React.js server side rendering with Java [without Node.js]

Trying to render a Javascript app serverside without NodeJS is an excellent way to torture yourself. Trying to run javascript inside a jvm is even worse. I would recommend against it.

It is possible to render the complete client server side using PhantomJS (which technically runs without Node) or even using xvfb and Chrome on *nix. All have been done, with various degrees of painful debugging.

Running the javascript inside tomcat itself is rather unusual… I can't see the point other than "because we can". My best guess is that nobody is doing that in production.