<table border="1" width="200">
<tr>
<td>
1
</td>
<td>
2
</td>
</tr>
<tr>
<td onclick="alert(this.parentNode.previousSibling.lastChild.innerText)">
3
</td>
<td>
4
</td>
</tr>
</table>
<tr>
<td>
1
</td>
<td>
2
</td>
</tr>
<tr>
<td onclick="alert(this.parentNode.previousSibling.lastChild.innerText)">
3
</td>
<td>
4
</td>
</tr>
</table>
使得原来是两行两列的表格变成两行四列