I was very much looking forward to this book, pre-purchased it the instant I saw the email it available. I have been enjoying it so far. Best part is that you can follow along with making it in any language, for any input and output language. The author just happens to use Typescript as the language for the compiler, a subset of typescript for the input, and ARM for the output. I'm keeping the same input and output languages for the compiler, but switching to using C++ for actually building the compiler.
I'm currently loving the draft of the book. I'm moderately well off with javascript, but I've never used typescript before so I'm working on figuring that out as well.
In any case, it's a wonderful book with plenty of diagrams with explanations. Highly recommended!
I've spent years dabbling with programming language as well as compiler/debugger/simulator design, so all of this is right up my alley. :)