如何使用javascript将表单数据附加和保存到txt文件

<form id="myForm">
  <label for="name">姓名:</label>
  <input type="text" id="name" name="name"><br><br>
  <label for="email">邮箱:</label>
  <input type="email" id="email" name="email"><br><br>
  <label for="message">留言:</label>
  <textarea id="message" name="message"></textarea><br><br>
  <input type="submit" value="提交">
</form>

document.getElementById("myForm").addEventListener("submit", function(event) {
  event.preventDefault(); // 阻止表单提交
  saveFormData();
});

function saveFormData() {
  var form = document.getElementById("myForm");
  var formData = new FormData(form);
  var data = {};

  for (var pair of formData.entries()) {
    data[pair[0]] = pair[1];
  }

  var jsonData = JSON.stringify(data);
  saveToFile(jsonData);
}

function saveToFile(data) {
  var blob = new Blob([data], { type: "text/plain" });
  var url = URL.createObjectURL(blob);

  var link = document.createElement("a");
  link.href = url;
  link.download = "form_data.txt";
  link.click();

  URL.revokeObjectURL(url);
}