效果如下：
demo code:
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>全选全不选以及监听取消全选或自动全选</title>
<style>
.bg{
background-image: url(images/list_bg.gif);
background-repeat: no-repeat;
width: 730px;
}
td{text-align:center;
font-size:13px;
line-height:25px;
}
body{margin:0}
</style>
</head>
<body>
<table border="0" cellspacing="0" cellpadding="0" class="bg">
<form action="" method="post">
<tr>
<td style="height:40px;"> </td>
<td> </td>
<td> </td>
<td> </td>
</tr>
<tr style="font-weight:bold;">
<td>
<input id="all" type="checkbox" value="全选" />
全选
</td>
<td>商品图片</td>
<td>商品名称/出售者/联系方式</td>
<td>价格</td>
</tr>
<tr>
<td colspan="4">
<hr style="border:1px #CCCCCC dashed" />
</td>
</tr>
<tr>
<td>
<input name="product" type="checkbox" value="1" />
</td>
<td>
<img src="images/list0.jpg" alt="alt" />
</td>
<td>
杜比环绕，家庭影院必备，超真实享受<br />
出售者：ling112233<br />
<img src="images/online_pic.gif" alt="alt" />
<img src="images/list_tool_fav1.gif" alt="alt" />
收藏
</td>
<td>一口价<br />
2833.0
</td>
</tr>
<tr>
<td colspan="4"><hr style="border:1px #CCCCCC dashed" /></td>
</tr>
<tr>
<td>
<input name="product" type="checkbox" value="2" />
</td>
<td>
<img src="images/list1.jpg" alt="alt" />
</td>
<td>
NVDIA 9999GT 512MB 256bit极品显卡，不容错过<br />
出售者：aipiaopiao110 <br />
<img src="images/online_pic.gif" alt="alt" />
<img src="images/list_tool_fav1.gif" alt="alt" /> 收藏
</td>
<td>
一口价<br />
6464.0
</td>
</tr>
<tr>
<td colspan="4"><hr style="border:1px #CCCCCC dashed" /></td>
</tr>
<tr>
<td><input name="product" type="checkbox" value="3" /></td>
<td><img src="images/list2.jpg" alt="alt" /></td>
<td>精品热卖：高清晰，30寸等离子电视<br />
出售者：阳光的挣扎 <br />
<img src="images/online_pic.gif" alt="alt" />
<img src="images/list_tool_fav1.gif" alt="alt" /> 收藏
</td>
<td>一口价<br />
18888.0
</td>
</tr>
<tr>
<td colspan="4"><hr style="border:1px #CCCCCC dashed" /></td>
</tr>
<tr>
<td><input name="product" type="checkbox" value="4" /></td>
<td><img src="images/list3.jpg" alt="alt" /></td>
<td>Sony索尼家用最新款笔记本 <br />
出售者：疯狂的镜无<br />
<img src="images/online_pic.gif" alt="alt" />
<img src="images/list_tool_fav1.gif" alt="alt" /> 收藏
</td>
<td>一口价<br />
5889.0
</td>
</tr>
<tr>
<td colspan="4"><hr style="border:1px #CCCCCC dashed" /></td>
</tr>
</form>
</table>
</body>
</html>
<script>
/*
* 点全选，全部选择或者全部取消
* 点其余任意一个自动判断全选是否需要选上[重点]
* js必须写在下面，否则需要onload函数
* */
var all = document.getElementById("all"),
product = document.getElementsByName("product"),
l = product.length;
all.onclick = function(){
for(var i=l;i--;){
product[i].checked = all.checked;
}
};
for(var i=l;i--;){
product[i].onclick = function(){
var k = 0;
for(var i=l;i--;)product[i].checked && k++;
all.checked = l==k;
};
}
</script>