有关JS显示本列相同字符的问题
菜鸟跪求指点,谢谢
1、有三列数字如:
6	7	4
8	1	2
5	4	5
4	5	7
5	7	7
2	1	2
4	7	5
5	2	7
2、当鼠标光标经过或者点击某一个
数字的时候,该数字和它上面的数
字如果在该列出来过,则把这两个数
字标示出来。如:  
6	7	4
8	1	2
5	4	5
4	5	7
5	7	7
2	1	2
4	7	5
5	2	7
求高人指点,谢谢
------解决方案--------------------
<!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 http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script type="text/javascript">
	function init(){
		var table=document.getElementById("test");
		var tds=table.getElementsByTagName("td");
		for(var i=0;i<tds.length;i++){
			tds[i].setAttribute("num",i);
			tds[i].onclick=change;
		}
	}
	function change(){	
		var table=document.getElementById("test");
		var num=this.getAttribute("num");
		var tds=table.getElementsByTagName("td");
		for(var i=num-3;i>=0;i-=3){
			if(tds[i].innerHTML==this.innerHTML){
				tds[i].innerHTML="<font color=red>"+tds[i].innerHTML+"</font>"
			}
		}
		this.innerHTML="<font color=red>"+this.innerHTML+"</font>";
	}
	window.onload=init;
</script>
</head>
<body>
<table id="test">
	<tr>
   	<td>6</td>
       <td>7</td>
       <td>4</td>
   </tr>
   <tr>
   	<td>8</td>
       <td>1</td>
       <td>2</td>
   </tr>
   <tr>
   	<td>5</td>
       <td>4</td>
       <td>5</td>
   </tr>
   <tr>
   	<td>4</td>
       <td>5</td>
       <td>7</td>
   </tr>
   <tr>
   	<td>5</td>
       <td>7</td>
       <td>7</td>
   </tr>
   <tr>
   	<td>2</td>
       <td>1</td>
       <td>2</td>
   </tr>
   <tr>
   	<td>4</td>
       <td>7</td>
       <td>5</td>
   </tr>
   <tr>
   	<td>5</td>
       <td>2</td>
       <td>7</td>
   </tr>
</table>
</body>
</html>
这样试试