​x
 
<!DOCTYPE html>
<html>
<body>
​
<h3>演示如何创建 OPTGROUP 元素</h3>
​
<p>点击按钮来创建 OPTGROUP 元素。</p>
​
<button onclick="myFunction()">试一下</button>
​
<select id="mySelect" size="6">
<option>BMW
<option>Mercedes
<option>Ford
<option>Volvo
<option>Toyota
</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>
​
</body>
</html>
​