在循环中执行异步XMLHttpRequests，并在所有请求完成后继续

function makeAsyncRequest(url, callback) {
  var xhr = new XMLHttpRequest();
  xhr.open('GET', url, true);
  xhr.onreadystatechange = function() {
    if (xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
      callback(xhr.responseText);
    }
  };
  xhr.send();
}

function executeAsyncRequests(urls, callback) {
  var counter = 0;
  var responses = [];

  for (var i = 0; i < urls.length; i++) {
    makeAsyncRequest(urls[i], function(response) {
      responses.push(response);
      counter++;

      if (counter === urls.length) {
        callback(responses);
      }
    });
  }
}

var urls = ['url1', 'url2', 'url3']; // 替换为实际的请求URL
executeAsyncRequests(urls, function(responses) {
  // 所有请求完成后的回调函数
  console.log(responses); // 处理响应数据
  // 继续执行后续操作
});