The title "You Don't Know JS" isn't intended to be an insult. It's intended to be a challenge for all of us to take seriously the process -- ongoing, it never ends -- of learning JS more deeply. You never fully know JS, you just learn it better and better. I try to help developers move beyond surface "I can get stuff done" to deeper, more confident "I know why this code works" type of understanding.
I truly believe that if you don't know why a piece of code works, you have no hope of understanding why it broke.
If there's anything I can do to help you learn JS better, please let me know!