vis.js - how to place item in center of graph

问题

I have tree structure like next :

• id: 1
  • id: 2
    • id: 8
    • id: 9
    • id: 10
    • id: 11
    • id: 12
  • id: 3
    • id: 13
  • id: 4
  • id: 5
  • id: 6
  • id: 7
  • id: 8

And need to show it (as network graph, not as tree) After page loading graph must be centered on {id:1} item.

How can I make it?

来源：https://stackoverflow.com/questions/32853591/vis-js-how-to-place-item-in-center-of-graph