convert.js

/*
 * @Author: yangyuan
 * @Date: 2019-10-24 14:00:02
 * @Email: 1367511704@qq.com
 * @LastEditTime: 2019-10-24 14:06:16
 * @Description: 
 */
// 原始 list 如下
let list =[
    {id:1,name:'部门A',parentId:0},
    {id:2,name:'部门B',parentId:0},
    {id:3,name:'部门C',parentId:1},
    {id:4,name:'部门D',parentId:1},
    {id:5,name:'部门E',parentId:2},
    {id:6,name:'部门F',parentId:3},
    {id:7,name:'部门G',parentId:2},
    {id:8,name:'部门H',parentId:4}
];
const result = convert(list, ...);

// 转换后的结果如下
let result = [
    {
      id: 1,
      name: '部门A',
      parentId: 0,
      children: [
        {
          id: 3,
          name: '部门C',
          parentId: 1,
          children: [
            {
              id: 6,
              name: '部门F',
              parentId: 3
            }, {
              id: 16,
              name: '部门L',
              parentId: 3
            }
          ]
        },
        {
          id: 4,
          name: '部门D',
          parentId: 1,
          children: [
            {
              id: 8,
              name: '部门H',
              parentId: 4
            }
          ]
        }
      ]
    }
];


function convert(list) {
    const res = [];
    const map = list.reduce((res,v) => (res[v.id] = v, res), {});
    for (const item of list) {
        if (item.parentId === 0) {
            res.push(item);
            continue
        }
        if (item.parentId in map) {
            const parent = map[item.parentId]
            parent.children = parent.children || []
            parent.children.push(item)
        }
    }
    return res;
}