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Javascript implements ceiling effect (code example)

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2018-03-31 10:03:093148browse

What this article brings to you is Javascript to implement ceiling effects (code example). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

Javascript implements ceiling effect (code example)

Knowledge points

1. Combined use of scroll family and offset family

2. When the offsetTop of the nav is greater than the height of the screen scrolling, perform ceiling lifting

3. Add a fixed class. If the conditions are met, add a class name to the nav

Running effect

Javascript implements ceiling effect (code example)

When scrolling the page, ensure that the navigation bar is ceiling-mounted

Javascript implements ceiling effect (code example)

Code:

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title></title>
 <style>
 *{margin: 0;padding: 0;list-style: none;border:none}
 img{vertical-align: top;width: 100%;}
 section{width: 70%;margin: 0 auto;}
 .nav{position: fixed;left: 0;top: 0;width: 100%}
 </style>
</head>
<body>
 <header id="head">
 <img src="images/top.png" alt="">
 </header>
 <nav id="nav">
 <img src="images/nav.png" alt="">
 </nav>
 <section>
 <img src="images/body01.png" alt="">
 <img src="images/body02.png" alt="">
 </section>
 <script src="../../MyTools/MyTools.js"></script>
 <script>
 window.addEventListener(&#39;load&#39;,function (ev) {
  // 1. 求出头部高度
  var navTopHeight = myTool.$(&#39;nav&#39;).offsetTop;
  // 2. 监听页面滚动
  window.addEventListener(&#39;scroll&#39;,function (ev1) {
  var scrollTopHeight = myTool.scroll().top;
  // 2.1 判断
  if(scrollTopHeight >= navTopHeight){
   myTool.addClassName(myTool.$(&#39;nav&#39;),&#39;nav&#39;)
  }else{
   myTool.removeClassName(myTool.$(&#39;nav&#39;),&#39;nav&#39;);
  }
  })
 })
 </script>
</body>
</html>

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