front-end code (same for all pages)

        window.fbAsyncInit = function () {
            FB.init({
                appId: '672221882789824', // App ID
                channelUrl: '//'+ gameForestIP +':46069/channel.html',
                status: true, // check login status
                cookie: true, // enable cookies to allow the server to access the session
                xfbml: true  // parse XFBML
            });

            // Initialize when a user has authenticated with FB and this app
            // Handle events accordingly
            FB.Event.subscribe('auth.authResponseChange', function (response) {

                if (response.status === 'connected') {
                    // user is logged in to FB
                    // has authorized app

                    console.log('Welcome, fetching information');

                    FB.api('/me', function (response) {

                        var fbid = response.id;
                        var fbuser = response.username;
                        var fname = response.first_name;
                        var lname = response.last_name;

                        var request = $.ajax({
                            url: "http://"+ gameForestIP +":1193/service/user/fb?fbid=" + fbid + "&username=" + fbuser + "&firstname=" + fname + "&lastname=" + lname,
                            async: true,
                            type: "POST"
                        });

                        request.done(function (msg) {
                            if (msg.ResponseType != 0) {
                                // show error (maybe in an error div?)
                                $("#alertDialog").show();
                                $("#alertDialog").html("<p class='glyphicon glyphicon-warning-sign' style='margin-right:10px'/>" + msg.AdditionalData);
                            }
                            else {
                                // store session ID to local storage
                                localStorage.setItem("user-session", msg.AdditionalData);
                                console.log("sessionid: " + localStorage.getItem("user-session"));
                            }

                            $("buttonSignIn").button('reset');
                            $("#fbLogout").show();
                            $("#linkLogout").hide();
                        });

                        request.fail(function (nothing, textStatus, something) {
                            $("#alertDialog").show();

                            $("#alertDialog").css("class", "alert alert-danger");
                            $("#alertDialog").html("<p class='glyphicon glyphicon-warning-sign' style='margin-right:10px'/>" + "Something went wrong! :(");

                            $("buttonSignIn").button('reset');
                        });

                        $("#login-well").hide();
                        $("#userinfo-well").show();

                        document.getElementById('fb-log-well').style.display = 'none';
                    })

// -------------------- LOGOUT --------------------------
                    document.getElementById('fbLogout').addEventListener('click', function () {
                        var request = $.ajax({
                            url: "http://"+ gameForestIP + ":1193/service/user/login?usersessionid=" + localStorage.getItem("user-session"),
                            async: true,
                            type: "DELETE"
                        });

                        request.success(function (data) {
                            if (data.ResponseType != 0) {
                                // hehe, this is imposible...
                            }
                            else {
                                FB.logout(function () {
                                    // wipe user
                                    window.location.reload(true);
                                });
                            }
                        });
                    });
// ---------------- END LOGOUT -----------------------------
                } else if (response.status === 'not_authorized') {
                    // user is logged in to FB
                    // has not authorized app

                    document.getElementById('fb-log-well').style.display = 'block';
                } else {
                    // user is not logged in to FB
                    // has not authorized app

                    document.getElementById('fb-log-well').style.display = 'block';
                }
            });


        }