JS 用更函数式的方法实现树形结构和扁平数组间的转换

const tree = [ { name: "one", id: "1", list: [ { name: "oneOne", id: "11", list: [{ name: "oneOneOne", id: "111" }] }, { name: "oneTwo", id: "12", list: [ { name: "oneTwoOne", id: "121" }, { name: "oneTwoTwo", id: "122" }, { name: "oneTwoThree", id: "123" }, ], }, ], }, { name: "two", id: "2", list: [ { name: "twoOne", id: "21", list: [{ name: "twoOneOne", id: "211" }] }, { name: "twoTwo", id: "22", list: [ { name: "twoTwoOne", id: "221" }, { name: "twoTwoTwo", id: "222" }, ], }, ], }, ];

const flatten = (
  children: any[],
  parentId?: string | number,
  parentName?: string,
  level = 1,
  parentNodes?: any[]
) =>
  Array.prototype.concat.apply(
    children.map((x) => ({
      // ...x,
      name: x.name,
      id: x.id,
      parentId,
      parentName,
      level,
      parentNodes: JSON.parse(JSON.stringify(parentNodes || [])),
    })),
    children.map((x) =>
      flatten(
        x.list || [],
        x.id,
        x.name,
        (level || 1) + 1,
        Array.isArray(parentNodes)
          ? [...parentNodes, { id: x.id, name: x.name }]
          : x.id !== undefined
          ? [{ id: x.id, name: x.name }]
          : []
      )
    )
  );

const flat = flatten(tree);

console.log(flat);

const flat = [ { name: "one", id: "1", parentId: undefined, parentName: undefined, }, { name: "two", id: "2", parentId: undefined, parentName: undefined, }, { name: "oneOne", id: "11", parentId: "1", parentName: "one", }, { name: "oneTwo", id: "12", parentId: "1", parentName: "one", }, { name: "oneOneOne", id: "111", parentId: "11", parentName: "oneOne", }, { name: "oneTwoOne", id: "121", parentId: "12", parentName: "oneTwo", }, { name: "oneTwoTwo", id: "122", parentId: "12", parentName: "oneTwo", }, { name: "oneTwoThree", id: "123", parentId: "12", parentName: "oneTwo", }, { name: "twoOne", id: "21", parentId: "2", parentName: "two", }, { name: "twoTwo", id: "22", parentId: "2", parentName: "two", }, { name: "twoOneOne", id: "211", parentId: "21", parentName: "twoOne", }, { name: "twoTwoOne", id: "221", parentId: "22", parentName: "twoTwo", }, { name: "twoTwoTwo", id: "222", parentId: "22", parentName: "twoTwo", }, ];

const buildTree = (data: typeof flat) =>
  data
    .reduce(
      (m, { id, name, parentId }) => (
        m.get(parentId)!.push({ id, name, list: m.set(id, []).get(id) }), m
      ),
      new Map<string | undefined, any[]>([[undefined, []]])
    )
    .get(undefined);

const tree = buildTree(flat);

console.log(tree);