JavaScript对象的对象中如何互相取值？

http://jsbin.com/qeleboyeme/1/edit?js,console

var a = {
  apple:{
    apple1:"ap1",
    apple2:"ap2"
  },
  banana:{
    banana1:"ba1",
    banana2:"ba2",
    //banana3:a.apple.apple1,
    banana4:this.banana1,
  },
  pear:function(){
    console.log(this.banana.banana1);
  }
};

console.log(a.banana.banana1);
console.log(a.banana.banana2);
console.log(a.banana.banana3);
console.log(a.banana.banana4);
a.pear();

//a.banana想取a.apple里面的值怎么办？

如题，a.banana想取a.apple里面的值怎么办？pear中的this指向的是a，banana4中的this指向的是global
如果把banana3那里的注释去掉会直接报错

---

http://stackoverflow.com/questions/4892221/i-need-to-call-a-parent-property-from-child-object-in-an-object-literal

http://stackoverflow.com/questions/1789892/access-parent-object-in-javascript

---

        var a = {
          apple:{
            apple1:"ap1",
            apple2:"ap2"
          },
          banana:{          
            banana1:"ba1",
            banana2:"ba2",
            banana4: function(){
                return a.apple.apple1;
            }
          },
          pear:function(){              
                console.log(this.banana.banana4());
          }
        }
        a.pear();