How to access parent variable from child

Question

I am trying to access a variable in A from B (in my example bellow). I didn't extend B from A, because A is just a container.

function A() {
  var Parent = this;
  this.container = [];
}

A.prototype.add = function(Item) {
  Parent.container.push(Item);
}

function B() {

}
B.prototype.exec = function() {
  console.log(Parent.container[0]) //Uncaught ReferenceError: Parent is not defined
}

var Manager = new A();
var Item = new B();
Manager.add(B);
Item.exec();

How to access Parent from Item ?

Answer 1

function A() {
  this.container = [];
}

A.prototype.add = function(Item) {
  this.container.push(Item);
}

function B(Parent) {
   this.Parent = Parent;
}
B.prototype.exec = function() {
  console.log(this.Parent.container[0]) //Uncaught ReferenceError: Parent is not defined
}

var Manager = new A();
var Item = new B(Manager);
A.add(B);
B.exec();

Answer 2

function A() {
  this.container = [];
}

A.prototype.add = function(Item) {
  //assigning parent property only if Item is added
  Item.Parent = this;
  this.container.push(Item);
}

function B() {
   this.Parent = null;
}
B.prototype.exec = function() {
  console.log(this.Parent.container[0])
}

var Manager = new A();
var Item = new B();
Manager.add(Item);
Item.exec();