ElementUI Table组件，如何在多页数据下勾选多行

ElementUI Table组件，选择多行数据时使用 Checkbox。如下图：

但是业务中，表格数据往往不只一页。多页数据情况下，表格勾选某些行，就会遇到返回上一页，勾选消失的情况。这种情况，需要一些技巧和处理。具体代码如下：

<template>
  <div class="demo-example">
    <el-table
      ref="table"
      v-loading="loading"
      :data="list"
      height="650"
      border
      @select="onSelect"
      @select-all="onSelectAll"
      @selection-change="onSelectionChange"
    >
      <el-table-column type="selection" width="55"></el-table-column>
      <el-table-column prop="u_createTime" label="注册时间"></el-table-column>
      <el-table-column prop="u_id" label="用户ID"></el-table-column>
      <el-table-column prop="u_nickname" label="用户名称"></el-table-column>
      <el-table-column prop="u_phone" label="用户账户"></el-table-column>
      <el-table-column prop="u_gender" label="性别"></el-table-column>
      <el-table-column label="角色">
        <template slot-scope="scope">
          <span>{{scope.row.u_role === 1 ? '团队长' : '保险人'}}</span>
        </template>
      </el-table-column>
      <el-table-column prop="u_companyNum" label="所属企业数量"></el-table-column>
      <el-table-column prop="ha_addPeople" label="所属群组">
        <template slot-scope="scope">
          <el-button @click="onChakan(scope.row)" type="text" style="color:#67c23a" size="small">查看</el-button>
        </template>
      </el-table-column>
      <el-table-column prop="u_lastLoginTime" label="最近登录时间"></el-table-column>
    </el-table>

    <div class="block pag" v-if="total">
      <el-pagination
        @current-change="onChangePage"
        :current-page="currentPage"
        :page-size="10"
        layout="total, prev, pager, next, jumper"
        :total="total"
      ></el-pagination>
    </div>
  </div>
</template>
<script>

export default {
  data() {
    return {
      selections: {}, // 保存已选择过的row
      list: [],
      total: 0,
      curPage: 1,
    };
  },

  //方法事件
  methods: {
    // 勾选时候，记录[{u_id: row}, ...]
    onSelect(selection, row) {
      if (this.selections[row.u_id]) {
        delete this.selections[row.u_id];
      } else {
        this.selections[row.u_id] = row;
      }
    },

    // 全选情况
    onSelectAll(selection) {
        // 全选
        if (selection.length) {
            selection.forEach(row => {
                this.selections[row.u_id] = row;
            })
        } else {
            // 取消全选
            this.list.forEach(row => {
                delete this.selections[row.u_id];
            })
        }

    },

    // 对已选择过的row勾选，返回到上一页时候
    checkRows() {
      const keys = Object.keys(this.selections);
      const rows = this.list.filter(row => {
        return keys.includes(String(row.u_id));
      });

      rows.map(row => {
        this.$refs.table.toggleRowSelection(row);
      });
    },

    // 省略...

    // 获取数据列表
    getData() {
      // ...
    },

  },

  created() {
    this.getData();
  }
};
</script>

现在分页切换，勾选依然会显示，对应每页勾选过的行数据。需要提交的勾选数据，也都在this.selections对象中。