[bopcrane]

I don't have a wealth of knowledge on the subject as I'm not really a javascript dev, but I do know that Javascript and unity work pretty well together using it as a scripting language. Where nodejs would fit into this, I'm not so sure, but hopefully someone else can chime in on their experience

[rpeden]

If it's multiplayer, you could use Node along with something like socket.io to handle real time communication between players.

You could maybe, possibly, use WebRTC for peer-to-peer communication if you don't mind excluding anyone running Safari and IE. But with a game written in JS and running in the browser, it seems like it would be too easy for someone to modify the code and cheat without a server side component at least trying to verify that everyone is behaving.