JavaScript: The Definitive Guide, Fourth Edition

The Internet Explorer Event Model

The event model supported by Internet Explorer 4, 5, 5.5, and 6 is an intermediate model, halfway between the original Level 0 model and the standard DOM Level 2 model. The IE event model includes an Event object that provides details about events that occur. Instead of being passed to event handler functions, however, the Event object is made available as a property of the Window object. The IE model supports event propagation by bubbling, but not by capturing, as the DOM model does. In IE 4, event handlers are registered in the same way as they are in the original Level 0 model. In IE 5 and later, however, multiple handlers may be registered with special (but nonstandard) registration functions.

The following sections provide more detail about this event model and document it by comparison to the original Level 0 event model and the standard Level 2 event model. Therefore, you should be sure you understand those two event models before reading about the IE model.

The IE Event Object

Like the standard DOM Level 2 event model, the IE event model provides details about each event that occurs in the properties of an Event object. The Event objects defined in the standard model were in fact modeled on the IE Event object, so you’ll notice a number of similarities between the properties of the IE Event object and the properties of the DOM Event, UIEvent, and MouseEvent objects.

The most important properties of the IE Event object are:

type

A string ...