A plural ES5 + ES6 friendly version of Object.getOwnPropertyDescriptor

Object.getOwnPropertyDescriptors.js

'getOwnPropertyDescriptors' in Object || (
  Object.getOwnPropertyDescriptors = function (Object) {
    var
      gOPD    = Object.getOwnPropertyDescriptor,
      gOPN    = Object.getOwnPropertyNames,
      gOPS    = Object.getOwnPropertySymbols,
      gNS     = gOPS ? function (object) {
                         return gOPN(object).concat(gOPS(object));
                       } :
                       gOPN,
      descriptors
    ;
    function copyFrom(key) {
      descriptors[key] = gOPD(this, key);
    }
    return function getOwnPropertyDescriptors(object) {
      var result = descriptors = {};
      gNS(object).forEach(copyFrom, object);
      descriptors = null;
      return result;
    };
  }(Object)
);

the aim of this proposal is to make possible to create a shallow copy of a generic JS object in this way

var shallowCopy = Object.create(
  Object.getPrototypeOf(originalObject),
  Object.getOwnPropertyDescriptors(originalObject)
);

another pattern solved by this proposal is the following:

Object.defineProperties(
  target,
  Object.getOwnPropertyDescriptors(source)
);

which is useful to simulate Object.mixin which didn't make it in ES6, together with previously mentioned Object.clone or copy as shallow.

this has been written also as ES6 specification

Looking forward for the next TC39 meeting in April

An alternate polyfillable ES6 version that relies on Reflect.ownKeys, Array#reduce, and Object.getOwnPropertyDescriptor:

function getOwnPropertyDescriptors(obj) {
  return Reflect.ownKeys(obj).reduce(function (acc, key) {
    acc[key] = Object.getOwnPropertyDescriptor(obj, key);
    return acc;
  }, {});
}

(just posting this comment here so I don't forget it later ;-) )

A possible Object.copy that works like Object.assign but includes getters, setters, and non enumerable properties too.

Object.copy = (function (O) {
  var
    dP    = O.defineProperty,
    gOPD  = O.getOwnPropertyDescriptor,
    gOPN  = O.getOwnPropertyNames,
    gOPS  = O.getOwnPropertySymbols,
    set   = function (target, source) {
      for (var
        key,
        keys = gOPN(source).concat(gOPS(source)),
        i = 0,
        l = keys.length; i < l; i++
      ) {
        key = keys[i];
        dP(target, key, gOPD(source, key));
      }
    }
  ;
  return function copy(target) {
    for (var i = 1, l = arguments.length; i < l; i++) {
      set(target, arguments[i]);
    }
    return target;
  };
}(Object));