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)