js 计算两个日期之间距离的天数（有上午下午的区分）

day: function() {
      if (this.startDate == "" && this.endDate == "") {
        return "自动计算/最小单位0.5天";
      } else {
        var sdate = new Date(this.startDate);
        var now = new Date(this.endDate);
        var days = now.getTime() - sdate.getTime();
        var day = parseInt(days / (1000 * 60 * 60 * 24));
        console.log(day);
        if (
          now == sdate ||
          (this.form.startDateFrom == "上午" &&
            this.form.endDateTo == "上午") ||
          (this.form.startDateFrom == "下午" && this.endDateTo == "下午")
        ) {
          day = day + 0.5;
        } else if (
          this.startDateFrom == "上午" &&
          this.endDateTo == "下午"
        ) {
          day = day + 1;
        }
        this.leaveLength = day;
        return day;
      }
    }