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DOM Enlightenment
book

DOM Enlightenment

by Cody Lindley
February 2013
Intermediate to advanced
178 pages
3h 2m
English
O'Reilly Media, Inc.
Content preview from DOM Enlightenment

Chapter 1. Node Overview

1.1 The Document Object Model (a.k.a. the DOM) Is a Hierarchy/Tree of JavaScript Node Objects

When you write an HTML document, you encapsulate HTML content inside other HTML content. By doing this, you set up a hierarchy that can be expressed as a tree. Often this hierarchy or encapsulation system is indicated visually by indenting markup in an HTML document. The browser, when loading the HTML document, interrupts and parses this hierarchy to create a tree of node objects that simulates how the markup is encapsulated.

<!DOCTYPE html>
<html lang="en">
    <head>
        <title>HTML</title>
    </head>
    <body>
        <!-- Add your content here-->
    </body>
</html>

The preceding HTML code, when parsed by a browser, creates a document that contains nodes structured in a tree format (i.e., DOM). In Figure 1-1, I reveal the tree structure from the preceding HTML document using Opera’s Dragonfly DOM Inspector.

Viewing a web page in Opera Dragonfly Developer Tools
Figure 1-1. Viewing a web page in Opera Dragonfly Developer Tools

On the left, you see the HTML document in its tree form. And on the right, you see the corresponding JavaScript object that represents the selected element on the left. For example, the selected <body> element, highlighted in blue, is an element node and an instance of the HTMLBodyElement interface.

What you should take away here is that HTML documents get parsed by a browser and converted into a tree structure of node objects ...

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Publisher Resources

ISBN: 9781449344498Errata Page