with the error from the last attempt.
Treat a synchronous throw from fn the same as a rejected Promise.
Wait delayMs milliseconds between attempts (not after the last one).
Reject when attempts is not a positive integer.

Expected output

await retry(makeFlaky(2), 3) → 'ok' (fails twice, succeeds on the 3rd call) await retry(makeFlaky(5), 3) → rejects with the 3rd failure's error

Test cases (7)

○succeeds after transient failures
○rejects with the last error when every attempt fails
○calls fn exactly attempts times on failure
○stops calling fn after the first success
○handles functions that throw synchronously
○waits delayMs between attempts
○rejects when attempts is less than 1

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Results

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Retry a flaky async call

Requirements

Expected output

Test cases (7)

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