How to get a variable from the server and write it to a global variable?

Question

JavaScript

Hello.
There is such a method in laravel:

public function ifAdmin()
    {
        if(Auth::check()){
            $auth = Auth::user()->email;
            $role = Role::where([
                ['email',$auth],
                ['role_name','admin']
            ])->get();

            return response()->json($role);
        }
    }

How to get it and write it to the window object?