Question

http://jsbin.com/ifoguf/19/edit

I’m unable to access the get area function of Triangle, and getting a deprecated error. Google(ed) the Crockford solution to __Proto__, but could use help applying it to the jsbin example.

    function extend(Child, Parent) {
        var F = function () {};
        F.prototype = Parent.prototype;
        Child.prototype = new F();
        Child.prototype.constructor = Child;
        Child.uber = Parent.prototype;
    }
    function extend2(Child, Parent) {
        var p = Parent.prototype;
        var c = Child.prototype;
        for (var i in p) {
            c[i] = p[i];
        }
        c.uber = p;
    }
    var Shape = function () {};
    var TwoDShape = function () {};
    var Triangle = function (side, height) {
        this.side = side;
        this.height = height;
    };
    // agument prototype of Shape;
    Shape.prototype.name = 'shape';
    Shape.prototype.toString = function () {
        return this.name;
    };
    // augment prototype of Triangle;
    Triangle.prototype.name = 'Triangle';
    Triangle.prototype.getArea = function () {
        return this.side * this.height / 2;
    };
    extend2(TwoDShape, Shape);
    extend2(Triangle, TwoDShape);
    var td = new TwoDShape();
    var tri = new Triangle(5, 10);
    alert(tri.__proto__.hasOwnProperty('name'));

   alert(td.name);
   alert(tri.constructor.getArea()); 

Answer 1

Use Object.getPrototypeOf instead (docs)

var prot = Object.getPrototypeOf(tri);
alert(prot.hasOwnProperty('name'));

You would also use that to hit the constructor, so tri.__proto__.constructor is now Object.getPrototypeOf(tri).constructor

Note that this is not backward compatible with IE<9, so you will still have to use the deprecated method for those browsers. John Resig suggested this as a potential “good enough for now” function to address the lack of user agent support for getPrototypeOf:

if ( typeof Object.getPrototypeOf !== "function" ) {
  if ( typeof "test".__proto__ === "object" ) {
    Object.getPrototypeOf = function(object){
      return object.__proto__;
    };
  } else {
    Object.getPrototypeOf = function(object){
      // May break if the constructor has been tampered with
      return object.constructor.prototype;
    };
  }
}

Reference: http://ejohn.org/blog/objectgetprototypeof/

I find this to be functional, but perhaps a bit over-blown – this is what I use:

function getProto(obj) {
  return (typeof Object.getPrototypeOf !== 'undefined' ? Object.getPrototypeOf(obj) : obj.__proto__);
}