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jQuery实现判断滚动条到底部

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判断滚动条到底部,需要用到DOM的三个属性值,即scrollTop、clientHeight、scrollHeight。

scrollTop为滚动条在Y轴上的滚动距离。

clientHeight为内容可视区域的高度。

scrollHeight为内容可视区域的高度加上溢出(滚动)的距离。

从这个三个属性的介绍就可以看出来,滚动条到底部的条件即为scrollTop + clientHeight == scrollHeight。

废话不多少说,赶紧上代码(兼容不同的浏览器)。

lazyload.js


//滚动条在Y轴上的滚动距离 
 function getScrollTop(){
  var scrollTop = 0, bodyScrollTop = 0, documentScrollTop = 0;
  if(document.body){
    bodyScrollTop = document.body.scrollTop;
  }
  if(document.documentElement){
    documentScrollTop = document.documentElement.scrollTop;
  }
  scrollTop = (bodyScrollTop - documentScrollTop > 0) ? bodyScrollTop : documentScrollTop;
  return scrollTop;
} 
 //文档的总高度 
 function getScrollHeight(){
  var scrollHeight = 0, bodyScrollHeight = 0, documentScrollHeight = 0;
  if(document.body){
    bodyScrollHeight = document.body.scrollHeight;
  }
  if(document.documentElement){
    documentScrollHeight = document.documentElement.scrollHeight;
  }
  scrollHeight = (bodyScrollHeight - documentScrollHeight > 0) ? bodyScrollHeight : documentScrollHeight;
  return scrollHeight;
} 
 //浏览器视口的高度 
 function getWindowHeight(){
  var windowHeight = 0;
  if(document.compatMode == "CSS1Compat"){
    windowHeight = document.documentElement.clientHeight;
  }else{
    windowHeight = document.body.clientHeight;
  }
  return windowHeight;
} 
 window.onscroll = function(){
  if(getScrollTop() + getWindowHeight() == getScrollHeight()){
    alert("you are in the bottom!");
  }
};

lazyload-jQuery.js

$(window).scroll(function(){
  var scrollTop = $(this).scrollTop();
  var scrollHeight = $(document).height();
  var windowHeight = $(this).height();
  if(scrollTop + windowHeight == scrollHeight){
    alert("you are in the bottom");
  }
});

lazyLoad.html

<!doctype html>
<html lang="en" style="height:900px;">
 <head>
 <meta charset="UTF-8">
 <meta name="Author" content="forever">
 <link rel="stylesheet" href="css/lazyload.css" />
 <script type="text/javascript" src="js/jquery-1.7.2.min.js"></script>
 <title>lazyLoad</title>
 <script type="text/javascript">
   
  $(function(){
    var $ul=$("#lazyLoadWrap").find("ul");
    $(window).scroll(function(){
        var scrollTop = $(this).scrollTop();
        var scrollHeight = $(document).height();
        var windowHeight = $(this).height();
       if(scrollTop + windowHeight == scrollHeight){
          for(var i=0;i<6;i++){
            $ul.append("<li>Hello</li>");
          }
       }
    });
  });
 </script>
 </head>
 <body>
  <div id="lazyLoadWrap">
    <ul>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
      <li>12</li>
    </ul>
  </div>
 </body>
</html>

以上所述就是本文的全部内容了,希望大家能够喜欢。

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