javascript - 如何传递元素前面的类总数？

这是我目前正在做的事情：

<script>
function Answered(str) {
   var script = document.getElementsByClassName('Answered')[str];
   if(script!==null) {script.setAttribute("style", "");}
}
</script>

<span class=Answered style="background-color: #FFBED1">Is the sky blue?</span><br>
<select name="SkyBlue" onchange="Answered(0)">
    <option value="">Please Select</option>
    <option value="Yes">Yes</option>
    <option value="No">No</option>
</select><br>
<br>

<span class=Answered style="background-color: #FFBED1">How old are you?</span><br>
<input name=Age onchange="Answered(1)"><br>
<br>

<span class=Answered style="background-color: #FFBED1">Is grass green?</span><br>
<select name="GrassGreen" onchange="Answered(2)">
    <option value="">Please Select</option>
    <option value="Yes">Yes</option>
    <option value="No">No</option>
</select><br>

我想将“ Answered（0）”，“ Answered（1）”，“ Answered（2）”替换为“ Answered（classes =='Answered'在此元素之前）”之类的内容，以使元素可以移动或插入，不必重新编号。

最佳答案

更新！

如我所见，评论意识到先前的答案存在一些错误。因此，此处已进行了更新以在DOM树中查找实际元素。

而是传递this：

function Answered(el) {
  var isSpan = el.previousElementSibling;
  var elem = checkPrev(el);
  if (el.value === "") {
    return false;
  }
  if (isSpan.nodeName === "SPAN") {
    isSpan.setAttribute("style", "");
  }

  function checkPrev(currElem) {
    if (currElem.previousElementSibling.nodeName !== 'SPAN') {
      Answered(currElem.previousElementSibling)
    } else {
      return currElem.previousElementSibling;
    }
  }
}

<span class=Answered style="background-color: #FFBED1">Is the sky blue?</span>
<br>
<select name="SkyBlue" onchange="Answered(this)">
  <option value="">Please Select</option>
  <option value="Yes">Yes</option>
  <option value="No">No</option>
</select>
<br>
<br>

<span class=Answered style="background-color: #FFBED1">How old are you?</span>
<br>
<input name=Age onchange="Answered(this)">
<br>
<br>

<span class=Answered style="background-color: #FFBED1">Is grass green?</span>
<br>
<select name="GrassGreen" onchange="Answered(this)">
  <option value="">Please Select</option>
  <option value="Yes">Yes</option>
  <option value="No">No</option>
</select>
<br>

Fiddle