public interface EventTarget
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
See also the Document Object Model (DOM) Level 2 Events Specification.
void addEventListener(String type, EventListener listener, boolean useCapture)
This method allows the registration of event listeners on the event target. If an
EventListener is added to an
EventTarget while 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 identical
EventListeners are registered on the same
EventTarget with the same parameters the duplicate instances are discarded. They do not cause the
EventListener to be called twice and since they are discarded they do not need to be removed with the
type- The event type for which the user is registering
listenerparameter 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 registered
EventListenerbefore being dispatched to any
EventTargetsbeneath them in the tree. Events which are bubbling upward through the tree will not trigger an
EventListenerdesignated to use capture.
void removeEventListener(String type, EventListener listener, boolean useCapture)
This method allows the removal of event listeners from the event target. If an
EventListener is removed from an
EventTarget while it is processing an event, it will not be triggered by the current actions.
EventListeners can never be invoked after being removed.
removeEventListener with arguments which do not identify any currently registered
EventListener on the
EventTarget has no effect.
type- Specifies the event type of the
EventListenerparameter indicates the
EventListenerto be removed.
useCapture- Specifies whether the
EventListenerbeing 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.
boolean dispatchEvent(Event evt) throws EventException
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 the
EventTarget on which
dispatchEvent is called.
evt- Specifies the event type, behavior, and contextual information to be used in processing the event.
dispatchEventindicates whether any of the listeners which handled the event called
preventDefaultwas called the value is false, else the value is true.
EventException- UNSPECIFIED_EVENT_TYPE_ERR: Raised if the
Event's type was not specified by initializing the event before
dispatchEventwas called. Specification of the
Event's type as
nullor an empty string will also trigger this exception.
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