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オンラインプログラム

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function prefetch(nodeList) { if (navigator.connection && (navigator.connection.effectiveType === 'slow-2g' || navigator.connection.effectiveType === '2g')) { return; } if (navigator.deviceMemory && navigator.deviceMemory <= 2) { return; } const fetched = {}; const observer = new IntersectionObserver(function (entries) { entries.forEach(function (entry) { if (entry.isIntersecting) { const link = entry.target.href; if (!fetched[link]) { fetched[link] = true; fetch(link, { priority: 'low' }); } observer.unobserve(entry.target); } }); }); nodeList.forEach(link => observer.observe(link)); } const idleCallback = window.requestIdleCallback || function (cb) { return setTimeout(() => cb(), 1); }; idleCallback(function () { const links = document.querySelectorAll('a[href]'); prefetch(links); });