<cn>
#### 滚动加载无限长列表
结合 [vue-virtual-scroller](https://github.com/Akryum/vue-virtual-scroller) 实现滚动加载无限长列表，带有虚拟化（[virtualization](https://blog.jscrambler.com/optimizing-react-rendering-through-virtualization/)）功能，能够提高数据量大时候长列表的性能。
可以结合 [vue-infinite-scroll](https://github.com/ElemeFE/vue-infinite-scroll) 实现滚动自动加载无限长列表。
`virtualized` 是在大数据列表中应用的一种技术，主要是为了减少不可见区域不必要的渲染从而提高性能，特别是数据量在成千上万条效果尤为明显。
</cn>

<us>
#### Infinite & virtualized
An example of infinite list & virtualized loading using [vue-virtual-scroller](https://github.com/Akryum/vue-virtual-scroller).
`Virtualized` rendering is a technique to mount big sets of data. It reduces the amount of rendered DOM nodes by tracking and hiding whatever isn't currently visible.
</us>

```html
<template>
  <a-list>
    <virtual-scroller
      style="height: 400px"
      :items="data"
      item-height="73"
      v-infinite-scroll="handleInfiniteOnLoad"
      :infinite-scroll-disabled="busy"
      :infinite-scroll-distance="10"
    >
      <a-list-item slot-scope="{item}">
        <a-list-item-meta :description="item.email">
          <a slot="title" :href="item.href">{{item.name.last}}</a>
          <a-avatar slot="avatar" src="https://zos.alipayobjects.com/rmsportal/ODTLcjxAfvqbxHnVXCYX.png" />
        </a-list-item-meta>
        <div>Content {{item.index}}</div>
      </a-list-item>
    </virtual-scroller>
    <a-spin v-if="loading"  class="demo-loading" />
  </a-list>
</template>
<script>
import reqwest from 'reqwest'
import infiniteScroll from 'vue-infinite-scroll'
import { VirtualScroller } from 'vue-virtual-scroller'
const fakeDataUrl = 'https://randomuser.me/api/?results=10&inc=name,gender,email,nat&noinfo'
export default {
  directives: { infiniteScroll },
  data () {
    return {
      data: [],
      loading: false,
      busy: false,
    }
  },
  beforeMount () {
    this.fetchData((res) => {
      this.data = res.results.map((item, index) => ({ ...item, index }))
    })
  },
  methods: {
    fetchData (callback) {
      reqwest({
        url: fakeDataUrl,
        type: 'json',
        method: 'get',
        contentType: 'application/json',
        success: (res) => {
          callback(res)
        },
      })
    },
    handleInfiniteOnLoad  () {
      const data = this.data
      this.loading = true
      if (data.length > 100) {
        this.$message.warning('Infinite List loaded all')
        this.busy = true
        this.loading = false
        return
      }
      this.fetchData((res) => {
        this.data = data.concat(res.results).map((item, index) => ({ ...item, index }))
        this.loading = false
      })
    },
  },
  components: {
    'virtual-scroller': VirtualScroller,
  },
}
</script>
<style>
.demo-loading {
  position: absolute;
  bottom: 40px;
  width: 100%;
  text-align: center;
}
</style>
```
