前端虚拟列表实现：避免万级 DOM 节点渲染
为什么需要虚拟列表
一次性渲染大量列表项（如 5000+）会导致页面卡顿，严重影响用户体验。
反面案例
function BigList({ items }) {
return (
<ul style={{ height: '400px', overflow: 'auto' }}>
{items.map(item => (
<li key={item.id} style={{ height: '50px' }}>{item.name}</li>
))}
</ul>
);
}
// 使用示例
<BigList items={Array.from({ length: 10000 }, (_, i) => ({ id: i, name: `Item ${i}` }))} />
基础实现
import { useState, useRef, useMemo, useCallback } from 'react';
function VirtualList({ items, itemHeight, containerHeight }) {
const [scrollTop, setScrollTop] = useState(0);
const containerRef = ();
visibleCount = .(containerHeight / itemHeight);
totalHeight = items. * itemHeight;
startIndex = .(scrollTop / itemHeight);
endIndex = .(startIndex + visibleCount + , items.);
visibleItems = ( {
items.(startIndex, endIndex);
}, [items, startIndex, endIndex]);
offsetY = startIndex * itemHeight;
handleScroll = ( {
(e..);
}, []);
(
);
}