Use application variable in Shell page javascript file for custom functions.

Summary:

I am using "DashBoard Example Template" in VBCS project which is creating the oj-drawer-layout based on menu.json file in config folder. But I want to modify this code to call a rest service on "vbEnter" event and then populate a variable at application level with the json of the menu tree. Then use this json object variable instead of static menu.json. I am able to do the first part of calling the service in action chain and populate the variable at application scope with menu json object.

I am not able to find a way to access this variable in shell.js ?