Element-UI的表格合计行的列添加操作按钮

我是操作DOM元素的绑定的，如果你有好的方法，欢迎留言。

需求

 代码

<div id="app">
        <el-table :data="tableData" show-summary ref="tableRef" style=" 100%">
            <el-table-column prop="id" label="ID" width="180">
            </el-table-column>
            <el-table-column prop="name" sortable label="姓名">
            </el-table-column>
            <el-table-column prop="amount1" sortable label="数值 1">
            </el-table-column>
            <el-table-column prop="amount2" sortable label="数值 2">
            </el-table-column>
            <el-table-column prop="amount3" sortable label="数值 3">
            </el-table-column>
            <el-table-column prop="" sortable label="操作">
                <template slot-scope="scope">

                    <el-button size="mini" type="danger" @click="handle(scope.$index, scope.row)">查看</el-button>
                </template>
            </el-table-column>

        </el-table>
    </div>

<script type="text/javascript">
    var vm = new Vue({
        el: "#app",
        data: {
            tableData: [],
        },
        mounted() {
            this.gettable();
        },
        methods: {
            handle(index, row) {

            },
            detail(){
                
            },
            gettable() {
                this.tableData = [{
                    id: '12987122',
                    name: '王小虎',
                    amount1: '234',
                    amount2: '3.2',
                    amount3: 10
                }, {
                    id: '12987123',
                    name: '王小虎',
                    amount1: '165',
                    amount2: '4.43',
                    amount3: 12
                }, {
                    id: '12987124',
                    name: '王小虎',
                    amount1: '324',
                    amount2: '1.9',
                    amount3: 9
                }, {
                    id: '12987125',
                    name: '王小虎',
                    amount1: '621',
                    amount2: '2.2',
                    amount3: 17
                }, {
                    id: '12987126',
                    name: '王小虎',
                    amount1: '539',
                    amount2: '4.1',
                    amount3: 15
                }];
            }
        },
        watch: {
            tableData: function () {
                let _this = this;
                this.$nextTick(() => {
                    debugger;
                    console.log(_this.$refs.tableRef.$refs);
                    let html=_this.$refs.tableRef.$refs.footerWrapper.querySelector('.el-table__footer').querySelectorAll('td')[5].querySelector('.cell');
                    html.innerHTML = "<button onclick='vm.detail()'>查看</button>";
                })
            }
        }
    });
</script>