modal 여러개 겹칠 때 z-index 설정하기

            $(document).on('show.bs.modal', '.modal', function (event) {
                var zIndex = 1040 + (10 * $('.modal:visible').length);
                $(this).css('z-index', zIndex);
                setTimeout(function() {
                    $('.modal-backdrop').not('.modal-stack').css('z-index', zIndex - 1).addClass('modal-stack');
                }, 0);
            });