<!DOCTYPE html>
<html>
<head>
    <link rel="stylesheet" href="//apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css">
<script src="/jquery/jquery-1.11.1.min.js"></script>
    <script src="//apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script> 
$(document).ready(function(){
  $("button").click(function(){
    var div=$("div");
    div.animate({width:'300px',opacity:'1'},"slow");
    div.animate({width:'200px',opacity:'0.5'},"slow");
  });
});
</script> 
</head>

<body>

<button>开始动画</button>
<p>默认情况下，所有 HTML 元素的位置都是静态的，并且无法移动。如需对位置进行操作，记得首先把元素的 CSS position 属性设置为 relative、fixed 或 absolute。</p>
<div style="background:#98bf21;height:100px;width:20px;position:absolute;opacity:0;color:#fff;font-size:20px;">
<i class="glyphicon glyphicon-stop" style="color:#fff;font-size:20px;"></i>
</div>

</body>
</html>