It's a great idea and I think the world does need a new book for pure JS.

There was a book released about 10 years ago by the guy who wrote jQuery. It started with basic JS and went all the way through to advanced features. It really helped me master JS.

Where I think that book is better then yours is that it focuses entirely on JS where as you spend a lot of time talking about http and the web works. Anyone reading your book to learn js will already know that.

An updated version for the modern day of the book I mentioned earlier would do very well.

I don't mean to sound negative and I applaud your effort and the time you put in to do it and wish you the best of luck!