Cacher is the code snippet organizer for pro developers

Send to the sender and noone else

socket.emit('hello', msg);

Send to everyone including the sender(if the sender is in the room) in the room "my room"

io.to('my room').emit('hello', msg);

Send to everyone except the sender(if the sender is in the room) in the room "my room"

socket.broadcast.to('my room').emit('hello', msg);

Send to everyone in every room, including the sender

io.emit('hello', msg); // short version io.sockets.emit('hello', msg);

Send to specific socket only (private chat)

socket.broadcast.to(otherSocket.id).emit('hello', msg);