I have just now pushed `happstack-websockets` to git:
It is mostly a thin wrapper around the `websockets` library. I will upload it to hackage once I have had time to test it a bit more and add documentation.
Now would be the ideal time to request changes to the API since it is not yet uploaded to hackage.
So you'll have to stick to text communication at the moment if you want to use ghcjs -- or patch your ghcjs-base.