Not only that, but some stuff seems really off. Like explaining lazy evaluation -- something only ES6 has -- with... lists. Yup, lazy evaluation, for the book, means adding things in a list only when you need to remove things from the list. It would make so much more sense if the author jumped into the ES6 bandwagon for this and explained the "yield" command... but no, he had to write some lazy text.
The fact that all examples are based on Game of Thrones -- with all being based on things that happen in Westeros -- don't make it funny or interesting. Worse, none of the examples are related, so the author just keeps jumping between weird scenarios to explain the "patterns".