如何设置组合框的默认值？

<select>
  <option value="option1">选项1</option>
  <option value="option2" selected>选项2</option>
  <option value="option3">选项3</option>
</select>

var select = document.createElement("select");
var option1 = document.createElement("option");
option1.text = "选项1";
select.add(option1);

var option2 = document.createElement("option");
option2.text = "选项2";
option2.selected = true; // 设置为默认选项
select.add(option2);

var option3 = document.createElement("option");
option3.text = "选项3";
select.add(option3);

document.body.appendChild(select);