Encapsulating Array Object to add a custom method

Array.myLast.js

var MyArray = function() { return this; } ;
MyArray.prototype = new Array();
MyArray.prototype.constructor = MyArray; // http://stackoverflow.com/a/10430875/842214
 
Object.defineProperty(MyArray.prototype, 'myLast', (function () {
    return {
      configurable : true,
      enumerable : true,
      get : function () {
        return this[this.length - 1];
      },
      set : function (val) {
        this.push(val);
      }
    };
  })());

var testMyArray = new MyArray();


console.log(testMyArray); // []
console.log(testMyArray.myLast); // undefined

testMyArray.myLast = 1;
console.log(testMyArray.myLast); // 1

testMyArray.myLast = 2;
console.log(testMyArray.myLast); // 2

testMyArray.pop();
console.log(testMyArray.myLast); // 1