How To: Add Features to Firefox with Mozilla’s New Jetpack

Mozilla Labs has announced a new project called Jetpack to provide an easy way for users and developers to enhance the Firefox web browser. Jetpack is a lightweight extension system that makes it possible to build new Firefox features with HTML, JavaScript, and other conventional web technologies and, although it’s still at a relatively early stage of development, the project already delivers some extremely useful capabilities. In this tutorial, we will look at what Jetpack has to offer, then show you how to use it to augment Firefox’s functionality.

The Firefox user interface is largely built with XUL, an XML-based user interface design language. Much like regular web content, XUL user interface elements can be styled with CSS and manipulated with JavaScript through the browser Document Object Model (DOM). These characteristics are what enable Firefox to offer its powerful extension system.