This book aims to make GAS coders out of VBA coders. I was never a VBA coder, but that didn't prevent me from getting a lot out of this text, which to my mind exemplifies O'Reilly publishing at its best. It is not a JavaScript tutorial. To appreciate how good it is, it helps to have experience programming explicitly object-oriented JavaScript apps, particularly of the RESTful variety. It does not focus on functional programming, so you will find for-i loops aplenty, but anybody who prefers functional programming should already know how to implement their preferences. To my knowledge no other book on GAS programming comes close to this one in the elegance and library-type usefulness of its code samples.Now for the main caveat: The text is dated because it was published in 2015, and, starting in 2019, Google added major new dimensions to GAS capabilities. The changes affect not just details but how one best architects a project from the top down. To my knowledge no published book covers GAS in its current iteration at the level of this book. I suppose the reason there hasn't been a second edition is simply that Google provides free online libraries of code appropriate for its current iteration. Among these, those published by Tanaike are notable, and there is much that can be learned from them.That said, there is much still relevant that can be learned from Going GAS, and it's my favorite book on the subject.