[Erolast]

В будущем будет что-то вроде Object.assing - вроде то, что нужно.

The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.
Syntax:
Object.assign(target, ...sources)

Полифилл:

if (!Object.assign) {
  Object.defineProperty(Object, "assign", {
    enumerable: false,
    configurable: true,
    writable: true,
    value: function(target, firstSource) {
      "use strict";
      if (target === undefined || target === null)
        throw new TypeError("Cannot convert first argument to object");

      var to = Object(target);

      var hasPendingException = false;
      var pendingException;

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

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

        if (hasPendingException)
          throw pendingException;
      }
      return to;
    }
  });
}

https://developer.mozilla.org/en-US/.../Object/assign