js onchange提交默认select选项

<select id="mySelect" onchange="submitForm()">
  <option value="default">请选择</option>
  <option value="option1">选项1</option>
  <option value="option2">选项2</option>
  <option value="option3">选项3</option>
</select>

function submitForm() {
  var selectElement = document.getElementById("mySelect");
  var selectedValue = selectElement.value;
  
  if (selectedValue === "default") {
    // 默认选项被选择，执行表单提交操作
    var formElement = document.getElementById("myForm");
    formElement.submit();
  }
}

<form id="myForm" action="submit.php" method="post">
  <!-- 表单内容 -->
</form>