How to expand all child nodes of a node when expanding the particular node in igTree?

I am using IGtree. I have data in tree till 4 levels in tree. Initially all nodes are collapsed. On expanding any particular node, all its child nodes should get expanded also till the last level

let nodes = $("#configTree").igTree("children", event.element);
  if(nodes) {
    nodes.forEach((node1)=>{
      $("#configTree").igTree("expand", node1.element);
    })
  }