tryjsref_optgroup_create 在线代码实例

 <p>点击按钮创建 OPTGROUP 元素。</p>

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

<select id="mySelect" size="6">
<option>BMW
</option><option>Mercedes
</option><option>Ford
</option><option>Volvo
</option><option>Toyota
</option></select>

<script>
function myFunction()
{
var x = document.getElementById("mySelect");
var y = document.createElement("OPTGROUP");
y.setAttribute("label", "SwedishCars");
y.appendChild(x.options[3])
x.insertBefore(y,x.options[3]);
}
</script>