Recently did some POC's around WebRTC for video calling purpose.
Here's a working demo hosted on heroku https://videocall-reactjs-webrtc.herokuapp.com/
Here's the code https://github.com/harshalrj25/VideoCall-ReactJS-WebRTC
The demo is created using P2P MESH communication architecture hence beyond 4 users the solution won't scale properly.
There are other WebRTC architecture's like SFU which requires a media server.
Exploring further will try and implement an SFU architecture for better understanding of WebRTC.