<!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=gb2312" />
<title>无标题文档</title>
</head>
<body>
<input type="checkbox" id="id1" onclick="check(this,false)">不可<br/>
<input type="checkbox" id="id2" onclick="check(this,false)">不可<br/>
<input type="checkbox" id="id3" onclick="check(this,false)">不可<br/>
<input type="checkbox" id="id4" onclick="check(this,true)">可以<br/>
<input type="checkbox" id="id5" onclick="check(this,true)">可以<br/>
<input type="checkbox" id="id6" onclick="check(this,true)">可以<br/>
<button onclick="fun()">提交</button>
<script type="text/javascript">
var flag = 0;
function check(el,tag)//tag，true表示可以一起选，false表示不可一起选
{
if(!tag)
{
if(el.checked)
flag++;
else
flag--;
}
}
function fun()
{
if(flag>1)
alert("error");
}
</script>
</body>
</html>
function check(c){
if(document.getElementById('id1').checked&&document.getElementById('id2').checked
&&document.getElementById('id4')){
c.checked=''
alert('1,2,4 不能同时选择！');
return false;
}
return true;
}<tr> <td colspan=2 > <input type=submit value="提交" onsubmit='check()'> </tr>
<html>
<head>
<title>welcome </title>
</head>
<script>
function check(obj){
var chck1 = document.getElementById('id1');
var chck2 = document.getElementById('id2');
var chck3 = document.getElementById('id3');
var chck4 = document.getElementById('id4'); if(chck1.checked&&chck2.checked&&chck4.checked){
alert('1,2,4不能同时选中');
}
} function chck(){
var chck1 = document.getElementById('id1');
var chck2 = document.getElementById('id2');
var chck3 = document.getElementById('id3');
var chck4 = document.getElementById('id4');
if(chck1.checked&&chck2.checked&&chck4.checked){
alert('1,2,4不能同时选中');
chck1.checked = false;
chck2.checked = false;
chck3.checked = false;
chck4.checked = false;
return false;
}
}
</script>
<body>
<form action="2.asp" method="post" onsubmit="return chck();">
<table border=1 >
<tr>
<td>S1 </td> <td> <input type=checkbox name=num1 id=id1 value="s1" onclick='javascript:check(this)'> </td>
</tr>
<tr>
<td>s2 </td> <td> <input type=checkbox name=num2 id=id2 value="s2" onclick='javascript:check(this)'> </td>
</tr>
<tr>
<td>s3 </td> <td> <input type=checkbox name=num3 id=id3 value="s3" onclick='javascript:check(this)'> </td>
</tr>
<tr>
<td>s4 </td> <td> <input type=checkbox name=num4 id=id4 value="s4" onclick='javascript:check(this)'> </td>
</tr><tr> <td colspan=2 > <input type=submit value="提交"> </tr>
</table>
</form>
</body>
</html>