el-table滚动加载、懒加载（自定义指令）

我们在实际工作中会遇到这样的问题：

应客户要求，某一个列表不允许分页。但是不分页的话，如果遇到大量的数据加载，不但后端响应速度变慢，前端的渲染效率也会降低，页面出现明显的卡顿。

那如何解决这个问题呢 

 我们可以用模拟分页，当滚动条滚动到底部时再次加载剩余的部分数据，触底加载，直到加载完成。

先看一个线上的演示示例：

https://code.juejin.cn/pen/7273420104565456953

开发思想参考：

https://blog.csdn.net/weixin_43340372/article/details/132601018?spm=1001.2014.3001.5501

代码

 
<div id="app">
  <el-table
      :data="tableData"
      height="300"
      row-key="id"
      border
      size="mini"
      v-el-table-lazyloading="lazyloading"
    >
      <el-table-column prop="date" label="日期" width="180"> el-table-column>
      <el-table-column prop="name" label="姓名" width="180"> el-table-column>
      <el-table-column prop="address" label="地址"> el-table-column>
    el-table>
div>
 
<script>
// 伪造接口调用
class Api {
  #baseData = [{
    date: '2016-05-03',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-02',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-04',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-01',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-08',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-06',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-07',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-07',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-07',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }, {
    date: '2016-05-07',
    name: '王小虎',
    address: '上海市普陀区金沙江路 1518 弄'
  }]
  getData(currentPage = 1, pageNumber = 10) {
    return new Promise(resolve => {
      setTimeout(() => {
        let data = [];
        if (currentPage > 1) {
          data = this.#baseData.map(item => ({...item, name: item.name + `currentPage-${currentPage}`, address: item.address + `currentPage-${currentPage}` }))
        } else {
          data = this.#baseData;
        }
        resolve(data);
      }, 1000
      )
    })
  }
}
const api = new Api();
// 全局注册组件
new Vue({
  el: '#app',
  directives: {
    "el-table-lazyloading": {
      bind(el, binding) {
        let SELECT_DOM = el.querySelector(".el-table__body-wrapper");
        console.log("SELECT_DOM",SELECT_DOM)
        SELECT_DOM.addEventListener("scroll", function () {
          let condition =
            this.scrollHeight - this.scrollTop <= this.clientHeight;
          if (condition) {
            binding.value();
          }
        });
      },
    },
  },
  data() {
    return {
      currentPage: 1,
      pageNumber: 10,
      value: "",
      tableData: [],
    };
  },
  methods: {
    async lazyloading() {
      this.loading = true;
      const data = await api.getData(this.currentPage);
      this.loading = false;
      this.tableData.push(...data);
      this.currentPage++;
    }
  },
  mounted() {
    this.lazyloading();
  }
})
 
script>