Sys.WebForms.PageLoadingEventArgs panelsDeleting Property
Gets an array of HTML <div> elements that represent UpdatePanel controls that will be deleted from the DOM as a result of the current asynchronous postback.
To get or set property values for client API properties, you must call property accessor methods that are named with the get_ and set_ prefixes. For example, to get or set a value for a property such as cancel, you call the get_cancel or set_cancel methods.
var arr = eventArgs.get_panelsDeleted()
An array of <div> elements that will be deleted from the DOM. If no elements will be deleted, the property returns null.
If the contents of an UpdatePanel control will be deleted as the result of a partial-page update, the array that is referenced in the panelsDeleting property of the PageLoadingEventArgs class contains a reference to the corresponding <div> element. The pageLoading event of the Sys.WebForms.PageRequestManager class uses a PageLoadingEventArgs object to return its event data.