node.js socket.io emit way list

 // send to current request socket client
 socket.emit('message', "this is a test");

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

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

refer
http://stackoverflow.com/questions/10058226/send-response-to-all-clients-except-sender-socket-io