req.isSocketA flag indicating whether or not this request (req) originated from a Socket.io connection.
req.isSocket;
if (req.isSocket){
  // You're a socket.  Do cool socket stuff like subscribing.
  User.subscribe(req, [req.session.userId]);
}
else {
  // Just another HTTP request.
  // (`req.isSocket` is undefined)
}
- Useful for allowing HTTP requests to skip calls to PubSub or WebSocket-centric methods like
 subscribe()orwatch()that depend on an actual Socket.io request. This allows you to reuse backend code for both WebSocket and HTTP clients.- As you might expect,
 req.isSocketdoesn't need to be checked before running methods that publish to other connected sockets. Those methods don't depend on the request, so they work either way.