Is it possible to use WebRTC Data Channels on Node.js in a way that mimics the functionality (and preferably API) of Socket.io (WebSockets) except using UDP?
There is a WebRTC module for node.js: https://js-platform.github.io/node-webrtc/
The installation can be really cumbersome (to say the least) but if you succeed you'll be able to make your node.js server act as a WebRTC peer just as browsers do. This way you'd be able to open a Data Channel between a browser and your node.js server.
We have this in use in our research project to evaluate performance characteristics.
This recipe can be found in it's original form on Stack Over Flow.