解决el-select数据量过大的3种方案

<template>
    <el-select 
      v-model="value" 
      clearable filterable 
      :filter-method="filterMethod">
      <el-option
        v-for="(item, index) in options.slice(0, 100)"
        :key="index"
        :label="item.label"
        :value="item.value">
      </el-option>
    </el-select>
 </template>
 export default {
  name: 'Demo',
  data() {
    return {
      options: [],
      value: ''
    }
  },
  beforeMount() {
    this.getList();
  },
  methods: {
    // 模拟获取大量数据
    getList() {
      for (let i = 0; i < 25000; i++) {
        this.options.push({label: "选择"+i,value:"选择"+i});
      } 
    },
    filterMethod(val) {
      console.log('filterMethod', val);
      this.options = this.options.filter(item => item.value.indexOf(val) > -1).slice(0, 100);
    },
    visibleChange() {
      console.log('visibleChange');
    }
  }
}

<template>
  <div class="dashboard-editor-container">
    <el-select 
      v-model="value" 
      clearable
      filterable 
      v-el-select-loadmore="loadMore"
      :filter-method="filterMethod">
      <el-option
        v-for="(item, index) in options"
        :key="index"
        :label="item.label"
        :value="item.value">
      </el-option>
    </el-select>
  </div>
</template>
<script>
export default {
  name: 'Demo',
  data() {
    return {
      options: [],
      value: '',
      pageNo: 0
    }
  },
  beforeMount() {
    this.getList();
  },
  methods: {
    // 模拟获取大量数据
    getList() {
      const data = [];
      for (let i = 0; i < 25000; i++) {
        data.push({label: "选择"+i,value:"选择"+i});
      }
      this.allData = data;
      this.data = data;
      this.getPageList()
    },
    getPageList(pageSize = 10) {
      this.pageNo++;
      const list = this.data.slice(0, pageSize * (this.pageNo));
      this.options = list;
    },
    loadMore() {
      this.getPageList();
    },
    filterMethod(val) {
      this.data = val ? this.allData.filter(item => item.label.indexOf(val) > -1) : this.allData;
      this.getPageList();
    }
  },
  directives:{
    'el-select-loadmore':(el, binding) => {
      // 获取element-ui定义好的scroll父元素
      const wrapEl = el.querySelector(".el-select-dropdown .el-select-dropdown__wrap");
      if(wrapEl){
        wrapEl.addEventListener("scroll", function () {
          /**
           * scrollHeight 获取元素内容高度(只读)
           * scrollTop 获取或者设置元素的偏移值,
           *  常用于:计算滚动条的位置, 当一个元素的容器没有产生垂直方向的滚动条, 那它的scrollTop的值默认为0.
           * clientHeight 读取元素的可见高度(只读)
           * 如果元素滚动到底, 下面等式返回true, 没有则返回false:
           * ele.scrollHeight - ele.scrollTop === ele.clientHeight;
           */
          if (this.scrollTop + this.clientHeight >= this.scrollHeight) {
            // binding的value就是绑定的loadmore函数
            binding.value();
          }
        });
      }
    },
  },
}
</script>
</script>

<template>
  <div class="dashboard-editor-container">
    <el-select 
      v-model="value" 
      clearable
      filterable >
      <virtual-list
          class="list"
          style="height: 360px; overflow-y: auto;"
          :data-key="'value'"
          :data-sources="data"
          :data-component="item"
          :estimate-size="50"
        />
    </el-select>
  </div>
</template>
<script>
import VirtualList from 'vue-virtual-scroll-list';
import Item from './item';
export default {
  name: 'Demo',
  components: {VirtualList, Item},
  data() {
    return {
      options: [],
      data: [],
      value: '',
      pageNo: 0,
      item: Item,
    }
  },
  beforeMount() {
    this.getList();
  },
  methods: {
    // 模拟获取大量数据
    getList() {
      const data = [];
      for (let i = 0; i < 25000; i++) {
        data.push({label: "选择"+i,value:"选择"+i});
      }
      this.allData = data;
      this.data = data;
      this.getPageList()
    },
    getPageList(pageSize = 10) {
      this.pageNo++;
      const list = this.data.slice(0, pageSize * (this.pageNo));
      this.options = list;
    },
    loadMore() {
      this.getPageList();
    }
  }
}
</script>
// item组件
<template>
    <el-option :label="source.label" :value="source.value"></el-option>
</template>
  <script>
  export default {
    name: 'item',
    props: {
      source: {
        type: Object,
        default() {
          return {}
        }
      }
    }
  }
  </script>
  <style scoped>
  </style>