This section presents a brief summary of other technologies you should know about, covering their fundamental concepts. They include HTML DOM, JQuery, CSS, and HTML Canvas. You can skim or skip this section if you already know about and use these technologies. The next sections also provide code examples that can be downloaded from the GitHub repository for this chapter.
The structure of an HTML document is normally described with tags, but it can also be specified using JavaScript commands with a Document Object Model (DOM): a language-neutral API that represents an HTML or XML document as a tree. Consider the following HTML document (Examples/example-1.html):
<html>
<body>
<h1>Simple page</h1>
<p>Simple paragraph</p>
<div>
<img src="pluto.jpg" width="100"/>
<p>Click me!</p>
</div>
</body>
</html>This page builds a tree of...