JavaScript实现点击表格单元格动态改变背景色

<html>
<body>
<table onclick="SetColor(event)" id="_t" width="500" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="93" height="29" background="hotlinkbg.gif" align="center">出租信息</td>
<td width="93" height="29" background="hotlinkbg.gif" align="center">求租信息</td>
<td width="314" height="29" background="hotlinkbg.gif" ></td>
</tr>
</table>
<table width="500">
<tr>
<td>aaaaa</td>
<td>bbbbb</td>
<td>ccccc</td>
<td>ddddd</td>
</tr>
</table>
<script tyle="text/javascript">
var oldClr = new Array()
function SetColor(e)
{
 if (!e) e = window.event;
 var obj
 if(window.event)
 obj = e.srcElement
 else
 obj = e.target
if(obj.tagName != "TD") return
var oldTD = obj
 while( obj.tagName != "TR")
 obj = obj.parentNode
 var i
 for(i = 0;i<obj.cells.length;i++)
 {
 if(obj.cells[i] == oldTD) break
 }
 var table = document.getElementById("_t")
 for(j = 0;j<table.rows.length;j++)
 {
 //如果要删除其它列的颜色，请加上下面的3行
 for(m = 0;m < table.rows[j].cells.length;m++)
 {
  table.rows[j].cells[m].background = oldClr[m]
 }
  //table.rows[j].cells[i].bgColor = table.rows[j].cells[i].background="button1_on.gif"
  table.rows[j].cells[i].background = table.rows[j].cells[i].background==oldClr[i]?"button1_on.gif":oldClr[i]
 }
}
window.onload = function()
{
 var table = document.getElementById("_t")
 for(j = 0;j<table.rows[0].cells.length;j++)
 {
 oldClr[j] = table.rows[0].cells[j].background
 }
}
</script>
</body>
</html>