Javascript:分层对象排序

Question

我有一个对象数组，每个对象都有字段id、parentId和position。位置字段存储该项目的相对位置，所以如果我做这样的排序函数：

object.sort((a, b) => {
if(a.position < b. position) return -1;
if(a.position > b. position) return 1;
return 0;
})

结果是这样的：

{id: 1, parentId: null, position: 0}
{id: 3, parentId: null, position: 1}
{id: 5, parentId: 1, position: 1}
{id: 6, parentId: 3, position: 1}
{id: 4, parentId: null, position: 2}
{id: 2, parentId: 1, position: 2}

如何检查parentId和位置，以得到这样的结果？

{id: 1, parentId: null, position: 0}
{id: 5, parentId: 1, position: 1}
{id: 2, parentId: 1, position: 2}
{id: 3, parentId: null, position: 1}
{id: 6, parentId: 3, position: 1}
{id: 4, parentId: null, position: 2}

Answer 1

您可以通过parentId收集所有节点，并从null和有序数组开始获得有序结果。

const
getNodes = parent => (parents[parent] || [])
.sort((a, b) => a.position - b.position)
.flatMap(o => [o, ...getNodes(o.id)]),
data = [{ id: 1, parentId: null, position: 0 }, { id: 2, parentId: 1, position: 2 }, { id: 3, parentId: null, position: 1 }, { id: 6, parentId: 3, position: 1 }, { id: 4, parentId: null, position: 2 }, { id: 5, parentId: 1, position: 1 }],
parents = data.reduce((r, o) => ((r[o.parentId] ??= []).push(o), r), {}),
result = getNodes(null);
console.log(result);
console.log(parents);

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