JavaScript实现折叠与展开动画效果详解

CSS样式与HTML结构配置

<!DOCTYPE = html>
<html>
 <head>
  <title>www.jb51.net JS折叠展开动画</title>
  <style>
  body{
   margin: 0px;
   padding: 0px;
  }
  .red{
   background-color:red;
   width:200px;
   height:200px;
   position:relative;
   left:-200px;
   top:0px;
  }
  .blue{
   background:blue;
   width:20px;
   height:50px;
   position:absolute;
   left:200px;
   top:75px;
  }
  </style>
 </head>
 <body>
  <div class="red" id="cf1"><div class="blue" id="cf">分享</div></div>
  <script>
  window.onload = function(){
   var onDiv = document.getElementById("cf1");
   onDiv.onmouseover = function(){
    startmove(0);
   }
   onDiv.onmouseout = function(){
    startmove(-200);
   }
  }
  var timer ;
  function startmove(target){
   clearInterval(timer);//清除定时器，以免多次触发定时器导致速度越来越快而不是匀速前进
   var onDiv1 = document.getElementById("cf1");
   timer = setInterval(function(){
   var speed = 0;
   if(onDiv1.offsetLeft<target){
    speed = 10;
   }else{
    speed = -10;
   }
   if(onDiv1.offsetLeft==target){
    clearInterval(timer);
   }
   else{
   onDiv1.style.left = onDiv1.offsetLeft+speed+'px';
   }
   },30)
  }
  </script>
 </body>
</html>