How to show spinner on click of hyperlink using javascript

I have a hyperlink and I am trying to add spinner when you clink on the link.

Below is the code for the spinner, but it is not working for the hyperlink.
   
 <script type="text/javascript">
        function Spinner() {
           document.getElementById("spinning").style.display = "block";
            document.getElementById("testdiv").style.display = "none";
        }
    </script>
<div id="spinning" style="display: none;">
        <span>loading...</span>
    </div>
<div id="testdiv">

Hello, this is link for the test url
<asp:HyperLink ID="linkurl" runat="server" NavigateUrl="~/test.aspx"   OnClientClick="Spinner(); return true;">Testing</asp:HyperLink>
</div>

Can any one help me on this?
Thanks!