把原始 list 转换成树形结构

[peacelee]

把原始 list 转换成树形结构，parentId 为多少就挂载在该 id 的属性 children 数组下

let list =[
    {id:3,name:'部门C',parentId:1},
    {id:5,name:'部门E',parentId:2},
    {id:1,name:'部门A',parentId:0},
    {id:2,name:'部门B',parentId:0},
    {id:8,name:'部门H',parentId:4},
    {id:7,name:'部门G',parentId:2},
    {id:4,name:'部门D',parentId:1},
    {id:6,name:'部门F',parentId:3}
];
function convert(list) {
    const res = [];

    const map = list.reduce((pre, cur) => {
        pre[cur.id] = cur;
        return pre
    }, {});

    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)
        }
    }
    console.log('list==>', list);
    console.log('map==>', map);
    return res
}

let newList = convert(list);
console.log('newList==>', newList);