Inheritance in the DOM Model

DOM standards describe interfaces for various types of objects. The description is given assuming a class-based language, but it can be bound to any object-oriented language, including classless languages. All that DOM standards require is that the binding behaves as if the various DOM classes inherit from other classes. That is, objects of given DOM type have all attributes and methods

When you read documentation about DOM and its JavaScript bindings, it is useful to know a little bit about the implied DOM class hierarchy because you may have to search up the inheritance ancestry to find the attributes and methods that an object has. This search has already been done for the attributes and methods described in the following web pages, but these pages only scratch the surface. More complete documentation for a DOM class usually only describes attributes and methods added by the class.

The Node Hierarchy

For the DOM classes described in these web pages, the Node hierarchy is as follows.

• All HTML tag element classes are subclasses of HTMLElement.
• HTMLElement is a subclass of Element.
• Element is a subclass of Node.
• Text and Comment are subclasses of CharacterData.
• CharacterData is a subclass of Node.

The Document Hierarchy

For the DOM classes described in these web pages, the Document hierarchy is simple.

• HTMLDocument is a subclass of Document.