js 一维数组转多维数组

效果图：

    //源数组
    const arrList = [{
      "id": 1,
      "code": "001",
      "name": "第一个",
      "parentCode": "",
    },
    {
      "id": 2,
      "code": "00101",
      "name": "第一个的二级",
      "parentCode": "001",
    },
    {
      "id": 3,
      "code": "0010101",
      "name": "第一个的三级",
      "parentCode": "00101",
    },
    {
      "id": 4,
      "code": "0010102",
      "name": "第一个的三级",
      "parentCode": "00101",
    },
    {
      "id": 3,
      "code": "002",
      "name": "第二个",
      "parentCode": "",
    },
    {
      "id": 6,
      "code": "00201",
      "name": "第二个的二级",
      "parentCode": "002",
    },
    {
      "id": 7,
      "code": "0020101",
      "name": "第二个的三级",
      "parentCode": "00201",
    },
    {
      "id": 8,
      "code": "0020102",
      "name": "第二个的三级",
      "parentCode": "00201",
    }]

    const listToTreeRegion = (list, fromKey = 'code', parentId = 'parentCode') => {
      const data = JSON.parse(JSON.stringify(list)); //浅浅的拷贝一份
      const result = []; //组装的结果
      const map = {}; //查找
      if (!Array.isArray(data)) return result;

      for (const item of data) {
        if (!map[item[fromKey]]) {
          map[item[fromKey]] = {
            ...item,
            children: []
          };
        }

        const parent = map[item[parentId]];
        if (parent) {
          // 如果item有parent，则将其添加到parent的children中  
          parent.children.push(map[item[fromKey]]);
        } else {
          // 如果没有parent，则将其添加到树的根级别  
          result.push(map[item[fromKey]]);
        }
      }
      return result;
    }

    const treeList = listToTreeRegion(arrList);
    console.log(treeList)