Development builds are made available for those that don't mind dealing with bugs and want to try out the latest features and fixes.
All of my extensions are open source and you may use the source code under either the MPL (1.1 or later), GPL (2.0 or later) or LGPL (2.1 or later) licenses. If you wish to get the source code you must use mercurial. The repository is http://hg.oxymoronical.com/extensions/JSOptions. You may also browse the source code.