While ES6 is still being standardized and all the browsers are still working on supporting all the different features, it's worth getting a head start because Angular 2.0will be based on ECMAScript 6 in the future, when it's released.
Thanks to Traceur, we can start playing around with ES6 features today, as well as some of the things that Angular has started releasing, like DI, that already use ES6.
After you install Traceur using "npm install traceur," using the "-g" global flag or not...Here, I did. I just use Traceur to output this file, which is an ES6 file, to this Traceur-compiled file.
Then the browser will be able to use this file just fine. Again, you're not using the ES6 file. You're using the output Traceur-compiled file, then loading the Traceur runtime, and then loading your own compiled file.
If instead of using the browser, you want to invoke that file with Node, simply use Traceur. Instead of using it to compile, you can use it to run the output file and then run through the Traceur-compiled file, using Traceur as the "runtime."
While installing Traceur is as easy as "npm install traceur," if you want to jump right in, you can just open ES6 Fiddle in your browser and load one of the examples. Then hit run, and you can begin playing with ES6 right away.
Basically, behind the scenes, this is compiling this to a Traceur-compiled file and then running it through Traceur to give you what the output of the console is.