Facebook JavaScript SDK: Track Accepted Invitations

I have an app on facebook with a secure canvas URL (still not published).

I'm inviting friends in the following manner:

FB.ui({method: 'apprequests', message: message, to: ids}, onInvite);

How do I track which invitations were accepted?

After googling the matter I found only one answer for the PHP SDK, I need to understand how to do it using the JavaScript SDK.