Event handlers may be attached to various elements in the DOM. When an event occurs, an event object is dynamically created, and passed sequentially to the event listeners that are allowed to handle the event. The DOM Event interface is then accessible within the handler function, via the event object passed as the first (and the only) argument.

Applications may dispatch event objects using the EventTarget.dispatchEvent() method, and implementations must dispatch event objects as if through this method. The behavior of this method depends on the event flow associated with the underlying object. An event flow describes how event objects propagate through a data structure. As an example, when an event object is dispatched to an element in an XML document, the object propagates through parts of the document.

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	Interface	Description
	DocumentEvent DOM 2 Events	The DocumentEvent interface provides a mechanism by which the user can create an Event object of a type supported by the implementation.
	DocumentEventGroup DOM 3 Events	The DocumentEventGroup interface provides a mechanism by which the user can create an EventGroup of a type supported by the implementation.
	EventException DOM 2 Events	Event operations may throw an EventException as specified in their method descriptions.
	EventGroup DOM 3 Events	The EventGroup interface functions primarily as a placeholder for separating the event flows when there are multiple groups of listeners for a DOM tree.
	EventListener DOM 2 Events	The EventListener interface is the primary way for handling events.
	EventTarget DOM 2 Events	The EventTarget interface is implemented by all the objects which could be event targets in an implementation which supports an event flow.
	EventTargetGroup DOM 3 Events	The EventTargetGroup interface is implemented by the same set of objects that implement the EventTarget interface, namely all EventTargets in in implementation which supports the Event model and the EventGroup extension.

	Class	Description
	CustomEvent DOM 3 Events	The CustomEvent interface is the recommended interface for application-specific event types.
	Event DOM 2 Events	The Event interface is used to provide contextual information about an event to the listener processing the event.
	EventExceptionCode DOM 2 Events	An integer indicating the type of error generated.
	KeyboardEvent DOM 3 Events	The KeyboardEvent interface provides specific contextual information associated with keyboard devices.
	KeyEvent DOM 3 Events	The KeyEvent interface provides specific contextual information associated with Key Events.
	MessageEvent HTML 5	Messages in server-sent events, Web sockets, cross-document messaging, and channel messaging use the message event.
	MouseEvent DOM 2 Events	The MouseEvent interface provides specific contextual information associated with Mouse events.
	MouseMultiWheelEvent DOM 3 Events	The MouseMultiWheelEvent interface provides specific contextual information associated with mouse multi wheel events.
	MouseWheelEvent DOM 3 Events	The MouseWheelEvent interface provides specific contextual information associated with mouse wheel events.
	MutationEvent DOM 2 Events	The MutationEvent interface provides specific contextual information associated with Mutation events.
	MutationNameEvent DOM 3 Events	The MutationNameEvent interface provides specific contextual information associated with Mutation name event types.
	TextEvent DOM 3 Events	The TextEvent interface provides specific contextual information associated with Text Events.
	UIEvent DOM 2 Events	The UIEvent interface provides specific contextual information associated with User Interface events.