AngularJS Decorator without object.defineProperty

Question

How do I use decorators without having access to object.defineProperty?

I am looking into the shims available:

• es5-sham
• polyfill

but in case those don't pass testing, is there another way decorators were intended to work?

I am using the decorator for $onRootScope.

I am using angular 1.08. I need compatibility with IE7.

Update

I have tried out a few methods that seem to work but I don't know the difference between them: plunkr

var app = angular.module('plunker', []);

app.config(['$provide', function($provide){
  $provide.decorator('$rootScope', ['$delegate', function($delegate){
    $delegate.a = 1;
    $delegate.constructor.prototype.b = 2;
    Object.defineProperty($delegate.constructor.prototype, 'c', {
      value: 3
    });
    return $delegate;
  }]);
}]);

app.controller('MainCtrl', function($rootScope, $scope) {
  console.log($rootScope);   //reveals `a` property
  console.log($rootScope.constructor.prototype); //=> {b:2, c:3}
  console.log($rootScope.a); //=> 1
  console.log($rootScope.b); //=> 2
  console.log($rootScope.c); //=> 3
  $scope.name = 'World';
});

Thank You.

Answer 1

Well, an equivalent solution to the pice of code you shared is:

var proto = Object.getPrototypeOf(Object.getPrototypeOf($delegate));
proto['$onRootScope'] = function (name, listener) {
   var unsubscribe = $delegate.$on(name, listener);
   this.$on('$destroy', unsubscribe);
};

In the original code this line $delegate.constructor.prototype is getting access to the $delegate's prototype prototype.

Then, once you get access to it, you can simply define a new function in it. You do not need to use defineProperty. The only caveat is that by using defineProperty you can configure that the method is not enumerable (should not appear in for-each loops). In this other way, the method added would appear in for-each loops. It may not be a problem for you though.

I have created a JSFiddle for this.

You can use John Resig's polyfill for getObjectPrototypeOfif the function is not available for your current browser:

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;
    };
  }
}