tryjsref_optgroup_get 在线代码实例

 <h3>访问 OPTGROUP 元素</h3>

<select size="4">
  <optgroup id="myOptgroup" label="Swedish Cars">
    <option value="volvo">Volvo</option>
    <option value="saab">Saab</option>
    <option value="koenigsegg">Koenigsegg</option>
  </optgroup>
</select>

<p>点击按钮获取选项组的标签/描述。</p>

<p id="demo"></p>

<button onclick="myFunction()">尝试一下</button>

<script>
function myFunction()
{
var x = document.getElementById("myOptgroup").label;
document.getElementById("demo").innerHTML = x;
}
</script>