A function that runs async functions and prints how long they take to stderr with a given string as the prefix message

timed.ts

export async function timed<T>(
  cb: () => Promise<T>,
  message: string,
  debug = (...args: any[]) => console.warn(...args),
): ReturnType<typeof cb> {
  const start = performance.now();
  const result = await cb();
  const end = performance.now();
  let timeSpent = end - start;

  let unit = "ms";
  if (timeSpent > 1000) {
    timeSpent /= 1000;
    unit = "s";
  }
  // timed operations always print to stderr
  debug(message, `${timeSpent.toFixed(4)}${unit}`);
  return result;
}