Genrate Number To String

< html xmlns="http://www.w3.org/1999/xhtml"  >
< head runat="server" >
    < title > Untitled Page< /title >
    < script >
    
    function NtCode(RecVal)
    {
    var t2="";
   var t1=new Array("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z");  
   for(var i=0;i< RecVal.length;i++)
   {
   t2=t2+t1[i];  
   } 
   alert(t2);
  
   }
    < /script > 
< /head >
< body >
    < form id="form1" runat="server" >
   < asp:TextBox ID="Txt1" runat ="server" >< /asp:TextBox >    
   
< input type ="button" 
onclick ="NtCode(document.getElementById('Txt1').value);"  
value ="ClickHere" id="Button1"  / >
    
     < /form >
    

    
< /body >
< /html >