Question

I am quite new to nodeJS and Socket.IO and am facing a problem.

Is there any way to know the type of event inside a Socket.IO handler? I have this kind of code:

// Fire the appropriate callback when we receive a message
// that.received is an array of callback functions
for (var event in that.received) {
    socket.on(event, function(message) {
        // Of course, this won't work because of "event" scope
        that.received[event](message, this);
    });
}

So, what I want to know is the actual value of “event” that triggered my handler.
I tried to inspect available variables with Chrome developer tools, but I wasn’t able to find anything.

I need to do this because I am writing some kind of wrapper class around Socket.IO to handle multiple sockets (a long storty about fallback servers). I want it to be generic enough to pass my handlers to it.

Any ideas?

Answer 1

OK, stupid question.

I just need to do this:

// Fire the appropriate callback when we receive a message
for (var event in that.received) {
    socket.on(event, that.received[event]);
}

I was passing “this” to my callback function, which is just stupid. My callbacks looked like this:

function myCallback(message, socket) {
    // Some code...
    socket.emit('ack', message.id);
    // Some code...
}

But all I have to do is this:

function myCallback(message) {
    // Some code...
    this.emit('ack', message.id);
    // Some code...
}

So I don’t have the scope problem anymore.