Are there any methods in the Web SDK (js) that we use to create sessions and streams that archive the same result?
No, we do not allow any data receiving about stream subscribers on client side due to security reason.
You can delpoy your own backend server which will use HTTP GET query
http://wcs:8081/?action=stat¶ms=streams_viewers&format=json
once per second to collect an actual state, then implement your own websocket API to pass the state to the publishing client.
Another way to collect stream subscribers is to deploy a backend server to accept
/playStream REST hook. Then again, you can implement your own websocket API to pass the state to the publishing client.