Accessing ASP.NET PlaceHolder Control in RadPane Using JavaScript
Environment
| Product | RadSplitter for ASP.NET AJAX |
Description
In ASP.NET WebForms, I'm using a asp:PlaceHolder control inside a RadPane to dynamically add several controls. However, I cannot locate the PlaceHolder using JavaScript functions like $find('RecordForm') or document.getElementById('RecordForm'). Both return null. How can I access the PlaceHolder control with JavaScript?
This knowledge base article also answers the following questions:
- How to make a PlaceHolder control accessible via JavaScript in ASP.NET AJAX?
- What is the method to interact with dynamically added controls in a PlaceHolder on the client side?
- Why can't JavaScript find a PlaceHolder control and how to solve it?
Solution
The asp:PlaceHolder control does not render any HTML element, making it inaccessible through JavaScript's $get() or document.getElementById(). To interact with the PlaceHolder or its dynamically added controls on the client side, wrap the PlaceHolder in a server control that renders an HTML element, such as asp:Panel.
Modify your markup to include the PlaceHolder within a Panel:
<telerik:RadPane id="PaneLeftTop" runat="server" Scrolling="None" BackColor="#F5F5F5" OnClientResized="OnClientPaneLeftTopResized">
<div style="margin-top:3px;margin-left:7px;line-height:2.25">
<asp:Panel id="RecordFormPanel" runat="server">
<asp:PlaceHolder id="RecordForm" runat="server" />
</asp:Panel>
</div>
</telerik:RadPane>Access the Panel with JavaScript by its ID:
var panel = document.getElementById('RecordFormPanel'); // or $get('RecordFormPanel')The asp:Panel control renders as a <div> element in HTML, making it accessible through JavaScript. This approach allows you to maintain the server-side functionality of dynamically adding controls to the PlaceHolder while also providing a way to interact with those controls or their container on the client side.