<script type="text/javascript" language="javascript">
    function checkValidateData()
    {
    var che =document.getElementById("txtChe.Text");
    var phy=document.getElementById("txtPhy.Text");
    var math=document.getElementById("txtMath.Text");
 
//    if(isNaN(che))
//    {
//    alert('Please Enter Marks');
//    return true;
//    }
    
    var uid;
    var temp=document.getElementById("<%=txtChe.ClientID %>");
    uid=temp.value;
    if(uid=="")
    {
    alert ('Please Enter UserName');
    return false;
    }

    if(isNaN(uid))
    {
    alert('Please Enter number');
    uid.Focus();
    return false;
    }
   
    }
    </script>