doc.txt

 // author: Fábio S. Takaki

 // sending to sender-client only
 socket.emit('message', "this is a test");

 // sending to all clients, include sender
 io.emit('message', "this is a test");

 // sending to all clients except sender
 socket.broadcast.emit('message', "this is a test");

 // sending to all clients in 'game' room(channel) except sender
 socket.broadcast.to('game').emit('message', 'nice game');

 // sending to all clients in 'game' room(channel), include sender
 io.in('game').emit('message', 'cool game');

 // sending to sender client, only if they are in 'game' room(channel)
 socket.to('game').emit('message', 'enjoy the game');

 // sending to all clients in namespace 'myNamespace', include sender
 io.of('myNamespace').emit('message', 'gg');

 // sending to individual socketid
 socket.broadcast.to(socketid).emit('message', 'for your eyes only');