实现的方法是：通过dom树API操作
代码实现如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>表格偶数行变色</title>
<style>
#data {
width: 600px;
}
#data,td,th {
border-collapse: collapse;
border: 1px solid #aaaaaa;
}
th,td {
height: 28px;
}
#data thead {
background-color: #333399;
color: #ffffff;
}
#data .blue1 {
background-color: #CCCCFF;
}
</style>
</head>
<body>
<table id="data">
<thead>
<tr>
<th>姓名</th>
<th>工资</th>
<th>入职时间</th>
<th>操作</th>
</tr>
</thead>
<tbody>
<tr>
<td>Tom</td>
<td>$3500</td>
<td>2010-10-25</td>
<td><a href="javascript:void(0)">删除</a></td>
</tr>
<tr>
<td>Mary</td>
<td>$3400</td>
<td>2010-12-1</td>
<td><a href="javascript:void(0)">删除</a></td>
</tr>
<tr>
<td>King</td>
<td>$5900</td>
<td>2009-08-17</td>
<td><a href="javascript:void(0)">删除</a></td>
</tr>
<tr>
<td>Scott</td>
<td>$3800</td>
<td>2012-11-17</td>
<td><a href="javascript:void(0)">删除</a></td>
</tr>
<tr>
<td>Smith</td>
<td>$3100</td>
<td>2014-01-27</td>
<td><a href="javascript:void(0)">删除</a></td>
</tr>
<tr>
<td>Allen</td>
<td>$3700</td>
<td>2011-12-05</td>
<td><a href="javascript:void(0)">删除</a></td>
</tr>
</tbody>
</table>
</body>
<script>
window.$ = HTMLElement.prototype.$ = function(selector){
return (this==window?document:this).querySelectorAll(selector);
}
var tbody = $("table tbody")[0];
for (var i= 0,n= 0,len=tbody.childNodes.length;i<len;i++){
if(tbody.childNodes[i].nodeName=="TR"){
n++;
if (n%2==0){
tbody.childNodes[i].className="blue1";
}
}
}
</script>
</html>