get facebook userId once they like they page/website

I read that we can get teh facebook userId if someone likes my website.. I found the following code which doesnt seem to work, can anyone please help..

/* FB.Event.subscribe('edge.create', function(href) { session = FB.getSession(); uid = session['uid']; alert(asdsdsa); // do whatever you wan开发者_开发技巧t }); */

regards

You're not going to have access to the particular user who's liked your page unless they login to your site in addition to liking your page.

At that point, with the proper permissions, you can check the like status of the user.