FUEL (Firefox User Extension Library)
Firefox User Extension Library (FUEL) is a JavaScript library intended for developing Firefox extensions. Co-created by Mark Finkle and John Resig, it provides JavaScript libraries and wrappers for the most commonly used operations in Firefox extensions.
Design principles
FUEL is intended to narrow the gap between two modes of development in Firefox. One mode of development extends from the core elements of Firefox and the Firefox code base, which is predominantly based on C++. The other mode of development extends from the client-side functionality of the browser itself, which is predominantly based on JavaScript.
This latter mode of development is arguably more familiar to a wide range of users who program web applications. FUEL is intended to make extensions easier to create, especially for this latter group of people.