jquery on scroll down

1Check current scrollTop vs previous scrollTop
2
3var lastScrollTop = 0;
4$(window).scroll(function(event){
5   var st = $(this).scrollTop();
6   if (st > lastScrollTop){
7       // downscroll code
8   } else {
9      // upscroll code
10   }
11   lastScrollTop = st;
12});

1Syntax
2Trigger the scroll event for the selected elements:
3$(selector).scroll()
4
5Attach a function to the scroll event:
6$(selector).scroll(function)