[JavaScript知识库]vue-table数据量上万卡顿解决（指令）

场景

前端UI框架使用的是ElementUI,项目要求数据不分页一个表格至少要1000条数据，这时点击其他DOM操作，会出现卡顿的现象。如点击复选框。

现状

已解决3000条数据点击其他DOM操作卡顿的问题。

求助

助如何解决初次放入数据时卡顿的情况？（内附解决加载完成后卡顿的思路）**

结果分享

优化了大概三个版本，保留第一次的分享的，后面直接贴出最终版
解决3000条数据点击其他DOM操作卡顿的思路
通过指令添加表格滚动后的事件，设置非显示区域的其他DOM节点隐藏。

基于elementUI的table，在不修改源码的情况下支持大数据了渲染的场景

loadmore.js

var spillDataNum = 120;
// 设置默认溢出显示数量 比如当前显示 5 条    spillDataNum的值就是还有120条还没显示
// 设置隐藏函数
var timeout = false;
let setRowDisableNone = function (topNum, showRowNum, binding) {
  if (timeout) {
    clearTimeout(timeout);
  }
  timeout = setTimeout(() => {
    console.log('event argument----->')
    console.log(topNum, topNum + showRowNum + spillDataNum)
    //topNum是开始下标, topNum + showRowNum + spillDataNum  是结束下标
    binding.value.call(null, topNum, topNum + showRowNum + spillDataNum);
  });
};
export default {
  name: 'loadmore',
  componentUpdated: function (el, binding, vnode, oldVnode) {
    setTimeout(() => {
      const dataSize = vnode.data.attrs['data-size'];
      const oldDataSize = oldVnode.data.attrs['data-size'];
      console.error('size------------->')
      console.log(dataSize,oldDataSize)
      if(dataSize === oldDataSize){
        return;
      }
      const selectWrap = el.querySelector('.el-table__body-wrapper');
      const selectTbody = selectWrap.querySelector('table tbody');
      const selectRow = selectWrap.querySelector('table tr');
      if (!selectRow) {
        return;
      }
      const rowHeight = selectRow.clientHeight;
      let showRowNum = Math.round(selectWrap.clientHeight / rowHeight);
      console.error('showRowNum------------->')
      console.log(selectWrap.clientHeight,showRowNum)
      const createElementTR = document.createElement('tr');
      let createElementTRHeight = (dataSize - showRowNum - spillDataNum) * rowHeight;
      createElementTR.setAttribute('style', `height: ${createElementTRHeight}px;`);
      selectTbody.append(createElementTR);

      // 监听滚动后事件
      selectWrap.addEventListener('scroll', function () {
        //滚动当前距离大于spillDataNum 数量的时候高度topPx  从而得出topNum 数量的个数
        let topPx = this.scrollTop - spillDataNum * rowHeight;
        let topNum = Math.round(topPx / rowHeight);
        let minTopNum = dataSize - spillDataNum - showRowNum;
        //最后的高度不会大于展示的数据加溢出的数据高度  
        if (topNum > minTopNum) {
          topNum = minTopNum;
        }
        if (topNum < 0) {
          topNum = 0;
          topPx = 0;
        }
        selectTbody.setAttribute('style', `transform: translateY(${topPx}px)`);
        //初始化的高度是createElementTRHeight 滚动之后需要减去滚动的高度
        createElementTR.setAttribute('style', `height: ${createElementTRHeight-topPx > 0 ? createElementTRHeight-topPx : 0}px;`);
        setRowDisableNone(topNum, showRowNum, binding);
      })
    });
  }
};

main.js

add代码文件
import loadmore from './directive/loadmore'
Vue.directive(loadmore.name,loadmore.componentUpdated);

table文件

<template>
  <div>
    <el-table border :data="filteredData" style="width: 100%" height="300" :data-size="tableData.length" v-loadmore="handelLoadmore">
      <el-table-column type="selection" width="55">
      </el-table-column>
      <el-table-column label="日期" width="180">
        <template slot-scope="scope">
          <div>
            <i class="el-icon-time"></i>
            <span style="margin-left: 10px">{{ scope.row.date }}</span>
          </div>
        </template>
      </el-table-column>
      <el-table-column label="日期" width="180">
        <template slot-scope="scope">
          <div>
            <i class="el-icon-time"></i>
            <span style="margin-left: 10px">{{ scope.row.date }}</span>
          </div>
        </template>
      </el-table-column>
      <el-table-column label="日期" width="180">
        <template slot-scope="scope">
          <div>
            <i class="el-icon-time"></i>
            <span style="margin-left: 10px">{{ scope.row.date }}</span>
          </div>
        </template>
      </el-table-column>
      <el-table-column label="日期" width="180">
        <template slot-scope="scope">
          <div>
            <i class="el-icon-time"></i>
            <span style="margin-left: 10px">{{ scope.row.date }}</span>
          </div>
        </template>
      </el-table-column>
      <el-table-column label="姓名" width="180">
        <template slot-scope="scope">
          <div>
            <el-popover trigger="hover" placement="top">
              <p>姓名: {{ scope.row.name }}</p>
              <p>住址: {{ scope.row.address }}</p>
              <div slot="reference" class="name-wrapper">
                <el-tag size="medium">{{ scope.row.name }}</el-tag>
              </div>
            </el-popover>
          </div>
        </template>
      </el-table-column>
      <el-table-column label="操作">
        <template slot-scope="scope">
          <div>
            <el-button size="mini"  @click="handleEdit(scope.$index, scope.row)">编辑</el-button>
            <el-button size="mini" type="danger"  @click="handleDelete(scope.$index, scope.row)">删除</el-button>
          </div>
        </template>
      </el-table-column>
    </el-table>
  </div>
</template>

<script>

export default {
  name: 'test',
  components: {},
  data () {
    return {
      tableData: [],
      currentStartIndex: 0,
      currentEndIndex: 20
    };
  },
  created () {
    this.getTableData();
  },
  computed: {
    filteredData () {
      return this.tableData.filter((item, index) => {
        if (index < this.currentStartIndex) {
          return false;
        } else if (index > this.currentEndIndex) {
          return false;
        } else {
          return true;
        }
      });
    }
  },
  methods: {
    handelLoadmore (currentStartIndex, currentEndIndex) {
      console.log(currentStartIndex, currentEndIndex)
      // 23687 23712
      //23688 23713
      this.currentStartIndex = currentStartIndex;
      this.currentEndIndex = currentEndIndex;
    },
    getTableData () {
      let cont = 0;
      let tableData = [];
      while (cont < 30000) {
        cont = cont + 1;
        let object = {
          date: cont,
          name: '王小虎' + cont,
          address: '上海市普陀区金沙江路 cont 弄'
        }
        tableData.push(object);
      }
      setTimeout(() => {
        this.tableData = tableData;
      }, 2000);
    }
  },
  watch: {}
}
</script>

<style scoped>
.el-table__body-wrapper .el-table__row td {
  display: none;
}
.el-table__body-wrapper .el-table__row {
  height: 38px;
}
</style>