If you’re in the search for a JavaScript interpreter for Your-Amazing-Application, I think this can be a valuable option.
The good Gordon Williams implemented this tiny little interpreter some time ago.
I really appreciate the spirit of the projects itself. Not aiming to be a full-fledged Javascript behemoth with a complex API and heavy memory footprint. But being a mean and lean implementation that, while lacking many the advanced Javascript features and not being byte(pre)compiled (i.e. not so blazing fast), it is small enough (consisting in a single .h and .cpp pair) to be incorporated with almost no hassle.
I took the liberty to fork the original (no longer maintained?) project on GitHub and make some minor modifications to suit my needs.
I will certainly use it anytime I need some basic but versatile scripting facility in my applications without weighting them too much.
( for any advanced and mission critical uses I will go and use Lua, instead )