const flatData = [
  {
    _id: '625417e3453b6cf65dddff6c',
    menuName: '菜单管理',
    menuIcon: 'el-icon-menu',
    menuPath: '/menu',
    __v: 0,
  },
  {
    _id: '6254181d453b6cf65dddff6e',
    menuName: '菜单添加',
    menuIcon: 'el-icon-menu',
    menuPath: '/menu/add',
    parentid: '625417e3453b6cf65dddff6c',
    __v: 0,
  },
  {
    _id: '6254182b453b6cf65dddff70',
    menuName: '菜单修改',
    menuIcon: 'el-icon-menu',
    menuPath: '/menu/edit',
    parentid: '625417e3453b6cf65dddff6c',
    __v: 0,
  },
  {
    _id: '62541856453b6cf65dddff72',
    menuName: '菜单添加的子菜单',
    menuIcon: 'el-icon-menu',
    menuPath: '/menu/add/submenu',
    parentid: '6254181d453b6cf65dddff6e',
    __v: 0,
  },
  {
    _id: '6263d22b8a09ec1a4cb6e9cc',
    menuName: '菜单添加的子菜单的子菜单',
    menuIcon: 'el-icon-menu',
    menuPath: '/menu/add/submenu/submenu1',
    parentid: '62541856453b6cf65dddff72',
    __v: 0,
  },
]
const arrMap = new Map()
// 将数组抓换位map,key是id,value是本身
flatData.map((value, index) => {
  arrMap.set(value._id, value)
})
const treeData = []
treeData.push(flatData[0])
flatData[0].menuName = 'zf'
console.log(flatData[0], 'flatData[0]')
console.log(arrMap.get('625417e3453b6cf65dddff6c'), 'arrMap')
console.log(treeData[0], 'treeData[0]')
console.log(flatData[0] === arrMap.get('625417e3453b6cf65dddff6c'))
console.log(treeData[0] === arrMap.get('625417e3453b6cf65dddff6c'))
// console.log arrMap.has('62541856453b6cf65dddff71'))

for (const item of flatData) {
  // 如果该项没有parentid则是根节点,直接push,否则就是子节点,用该pid在map里查找到对应的项,
  // 然后将该项push到该项的children属性上
  if (!item.parentid) {
    treeData.push(item)
    continue
  }
  // 找到该项的父元素
  const aa = arrMap.get(item.parentid)
  // console.log(aa, 'aa')
  if (!aa.children) {
    aa.children = []
  }
  aa.children.push(item)
}
console.log(treeData)