ES6 Suggestion: Deterministic property order in Javascript objects

sorted_objects.js

var json = '{"d": "D", "c": "C", "b": "B"}';

var obj = JSON.parse(json);

Object.keys(); // => ["d", "c", "b"]

// Insertion order matters
obj["a"] = "A";

// Insertion at a certain position? (e.g. after key)
obj["x", "c"] = "X";

// Iteration
obj.forEach(function(value, key) {
  console.log(key);  // => "d", "c", "x", "b", "a"
});

Object.keys(obj); // => ["d", "c", "x", "b", "a"]

JSON.stringify(obj); // => '{"d": "D", "c": "C", "x": "X", "b": "B", "a": "A"}'

Background: http://substance.io/#michael/data-js/_section_aac6c7ea55131dc591ed8cafd8eedb13