如何使用Javascript创建电子邮件事件

<form id="emailForm">
  <label for="recipient">收件人：</label>
  <input type="email" id="recipient" required><br>
  <label for="subject">主题：</label>
  <input type="text" id="subject" required><br>
  <label for="message">正文：</label>
  <textarea id="message" required></textarea><br>
  <button type="submit">发送邮件</button>
</form>

document.getElementById("emailForm").addEventListener("submit", function(event) {
  event.preventDefault(); // 阻止表单提交的默认行为

  var recipient = document.getElementById("recipient").value;
  var subject = document.getElementById("subject").value;
  var message = document.getElementById("message").value;

  var xhr = new XMLHttpRequest();
  xhr.open("POST", "https://example.com/email-api", true);
  xhr.setRequestHeader("Content-Type", "application/json");

  xhr.onreadystatechange = function() {
    if (xhr.readyState === XMLHttpRequest.DONE) {
      if (xhr.status === 200) {
        alert("邮件发送成功！");
      } else {
        alert("邮件发送失败，请稍后重试。");
      }
    }
  };

  var data = JSON.stringify({
    recipient: recipient,
    subject: subject,
    message: message
  });

  xhr.send(data);
});