Add `onReattempt` option about p-retry

[sindresorhus]

When would it call onError? Can you elaborate on what you need and how you would use it?

[kilianc]

await retry(() => foo(), {
  onError: (err, attemptNumber, attemptsLeft) => {
    console.error(`Attempt number ${attemptNumber} failed: ${err.message} (${attemptsLeft} left)`)
  }
})

[sindresorhus]

@kilianc I mean, in what situation would node-retry call the onError function you supply? From your example, it seems like rejecting the promise might be a better option and including the attemptNumber and attemptsLeft as properties on the error.

[SamVerschueren]

I think what @kilianc wants is a function to be called after every failed attempt so you can show status updates on network requests or something. So if we go for it, it might be better to call the function onFailure instead of onError.

[kilianc]

@SamVerschueren correct. It's mostly for network reattempts. onFailure and onError sound exactly the same. maybe onReattempt ?

[sindresorhus]

onReattempt 👍

I assume this would only be called on the second attempt and forward?

[kilianc]

onFailedAttempt ?

[acostalima]

I've just pushed PR #5 to add this feature. 😄