JS計算兩個時間差

const calculateTime= function(begin: string, end: string) {
  var dateBegin = new Date(begin);
  var dateEnd = new Date(end);
  var dateDiff = dateEnd.getTime() - dateBegin.getTime(); //時間差的毫秒數
  var dayDiff = Math.floor(dateDiff / (24 * 3600 * 1000)); //計算出相差天數
  var leave1 = dateDiff % (24 * 3600 * 1000); //計算天數后剩余的毫秒數
  var hours = Math.floor(leave1 / (3600 * 1000)); //計算出小時數
  //計算相差分鍾數
  var leave2 = leave1 % (3600 * 1000); //計算小時數后剩余的毫秒數
  var minutes = Math.floor(leave2 / (60 * 1000)); //計算相差分鍾數
  //計算相差秒數
  var leave3 = leave2 % (60 * 1000); //計算分鍾數后剩余的毫秒數
  var seconds = Math.round(leave3 / 1000);