C# OnclientClick doens't render asp tags?

I have an ASP button that lookts like this:

<asp:Button 
  ID="btnReset" 
  runat="server" 
  OnClientClick = "hideOverlay('<%=pnlOverlay.ClientID %>', '<%=pnlAddComment.ClientID  %>');"
  CssClass ="btnCancel PopUpButton"
/>

The problem are the asp tags in de hideOverlay part.I don't get it working. Why isn't working? And how do i fix it?

Solution

Try below examples

First Example

In aspx

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Button ID="btnReset" runat="server" CssClass="btnCancel PopUpButton" />
        <asp:Panel ID="pnlOverlay" runat="server">
        </asp:Panel>
        <asp:Panel ID="pnlAddComment" runat="server">
        </asp:Panel>        
    </div>
    </form>
</body>
</html>

In Codebehind

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Default10 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
       btnReset.Attributes.Add("onclick", string.Format("hideOverlay('{0}','{1}')", pnlOverlay.ClientID, pnlAddComment.ClientID));

    }
}

It will generate the below source for the button

<input type="submit" name="btnReset" value="" onclick="hideOverlay('pnlOverlay','pnlAddComment');" id="btnReset" class="btnCancel PopUpButton" />

Second Example

In Aspx

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Button ID="btnReset" runat="server" CssClass="btnCancel PopUpButton" OnClientClick=<%# "hideOverlay('" + pnlOverlay.ClientID + "', '" + pnlAddComment.ClientID +"');" %> />
        <asp:Panel ID="pnlOverlay" runat="server">
        </asp:Panel>
        <asp:Panel ID="pnlAddComment" runat="server">
        </asp:Panel>        
    </div>
    </form>
</body>
</html>

In CodeBehind

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Default10 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        btnReset.DataBind(); 
    }
}

It will generate the below source for the button

<input type="submit" name="btnReset" value="" onclick="hideOverlay('pnlOverlay', 'pnlAddComment');" id="btnReset" class="btnCancel PopUpButton" />

Third Example

In aspx

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Button ID="btnReset" runat="server" CssClass="btnCancel PopUpButton" OnClientClick="hideOverlay();" />
        <asp:Panel ID="pnlOverlay" runat="server">
        </asp:Panel>
        <asp:Panel ID="pnlAddComment" runat="server">
        </asp:Panel>        
    </div>
    </form>
</body>
<script type="text/javascript" >
    function hideOverlay()
    {
        var pnlOverlayID = '<%= pnlOverlay.ClientID %>';
        var pnlAddCommentID = '<%= pnlAddComment.ClientID %>';

        //Do your stuff
    }
</script> 
</html>

It will generate the follwing source for the script portion

<script type="text/javascript" >
    function hideOverlay()
    {
        var pnlOverlayID = 'pnlOverlay';
        var pnlAddCommentID = 'pnlAddComment';

        //Do your stuff
    }
</script>