Co-created by Mark Finkle and John Resig, it provided JavaScript libraries and wrappers for the most commonly-used operations in Firefox extensions.
FUEL was intended to narrow the gap between two modes of development in Firefox.
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 more familiar to a wide range of users who program web applications.
[citation needed] FUEL was intended to make extensions easier to create, especially for this latter group of people.