Javascript Function to compare two dates (Disable back dates)

    var EnteredDate = document.getElementById('<%=FrDate.ClientID%>').value;
        var date = EnteredDate.substring(0, 2);
        var month = EnteredDate.substring(3, 5);
        var year = EnteredDate.substring(6, 10);
        var myDate = new Date(year, month - 1, date);
        var today = new Date();
        today.setDate(today.getDate() - 1);
        if (myDate < today) {
            document.getElementById('<%=FrDate.ClientID%>').value = "";
            alert("You cannot select a day earlier than today! ");
            return false;
        }


<cc1:calendarextender id="CalendarExtender1" runat="server" targetcontrolid="txtfrom" PopupButtonID="ImageButton1" Format="dd/MM/yyyy"></cc1:calendarextender>


                 var fromDate =document.getElementById("ContentPlaceHolder1_txt_FromDate").value;
                     var ToDate = document.getElementById("ContentPlaceHolder1_txt_ToDate").value;
                     var dt1 = parseInt(fromDate.substring(0, 2), 10);

                     var mon1 = parseInt(fromDate.substring(3, 5), 10);

                     var yr1 = parseInt(fromDate.substring(6, 10), 10);

                     var dt2 = parseInt(ToDate.substring(0, 2), 10);

                     var mon2 = parseInt(ToDate.substring(3, 5), 10);

                     var yr2 = parseInt(ToDate.substring(6, 10), 10);

                     mon1 = mon1 - 1;

                     mon2 = mon2 - 1;

                     var date1 = new Date(yr1, mon1, dt1);

                     var date2 = new Date(yr2, mon2, dt2);

                     if (date2 >= date1) {
                   
                         return true;
                     }

                     else
                     {
                         alert("From Date Cannot be greater than To Date")
                         return false;
                     }