如图所示，可以实现树状数据的新增子项，新增平级，删除。主要用到了递归

代码：

<template><el-table :data="tableData" style="width: 100%; margin-bottom: 20px" row-key="id" border default-expand-all><el-table-column prop="date" label="Date" /><el-table-column prop="name" label="Name" /><el-table-column prop="address" label="Address" /><el-table-column label="Operations"><template #default="scope"><el-button size="small" @click="add(scope.row)">新增平级</el-button><el-button size="small" @click="addSon(scope.row)">新增子级</el-button><el-button size="small" type="danger" @click="delItem(scope.row)">删除</el-button></template></el-table-column></el-table>
</template><script lang="ts" setup>
import { ref } from 'vue'const tableData = ref([{id: 1,date: '2016-05-02',name: 'wangxiaohu',address: 'No. 189, Grove St, Los Angeles',},{id: 2,date: '2016-05-04',name: 'wangxiaohu',address: 'No. 189, Grove St, Los Angeles',},{id: 3,date: '2016-05-01',name: 'wangxiaohu',address: 'No. 189, Grove St, Los Angeles',children: [{id: 31,date: '2016-05-01',name: 'wangxiaohu',address: 'No. 189, Grove St, Los Angeles',},{id: 32,date: '2016-05-01',name: 'wangxiaohu',address: 'No. 189, Grove St, Los Angeles',},],},{id: 4,date: '2016-05-03',name: 'wangxiaohu',address: 'No. 189, Grove St, Los Angeles',},
])// 平级新增递归的方法
const addLeaveLoop = (arr: any[], id: number | string) => {for (let i = 0; i < arr.length; i++) {if (arr[i].id === id) {arr.splice(i + 1, 0, { id: +new Date(), date: '2023-11-03', name: '辉辉', address: 'dashjdsakljdl' })} else if (arr[i].children) {arr[i].children = addLeaveLoop(arr[i].children, id)}}return arr
}
// 新增平级
const add = (row: any) => {addLeaveLoop(tableData.value, row.id)
}// 新增一个子节点的方法
const addSonLoop = (arr: any[], id: number | string) => {for (let i = 0; i < arr.length; i++) {if (arr[i].id === id) {// 判断有没有children，有就前面新增，没有就创建if (arr[i].children && arr[i].children.length) {arr[i].children.unshift({ id: +new Date(), date: '2023-11-03', name: '张三', address: 'dashjdsakljdl' })} else {arr[i].children = [{ id: +new Date(), date: '2023-11-03', name: '李四', address: 'dashjdsakljdl' }]}} else if (arr[i].children) {arr[i].children = addSonLoop(arr[i].children, id)}}return arr
}
// 新增子级
const addSon = (row: any) => {addSonLoop(tableData.value, row.id)
}// 删除递归的方法
const delLoop = (arr: any[], id: number | string) => {for (let i = 0; i < arr.length; i++) {if (arr[i].id === id) {arr.splice(i, 1)} else if (arr[i].children) {arr[i].children = delLoop(arr[i].children, id)}}return arr
}
// 删除
const delItem = (row: any) => {delLoop(tableData.value, row.id)
}
</script>