​x
 
<html>
<head>
<script type="text/javascript">
function changeColSpan()
  {
  document.getElementById("td1").colSpan="2";
  }
</script>
</head>
<body>
​
<table border="1">
<tr>
<th>名</th>
<th>姓</th>
</tr>
<tr>
<td id="td1">John</td>
<td id="td2">Adams</td>
</tr>
</table>
<br />
<input type="button" onclick=changeColSpan() value="改变 colspan" />
​
</body>
</html>
​