XMLHttpRequest OnReadyStateChange不在IE11上返回正确的状态

Question

我有此表单来填写电子邮件地址并提交按钮，如果服务器成功处理了电子邮件地址，则应显示成功组件，如果没有成功，则应显示错误组件，现在提交时，Chrome和IE11都将发送从服务器到电子邮件地址的电子邮件成功，但是只有chrome显示成功消息，而IE11首先显示错误消息，然后显示成功消息。我想知道是什么问题？

Form.addEventListener('submit', function(e) {
e.preventDefault();
handleSubmit();
});


function handleSubmit() {
var url = 'https://serveURLXXXXX';
var xhr = new XMLHttpRequest();
xhr.open('POST', url, true);
xhr.responseType = 'json';
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.onerror = function () {
  console.log('** An error occurred while sending email address.');
};
xhr.onreadystatechange = function (oEvent) {
  if (xhr.readyState === 4 && xhr.status === 200) {
    emailSuccess.style.display = 'block'; //(here an component will show: 
you email has been sent, successfully)
  } else {
    emailError.style.display = 'block';  //(there is someting wrong with 
the email sending).
  }
};
xhr.send(
  JSON.stringify({email: emailAddressInput.value})
);
}