How are variables and references stored in anonymous functions in javascript?

I'm making a server in node.js (with socket.io), and this specific problem has been haunting me for the longest time now. I made an easily extendable handler for socket connections to route each different connection to a different function.

... <previous code> ...
var socketHandlers = {
                        'chat':chat.onMessage,
                        'chatNameRequest':chat.onNameRequest,
                        'changeRooms':commands.onPlayerRoomChange,
                        'commandEnter':commands.onCommandEnter
                    };

io.sockets.on('connection', function (socket) {
    console.log("New client connected.");

    // add all handlers to this socket when connected
    for (var handler in socketHandlers) {
        socket.on(handler, function(data) {
            console.log("Resolved handler for " + handler + ", called function " + socketHandlers[handler]);

            // sanitize each handler before sending it to the inner functions
            // leave more specific sanitization for the inner function
            data = valid.cleanData(data);
            socket = valid.cleanSocket(socket);

            // finally send it to the inner functions
            socketHandlers[handler](socket, data);
        });
    }
});

However, it doesn't seem to be working. This is the console output from the server:

   debug - flashsocket received data packet 5:::{"args":{"name":"Timothy"},"name":"chatNameRequest"}
Resolved handler for commandEnter, called function function (socket, data) {
<function contents, etc>

As you can see, the program received a request of "chatNameRequest", but it incorrectly routed it to "commandEnter." Could someone shed some light on what is going on here?