Element 懒加载表格el-table数据实现全选功能

<el-table 
          v-loading="loading.list"
          ref="table"
          :data="tableData"
          style=" 100%"
          max-height="400"
          border
          lazy
          row-key="key"
          :tree-props="{children: 'children', hasChildren: 'hasChildren'}"
          :load="load"
          :header-cell-class-name="cellClass"
          @select="selectRow"
          @selection-change="selectionChange"
                    @select-all="selectAll">
          <el-table-column
            type="selection"
            width="55">
          </el-table-column>
          <el-table-column prop="key" label="编号"></el-table-column>
          <el-table-column prop="identityName" label="姓名"></el-table-column>
        </el-table>

data() {
    return {
      form: {
        dimId: 1,
        name: '',
        key: '',
        tenantId: ''
      },
      treeData: [],
      tableData: [],
      loading: {
        tree: false
      },
      multipleSelection: [],
      tableAllData: [], // 存储所有的表格数据
      checkAll: false, // 判断当前是否全选
    } 
  },

// 全选
selectAll(selection) {
      this.checkAll = !this.checkAll;
      this.tableAllData.map(row => {
        this.$refs.table.toggleRowSelection(row, this.checkAll);
      })
},
async load(row, treeNode, resolve) {
      try {
        let self = this;
        let params = { parentId: row.groupId, groupId: row.groupId }
        const data = await getOrganizeList({ ...self.form }, params)
        let arr = data.map(item => {
          return {
            ...item,
            hasChildren: item.childs && item.childs > 0,
            children: []
          }
        })
        this.tableAllData = this.tableAllData.concat(arr) // 保存表格数据
        resolve(arr)
        return 

      } catch (error) {
        console.log(error)
      }
},