如何使用ES6过滤器和映射将平面结构转换为嵌套结构

// 假设我们有一个平面结构的数据数组
const flatData = [
  { id: 1, name: 'A', parentId: null },
  { id: 2, name: 'B', parentId: 1 },
  { id: 3, name: 'C', parentId: 1 },
  { id: 4, name: 'D', parentId: 2 },
  { id: 5, name: 'E', parentId: 3 },
];

// 定义一个递归函数，用于将平面结构转换为嵌套结构
const buildNestedStructure = (data, parentId = null) => {
  return data
    .filter(item => item.parentId === parentId)
    .map(item => ({
      ...item,
      children: buildNestedStructure(data, item.id),
    }));
};

// 调用递归函数，将平面结构转换为嵌套结构
const nestedData = buildNestedStructure(flatData);

console.log(nestedData);

[
  {
    id: 1,
    name: 'A',
    parentId: null,
    children: [
      {
        id: 2,
        name: 'B',
        parentId: 1,
        children: [
          {
            id: 4,
            name: 'D',
            parentId: 2,
            children: [],
          },
        ],
      },
      {
        id: 3,
        name: 'C',
        parentId: 1,
        children: [
          {
            id: 5,
            name: 'E',
            parentId: 3,
            children: [],
          },
        ],
      },
    ],
  },
]