wehub-resource-sync
59 lines
1.5 KiB
Markdown
59 lines
1.5 KiB
Markdown
# Infinite Scroll
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**Task:** "Load more items when the user scrolls to the bottom."
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## Without Ponytail
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```bash
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npm install react-infinite-scroll-component
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```
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```jsx
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import InfiniteScroll from "react-infinite-scroll-component";
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export function Feed({ items, fetchMore, hasMore }) {
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return (
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<InfiniteScroll
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dataLength={items.length}
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next={fetchMore}
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hasMore={hasMore}
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loader={<Spinner />}
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endMessage={<p>No more items</p>}
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scrollThreshold={0.9}
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>
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{items.map(item => <Card key={item.id} item={item} />)}
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</InfiniteScroll>
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);
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}
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```
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A dependency to watch scroll position and fire a callback.
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## With Ponytail
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```jsx
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// ponytail: IntersectionObserver does this, no scroll listener needed
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import { useEffect, useRef } from "react";
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export function Feed({ items, fetchMore, hasMore }) {
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const sentinel = useRef(null);
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useEffect(() => {
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const observer = new IntersectionObserver(([entry]) => {
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if (entry.isIntersecting && hasMore) fetchMore();
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});
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if (sentinel.current) observer.observe(sentinel.current);
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return () => observer.disconnect();
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}, [hasMore, fetchMore]);
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return (
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<>
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{items.map(item => <Card key={item.id} item={item} />)}
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<div ref={sentinel} />
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</>
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);
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}
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```
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**1 dependency → 0 dependencies.** `IntersectionObserver` fires only when the sentinel enters the viewport, no scroll event, no throttling, no jank. Ships in every browser. The library wraps exactly this API.
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