Load content on demand when expanding RadSlidingPane

## HOW TO:

The scenario of loading content on demand when a RadSlidingPane is expanded is useful in cases when the content slows down the performance and it is not needed to render additional HTML.

SOLUTION

In order to implement it, you can hook up the RadSlidingPane's OnClientExpanding event and perform an AJAX request which loads the content e.g as shown below:

<script type="text/javascript">

function OnClientExpanding()
{ 
   if(!sender._loaded)
   {
   $find("<%=RadAjaxPanel1.ClientID %>").ajaxRequest(); 
      sender._loaded = true;
   } 
   }
</script>
<telerik:RadSplitter ID="RadSplitter1" runat="server">
   <telerik:RadPane ID="RadPane1" runat="server" Width="22">
      <telerik:RadSlidingZone ID="RadSlidingZone1" runat="server">
            <telerik:RadSlidingPane ID="RadSlidingPane1" runat="server" Title="LOD" OnClientExpanding="OnClientExpanding">
               <telerik:RadAjaxPanel ID="RadAjaxPanel1" runat="server" OnAjaxRequest="OnAjaxRequest">
               </telerik:RadAjaxPanel>
            </telerik:RadSlidingPane>
      </telerik:RadSlidingZone>
   </telerik:RadPane>
   <telerik:RadPane ID="RadPane2" runat="server">
   </telerik:RadPane>
</telerik:RadSplitter>

protected void OnAjaxRequest(object sender, AjaxRequestEventArgs e)
{
    RadAjaxPanel1.Controls.Add(Page.LoadControl("~/WebUserControl.ascx"));
}

Protected Sub OnAjaxRequest(ByVal sender As Object, ByVal e As AjaxRequestEventArgs)
    RadAjaxPanel1.Controls.Add(Page.LoadControl("~/WebUserControl.ascx"))
End Sub

You can find a sample running demo attached to the article.