从平面到树的Javascript数组

const flatArray = [
  { id: 1, name: 'Node 1', parentId: null },
  { id: 2, name: 'Node 1.1', parentId: 1 },
  { id: 3, name: 'Node 1.2', parentId: 1 },
  { id: 4, name: 'Node 1.1.1', parentId: 2 },
  { id: 5, name: 'Node 2', parentId: null },
  { id: 6, name: 'Node 2.1', parentId: 5 },
];

function convertToTree(flatArray) {
  const tree = {};

  flatArray.forEach(item => {
    const { id, parentId, ...data } = item;

    if (parentId === null) {
      tree[id] = { id, ...data, children: [] };
    } else {
      const parent = tree[parentId];
      if (parent) {
        parent.children.push({ id, ...data, children: [] });
      }
    }
  });

  return Object.values(tree);
}

const treeArray = convertToTree(flatArray);
console.log(treeArray);