如何仅通过响应头获得ajax承诺？

function makeAjaxRequest(url) {
  return new Promise(function(resolve, reject) {
    var xhr = new XMLHttpRequest();
    xhr.open('GET', url, true);
    xhr.onreadystatechange = function() {
      if (xhr.readyState === 4) {
        if (xhr.status === 200) {
          resolve(xhr.responseText);
        } else {
          reject(xhr.statusText);
        }
      }
    };
    xhr.send();
  });
}

var url = 'https://example.com/api/data';
makeAjaxRequest(url)
  .then(function(response) {
    console.log('请求成功:', response);
  })
  .catch(function(error) {
    console.log('请求失败:', error);
  });

function makeAjaxRequest(url) {
  return fetch(url)
    .then(function(response) {
      if (!response.ok) {
        throw new Error(response.statusText);
      }
      return response.text();
    });
}

var url = 'https://example.com/api/data';
makeAjaxRequest(url)
  .then(function(response) {
    console.log('请求成功:', response);
  })
  .catch(function(error) {
    console.log('请求失败:', error);
  });