Count Days in between from date and to date in asp.net with jquery in asp.net

$(document).ready(function() {

    var FistDate, SecondDate;
    if ($('#ctl00_ContentPlaceHolder1_ToDate').blur(function() {

        FistDate = $('#ctl00_ContentPlaceHolder1_FromDate').val();
        SecondDate = $('#ctl00_ContentPlaceHolder1_ToDate').val();
        compareDate(FistDate, SecondDate);
        var FistDate = new Date($("#ctl00_ContentPlaceHolder1_FromDate").val().split("/").reverse().join(","));
        var SecondDate = new Date($("#ctl00_ContentPlaceHolder1_ToDate").val().split("/").reverse().join(","));
        var days = (SecondDate - FistDate) / 86400000;
        //alert(FistDate + '  ' + SecondDate);
        $("#ctl00_ContentPlaceHolder1_TotalLeave").val(days + 1);
        //DayCalculate(FistDate, SecondDate);
    }));

    function compareDate(dateTo, dateFrom) {
        var str2 = dateTo;
        var str4 = dateFrom;
        var ONE_DAY = 1000 * 60 * 60 * 24;
        var dt2 = parseInt(str2.substring(0, 2), 10);
        var mon2 = parseInt(str2.substring(3, 5), 10);
        var yr2 = parseInt(str2.substring(6, 10), 10);
        var dt4 = parseInt(str4.substring(0, 2), 10);
        var mon4 = parseInt(str4.substring(3, 5), 10);
        var yr4 = parseInt(str4.substring(6, 10), 10);
        var date2 = new Date(yr2, mon2 - 1, dt2);
        var date4 = new Date(yr4, mon4 - 1, dt4);
        var date2_ms = date2.getTime();
        var date4_ms = date4.getTime();
        var difference_ms = Math.abs(date2_ms - date4_ms)
        var y = Math.round(difference_ms / ONE_DAY)
        if (date2 > date4) {
            $("#ctl00_ContentPlaceHolder1_FromDate").val('');
            $("#ctl00_ContentPlaceHolder1_ToDate").val('');
            alert("From Date Is Less Than To Date");
            $("#ctl00_ContentPlaceHolder1_TotalLeave").val('');
        }
    }

  

})