[
  {
    id: 1,
    name: '部门A',
    children: [
      {
        id: 2,
        name: '小组A1',
        children: [
          { id: 5, name: '员工小张', children: [] }
        ]
      }
    ]
  },
  {
    id: 3,
    name: '部门B',
    children: []
  }
]

function findNodeById(tree, targetId) {
  for (let node of tree) {
    if (node.id === targetId) {
      return node;
    }
    if (node.children && node.children.length > 0) {
      const found = findNodeById(node.children, targetId);
      if (found) return found;
    }
  }
  return null;
}

// 使用
const result = findNodeById(tree, 5); // 返回员工小张的节点

function addNode(tree, parentId, newNode) {
  for (let node of tree) {
    if (node.id === parentId) {
      node.children = node.children || [];
      node.children.push(newNode);
      return true;
    }
    if (node.children && node.children.length > 0) {
      const added = addNode(node.children, parentId, newNode);
      if (added) return true;
    }
  }
  return false;
}

// 使用：给 id=2 的节点添加子节点
addNode(tree, 2, { id: 6, name: '员工小李', children: [] });

function removeNode(tree, targetId) {
  for (let i = 0; i < tree.length; i++) {
    if (tree[i].id === targetId) {
      tree.splice(i, 1); // 删除当前节点
      return true;
    }
    if (tree[i].children && tree[i].children.length > 0) {
      const removed = removeNode(tree[i].children, targetId);
      if (removed) return true;
    }
  }
  return false;
}

// 使用
removeNode(tree, 6); // 删除 id=6 的节点