单选按钮检查w/jQuery

Question

循环浏览页面上所有单选按钮的最佳方法是什么,如果其中一个单元格未针对特定问题取消选中,则提醒用户？

注意:一页上有多个问题.

<li>
  <fieldset>
  <h3>What music do you listen to?</h3>  

        <ul class="answerList">
            <li>
                <input type="radio" id="choice_22" name="answer8" value="1" class=""/>
                <label for="choice_22" class="">Heavy Metal  </label>
            </li>
            <li>
                <input type="radio" id="choice_23" name="answer8" value="2" class=""/>
                <label for="choice_23" class="">Pop music</label>
            </li>
            <li>
                <input type="radio" id="choice_24" name="answer8" value="3" class=""/>
                <label for="choice_24" class="">Oh, a mix of stuff </label>
            </li>
         </ul>
       </fieldset>   
      </li>

Answer 1

if (undefined === $("input[name='answer8']:checked").val()) {
    // do something
}