This code determines if the user is online :

/* User online status */
    var online = true;
    var activeTimeout = setTimeout(_setUserInactive, 5000);

    $(document).on("mousemove keydown keyup click", function () {
        clearTimeout(activeTimeout);
        activeTimeout = setTimeout(_setUserInactive, 5000);

        if (!online) {
            _setUserActive();
        }
    });

Pretty simple. But, is this going to cause performance issues? It will call every time the mouse is moved. Thanks.