创建树

将扁平化的节点数组，变成一棵树，使用tree-with-array
npm i tree-with-array

创建树的算法，通过idMapping的方式高效创建
https://blog.csdn.net/sinat_34560749/article/details/103832350

const data = [
    { id: 56, parentId: 62 },
    { id: 81, parentId: 80 },
    { id: 74, parentId: null },
    { id: 75, parentId: null },
    { id: 76, parentId: 80 },
    { id: 63, parentId: 62 },
    { id: 80, parentId: 86 },
    { id: 87, parentId: 86 },
    { id: 62, parentId: 74 },
    { id: 86, parentId: 75 },
];

const idMapping=data.reduce((prev,next,i)=>{
    prev[next.id]=i;
    return prev;
},{})

const rootArr=[];
data.forEach(node=>{
    if(!node.parentId){
        rootArr.push(node)
        return;
    }
    const parent=data[idMapping[node.parentId]];
    parent.children=[...parent.children|| [],node];
})

console.log(rootArr)