如何在选择下拉菜单时更改标题文本

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

document.getElementById("mySelect").addEventListener("change", changeTitle);

function changeTitle() {
  var select = document.getElementById("mySelect");
  var selectedOption = select.options[select.selectedIndex];
  var title = document.getElementById("title");
  title.innerHTML = selectedOption.text;
}

<h1 id="title">默认标题</h1>