38 lines
1.1 KiB
TypeScript
38 lines
1.1 KiB
TypeScript
"use client";
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import { useEffect, useRef, useState, type ReactNode } from "react";
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export default function LazySection({ children }: { children: ReactNode }) {
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const ref = useRef<HTMLDivElement>(null);
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const [mounted, setMounted] = useState(false);
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useEffect(() => {
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const el = ref.current;
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if (!el) return;
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// iOS < 12.2 has no IntersectionObserver — mount everything immediately.
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if (!("IntersectionObserver" in window)) {
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setMounted(true);
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return;
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}
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const observer = new IntersectionObserver(
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([entry]) => {
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// intersectionRatio > 0 guards against a Safari bug where
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// isIntersecting fires as false on the initial sync callback.
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if (entry.isIntersecting || entry.intersectionRatio > 0) {
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setMounted(true);
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observer.disconnect();
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}
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},
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{ rootMargin: "1000px 0px" },
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);
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observer.observe(el);
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return () => observer.disconnect();
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}, []);
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// min-height: 1px prevents the wrapper collapsing to zero height before
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// content mounts, which would cause iOS to jump scroll position on mount.
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return <div ref={ref} style={{ minHeight: "1px" }}>{mounted ? children : null}</div>;
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}
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