<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
  <title>豪情</title>
  <meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
  <style type="text/css">
    #test{width:100px;height:100px;border:1px solid #ccc;background:#eee;display:none;}
  </style>
</head>
<body>
  <div id="test">this is a</div>
  <input type="button" value="test-btn" id="btn" onclick="show('obj')" />
  <script type="text/javascript">
  var $ = function(id){ return document.getElementById(id); };
  var obj = $('test'), btn = $('btn');
  var show = function(id){$(id).style.display = 'block'; }
  var hide = function(id){$(id).style.display = 'none'; }
  btn.onclick = function(){
    show('test');
  }
  setInterval(function(){hide('test')}, 3000);
  </script>
</body>
</html>
运行代码