The Document Object Model, or DOM, is the fundamental API
for representing and manipulating the content of HTML documents. The API
is not particularly complicated, but there are a number of architectural
details you need to understand. First, you should understand that the
nested elements of an HTML or XML document are represented in the DOM as a
tree of objects. The tree representation of an HTML document contains
nodes representing HTML tags or elements, such as
<p>, and nodes representing strings of
text. An HTML document may also contain nodes representing HTML comments.
Consider the following simple HTML document:
<html> <head> <title>Sample Document</title> </head> <body> <h1>An HTML Document</h1> <p>This is a <i>simple</i> document. </html>
The DOM representation of this document is the tree pictured in Figure 11-1.
Figure 11-1. The tree representation of an HTML document
If you are not already familiar with tree structures in computer ...