Sys.Observer.isUpdating Property
Gets a boolean value that indicates whether the target is updating.
Note
To get property values for client API properties, you must call the property accessor method that is named with the get_ prefix. For example, to get a value for a property such as cancel, you call the get_cancel method.
var o = Sys.Observer.isUpdating(target);
Return Value
true if the target is being updated, otherwise, false.