$('.breadcrumb-item a').on('click', function () {
    var currentPage = $('ol.breadcrumb li.active a').attr('data-page');
    var nextPage = $(this).attr('data-page');

    if (nextPage === 'model' && currentPage === 'machine') {
        backToModel();
    } else if (nextPage === 'brand' && (currentPage === 'machine' || currentPage === 'model')) {
        backToBrand();
    }

    return false;
});