如何在自动补全物料-界面中默认打开下拉列表？

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

<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>

<script>
  document.getElementById("mySelect").selectedIndex = 0;
</script>

<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>

<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<script>
  $(document).ready(function() {
    $("#mySelect").val("option1");
  });
</script>