var scrolltop = new Array();

 var index = 0;

 scrolltop[0] = 0;

 $(document).scroll(function(){

      index ++;

      scrolltop[index] = $(document).scrollTop();

      if (scrolltop[index] > scrolltop[index-1]) {

             console.log("scroll down");

      }else{

             console.log("scroll up");

      };

 })