Create a list of Connected Clients using socket.io

Question

Here are 2 related questions. Posting them together makes more sense.

Question 1

I have a node.js app which emits an event out to all client

Answer 1

You will need to keep track of the connected clients yourself. The simple way to do that would be to use an array:

var clients = [];

io.sockets.on('connect', function(client) {
    clients.push(client); 

    client.on('disconnect', function() {
        clients.splice(clients.indexOf(client), 1);
    });
});

Then you can references that clients array on the server wherever you need to, in your ready event handler or whatever. Something like:

io.sockets.on('connection', function(socket) {
    socket.on('ready', function() {
        // UPDATE N rows with client_id in column checkout.
        // Then SELECTS * from table where checkout = client_id
        clients.forEach(function(client, index) {
            var client_id = index; // Just use the index in the clients array for now
            getListings(client_id, function(listings) {
                socket.emit('job', listings);   // send jobs
            });
        });
    });
});

Answer 2

Socket.io provides you with a public api for that, so instead of hacking something up like Bryan suggest you can use:

io.sockets.clients()

That will returns an array of all connected clients.

If you want all clients connected to a certain namespace:

io.of('/namespace').clients()

But you can even filter it even more.. if you want to have all sockets in a room:

io.sockets.clients('room name here as first argument')

Will return a array of connected sockets for the room room name here as first argument