用不着JavaScript的吧，CSS就有这功能：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML Strict//EN"><META http-equiv="Content-Type" content="text/html; charset=utf-8">
<HTML xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>鼠标划过表格行变色－简洁实现</title>
<style type="text/css">
#tb{width:666px;border-collapse:collapse;border:1px solid #EEE;font-size:14px;}
#tb th{background:#EEE;border-bottom:1px solid #CCC;padding:4px;}
#tb td{border:1px solid #EEE;padding:4px;}
#tb tr:hover{background:#0EF}
</style>
</head>
<body>
<table id="tb">
<tr>
<th>商品名称</th>
<th>单价</th>
<th>库存数量</th>
<th>货位</th>
</tr>
<tr>
<td>丁学最喜欢的仙四豪华版-菱纱版</td>
<td>139</td>
<td>10000000</td>
<td>A12-253</td>
</tr>
<tr>
<td>仙四豪华版-梦璃版</td>
<td>139</td>
<td>10000000</td>
<td>A12-254</td>
</tr>
<tr>
<td>仙四普通版-首发</td>
<td>69</td>
<td>10000000</td>
<td>A12-255</td>
</tr>
</table>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML Strict//EN"><META http-equiv="Content-Type" content="text/html; charset=utf-8">
<HTML xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>鼠标划过表格行变色－简洁实现</title>
<style type="text/css">
#tb{width:666px;border-collapse:collapse;border:1px solid #EEE;font-size:14px;}
#tb th{background:#EEE;border-bottom:1px solid #CCC;padding:4px;}
#tb td{border:1px solid #EEE;padding:4px;}
#tb tr:hover{background:#0EF}
</style>
</head>
<body>
<table id="tb">
<tr>
<th>商品名称</th>
<th>单价</th>
<th>库存数量</th>
<th>货位</th>
</tr>
<tr>
<td>丁学最喜欢的仙四豪华版-菱纱版</td>
<td>139</td>
<td>10000000</td>
<td>A12-253</td>
</tr>
<tr>
<td>仙四豪华版-梦璃版</td>
<td>139</td>
<td>10000000</td>
<td>A12-254</td>
</tr>
<tr>
<td>仙四普通版-首发</td>
<td>69</td>
<td>10000000</td>
<td>A12-255</td>
</tr>
</table>
