client side validation error

Question

<%@ Page Language="C#" MasterPageFile="~/HomeMaster.master" AutoEventWireup="true" CodeFile="HomePage.aspx.cs" Inherits="Default2" Title="Untitled Page" %>

<asp:Content ID="Content1" ContentPlaceHolderID="cp1" Runat="Server">

<script language="javascript" type="text/javascript">
    function checkInput()  
{  
  var uname = document.getElementById("txtUName").value;  
  var pwd = document.getElementById("txtPWord").value;  
  var counter=0;  
  if(uname.length==0) counter++;  
  if(pwd.length==0) counter++;  
  if(counter > 0)  
   {
   document.getElementById("dvError").innerHTML = "user name or password can not be blank" ;
        // alert("blank field");  

      return false;
    }
   return true; 
   }  


    </script>
   <div id="dvError"  style="height: 102px; color:Red; "  ></div>


**on button click::**
<asp:Button ID="btnSin" runat="server" Text="SignIn" OnClientClick="return checkInput()" onclick="btnSin_Click" />

then i got an error:: Microsoft JScript runtime error: Object required

Answer 1

Try

var uname = document.getElementById("<%=txtUName.ClientID%>").value;  

You need to do this because id of the control on the content page gets changed. Try viewing the source of your page and you can see the changed ids.