ECMAScript 6–otherwise known as "Harmony"–packs a plethora of new exciting features for Javascript. Several browsers have been sneaking in these additions under the hood for quite some time as specifications have reached consensus. Most of these language updates aren't anything unique to Javascript–in fact, most of the syntax and APIs closely mirror other mature languages and preprocessors like Python, Ruby, and CoffeeScript. The most impressive support so far comes from Firefox, whose Javascript engine SpiderMonkey is leaps and bounds ahead of the competition. In this post we'll benchmark the Harmony-way, and the "old way" with just a handful of these new language additions.