Continuous Integration, unit and functionnal testings etc... All of these subjects are more and more important in Web projects. The success of tools like PhantomsJS or CasperJS prove that assertion.
However, because PhantomJS is built on top of Webkit, it doesn't give the opportunity for web developpers to do their tests or run their scripts with an other "web engine", like Gecko for example, the core of Firefox. After all, Firefox has significant market shares, and so that's a shame to run functional tests for your projects only with webkit.
This is why Laurent Jouanneau started to develop SlimerJS at the end of 2012, after a "twitter" discussion with Nicolas, the author of CasperJS :-).
Laurent is a long time contributor to the Mozilla Project, starting in 2003 by opening a web site, Xulfr.org, to promote (in french) Mozilla technologies like XUL. He has also contributed to Gecko as a C++ developer and he's working for many years on professional projects using Mozilla technologies (Firefox extensions, XulRunner applications).
Contact : firstname.lastname@example.org