Emit cheatsheet


  1. io.on('connection', 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');

    };

Note: The following events are reserved and should not be used as event names by your application:

  • connect
  • connection
  • connect_error
  • connect_timeout
  • error
  • disconnect
  • disconnecting
  • newListener
  • reconnect_attempt
  • reconnecting
  • reconnect_error
  • reconnect_failed
  • removeListener
  • ping
  • pong

Caught a mistake? Edit this page on GitHub