1socket.emit('message', "this is a test"); //sending to sender-client only
2socket.broadcast.emit('message', "this is a test"); //sending to all clients except sender
3socket.broadcast.to('game').emit('message', 'nice game'); //sending to all clients in 'game' room(channel) except sender
4socket.to('game').emit('message', 'enjoy the game'); //sending to sender client, only if they are in 'game' room(channel)
5socket.broadcast.to(socketid).emit('message', 'for your eyes only'); //sending to individual socketid
6io.emit('message', "this is a test"); //sending to all clients, include sender
7io.in('game').emit('message', 'cool game'); //sending to all clients in 'game' room(channel), include sender
8io.of('myNamespace').emit('message', 'gg'); //sending to all clients in namespace 'myNamespace', include sender
9socket.emit(); //send to all connected clients
10socket.broadcast.emit(); //send to all connected clients except the one that sent the message
11socket.on(); //event listener, can be called on client to execute on server
12io.sockets.socket(); //for emiting to specific clients
13io.sockets.emit(); //send to all connected clients (same as socket.emit)
14io.sockets.on() ; //initial connection from a client.