Question

'document.getElementById(...)' is null or not an object

Asked by: brgdotnet

I am using a Asp.net web form with some Java Script. When I navigate to my page named "ClubInfo.aspx", I get an error message displayed through a dialog box. It says: Line:175
Error: 'document.getElementById(...)' is null or not an object

I can't figure out what I am doing wrong? Am I checking for null the correct way, and if I am how do I prevent the error message from showing?


<script type="text/javascript">
    function resetLabel() {
    if (document.getElementById('<%=lblMakeChange.ClientID%>').value == null) { // This is line 175
 
        }
        else {
            var lbl = document.getElementById('<%=lblMakeChange.ClientID%>').innerText = "";
        }
  
    }
</script>
/* When the mouse cursor is placed in my texbox, then call method resetLabel() */
 
         <td class="style1">
                <asp:TextBox ID="TwitterId" runat="server" Width="180px" onfocus="resetLabel();"  ></asp:TextBox>
          </td>

                                  
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Asked On
2009-08-04 at 20:58:09ID24626947
Topics

Scripting Languages

,

JavaScript

Participating Experts
2
Points
400
Comments
2

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Answers

 

by: mr_egyptianPosted on 2009-08-04 at 21:42:53ID: 25020203

I think you mean to test whether the element is null.

if (document.getElementById('<%=lblMakeChange.ClientID%>') != null){
    var lbl = document.getElementById('<%=lblMakeChange.ClientID%>').innerText = "";
}else{
    ;
}

                                              
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by: pratima_mcsPosted on 2009-08-04 at 21:51:58ID: 25020237

try this 

 function resetLabel() {
  
    if (document.getElementById('<%=lblMakeChange.ClientID%>').innerText == "") { // This is line 175
 
        }
        else {
            var lbl = document.getElementById('<%=lblMakeChange.ClientID%>').innerText = "";
        }
  
    }

                                              
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