public static function js($pro = false)
    {
        if($pro)
        {
            $url = 'pro.fontawesome.com';
            $integrity = 'sha384-GBwm0s/0wYcqnK/JmrCoRqWYIWzFiGEucsfFqkB76Ouii5+d4R31vWHPQtfhv55b';
        }
        else
        {
            $url = 'use.fontawesome.com';
            $integrity = 'sha384-g5uSoOSBd7KkhAMlnQILrecXvzst9TdC09/VM+pjDTCM+1il8RHz5fKANTFFb+gQ';
        }

        return '<script defer src="https://' . $url . '/releases/v' .
        self::FA_VERSION . '/js/all.js" integrity="' . $integrity . '" crossorigin="anonymous"></script>';
    }