[Yoric]

Eh, Firefox/Thunderbird had multi-threaded JS in SpiderMonkey in the late 90s.

Then it was removed it because it made garbage-collection a real mess (the JavaScript gc needs to walk through lots of C++ data, some of it may have specific requirements for destruction/finalization).

I hope it's better this time :)

[pjmlp]

The JS / interoperability is why V8 eventually added a C++ GC.