Code Lab

Retry on failure

EasyAsync code5 min

Write a function retry(fn). It calls the async function fn with no arguments. If the promise from fn rejects, call fn again. Make no more than three attempts in total.

retry returns a promise with the result of the first successful attempt. If all three attempts fail, return a promise that rejects with the error of the last attempt.

Examples

await retry(() => Promise.resolve('ok'))

Returns 'ok'

The first attempt succeeds, so there is no retry.
await retry(() => Promise.reject(new Error('down'))).catch((e) => e.message)

Returns 'down'

All three attempts fail, and the last error comes out.

Source

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  1. Success on the first try, fn is called once
  2. Two failures, then success
  3. Three failures, the last error comes out

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