js 计算时间差

  /*计算相隔时间差 开始时间和结束时间的时间类型 yyyy-MM-dd HH:mm:ss*/
  static timeCHA(starttime, endtime) {
    var day1 = new Date(starttime);
    var day2 = new Date(endtime);
    if (starttime && endtime != "") {

      //计算天数
      var timediff = day2 - day1;
      var days = parseInt(timediff / 86400000);
      //计算小时数
      var remain = timediff % 86400000;
      var hours = parseInt(remain / 3600000);
      //计算分钟数
      var remain = remain % 3600000;
      var mins = parseInt(remain / 60000);
      //计算秒
      var remain = remain % 60000;
      var ss = parseInt(remain / 1000);
      var qx = "";
      if (days > 0) {
        qx += days + "天";
      }
      if (hours > 0) {
        qx += hours + "时";
      }
      if (mins > 0) {
        qx += mins + "分";
      }
      if (ss > 0) {
        qx += ss + "秒";
      }
    }
    return qx
  }