websocket send parameter in connection?

In your websocket request handler, it is normally passed the web socket as the first argument; the incoming HTTP request is passed as a second argument:

webSocketServer.on('connection', function connection(ws_client_stream, incoming_request) {
  console.log(incoming_request.url);
});

From there, you can use url.parse to get the components of the URL, such as the query string that you are interested in.