troubleshooting Question

Cannot call C# function on closing Asp.net web page

Avatar of Nick_011
Nick_011Flag for South Africa asked on
Web Development
4 Comments1 Solution750 ViewsLast Modified:
Hi

I get the following error "Microsoft JScript runtime error: 'null' is null or not an object"
at this line btn.click(btnHidden_Click) when running the code below ;

I just need some way of calling a server C# function to dispose a few variables
when a user closes the form. I think the issue is with the master form however
all variations of  document.getElementById('btnHidden'); thatI've tried doesnt seam
to work

Any assistance would be appreciated

Kind regards
Nick

Asp.net 2008 Aspx
<%@ Page Theme="MainTheme" Language="C#"  MasterPageFile="~/Yyyyyy.Master"   . . . . .
. . . . . . . . . . . .. . . .. . . ..
<asp:Content ID="Content1" ContentPlaceHolderID="cphTitle" runat="server" >   
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="cphBody" runat="server" >

<script type="text/javascript">

 window.onunload = ReleaseVariables()
 
 function ReleaseVariables ()
 
 {
    var btn = document.getElementById('btnHidden');
   
    btn.click(btnHidden_Click);

 }  

</script>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

.  .  .  .  .  .  .  .  

</table>

    <asp:Label ID="Label1" runat="server" Text=""></asp:Label>

    <input type="button" id="btnHidden" value="button" onclick=btnHidden_Click/>

</asp:Content>

c# code behind
protected void btnHidden_Click(object sender, EventArgs e)
        {
            if (dv != null) dv.Dispose();  
            if (dv2 != null) dv2.Dispose();
        }
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