DOM事件逐层上机传递

<!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">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
  <script type="text/javascript">
  $(function(){
      $("a").click(
          function(){
              alert('123');
              }
      );
      $("body").click(
      function(){
          alert('body');
          }
      );
    $("span").click(
      function(){
      alert('span');
      }
    );
  });
  </script>
</head>
  
<body>
  
  <div class="wrapper">
    <span> <a >1233123</a></span>
  </div>
   
</body>
<body>
</body>
</html>
123 span body