Tree with selection box in SlickGrid

My requirement a tree with expand, collapse and checkbox functionality. Done with display of tree with expand and collapse functionality . Need help in implementation of checbox functionality so that it covers below scenarios

1)parent node selected then all child nodes must be selected. 2)parent node unchecked then all child nodes must be unchecked. 3)if parent has 3 child node, out of which 1 child node is checked and 2 are unchecked then parent node must be in intermediate state of checkbox. Like half selected. 4)if user manually unchecked all child node then parent node must be unchecked.

Below is tree structure

- rootNode
  --child1
  --child2
     ---childOFChild2

Followed below link for tree implementation. http://ift.tt/2talJbh

Any help would be GREAT..