Client-side Programming Overview
RadToggleButton provides a flexible client-side API. You can easily interact with the button in the browser using the RadToggleButton client-side object. In addition to a variety of client-side events, the client-side object model lets you achieve complicated tasks while avoiding unnecessary postbacks.
Getting the RadToggleButton client-side object
RadToggleButton creates a client-side object with the ClientID of the button. You can obtain the reference using the following JavaScript code:
var toggleButton = $find("<%= RadToggleButton1.ClientID %>");
or
var toggleButton = $telerik.findToggleButton("<%= RadToggleButton1.ClientID %>");