前端工程师必知的 MCP 秘籍 包含渲染优化与性能提升等长尾知识要点

   npm install -g lighthouse

 import { getCLS, getFID, getLCP } from 'web-vitals';
   getCLS(console.log);
   getFID(console.log);
   getLCP(console.log);

// main.js
   const worker = new Worker('worker.js');
   worker.postMessage(data);
   worker.onmessage = (e) => {
     console.log('计算结果:', e.data);
   };

   // worker.js
   self.onmessage = (e) => {
     const result = heavyCalculation(e.data);
     self.postMessage(result);
   };

function processLargeData(data) {
     const chunkSize = 100;
     let index = 0;

     function processChunk(deadline) {
       while (index < data.length && deadline.timeRemaining() > 1) {
         // 处理数据块
         processData(data[index]);
         index++;
       }

       if (index < data.length) {
         requestIdleCallback(processChunk);
       }
     }

     requestIdleCallback(processChunk);
   }

   import { FixedSizeList } from 'react-window';

   const Row = ({ index, style }) => (
     <div style={style}>{items[index]}</div>
   );

   const List = () => (
     <FixedSizeList
       height={600}
       width={800}
       itemSize={35}
       itemCount={items.length}
     >
       {Row}
     </FixedSizeList>
   );

   const AsyncComponent = defineAsyncComponent(() =>
     import('./components/HeavyComponent.vue')
   );

   element.style.width = '100px';
   const width = element.offsetWidth; // 强制同步布局

   // 好的写法
   const width = element.offsetWidth; // 先读取
   element.style.width = '100px'; // 再写入

   const element = document.getElementById('my-element');
   element.classList.add('new-class');
   element.style.color = 'red';
   element.style.fontSize = '20px';

   // 使用DocumentFragment
   const fragment = document.createDocumentFragment();
   for (let i = 0; i < 1000; i++) {
     const div = document.createElement('div');
     fragment.appendChild(div);
   }
   document.body.appendChild(fragment);

 .animate-element {
     /\* 触发合成层 \*/
     will-change: transform;
     transform: translateZ(0);
   }

 /\* 谨慎使用will-change \*/
   .element {
     /\* 只在需要动画时添加will-change \*/
     will-change: opacity;
   }

   .element.animating {
     animation: fade 1s;
   }

// 使用Performance API测量渲染时间
   console.time('product-list-render');
   renderProductList(products);
   console.timeEnd('product-list-render');

   import { VirtualizedList } from 'react-native';

   const ProductList = ({ products }) => (
     <VirtualizedList
       data={products}
       renderItem={({ item }) => <ProductCard product={item} />}
       keyExtractor={(item) => item.id}
       getItemCount={(data) => data.length}
       getItem={(data, index) => data[index]}
       initialNumToRender={10}
       windowSize={21}
     />
   );

 /\* 优化图片加载 \*/
   .product-image {
     width: 100%;
     height: 200px;
     object-fit: cover;
     /\* 占位符颜色 \*/
     background-color: #f0f0f0;
     /\* 图片懒加载 \*/
     loading: lazy;
   }

   /\* 避免布局抖动 \*/
   .product-card {
     min-height: 300px;
   }

 // service-worker.js
   self.addEventListener('fetch', (event) => {
     event.respondWith(
       caches.match(event.request)
         .then((response) => {
           if (response) {
             return response;
           }
           return fetch(event.request);
         })
     );
   });

   const cache = new Map();

   async function fetchData(url) {
     if (cache.has(url)) {
       return cache.get(url);
     }

     const response = await fetch(url);
     const data = await response.json();
     cache.set(url, data);
     return data;
   }

<!-- 预加载关键资源 -->
   <link rel="preload" href="font.woff2" as="font" crossorigin>
   <link rel="preload" href="main.js" as="script">

   <link rel="prerender" href="https://example.com/checkout">

// 初始化Sentry
   import \* as Sentry from '@sentry/browser';

   Sentry.init({
     dsn: 'YOUR\_DSN',
     integrations: [new Sentry.BrowserTracing()],
     tracesSampleRate: 1.0,
   });

// 监控关键路径性能
   const start = performance.now();

   // 关键操作
   loadCriticalResources().then(() => {
     const end = performance.now();
     console.log(`关键资源加载时间: ${end - start}ms`);
   });

   npm install -g @lhci/cli

   # 配置Lighthouse CI
   lhci autorun