<script type="text/javascript"> function SetUserName() { var userName = "Shahid Bhat"; '<%Session["UserName"] = "' + userName + '"; %>'; alert('<%=Session["UserName"] %>'); } </script>
BY LOVE sessionStorage.setItem("SessionName", "SessionValue");
<script type="text/javascript"> function GetUserName() { var username = '<%= Session["UserName"] %>'; alert(username ); } </script>