ScriptManager.RegisterScriptDescriptors Method (IExtenderControl)
Calls back to an ExtenderControl class to return instance scripts that must be rendered to support the client object that represents a client control, component, or behavior.
Assembly: System.Web.Extensions (in System.Web.Extensions.dll)
If you derive from the ExtenderControl class and override the Render method, but you do not call the base class method, you must call the RegisterScriptDescriptors method. This enables the ScriptManager control to render the instance scripts that support the client object that the control represents.