// 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');
// list socketid
for (var socketid in io.sockets.sockets) {}
OR
Object.keys(io.sockets.sockets).forEach((socketid) => {});io.on('connection', function(socket){ socket.to('some room').emit('some event');});io.on('connection', socket => { socket.on('say to someone', (id, msg) => { socket.to(id).emit('my message', msg); });});io.to('room1').to('room2').to('room3').emit('some event');io.on('connection', socket => { socket.on('disconnecting', () => { const rooms = Object.keys(socket.rooms); // the rooms array contains at least the socket ID }); socket.on('disconnect', () => { // socket.rooms === {} });});io.on('connect', onConnect);function onConnect(socket){ // sending to the client socket.emit('hello', 'can you hear me?', 1, 2, 'abc'); // sending to all clients except sender socket.broadcast.emit('broadcast', 'hello friends!'); // sending to all clients in 'game' room except sender socket.to('game').emit('nice game', "let's play a game"); // sending to all clients in 'game1' and/or in 'game2' room, except sender socket.to('game1').to('game2').emit('nice game', "let's play a game (too)"); // sending to all clients in 'game' room, including sender io.in('game').emit('big-announcement', 'the game will start soon'); // sending to all clients in namespace 'myNamespace', including sender io.of('myNamespace').emit('bigger-announcement', 'the tournament will start soon'); // sending to a specific room in a specific namespace, including sender io.of('myNamespace').to('room').emit('event', 'message'); // sending to individual socketid (private message) io.to(socketId).emit('hey', 'I just met you'); // WARNING: `socket.to(socket.id).emit()` will NOT work, as it will send to everyone in the room // named `socket.id` but the sender. Please use the classic `socket.emit()` instead. // sending with acknowledgement socket.emit('question', 'do you think so?', function (answer) {}); // sending without compression socket.compress(false).emit('uncompressed', "that's rough"); // sending a message that might be dropped if the client is not ready to receive messages socket.volatile.emit('maybe', 'do you really need it?'); // specifying whether the data to send has binary data socket.binary(false).emit('what', 'I have no binaries!'); // sending to all clients on this node (when using multiple nodes) io.local.emit('hi', 'my lovely babies'); // sending to all connected clients io.emit('an event sent to all connected clients');};