tree-model-js如何获取上一个节点id

// 引入tree-model-js库
const TreeModel = require('tree-model');

// 创建树模型对象
const tree = new TreeModel();

// 创建树形结构数据
const root = tree.parse({
  id: 1,
  name: 'Root',
  children: [
    {
      id: 2,
      name: 'Node 1',
      children: [
        {
          id: 3,
          name: 'Node 1.1'
        },
        {
          id: 4,
          name: 'Node 1.2'
        }
      ]
    },
    {
      id: 5,
      name: 'Node 2'
    }
  ]
});

// 获取节点的上一个节点ID
const node = root.first(node => node.model.id === 4);
const previousNode = node.previousSibling();
const previousNodeId = previousNode ? previousNode.model.id : null;

console.log(previousNodeId);