复制表格行

<form>   
  <table  border=1   id="table1">
  <span id="sp1"> 
  	<tr id=sp><td>asdfklakds</td><td>sdi9934893</td></tr>
  </span>
  </table>   
  </form>   
  <input   type=button   onclick="ff()">   
  <script>   
  function   ff()   
  {
  var cl = document.getElementById("sp").cloneNode(true);
  //alert(cl.innerHTML)
  document.getElementById("sp").parentElement.appendChild(cl);
  
  }   
  </script> 
<form>