jQuery implements judging the scroll bar to the bottom

jQuery implements judging the scroll bar to the bottom_jquery

WBOY

Release： 2016-05-16 15:53:29

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To determine whether the scroll bar reaches the bottom, you need to use three attribute values of the DOM, namely scrollTop, clientHeight, and scrollHeight.

scrollTop is the scrolling distance of the scroll bar on the Y axis.

clientHeight is the height of the content visible area.

ScrollHeight is the height of the content’s visible area plus the overflow (scrolling) distance.

As can be seen from the introduction of these three attributes, the condition for the scroll bar to reach the bottom is scrollTop clientHeight == scrollHeight.

Without further ado, let’s quickly upload the code (compatible with different browsers).

lazyload.js

&#65279;
//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) &#63; 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) &#63; 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!");
　　}
};

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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");
　　}
});

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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>

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