//原始数据
let data = [
    { id: 12304, name: "0", pid: 0 },
    { id: 3579, name: "1", pid: 12304 },
    { id: 3481, name: "1", pid: 12304 },
    { id: 632, name: "2", pid: 3579 },
    { id: 733, name: "0", pid: 0 },
    { id: 5673, name: "5", pid: 733 },
    { id: 5768, name: "6", pid: 5673 },
    { id: 324, name: "6", pid: 5673 },
];
/*转化后数据
转化依据：若一个item.pid = 另一个item.id,则这个item属于另一个item的children
pid的意思就是parentId
*/
newData = 
[
    {
        "id": 12304,
        "name": "0",
        "pid": 0,
        "children": [{
            "id": 3579,
            "name": "1",
            "pid": 12304,
            "children": [{
                "id": 632,
                "name": "2",
                "pid": 3579
            }]
        }, {
            "id": 3481,
            "name": "1",
            "pid": 12304
        }]
    }, {
        "id": 733,
        "name": "0",
        "pid": 0,
        "children": [{
            "id": 5673,
            "name": "5",
            "pid": 733,
            "children": [{
                "id": 5768,
                "name": "6",
                "pid": 5673
            }, {
                "id": 324,
                "name": "6",
                "pid": 5673
            }]
        }]
    }
]
//实现方法
let arrayList = {};
let newData = [];
data.forEach((item) => {
    // id是唯一性的，pid是重复性的，所以根据id做arrayList
    arrayList[item.id] = item;
    let parent = arrayList[item.pid];
    parent ?
        (parent.children || (parent.children = [])).push(item):
        newData.push(item)
})
console.log(newData)