电子邮件和确认邮件匹配字段要求的自定义验证

<form>
  <label for="email">电子邮件地址：</label>
  <input type="email" id="email" name="email" required>
  <br>
  <label for="confirmEmail">确认电子邮件地址：</label>
  <input type="email" id="confirmEmail" name="confirmEmail" required>
  <br>
  <input type="submit" value="提交">
</form>

<script>
  const emailInput = document.getElementById('email');
  const confirmEmailInput = document.getElementById('confirmEmail');

  function validateEmail() {
    if (emailInput.value !== confirmEmailInput.value) {
      confirmEmailInput.setCustomValidity('确认邮件地址与输入的邮件地址不匹配');
    } else {
      confirmEmailInput.setCustomValidity('');
    }
  }

  emailInput.addEventListener('input', validateEmail);
  confirmEmailInput.addEventListener('input', validateEmail);
</script>