title: Cannot emit message to room using Flask-SocketIO
body: <p>I am building a simple chat app and I have been trying to emit messages to rooms with Flask-SocketIO.</p>
  
  <p>The "mesage_event" event from the client reaches the server well, but then, I cannot see anything on the client side. I don't know whether the server emits something to the room but on the client side, I cannot see anything in the console. <strong>I can only successfully send to all clients with broadcasting.</strong> </p>
  
  <p>Here is my code on the server side:</p>
  
  <pre><code>@socketio.on("send msg")
  def sendsocket(data):
      print("send msg start:", data["msg"])
      msg = data["msg"]
      room = data["room"]
      emit("message_event", msg, room = room)
  </code></pre>
  
  <p>And the client side:</p>
  
  <p>1- for sending the message:</p>
  
  <pre><code>socket.emit('send msg', {'msg': msg, 'room': room})
  </code></pre>
  
  <p>2- for triggering the event handler:</p>
  
  <pre><code>socket.on('message_event', data =&gt; {
      console.log("message received:", data);
  });
  </code></pre>