Currently there is no particular order in how you should read it. Some of the concepts already explained are: closures, operators, bind, call, apply, function scope, hoisting and many more.
One of the first things the authors want to make clear is that this is not a replacement for conventional learning by books, blogs and countless experimentations, but rather an additional resource to the existing set of learning paths.
For more information and a short brief on how you can contribute to this project checkout the README.
Don’t forget to submit this weeks challenge: “Tetris Bag” where you need to implement the same randomization algorithm as used in the popular nineties game Tetris.