gistfile1.js

FB_RequireFeatures(["Connect", "XFBML"], function() {
  FB.init(FacebookConfig.api_key, "facebook_crossdomain_comm_channel.html");
});

function facebookRequestPermissionIfNecessary(permission, callback) {
  FB.ensureInit(function() {
    FB.Facebook.apiClient.users_hasAppPermission(permission, function(result) {
        if (result == 0) {
            FB.Connect.showPermissionDialog(permission, callback);
        } else {
            callback(true);
        }
    });
  });
}