javascript Table 中2个列（TD）的交换实现代码

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> 
<HTML> 
<HEAD> 
<TITLE> New Document </TITLE> 
<META NAME="Generator" CONTENT="EditPlus"> 
<META NAME="Author" CONTENT="majianan"> 
<META NAME="Keywords" CONTENT=""> 
<META NAME="Description" CONTENT=""> 
<script type="text/javascript"></script> 
</HEAD> 
<BODY> 
<table> 
<tr> 
<td id='a'>[a]</td> 
<td id='b'>[b]</td> 
<td id='c'>[c]</td> 
<td id='d'>[d]</td> 
<td id='e'>[e]</td> 
</tr> 
</table> 
<tr><td><input id='t1' type="text" value="a"></td></tr> 
<tr><td><input id='t2' type="text" value="b"></td></tr> 
<tr><td><input type="button" value="swap" onclick="swap()"></td></tr> 
</BODY> 
</HTML>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]
上面的格式，比较奇怪，我用js稍微改了下，文本框分别是要转换的索引，不能随便输。

<!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 content="text/html;charset=gb2312" http-equiv=Content-Type> 
<TITLE> New Document </TITLE> 
<META NAME="Generator" CONTENT="EditPlus"> 
<META NAME="Author" CONTENT="majianan"> 
<META NAME="Keywords" CONTENT=""> 
<META NAME="Description" CONTENT=""> 
<script type="text/javascript"><!--

function swapNode(node1,node2) 
{ 
var _parent=node1.parentNode; 
var _t1=node1.nextSibling; 
var _t2=node2.nextSibling; 
if(_t1) 
_parent.insertBefore(node2,_t1); 
else 
_parent.appendChild(node2); 
if(_t2) 
_parent.insertBefore(node1,_t2); 
else 
_parent.appendChild(node1); 
}

function swap(){ 
var t1 = document.getElementById("t1").value; 
var t2 = document.getElementById("t2").value; 
swapNode(document.getElementById(t1),document.getElementById(t2)); 
} 
// --></script> 
</HEAD>

</table> 
<tr><td><input id='t1' type="text" value="a"></td></tr> 
<tr><td><input id='t2' type="text" value="b"></td></tr> 
<tr><td><input type="button" value="swap" onclick="swap()"></td></tr> 
</BODY> 
</HTML>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]