Chapter 16. Writing an Extension

IN THIS CHAPTER

• Setting Up the Development Environment

• Tools for Extension Development

• Understanding XML User Interface Language

• Working with JavaScript

• The Firefox window Object

• Creating a Unique GUID

• Firefox Command Options for Developers

• Working Through an Extension Development Example

• Extension Writing Secrets for Power Users

Firefox uses extensions to enhance its functionality. An extension is a package consisting of chrome modifications and executable content (usually in JavaScript). Extensions are installed using the Extensions Manager, found on the Tools menu.

Extensions provide varied functionality enhancements, variety, and versatility. There are navigation extensions, humor extensions, searching extensions, and so on in all, there are about 20 categories of extensions for Firefox. The actual number of possible extensions is impossible to estimate. The Mozilla website has perhaps 500 extensions for all its products, with many more posted on its developer's website.

In this chapter we will cover tools and extensions for extension development. We'll also discuss the Extensible User Interface Language (XUL), JavaScript, and resources for extension developers.