socket.emit code example

Example 1: socket.io emit to all other clients

// 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) => {});

Example 2: emit cheatsheet

io.on("connection", (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?", (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?");

  // 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");

});

Example 3: 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 4: socket emit to specific room using nodejs socket.io

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

Example 5: socket io script

<script src="/socket.io/socket.io.js"></script>
<script>
  const socket = io();
</script>

Example 6: js socket.emit

const socket = io('ws://localhost:3000');
socket.on('connect', () => {  
  // either with send()  
  socket.send('Hello!');
  // or with emit() and custom event names  
  socket.emit('salutations', 'Hello!', { 'mr': 'john' }, Uint8Array.from([1, 2, 3, 4]));});
// handle the event sent with socket.send()
socket.on('message', data => {
  console.log(data);
});
// handle the event sent with socket.emit()
socket.on('greetings', (elem1, elem2, elem3) => {
  console.log(elem1, elem2, elem3);
});