The concept of the Dynamic HTML Object Model, and the rules of inheritance that govern it, are at the core of the new directions in Web development, whether you're thinking about Dynamic HTML, or, further down the road, XML (Extensible MarkUp Language), which will act as sort of a template for other Web formats. The rules of inheritance as they pertain to Dynamic HTML follow the parent-child model, in which one element, the child, inherits properties from another, the parent.
The object model in Dynamic HTML is based on a hierarchy that generally starts with the window, and works its way down. The way in which it does so depends on the scripting mechanism being used.
new, and define its parameters with a function that carries the same name as the object.
a specific object is assigned to the variable
objectBig and accessed by navigating through the object hierarchy using dot syntax.
Microsoft has extended the Document Object Model for Dynamic HTML to include every element of HTML. Microsoft also defines properties and methods for HTML elements.
As it stands now, this particular kind of "event-driven" code is supported only by Internet Explorer 4.0. Understanding why requires closer scrutiny of Internet Explorer components.
The executable application called Internet Explorer is really little more than a shell that contains other components that do most of the work. One component is an ActiveX document called the HTML Viewer (MSHTML.DLL), which is called by the Web browser object. (By itself, the browser object can't do much more than ask the HTML Viewer ActiveX Control to display the requested URL through one of the browser object's functions.) The Web browser's functions are strictly navigational: refreshing and opening pages, going back and forward, and so on. The HTML viewer, in turn, acts as a manager of sorts, delegating calls to objects from one of the two scripting engines, which exist as yet additional components. The HTML viewer parses HTML, but when it encounters the
This access to each HTML element in Internet Explorer is made possible by built-in method calls. The disadvantage is that it doesn't work with Navigator; the advantage is that it is extremely easy to write, and because the calls are contained within the elements, their code is ignored by other browsers.Thus, you can write Navigator-specific code right next to it.
Finally, platform independent, vendor neutral specification for the Document Object Model is currently under consideration by the W3C. -- C. W.