How to add no of days in DateEdit using JavaScript

I have to Date Field one is From Date and another one is To Date i want to set To date as if From Date is suppose 01/01/2021 then max Date of To Date should be 01/01/2022. I am not able to Do the same Please help me

Function:

 function FromDateValidate() {
            var selToDate = deToDate.GetDate();
            if (deToDate.GetDate() == null || deToDate.GetDate() == '') {
                deToDate.SetMinDate(selFromDate);

                deToDate.SetMaxDate(new Date(deFromDate + 365)); //To date hide all date 
                //var Fromdate = deFromDate.GetDate();  
                //deToDate.SetDate(new Date(Fromdate.setDate(Fromdate.getDate() + 365))); Not working
            }
            var selFromDate = deFromDate.GetDate();
            if (selFromDate > selToDate) {
                deToDate.SetDate(selFromDate);
                deToDate.SetMinDate(selFromDate);
            }
        }

        function ToDateValidate() {
            if (deFromDate.GetDate() == null || deFromDate.GetDate() == '') {
                var selToDate = deToDate.GetDate();
                var selFromDate = deFromDate.GetDate();
                deFromDate.SetMaxDate(selToDate);
            }
            if (selFromDate > selToDate) {
                deToDate.SetDate(selFromDate);
                deToDate.SetMinDate(selFromDate);
            }
        }

AspxDateEdit :

  <dx:ASPxDateEdit CssClass="date" ID="deFromDate" runat="server" Width="131px" AllowUserInput="False" Height="25px"
   EditFormatString="dd-MMM-yyyy" DisplayFormatString="dd-MMM-yyyy" EditFormat="Custom"
   Theme="Office2003Blue" ClientInstanceName="deFromDate" OnInit="deFromDate_Init">
     <ClientSideEvents DateChanged="function(s, e) {
                        FromDateValidate();
                    }" />
 </dx:ASPxDateEdit>
 <dx:ASPxDateEdit CssClass="date" ID="deToDate" runat="server" Width="131px" AllowUserInput="False" Height="25px"
 EditFormatString="dd-MMM-yyyy" DisplayFormatString="dd-MMM-yyyy" EditFormat="Custom"
 Theme="Office2003Blue" ClientInstanceName="deToDate" OnInit="deToDate_Init">
 <ClientSideEvents DateChanged="function(s, e) {
                       ToDateValidate();
                   }" />
  </dx:ASPxDateEdit>