Here's a slightly modified version, printing the function name in the error and adding typescript types:

export async function retry<T>(
  fn: () => Promise<T>,
  retriesLeft: number = 3,
  interval: number = 1000,
  exponential: boolean = false
): Promise<T> {
  try {
    const val = await fn();
    return val;
  } catch (error) {
    if (retriesLeft) {
      await new Promise(r => setTimeout(r, interval));
      return retry(
        fn,
        retriesLeft - 1,
        exponential ? interval * 2 : interval,
        exponential
      );
    } else throw new Error(`Max retries reached for function ${fn.name}`);
  }
}

If fn() needs arguments, how to change the above code to make it work? thx

You could wrap your function in another function together with the arguments:

retry(() => fn(arg1, arg2))