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listWithFixedHeightAndPadding.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>固定高度虚拟列表</title>
<style>
html,
body {
width: 100%;
height: 100%;
margin: 0px;
}
.container {
width: 100%;
height: 100vh;
overflow: auto;
}
.item {
background-color: darkgray;
width: 100%;
border: thick solid darkgreen;
text-align: center;
}
</style>
</head>
<body>
<div class="container">
<div class="virtual_list"></div>
</div>
<script>
const container = document.querySelector('.container')
const virtualList = document.querySelector('.virtual_list')
const dataSource = Array.from({ length: 100 }, (v, i) => i )
const ITEM_HEIGTH = 100;
const SCROLL_CONTENT_HEIGHT = ITEM_HEIGTH * (dataSource.length); // 滚动区域大小
const CONTAINER_HEIGHT = container.clientHeight; //滚动窗口高度;
const ITEM_COUNT = Math.ceil(CONTAINER_HEIGHT/ITEM_HEIGTH); // 当前视图show出来的数量
const PADDING_ITEM = 5
function showCurrentList(target) {
let scrollTop = target.scrollTop; // 当前视图的scrollTop
let startIdx = Math.floor(scrollTop / ITEM_HEIGTH); // 开始值；
let endIdx = startIdx + ITEM_COUNT + PADDING_ITEM;
let itemList = '';
const paddingTop = startIdx * ITEM_HEIGTH
virtualList.setAttribute('style', `padding-top:${paddingTop}px;`)
startIdx = startIdx - PADDING_ITEM > 0 ? startIdx - PADDING_ITEM : startIdx
endIdx = endIdx > dataSource.length ? dataSource.length : endIdx
for (let i = startIdx; i < endIdx; i++) {
const element = dataSource[i];
itemList += `<div class="item" style="height:${ITEM_HEIGTH}px">${element}</div>`
}
virtualList.innerHTML = itemList;
}
showCurrentList(container)
container.addEventListener('scroll', (event) => {
showCurrentList(event.target)
})
</script>
</body>
</html>