vue element-ui el-table 选择框单选修改

<el-table
        ref="table"
        :data="tableData"
        style="width: 100%"
        border
        @selection-change="handleSelectionChange">
      <el-table-column
          type="selection"
          width="55">
      </el-table-column>
      <el-table-column
          label="日期"
          width="120">
        <template slot-scope="scope">{{ scope.row.date }}</template>
      </el-table-column>
      <el-table-column
          prop="name"
          label="姓名"
          width="120">
      </el-table-column>
      <el-table-column
          prop="address"
          label="地址"
          show-overflow-tooltip>
      </el-table-column>
</el-table>

　　

data() {
    return {
      tableData: [
        {
          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'
        }
      ],
      obj: {}, //保存当前选中内容
    }
  },

 methods: {
    handleSelectionChange(selection) {
      this.obj = selection[0];
      if (selection.length > 1) {
        this.$refs['table'].clearSelection();
        this.$refs['table'].toggleRowSelection(selection.pop());
      }

    }
  },