socket io rooms code example

Example 1: socket io emit from socket instance or server

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

Example 2: rooms in socket io

io.on('connection', socket => {
  socket.join('some room');
});
//And then simply use to or in (they are the same) when broadcasting or emitting:

io.to('some room').emit('some event');
//You can emit to several rooms at the same time:

io.to('room1').to('room2').to('room3').emit('some event');
//In that case, an union is performed: every socket that is at least in one of the rooms will get the event once (even if the socket is in two or more rooms).
//You can also broadcast to a room from a given socket:

io.on('connection', function(socket){
  socket.to('some room').emit('some event');
});