使用Javascript - 滾動方向的addEventListener「滾動」

Question

我有固定標題探測，這工作，鼠標滾動 如何更改此代碼只工作，向上滾動

function init() { 
        window.addEventListener('scroll', function(event) { 
         if(!didScroll) { 
          didScroll = true; 
          setTimeout(scrollPage, 250); //Scroll Page 
         } 
        }, false); 
       } 

//滾動功能

   function scrollPage() { 
        var sy = scrollY();      

        if (sy >= changeHeaderOn) { 
         if(!$('.template-content').hasClass('fixed-active') && (!$('.header-wrapper').hasClass('slider-overlap') || $('body').hasClass('breadcrumbs-type-9') || $('body').hasClass('breadcrumbs-type-default'))) 
         etTheme.headerHeight('set'); 
         classie.add(wrapper, 'fixed-active'); 
         setTimeout(function() { 
          classie.add(wrapper, 'fixed-active-animate'); 
         },250); 
        } 
        else { 
         classie.remove(wrapper, 'fixed-active'); 
         classie.remove(wrapper, 'fixed-active-animate'); 
         etTheme.headerHeight('unset'); 
        } 
        didScroll = false; 
       } 

//滾動位置

   function scrollY() { 
        return window.pageYOffset || docElem.scrollTop; 
       } 

//調用函數

   init(); 

Answer 1

function scrollPage() { 
        var sy = scrollY(); 
        if (sy >= changeHeaderOn && LastscrollY > sy) { 
         if(!$('.template-content').hasClass('fixed-active') && (!$('.header-wrapper').hasClass('slider-overlap') || $('body').hasClass('breadcrumbs-type-9') || $('body').hasClass('breadcrumbs-type-default'))) 
         etTheme.headerHeight('set'); 
         classie.add(wrapper, 'fixed-active'); 
         setTimeout(function() { 
          classie.add(wrapper, 'fixed-active-animate'); 
         },250); //150 
        } 
        else { 
         classie.remove(wrapper, 'fixed-active'); 
         classie.remove(wrapper, 'fixed-active-animate'); 
         etTheme.headerHeight('unset'); 
        } 
        didScroll = false; 
        LastscrollY = sy; 
       }