Detect all window properties that was added after script run

gistfile1.js

'use strict';

// ES6 Object.assign
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
if (!Object.assign) {
  Object.defineProperty(Object, 'assign', {
    enumerable: false,
    configurable: true,
    writable: true,
    value: function(target) {
      if (target === undefined || target === null) {
        throw new TypeError('Cannot convert first argument to object');
      }

      var to = Object(target);
      for (var i = 1; i < arguments.length; i++) {
        var nextSource = arguments[i];
        if (nextSource === undefined || nextSource === null) {
          continue;
        }
        nextSource = Object(nextSource);

        var keysArray = Object.keys(Object(nextSource));
        for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
          var nextKey = keysArray[nextIndex];
          var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
          if (desc !== undefined && desc.enumerable) {
            to[nextKey] = nextSource[nextKey];
          }
        }
      }
      return to;
    }
  });
}

(function(){
    var Detector = function(/*obj*/target){
        this.target = target;
        this.states = {
            before : Object.assign({}, target),
            after : {}
        };
        this.result = [];
    };

    Detector.prototype = {
        check : function(){
            this.result = [];
            this.states.after = Object.assign({}, this.target);

            for (var i in this.states.after) {
                if (!this.states.before[i]) {
                    this.result.push(i);
                }
            }

            return this.result;
        }
    };

    window.detector = new Detector(window);
}());

// run window.detector.check() when you need to see changes in window object