Fires on the client side before the expansion state of a group is changed.
The ExpandedChanging event's data class is ASPxClientNavBarGroupCancelEventArgs. The following properties provide information specific to this event:
|cancel||Gets or sets a value indicating whether the action which raised the event should be canceled. Inherited from ASPxClientProcessingModeCancelEventArgs.|
|group||Gets the group object related to the event.|
|processOnServer||Gets or sets a value that specifies whether the event should be finally processed on the server side. Inherited from ASPxClientProcessingModeEventArgs.|
Write a ExpandedChanging event handler to perform specific actions on the client side each time before a group's expansion state is changed. You can use the event parameter's properties to identify the group being manipulated, specify whether a postback should be generated to pass the event processing to the server side and cancel execution of the command, if necessary.
Note that if the cancel property is set to true in the event's handler, the execution of the current command is canceled on the client side and no further processing is performed (that is the expansion state of the related group is not changed). If the command execution is not canceled (the cancel property is set to the default false value), the further event processing depends upon the processOnServer property setting.
If the processOnServer property is set to false, the ExpandedChanging event is completely handled on the client side using the assigned JScript handler without a postback to the server. In this instance, processing of a group's expansion state change proceeds with firing the client ASPxClientNavBar.ExpandedChanged event.
Setting the processOnServer property to true indicates that the final processing of the event should be performed on the server side and so a round trip to the server is required. During such a round trip the corresponding server-side ASPxNavBar.ExpandedChanging event is fired which when handled allows any desired server-side action to be performed. In this instance, the server-side event processing proceeds with generating the server ASPxNavBar.ExpandedChanged event instead of its client-side ASPxClientNavBar.ExpandedChanged equivalent.