Access a base classes variable from within a child class
function BaseClass()
  {
     var privateMap = {"type": "BaseClass"};
  }

  function ChildClass()
  {
     // How can I access BaseClass's private variable privateMap?
     privateMap["type"] = "ChildClass";
  }

  ChildClass.prototype             = new BaseClass();
  ChildClass.prototype.constructor = ChildClass;

var Base = function()
  {
    var privateMap = {"type":"Base"};

    this.changeMap = function(arg) {
        privateMap['type'] = arg;
        console.log('Changed Map to ' + privateMap['type'])
    }

}
var Child = new Base;

Child.changeMap('Child1')

console.log(Child.privateMap)//undefined