vxe-select 下拉列表使用虚拟滚动加载上万选项列表

官网：https://vxeui.com

正常使用下拉框加载上万列表选项非常卡，使用虚拟滚的的下拉框之后就可以毫秒加载 50万行下拉选项

<template>
  <div>
    <p>
      <vxe-button @click="loadData(100)">加载1百条</vxe-button>
      <vxe-button @click="loadData(500)">加载5百条</vxe-button>
      <vxe-button @click="loadData(1000)">加载1千条</vxe-button>
    </p>
    <vxe-select v-model="val1" :options="opts1" :loading="loading" clearable filterable>
      <vxe-option v-for="item in opts1" :key="item.value" :value="item.value" :label="item.label"></vxe-option>
    </vxe-select>
  </div>
</template>

<script>
export default {
  data () {
    return {
      val1: null,
      loading: false,
      opts1: []
    }
  },
  methods: {
    loadData (size) {
      const list = []
      this.loading = true
      for (let i = 0; i < size; i++) {
        list.push({
          value: `${i}`,
          label: `选项 ${i}`
        })
      }
      setTimeout(() => {
        this.opts1 = list
        this.loading = false
      }, 300)
    }
  },
  created () {
    this.loadData(50)
  }
}
</script>