Talk is cheap, show code!
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.list-wrap {
position: relative;
overflow-y: scroll;
width: 200px;
margin: 100px auto;
box-sizing: border-box;
border: solid 1px red;
}
.list {
position: absolute;
top: 0;
left: 0;
}
.list li {
border: solid 1px blue;
line-height: 30px;
}
</style>
</head>
<body>
<ul id="app">
<div class="list-wrap" ref="listWrap" @scroll="scrollListener">
<div class="scroll-bar" ref="scrollBar"></div>
<ul class="list" ref="list">
<li v-for="val in showList">{{val}}</li>
</ul>
</div>
</ul>
<script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.14/vue.common.dev.js"></script>
<script>
new Vue({
el: '#app',
data() {
return {
listWrapElem: null,
scrollBarElem: null,
listElem: null,
list: [],//超长的显示数据
itemHeight: 30,//每一列的高度
showNum: 10,//显示几条数据
start: 0,//滚动过程显示的开始索引
end: 10,//滚动过程显示的结束索引
}
},
computed: {
//显示的数组，用计算属性计算
showList() {
return this.list.slice(this.start, this.end);
}
},
mounted() {
//构造一个超长列表
for (let i = 0; i < 10000; i++) {
this.list.push('列表' + i)
}
this.listWrapElem = this.$refs.listWrap
this.scrollBarElem = this.$refs.scrollBar
this.listElem = this.$refs.list
//计算滚动容器高度
this.listWrapElem.style.height = this.itemHeight * this.showNum + 'px';
//计算总的数据需要的高度，构造滚动条高度
this.scrollBarElem.style.height = this.itemHeight * this.list.length + 'px';
},
methods: {
scrollListener() {
//获取滚动高度
let scrollTop = this.listWrapElem.scrollTop;
//开始的数组索引
this.start = Math.floor(scrollTop / this.itemHeight);
//结束索引
this.end = this.start + this.showNum;
//绝对定位对相对定位的偏移量
this.listElem.style.top = this.start * this.itemHeight + 'px';
}
}
})
</script>
</body>
</html>
