使用XMLHttpRequest发送后，请求在nodejs服务器上挂起

const xhr = new XMLHttpRequest();
xhr.open('GET', 'http://example.com/api', true);
xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    // 处理响应数据
    console.log(xhr.responseText);
  }
};
xhr.send();

function request(url) {
  return new Promise(function(resolve, reject) {
    const 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();
  });
}

request('http://example.com/api')
  .then(function(response) {
    // 处理响应数据
    console.log(response);
  })
  .catch(function(error) {
    // 处理错误
    console.error(error);
  });

async function fetchData(url) {
  const response = await fetch(url);
  const data = await response.text();
  return data;
}

fetchData('http://example.com/api')
  .then(function(response) {
    // 处理响应数据
    console.log(response);
  })
  .catch(function(error) {
    // 处理错误
    console.error(error);
  });