JavaScript® Bible, Seventh Edition

Chapter 55. Application: Outline-Style Table of Contents

IN THIS CHAPTER

• Multiple frames

• Clickable images

• Persistent data

• Dynamic HTML positioning

• Reading XML data via Ajax

In your web surfing, you may have encountered sites that implement an expandable, outline-type table of contents. I've long thought that these elements were great ideas, especially for sites with lots of information. An outline, such as the Windows Explorer or the text-style Macintosh Finder windows, enables the author to present a large table of contents in a way that doesn't necessarily take up a ton of page space or bandwidth. From listings of top-level entries, a user can drill down to reveal only those items of interest.

No matter how much I like the idea, however, I dislike visiting most of these sites. Usually, a server program responds to each click, chews on my selection, and then sends back a completely new screen, showing my choice expanded or collapsed. After working with outlines in the operating system and outliner programs on personal computers, the delays in this processing seem interminable. It occurred to me that implementing the outline interface as a client-side JavaScript can significantly reduce the delay problem and make outlines a more viable interface to a site's table of contents. This chapter documents the process that went into a JavaScript-powered outliner, which works with all modern browsers.

The Implementation Plan

I admit to approaching the outline technique the first time without a specific ...