I've used many of the topics covered in this tutorial already, but didn't realize the impact they had for the JS language. For example, being able to change an objects properties at any time was interesting.
Pretty much the beginning of this tutorial was all review, especially after reading Speaking Javascripts chapters first.
This is a comment made in class and I've seen this at a meetup. But what's the difference between getter and setters? Also, what is addBack used for?