JavaScript: The Definitive Guide, Fourth Edition

The Netscape 4 Event Model

The Netscape 4 event model is like the original Level 0 event model, except that it provides event details in an Event object that is passed as an argument to handler functions. It also supports special methods to enable event capturing. These features are explained in the sections that follow.

The Netscape 4 Event Object

The Netscape 4 event model defines an Event object that contains details about the event that occurred. Like the DOM Level 2 model, it passes an Event object as an argument to all event handlers. Unfortunately, however, the properties of the Netscape 4 Event object are almost entirely different than those of the IE Event object and the various DOM Level 2 event objects. The key Event properties in the Netscape 4 event model are:

type

A string that specifies the type of event that occurred. This string is the name of the event handler, minus the “on” prefix (e.g., “click” or “mousedown”). This property is compatible with the IE and DOM Level 2 Event objects.

target

The document element on which the event occurred. This property is compatible with the target property of the DOM Level 2 Event object and comparable to srcElement in the IE Event object.

pageX , pageY

These properties specify the pixel coordinates at which the event occurred, relative to the upper-left corner of the window. For documents that are larger than the window, you need to add in the offsets window.pageXOffset and window.pageYOffset to convert these to document ...