I agree, it was a bit tough to find good docs and references. If anyone has othe...

lazerwalker · on Nov 22, 2013

It might not be that helpful, but you can actually download the JavaScriptCore source directly from the WebKit trunk (http://svn.webkit.org/repository/webkit/trunk/Source/JavaScr...).

It's worth noting that there are some discrepancies between that codebase and the actual behavior of the public iOS 7 framework, but if you're not doing anything too crazy it probably won't be an issue.