const data = {
  nodes: [
    {
      id: 'node1',
      label: 'node1',
    },
    {
      id: 'node2',
      label: 'node2',
    },
  ],
  edges: [
    {
      source: 'node1',
      target: 'node2',
    },
  ],
};
// graph是Graph的實例
graph.changeData(data);
// 若不指定該參數，則使用當前圖上的數據重新渲染
graph.changeData();

// .....
// 節(jié)點點擊事件
graph.on("node:click", function (evt) {
        const item = evt.item;
        const nodeId = item.get("id");
        console.log(nodeId);
        const model = item.getModel();
        const children = model.children;
        if (!children || children.length === 0) {
          //點擊節(jié)點獲取下級節(jié)點接口
          //...........
          const parentData = graph.findDataById(nodeId);
          if (!parentData.children) {
            parentData.children = [];
          }
          // 如果childData是一個數組，則直接賦值給parentData.children
          // 如果是一個對象，則使用parentData.children.push(obj)
          parentData.children = childData;
          graph.changeData();
        }
      });