document.getElementById("radioName") .value竟然行不通，google一下才知道不是这么写。
下面是示例：
<!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=utf-8" />
<title>无标题文档</title>
<script language="javascript">
function getRadioBoxValue(radioName)
{
var obj = document.getElementsByName(radioName);
for(i = 0; i < obj.length; i++) {
if(obj[i].checked) {
return obj[i].value;
}
}
return "undefined";
}
function abc(){
var a = getRadioBoxValue("radiobutton");
alert(a);
}
</script>
</head>
<body>
<form id="form1" name="form1" method="post" action="">
<label>
<input type="radio" name="radiobutton" value="aa" />
aa</label>
<label>
<input type="radio" name="radiobutton" value="bbb" checked/>
bbb</label>
<label>
<input type="radio" name="radiobutton" value="ccc" />
ccc</label>
<input type="submit" name="Submit" value="提交" onclick="abc()"/>
</form>
</body>
</html>