Question

I want to call a c# function using javascript, so I added an invisible asp.net button to my Default.aspx, and now I am tring to call it inside javascript so that it will trigger the c# function, but it gives ‘null’ is null or not an object. I tried to move my javascript part to many places to solve the problem but it didn’t work.

<asp:Content ID="HeaderContent" runat="server"
ContentPlaceHolderID="HeadContent">
</asp:Content>

    <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
        <h2>        WELCOME     </h2>
     <div style="display: none;">
            <asp:Button ID="button1" runat="server"
             OnClick="btn_SearchLibrary_Click" />
     </div>

        <script type="text/javascript">
            function displaymessage() {
                var button = document.getElementById('button1');
                button.click();
            }
        </script>


<!-- Some codes in here, below there is a gridview templatefield -->



    <asp:TemplateField HeaderText="BookName"
    SortExpression="BookName" ItemStyle-Width="150px">
                                <ItemTemplate>
                                    <asp:HyperLink ID="HyperLink1"
    runat="server" Text='<%# Bind("BookName") %>'
    NavigateUrl="javascript:displaymessage()"></asp:HyperLink>
                                </ItemTemplate>
                            </asp:TemplateField>

Answer 1

try this

     document.getElementById('<%=button1.ClientID%>')