how to change a css class of div in master page from update panel in content page

Question

I want to change div style (display) in master page from my child page , I used:

 protected void ShowMsgText(int MsgID)
{
    HtmlGenericControl MsgInner;
    MsgInner =((HtmlGenericControl)Master.FindControl("MsgInner"));
    MsgInner.Attributes["class"] = "MsgInnerShow";
}

The Problem : I want to change the class from update panel , the div in master page Not in the update panel , any way to achieve this without need to move the update panel to master page .

Answer 1

Without the UpdatePanel you would use FindControl to change the class.

Panel panel = Master.FindControl("Panel1") as Panel;
panel.CssClass = "myClass";

But since you use an UpdatePanel, the easiest way is to use jQuery.

On the master page the Panel and the script

<asp:Panel ID="Panel1" runat="server">Welcome to StackOverflow</asp:Panel>

<script type="text/javascript">
    function changeClass(className) {
        $("#<%= Panel1.ClientID %>").attr("class", className);
    }
</script>

Then in the code behind of the aspx page, you can call that javascript function on PostBack.

ScriptManager.RegisterStartupScript(Page, Page.GetType(), "changeClassName", "changeClass('myClass');", true);