使用表单post方法发送表时，动态添加到表中的类会丢失

<form action="submit.php" method="post">
  <!-- 表单中已存在的元素 -->
  <input type="text" name="username" />
  <input type="password" name="password" />
  
  <!-- 隐藏的元素 -->
  <input type="hidden" name="dynamicValue" id="dynamicValue" />
  
  <button type="submit">提交</button>
</form>

<script>
  // 动态添加元素
  function addElement() {
    var newValue = "动态添加的值";
    
    // 创建动态元素
    var dynamicElement = document.createElement("input");
    dynamicElement.type = "text";
    dynamicElement.name = "dynamicElement";
    dynamicElement.value = newValue;
    
    // 添加到表单中
    document.querySelector("form").appendChild(dynamicElement);
    
    // 将动态添加的值赋给隐藏元素
    document.getElementById("dynamicValue").value = newValue;
  }
  
  // 调用添加元素函数
  addElement();
</script>

<form id="myForm">
  <!-- 表单中已存在的元素 -->
  <input type="text" name="username" />
  <input type="password" name="password" />
  
  <button type="button" onclick="submitForm()">提交</button>
</form>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script>
  function submitForm() {
    var form = $("#myForm");
    var url = form.attr("action");
    var formData = form.serialize();
    
    // 发送Ajax请求提交表单数据
    $.ajax({
      type: "POST",
      url: url,
      data: formData,
      success: function(response) {
        console.log("表单提交成功！");
        console.log(response);
      },
      error: function(jqXHR, textStatus, errorThrown) {
        console.error("表单提交失败：" + textStatus + " - " + errorThrown);
      }
    });
  }
</script>