W3School TIY
编辑您的代码：
<!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>
查看结果: