Rhino can be used to run JS server-side atop the JVM, although maybe by this point they've switched to V8. I still find it hard to believe they built the whole

Rhino can be used to run JS server-side atop the JVM, although maybe by this point they've switched to V8. I still find it hard to believe they built the whole thing in JS. If it really is so, well... that's actually really, really cool.