object properties are indexed by the order in which they are added to the object

gistfile1.js

var object = {};
object.b = 'b';
object.a = 'a';
object.c = 'c'

console.log(object);
// Object {b: "b", a: "a", c: "c"}

var key, item;

for (key in object) {
  item = object[key];
  console.log(item);
}
// b
// a
// c