FUEL (JavaScript API for Mozilla development) provides wrappers for common tasks like events, iteration, preferences and storage to simplify extension development. The 0.1 version covers application events, preferences and storage while the 0.2 version adds support for bookmarks, browser windows and tabs. FUEL is written in JavaScript, runs in Firefox 3.0 and higher, and its API is documented on the Mozilla wiki.

1. FUEL
Paris - June 23, 2007
John Resig - Mozilla Corp.

2. What is FUEL?
• JavaScript API for Mozilla development
• Focus on solving most common problems
• Emphasis on Firefox Extension Dev
• Improve portability
• Targeting Web Developers

3. Implementation
• Written in pure JavaScript
• (Users can crack it open and see how it
works.)
• Wrappers around XPCOM objects

4. Simplify Concepts
• Provide a consistent means of doing these:
• Events
• foo.events.addListener( “test”, fn );
• Iteration
• foo.all.forEach( fn );
• Add/Remove
• foo.add( obj ) / obj.remove()

5. FUEL 0.1
• Preferences, Events, Storage
• In Firefox 3.0a4
• API: http://wiki.mozilla.org/FUEL/0.1/API

6. Application Events
• Make sure the application is ready to be
interacted with (all aspects are loaded):
Application.events.addListener(“ready”, fn);
• Handle when a user exits thefn); application:
Application.events.addListener(“quit”,

7. Preferences
• Coverage of the most common preference
tasks.
• Get/Set Preferences:
Application.prefs.getValue(“my.pref”, default);
Application.prefs.setValue(“my.pref”, “value”);
• Extension Preferences: true);
myExt.prefs.setValue(“autosave”,

8. Preferences (cont.)
• Get all preferences that have been modified
by the user:
Application.prefs.all.forEach(function(p){
if ( p.modified )
// do something
});

9. Storage
• Temporary, runtime, data storage and
retrieval.
• Application-wide storage:
Application.storage.set(“data”, 4);
• Extension-level storage:
myExt.storage.get(“data”, 0);

10. FUEL 0.2
• Window/Browser Tabs, Bookmarks
• Will be in Firefox 3.0a6 (under final review)
• API: http://wiki.mozilla.org/FUEL/0.2/API

11. Browser
• Get the current active browser window:
Application.activeWindow
• Get the URL of the active tab:
Application.activeWindow.activeTab.url

12. Browser (cont.)
• Open and activate a new tab:
Application.activeWindow
.open(quot;http://google.com/quot;).focus();
• Close all Google-related tabs:
Application.activeWindow.tabs.forEach(function(tab){
if ( tab.url.match(/google/) )
tab.remove();
});

13. Bookmarks
• Add a new bookmark:
Application.bookmarks.add(quot;Mozillaquot;, quot;http://mozilla.org/quot;);
• Remove all Google-related bookmarks:
Application.bookmarks.all.forEach(function(cur){
if ( cur.url.match(/google.com/) )
cur.remove();
});

14. Overview
• Application Events (0.1)
• Preferences (0.1)
• Storage (0.1)
• Bookmarks (0.2)
• Window / Browser Tabs (0.2)

15. More Info
• All about FUEL:
http://wiki.mozilla.org/FUEL
• Test Suite:
http://mxr.mozilla.org/seamonkey/source/browser/fuel/test/
• Contact:
• Mark Finkle (mfinkle@mozilla.com)
• John Resig (jresig@mozilla.com)