Multiplayer (Client/Server) game implementation in HTML5?

Does anyone have a reference/pointer for any multiplayer implementation of a game/app packaged as HTML5? Say, five HTML5 packaged clients (running in a browser) connect to a HTML5 packaged UE4 server? Or, these HTML5 clients connect to a UE4 server running on a PC?

The idea is to implement a small Javascript multiplayer game/chat app (~ 15 - 20 players) that can be played over networks. TIA.

If you do not need collision detection, physics simulation or something fancy on server side & just messaging, you can write your own simple blueprintable tcp socket implementation in c++ for ue4 (that will be converted to websocket while exporting by emscripten) and a simple tcp/websocket server (with node.js, will be easier to write and can use multithreading) for server side.