el-table排序的问题

<el-table
      ref="tableList"
      :data="tableData"
      :default-sort = "{prop: 'date', order: 'descending'}"
       @sort-change="sortChange"
>
      <el-table-column
        prop="date"
        label="日期"
        sortable="custom"  <!--后台排序-->
      ></el-table-column>
<el-table>

重置排序或清空排序

resetSort(){
      this.$refs.tableList.sort('date', 'descending')
},
clearSort(){
      this.$refs.tableList.clearSort()
}