How to know when channel is subscribed/unsubscribed with socket.io

Question

How to know when channel is subscribed/unsubscribed with socket.io

Just searched all the web to find how can I track inside node.js server when a channel is subscribed or unsubscribed. What I can do right know is the connect and disconnect bindings, but no clue how to do it with channels.

io.sockets.on('connection', function (socket) {
    console.log("["+socket.id+"] Connected");

    // handler to know when a socket subscribed a channel (*) ?
    // handler to know when a socket unsubscribed a channel (*) ?

    socket.on('disconnect', function () {
        console.log("["+socket.id+"] Disconnect");
    });
});

Is it possible?

javascript
node.js
socket.io

Answer 1

You are looking for "socket.of('channelName')" ... See Socket.io docs

SERVER:

var io = require('socket.io').listen(80);

var chat = io
  .of('/chat')
  .on('connection', function (socket) {
    socket.emit('a message', {
        that: 'only'
      , '/chat': 'will get'
    });
    chat.emit('a message', {
        everyone: 'in'
      , '/chat': 'will get'
    });
  });

var news = io
  .of('/news')
  .on('connection', function (socket) {
    socket.emit('item', { news: 'item' });
  });

CLIENT:

<script>
  var chat = io.connect('http://localhost/chat')
    , news = io.connect('http://localhost/news');

  chat.on('connect', function () {
    chat.emit('hi!');
  });

  news.on('news', function () {
    news.emit('woot');
  });
</script>