public interface EventTarget
The
EventTarget interface is implemented by all
Nodes in an implementation which supports the DOM Event
Model. Therefore, this interface can be obtained by using
binding-specific casting methods on an instance of the Node
interface. The interface allows registration and removal of
EventListeners on an EventTarget and dispatch
of events to that EventTarget.
See also the Document Object Model (DOM) Level 2 Events Specification.
- Since:
- 1.5, DOM Level 2
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Method Summary
Modifier and Type Method Description voidaddEventListener(String type, EventListener listener, boolean useCapture)This method allows the registration of event listeners on the event target.booleandispatchEvent(Event evt)This method allows the dispatch of events into the implementations event model.voidremoveEventListener(String type, EventListener listener, boolean useCapture)This method allows the removal of event listeners from the event target.
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Method Details
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addEventListener
This method allows the registration of event listeners on the event target. If anEventListeneris added to anEventTargetwhile it is processing an event, it will not be triggered by the current actions but may be triggered during a later stage of event flow, such as the bubbling phase.
If multiple identicalEventListeners are registered on the sameEventTargetwith the same parameters the duplicate instances are discarded. They do not cause theEventListenerto be called twice and since they are discarded they do not need to be removed with theremoveEventListenermethod.- Parameters:
type- The event type for which the user is registeringlistener- Thelistenerparameter takes an interface implemented by the user which contains the methods to be called when the event occurs.useCapture- If true,useCaptureindicates that the user wishes to initiate capture. After initiating capture, all events of the specified type will be dispatched to the registeredEventListenerbefore being dispatched to anyEventTargetsbeneath them in the tree. Events which are bubbling upward through the tree will not trigger anEventListenerdesignated to use capture.
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removeEventListener
This method allows the removal of event listeners from the event target. If anEventListeneris removed from anEventTargetwhile it is processing an event, it will not be triggered by the current actions.EventListeners can never be invoked after being removed.
CallingremoveEventListenerwith arguments which do not identify any currently registeredEventListeneron theEventTargethas no effect.- Parameters:
type- Specifies the event type of theEventListenerbeing removed.listener- TheEventListenerparameter indicates theEventListenerto be removed.useCapture- Specifies whether theEventListenerbeing removed was registered as a capturing listener or not. If a listener was registered twice, one with capture and one without, each must be removed separately. Removal of a capturing listener does not affect a non-capturing version of the same listener, and vice versa.
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dispatchEvent
This method allows the dispatch of events into the implementations event model. Events dispatched in this manner will have the same capturing and bubbling behavior as events dispatched directly by the implementation. The target of the event is theEventTargeton whichdispatchEventis called.- Parameters:
evt- Specifies the event type, behavior, and contextual information to be used in processing the event.- Returns:
- The return value of
dispatchEventindicates whether any of the listeners which handled the event calledpreventDefault. IfpreventDefaultwas called the value is false, else the value is true. - Throws:
EventException- UNSPECIFIED_EVENT_TYPE_ERR: Raised if theEvent's type was not specified by initializing the event beforedispatchEventwas called. Specification of theEvent's type asnullor an empty string will also trigger this exception.
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