RadControls for ASP.NET AJAX
The RadNotification object provides a client-side API that lets you interact with the control in client-side code. In addition to a full set of client-side events, the client-side object model lets you manipulate notifications while avoiding unnecessary post-backs.
Getting the RadNotification client-side object
var radNotification1 = $find("<%= RadNotification1.ClientID %>");
Cancelling an action
Some client-side events occur immediately before RadNotificationperforms some action. You can use these events to cancel the impending action by using the cancel property of the eventArgs passed to the handler:
function OnClientShowing(sender, eventArgs)