Priority Hints 与 fetchpriority 优化资源加载实战

HTML 示例：<img src="/hero.jpg" width="1200" height="600" fetchpriority="high" alt="hero"> <img src="/below-the-fold.jpg" width="1200" height="600" fetchpriority="low" alt="below"> 预加载脚本：<link rel="preload" as="script" href="/app-critical.js" fetchpriority="high"> 脚本内控制：const link = document.createElement('link') link.rel = 'preload' link.as = 'style' link.href = '/app.css' link.fetchPriority = 'high' document.head.appendChild(link)