javascript 检测向上或向下滚动

Posted 2021-05-03

detectScrollUpOrDown: function () {
    var $el = $('.mega-menu .filters-blade');
    var lastOffsetTop = $el.offset().top - $(window).scrollTop();

    $(window).on('scroll', function () {
        var currentOffsetTop = $el.offset().top - $(window).scrollTop();

        if (currentOffsetTop < lastOffsetTop) {
            // Scrolling down
            console.log('Scrolling down...');
        } else {
            console.log('Scrolling up...');
        }
        
        setTimeout(function(){
            lastOffsetTop = $el.offset().top - $(window).scrollTop();
        }, 250);

    });

}