nodejs api to logged in users count on an application

1var io = require('socket.io').listen(8080);
2var count = 0
3
4io.sockets.on('connection', function(socket) {
5    count++;
6    io.sockets.emit('message', { count: count });
7
8    socket.on('disconnect', function(){
9        count--;
10        io.sockets.emit('message', { count: count });
11    })
12});
13