You Don't Know JS

You Don't Know JS Yet by Kyle Simpson (or the earlier edition You Don't Know JS, which is the version I read) is the best Javascript book I've ever read. It is not for beginners, there is an expectation that you have a decent programming background with some Javascript experience already. What this book covers is a deep dive into the Javascript language and how it behaves.

The first edition covers the inner workings of Javascript including topics such as variable scope, closures, and Javascript's use of the this keyword. The focus of the book is on clearly explaining many of the language-specific topics that cause confusion with the Javascript language and to help you develop a deep understanding the of the language to take your Javascript engineering skills to a whole new level.