title: JsTree how to get IDs of group node
body: <p>I want to get IDs of all child, Surface nodes, and a higher level.
  See the image below</p>
  
  <p><a href="https://i.stack.imgur.com/MQaLR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MQaLR.png" alt="enter image description here"></a></p>
  
  <p>When i click on <code>C1</code> node :</p>
  
  <p>1 - I want the IDs of all the lower level nodes contains : D1 , D2</p>
  
  <p>2 - I want the IDs of node that is a higher direct level : B2</p>
  
  <p>3 - And i want the IDs of all IDs of straight level : C2</p>