JS计算两个时间差

const calculateTime= function(begin: string, end: string) {
  var dateBegin = new Date(begin);
  var dateEnd = new Date(end);
  var dateDiff = dateEnd.getTime() - dateBegin.getTime(); //时间差的毫秒数
  var dayDiff = Math.floor(dateDiff / (24 * 3600 * 1000)); //计算出相差天数
  var leave1 = dateDiff % (24 * 3600 * 1000); //计算天数后剩余的毫秒数
  var hours = Math.floor(leave1 / (3600 * 1000)); //计算出小时数
  //计算相差分钟数
  var leave2 = leave1 % (3600 * 1000); //计算小时数后剩余的毫秒数
  var minutes = Math.floor(leave2 / (60 * 1000)); //计算相差分钟数
  //计算相差秒数
  var leave3 = leave2 % (60 * 1000); //计算分钟数后剩余的毫秒数
  var seconds = Math.round(leave3 / 1000);