Retry with exponential backoff and jitter

Medium25 minFree, no account

Easy to write, easy to write in a way that makes an outage worse.

The question

Write retry(fn, { attempts, baseMs, maxMs, signal }) that retries a failing async function with exponential backoff.

Explain why jitter matters and which errors you should not retry.

await retry(() => fetch(url), {
  attempts: 5, baseMs: 100, maxMs: 10_000, signal
});

// delays roughly: 100, 200, 400, 800, each randomised

25:00Commit to an answer before you open the solution. Reading it first teaches you to recognise good answers, which is not the skill being tested.

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The worked solution

written by a person · not a grade

Score yourself

0 of 5 marked

Exponential backoff with a cap20
Jitter, with the thundering-herd explanation25
A retryable-error predicate rather than retrying everything25
Raised idempotency20
Cancellation that interrupts the wait10

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