Extensions are packaged and distributed in archive files (also known as Bundles), with the
XPI (pronounced “zippy”) file extension. At a minimum, they contain an install.rdf, the chrome.manifest and a chrome/ folder. The chrome/ folder contains a content/ folder that contains the actual content files. These files contain the code that makes your extension actually do something. When this tutorial is finished, our extension will look like this:
myfirstext.xpi: //created in step 8 /install.rdf //created in step 3 /chrome.manifest //created in step 4 /chrome/ /chrome/content/ /chrome/content/myhelloworld.xul //created in step 5 /chrome/content/overlay.js //created in step 6 /chrome/locale/* //Building an Extension# Localization /chrome/skin/ /defaults/preferences/ //Building an Extension# Defaults Files
Rather than creating these files manually, you should use the Add-On Packager which will assist you in creating the necessary files to get started.
The following tutorial pages will explain how to write each of these files (except locale/ and defaults/) and package them into an XPI (zippy) file. You can find information about the locale/ and defaults/ folders in the more general "Building an Extension" documentation.