<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script 
language="javascript">
function selected() {
var allsel=document.getElementsByName("car");
for(var i=0;i<allsel.length;i++)
{ allsel[i].checked=!allsel[i].checked; }
}
</script>
</head>
<body>
<h1>全选/全不选</h1> 全选/取消<br />
<input type="checkbox" id="sel" name="sel" value="yes" onclick="selected()"> <br/>
<input type="checkbox" id="car" name="car" value="two">aa<br/>
<input type="checkbox" id="car" name="car" value="three">bb<br/> <input type="checkbox" id="car" name="car" value="four">cc<br/> </body> </html>