如果使用这个库的话,十分简单,他提供了函数 $F("formId");

<script type="text/javascript">
<!--
function getRadioValue(str)
{
 var r=document.getElementsByName(str);
 for (var i=0;i<r.length;i++)
 if(r[i].checked) return r[i].value;
}
//-->
</script>

不过它有这个用法，对radio也适用。

<form id="person-example" class="example" action="#">

       <input type="text" name="username" id="username" value="Sulien" />

       <input type="text" name="age" id="age" size="3" value="22" />

       <select name="hobbies" id="hobbies">

               <option value="coding">Coding</option>

               <option value="swimming">Swimming</option> <!-- selected -->

               <option value="hiking">Hiking</option>

               <option value="drawing">Drawing</option>

       </select>

       <button type="submit">Send</button>

</form>

$('person-example').serialize()

// -> 'username=sulien&age=22&hobbies=swimming'

可以参考文档：
https://compdoc2cn.dev.java.net/prototype/html/prototype.js.cn.html#ajax_request_reference