Dynamic JavaScript time counter

dynamicTimeLeft.ts

export const dynamicTimeLeft = (date1: Date, date2: Date) => {
  const distance = date2.getTime() - date1.getTime();

  const hours = Math.floor(
    (distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60)
  );
  const minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
  const seconds = Math.floor((distance % (1000 * 60)) / 1000);
  const addZero = (t: number) => (t > 9 ? t : `0${t}`);

  return `${addZero(hours)}:${addZero(minutes)}:${addZero(seconds)}`;
};