JAVASCRİPT C# suanki tarihi textbox'a yazdırmak

<script language="javascript">
         function GetAlert() {
             var monthNames = [
  "01", "02", "03",
  "04", "05", "06", "07",
  "08", "09", "10",
  "11", "12"
             ];

             var date = new Date();
             var day = date.getDate();
             var monthIndex = date.getMonth();
             var year = date.getFullYear();
             alert(day + '/' + monthNames[monthIndex] + '/' + year);
             
             document.getElementById("<%=******.ClientID%>").value = year + '-' + monthNames[monthIndex] + '-' + day;
            
         }
   </script>