Jeena pointed out today that Google V8 may be a good alternative to SpiderMonkey, and it indeed seems so. In short, here is how we can implement callbacks in JS->Erl using erlv8 I have forked the repo Jeena hosts on GitHub to one I host, while playing with V8.
Jan 26, we had a meeting between 13-15, so 2 hours
I worked with V8 between 00.30-02.00, so 1.5 hours
In total: 3.5 hours.