FBAuthorize.js

var fb_api_key = 'xxxxxxxxxxxxxxxxxxxxxx';
var fb_channel_path = '/xd_receiver.htm';
var FBApi;
var XFBML;

FB_RequireFeatures(["Api","XFBML"], function(){
    FB.XFBML.Host.autoParseDomTree = false;
    // Create an ApiClient object, passing app's API key and 
    // a site relative URL to xd_receiver.htm
    FB.Facebook.init(fb_api_key, fb_channel_path, null);

    FBApi = FB.Facebook.apiClient;
    XFBML = FB.XFBML.Host;

    // Forces Facebook Connect / Login
    FBApi.requireLogin(function(exception){
      $('#params_log').append("Current user id is " + FBApi.get_session().uid);
    });
});