Fires on the client side before the active tab is changed within a tab control.
The ActiveTabChanging event's data class is ASPxClientTabControlTabCancelEventArgs. 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.|
|processOnServer||Gets or sets a value that specifies whether the event should be finally processed on the server side. Inherited from ASPxClientProcessingModeEventArgs.|
|reloadContentOnCallback||Gets or sets a value specifying whether a callback should be sent to the server to reload the content of the page being activated.|
|tab||Gets the tab object related to the event.|
Write a ActiveTabChanging event handler to perform specific actions on the client side each time before the selected tab changes. You can use the event parameter's properties to identify the newly selected tab (ASPxClientTabControlTabCancelEventArgs.tab), specify whether a postback should be generated to pass the event processing to the server side (ASPxClientProcessingModeEventArgs.processOnServer) and cancel the execution of the command, if necessary (ASPxClientCancelEventArgs.cancel).
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 thus no further processing is performed (that is the active tab 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 ActiveTabChanging event is completely handled on the client side using the assigned JScript handler without a postback to the server. In this instance, processing of an active tab change proceeds with firing the client ASPxClientTabControlBase.ActiveTabChanged 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 ASPxTabControlBase.ActiveTabChanging 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 ASPxTabControlBase.ActiveTabChanged event instead of its client-side ASPxClientTabControlBase.ActiveTabChanged equivalent.