async function sequentialRequests(urls) {
  const results = [];
  for (const url of urls) {
    try {
      const response = await fetch(url);
      const data = await response.json();
      results.push(data);
    } catch (error) {
      console.error(`Request failed for ${url}:`, error);
      results.push(null); // 或用其他方式处理错误
    }
  }
  return results;
}

// 使用示例
sequentialRequests(['/api/data1', '/api/data2', '/api/data3'])
  .then(results => console.log(results));

function orderedParallelRequests(urls) {
  const promises = urls.map(url => fetch(url).then(res => res.json()));
  
  return Promise.all(promises).then(results => {
    // 结果已经按请求顺序排列
    return results;
  });
}

// 使用示例
orderedParallelRequests(['/api/data1', '/api/data2', '/api/data3'])
  .then(results => console.log(results));

class RequestQueue {
  constructor() {
    this.queue = [];
    this.isProcessing = false;
  }

  add(url, callback) {
    this.queue.push({ url, callback });
    if (!this.isProcessing) {
      this.processNext();
    }
  }

  processNext() {
    if (this.queue.length === 0) {
      this.isProcessing = false;
      return;
    }

    this.isProcessing = true;
    const { url, callback } = this.queue.shift();
    
    fetch(url)
      .then(res => res.json())
      .then(data => {
        callback(null, data);
        this.processNext();
      })
      .catch(error => {
        callback(error);
        this.processNext();
      });
  }
}

// 使用示例
const queue = new RequestQueue();
queue.add('/api/data1', (err, data) => console.log('Response 1:', data));
queue.add('/api/data2', (err, data) => console.log('Response 2:', data));
queue.add('/api/data3', (err, data) => console.log('Response 3:', data));

function orderedRequests(urls) {
  const requests = urls.map((url, index) => 
    fetch(url)
      .then(res => res.json())
      .then(data => ({ index, data }))
  );

  return Promise.all(requests)
    .then(results => {
      // 按原始顺序排序
      results.sort((a, b) => a.index - b.index);
      // 返回数据数组
      return results.map(result => result.data);
    });
}

// 使用示例
orderedRequests(['/api/data1', '/api/data2', '/api/data3'])
  .then(results => console.log(results));