스크롤 막대 스크롤 방향을 결정하기 위해 jquery를 사용하는 방법 예제 코드 분석

function scroll( fn ) {
  var beforeScrollTop = document.body.scrollTop,
    fn = fn || function() {};
  window.addEventListener("scroll", function() {
    var afterScrollTop = document.body.scrollTop,
      delta = afterScrollTop - beforeScrollTop;
    if( delta === 0 ) return false;
    fn( delta > 0 ? "down" : "up" );
    beforeScrollTop = afterScrollTop;
  }, false);
}

scroll(function(direction) { console.log(direction) });

scrollDirect: function (fn) {
  var beforeScrollTop = document.body.scrollTop;
  fn = fn || function () {
  };
  window.addEventListener("scroll", function (event) {
    event = event || window.event;

    var afterScrollTop = document.body.scrollTop;
    delta = afterScrollTop - beforeScrollTop;
    beforeScrollTop = afterScrollTop;

    var scrollTop = $(this).scrollTop();
    var scrollHeight = $(document).height();
    var windowHeight = $(this).height();
    if (scrollTop + windowHeight > scrollHeight - 10) { //滚动到底部执行事件
      fn('up');
      return;
    }
    if (afterScrollTop < 10 || afterScrollTop > $(document.body).height - 10) {
      fn(&#39;up&#39;);
    } else {
      if (Math.abs(delta) < 10) {
        return false;
      }
      fn(delta > 0 ? "down" : "up");
    }
  }, false);
}

  var upflag=1;
  var downflag= 1;
  //scroll滑动,上滑和下滑只执行一次！
scrollDirect(function (direction) {
    if (direction == "down") {
      if (downflag) {
        $(".footer_wrap").slideUp(200);
        downflag = 0;
        upflag = 1;
      }
    }
    if (direction == "up") {
      if (upflag) {
        $(".footer_wrap").slideDown(200);
        downflag = 1;
        upflag = 0;
      }
    }
 });

BottomJumpPage: function () {
      var scrollTop = $(this).scrollTop();
      var scrollHeight = $(document).height();
      var windowHeight = $(this).height();
      if (scrollTop + windowHeight == scrollHeight) { //滚动到底部执行事件
          console.dir("我到底部了")；

      }
      if (scrollTop == 0) { //滚动到头部部执行事件
      console.dir("我到头部了")；

      }
 }

$(window).scroll(BottomJumpPage);

 $(document).ready(function (){
    var nScrollHight = 0; //滚动距离总长(注意不是滚动条的长度)
    var nScrollTop = 0;  //滚动到的当前位置
    var npHight = $("#p1").height();
    $("#p1").scroll(function(){
     nScrollHight = $(this)[0].scrollHeight;
     nScrollTop = $(this)[0].scrollTop;
     if(nScrollTop + npHight >= nScrollHight)
      alert("滚动条到底部了");
     });
});

　　var container = $('p'), 
　　scrollTo = $('#row_8');

　　container.scrollTop( 
　　scrollTo.offset().top - container.offset().top + container.scrollTop() 
　　);

　　// Or you can animate the scrolling: 
　　container.animate({ 
　　scrollTop: scrollTo.offset().top - container.offset().top + container.scrollTop() 
　　});?