1、<iframe id="list_iframe" name="list_iframe"></iframe>
iframe頁面元素：
<input type="radio" name="radios" value="1" />
<input type="radio" name="radios" value="2" />
<input type="radio" name="radios" value="3" />
2、獲取iframe元素的對象：document.getElementById("list_iframe").contentWindow.document.getElementsByName('radios')