// 使用CDN加速静态资源
const CDN_URL = 'https://your-cdn-domain.com/api/data';

// 减少请求数据量，只请求必要字段
fetch('/api/data?fields=id,name,date')
  .then(response => response.json())
  .then(data => console.log(data));

// 使用压缩传输
fetch('/api/data', {
  headers: {
    'Accept-Encoding': 'gzip, deflate'
  }
});

// 实现分页加载
const page = 1;
const pageSize = 20;
fetch(`/api/data?page=${page}&pageSize=${pageSize}`);

// 设置合理的超时时间
const controller = new AbortController();
const signal = controller.signal;

setTimeout(() => controller.abort(), 5000); // 5秒超时

fetch('/api/data', { signal })
  .then(response => response.json())
  .catch(err => {
    if (err.name === 'AbortError') {
      console.log('请求超时');
    }
  });

// 使用Web Workers处理大数据
const worker = new Worker('data-processor.js');
worker.postMessage(largeData);
worker.onmessage = (e) => {
  console.log('处理完成', e.data);
};

// 使用本地缓存
async function fetchWithCache(url) {
  const cacheKey = `cache_${url}`;
  const cachedData = localStorage.getItem(cacheKey);
  
  if (cachedData) {
    return JSON.parse(cachedData);
  }
  
  const response = await fetch(url);
  const data = await response.json();
  
  localStorage.setItem(cacheKey, JSON.stringify(data));
  return data;
}

// 使用请求合并
let pendingRequests = {};

async function getData(key) {
  if (pendingRequests[key]) {
    return pendingRequests[key];
  }
  
  const promise = fetch(`/api/data/${key}`);
  pendingRequests[key] = promise;
  
  try {
    const response = await promise;
    const data = await response.json();
    delete pendingRequests[key];
    return data;
  } catch (error) {
    delete pendingRequests[key];
    throw error;
  }
}

// 使用节流减少频繁请求
let lastRequestTime = 0;
const throttleDelay = 1000; // 1秒

function throttledFetch(url) {
  const now = Date.now();
  if (now - lastRequestTime < throttleDelay) {
    return Promise.reject('请求过于频繁');
  }
  lastRequestTime = now;
  return fetch(url);
}

// 测量请求时间
function measureRequest(url) {
  const start = performance.now();
  
  return fetch(url)
    .then(response => {
      const duration = performance.now() - start;
      console.log(`请求耗时: ${duration.toFixed(2)}ms`);
      return response;
    });
}

// 使用Performance API分析
performance.mark('ajaxStart');
fetch('/api/data')
  .then(() => {
    performance.mark('ajaxEnd');
    performance.measure('ajaxRequest', 'ajaxStart', 'ajaxEnd');
    const measures = performance.getEntriesByName('ajaxRequest');
    console.log('请求耗时:', measures[0].duration);
  });