async/retry: only retry on certain types of errors #6196

Is your feature request related to a problem? Please describe.

A common use case of async/retry is when fetching data from an API, which has various error scenarios:

• 5xx error: server-side error, retriable
• 429 error: too many requests, retriable
• Other 4xx error: other client-side error, not retriable
• Various non-HTTP-status errors, pretend they don't exist to simplify this example

Describe the solution you'd like

An option called something like isRetriable that can be provided a callback to check whether to retry a given error.

class HttpError extends Error {
    constructor(public status: number) {
        super()
    }
}

// retry only if the status indicates it's retriable, otherwise reject immediately
const res = await retry(async () => {
    const res = await fetch('https://example.com/api/endpoint')
    if (!res.ok) throw new HttpError(res.status)
    return res
}, {
    isRetriable: (e) => e instanceof HttpError && (e.status === 429 || e.status >= 500),
})

Describe alternatives you've considered

N/A