Simple retry helper with typescript

retry.ts

type Args<T> = {
  fn: () => Promise<T>;
  retries: number;
  delay: number;
  backoffFactor: number;
  onFailedAttempt?: (error: unknown, attemptNumber: number) => Promise<void>;
};

const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));

class RetryExhaustedError extends Error {
  constructor() {
    super("Retry attempts have been exhausted");
    this.name = "RetryExhaustedError";
  }
}

class OnFailedAttemptError extends Error {
  constructor(error: unknown) {
    super(
      `Error in onFailedAttempt: ${
        error instanceof Error ? error.message : "Unknown error"
      }`
    );
    this.name = "OnFailedAttemptError";
  }
}

async function retry<T>(
  {
    fn,
    retries = 3,
    delay = 1000,
    backoffFactor = 2,
    onFailedAttempt,
  }: Args<T>,
  attempt = 1
): Promise<T> {
  try {
    return await fn();
  } catch (_aError) {
    if (attempt > retries) throw new RetryExhaustedError();

    try {
      await onFailedAttempt?.(_aError, attempt);
    } catch (_hError) {
      throw new OnFailedAttemptError(_hError);
    }

    await sleep(delay * Math.pow(backoffFactor, attempt - 1));

    return await retry(
      { fn, retries, delay, backoffFactor, onFailedAttempt },
      attempt + 1
    );
  }
}