如何在javascript中构建树json

class Node {
  constructor(id, name, parentId) {
    this.id = id;
    this.name = name;
    this.parentId = parentId;
    this.children = [];
  }
}

const nodeMap = {};

const rawData = [
  { 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 2', parentId: null },
  { id: 5, name: 'Node 2.1', parentId: 4 },
  { id: 6, name: 'Node 2.2', parentId: 4 },
];

rawData.forEach(item => {
  const node = new Node(item.id, item.name, item.parentId);
  nodeMap[item.id] = node;
});

Object.values(nodeMap).forEach(node => {
  if (node.parentId) {
    const parent = nodeMap[node.parentId];
    parent.children.push(node);
  }
});

const rootNodes = Object.values(nodeMap).filter(node => !node.parentId);
const treeJson = JSON.stringify(rootNodes);