The HTML 4.0 standard refers to events relating to HTML as intrinsic events. That includes the following:

• Conditions that cause events

• Attributes in tags that support events

• Scripts in the page that handle events

• A JavaScript host object that an event operates on

• Control being passed temporarily to the interpreter during the event handling

• Data associated with and passed to the handler by the event

The DOM level 2 standard introduces an event model based on the MSIE event bubbling technique. It is embodied in the following object classes:

• EventTarget

• EventListener

• Event

• EventException

• DocumentEvent

• UIEvent

• MouseEvent

• MutationEvent

Events can be added using the addEventListener() method that is inherited by any Elements that can be treated as EventTarget objects. The EventTarget class is not a concrete class in its own right but is an extension of an existing object class to add event handling capabilities to it.

DOM level 3 is expected to enhance the event model further with the addition of the following classes:

• KeyEvent

• EventGroup

• EventGrouped

• DocumentEventGroup