High Performance JavaScript: Build Faster Web Application Interfaces

I am liking this book. I learned a lot and have been using the techniques indicated in the book. The websites that I make have a lot of JavaScript codes and these techniques improved the performance. Thanks to Nicholas Zakas for a great book!

While reading Nicholas Zakas' "High Performance JavaScript", it occurred to me that there were actually two different reviews that I wanted to write. So, rather than try to reconcile them into one review, I'll simply apply them here as an ordered list.(1) To continue with the JavaScript University metaphor (from my review of Zakas' Professional JavaScript for Web Developers (Wrox Programmer to Programmer)): Finals are coming up in Prof. Crockford's upper-division JavaScript class. You've been a diligent student all semester and although you're not failing, it always seems like you're somewhere in the middle of the pack. You want desperately to ace the final exam, so you reach out for some help. Zakas (the graduate student/teaching assistant for the class) offers to show you the thesis he is working on. Then It hits you like a bolt from the blue -- every bit of it resonates with you. "It's so simple! so clear!" you exclaim. The inner machinations of the language snap together in a way that makes it all feel new and exciting -- the possibilities are boundless! You go back over your notes. You were close -- oh so close -- the whole time. But the last little bits drop in. A refinement here, a re-factor there... and the next thing you know, things are blazing. Your pages load 60% faster, execution time is down an average of 40%. You're amazed at yourself. And when the grades for the final exam come back, you're pleased to see that you aced it (aside from that little Oops on scoping closures -- but you try to think of that as a conscious trade-off). Prof. Crockford is pleased (if a little disappointed that it took you this long to Get It) and you're the envy of your peers. At least until next semester's RegEx class with Prof. Levithan. [Rated: 5 of 5](2) The frustrating part about working at a well-organized shop is that you get yourself all excited for a book like this and then half the recommendations in there are things that you're already doing. Put scripts at the bottom of the document? Check. Minify and compress? Check. Concatenate and package? Check. So on the one hand you say: "I guess I can sleep a little easier at night knowing that our build system adheres to the best practices recommended by the experts out there." But on the other hand, you're a little disappointed because you were hoping for some startling revelations. Again: not that this makes it without merit. From this perspective, what is noteworthy about this book is that these best practices and techniques are all gathered up in one place and presented in a logical order; even if "you're already doing it right", it is still a worthwhile exercise to meditate on the specifics, and to really go deep on why these best practices are important. (Plus, it's great to see the data -- nothing beats a little chartporn for proving the point.) [Rated: 4 of 5]

There are things covered in this book that I haven't seen elsewhere but I have often wondered about. Highlights were string processing optimization, techniques in adding non-blocking scripts, and in-depth look at array processing.. I also really enjoyed detailed look at different ways to implement a javascript String trim() method - made me realise again how bad the advice a google search can return sometimes. The most disappointing was Ch9. It's rather confusing and wordy. I didn't think it did a great job of explaining how to package up scripts into one file - it probably needs a few more chapters to explain it better and the author may have been struggling to squash it all in there.Having said that. LOVED how small the book was - it was very refreshing and I got through it in less than a week. If you already have Nicolas other book Professional JavaScript and you're wondering whether to get this book - I would recommend you do. There is more than enough variation and new content and the chapters by other authors are a real bonus.

What I already know about optimization was written exactly how I experienced it. Other things were completely new and made my code a lot more efficient. This book is definitely worth the price. At some points (like regex tuning) it's a bit too much of geekness but I'd still give 6 stars overall.

For anyone concerned with optimizing JavaScript performance, this is the book for you. Nothing in here should be a surprise for an experienced and good developer and some of the techniques you already know, but it's a valuable collection to have at your fingertips. The topics are neither academic/theoretical nor obscure. They are practical, imminently usable, and immediately applicable. I'm the lead developer for a fashion retailer and bought this book in order to learn more about how to make the site faster, especially because we have a lot of third party scripts. From the get-go, the author just dives in and I learned about blocking scripts and techniques on how to stack code to minimize page render time.This is a mercifully thin book, but densely packed with information and techniques. Be warned however, that this is not for JavaScript newbies. You should have advanced coding experience and know about the DOM and DOM scripting. Many of the techniques the author teaches you will also apply to any programming language: things like minimizing loops, putting the most likely condition first in an if/else block, avoiding accidental infinite loops, memoization (a new technique to me). Some parts are highly technical and he lost me for a bit on the discussion of the scope chain, but the rest of the book is concise and clear. He discusses methods that are inherently slow and gives comparisons on alternative methods, with charts to show the computational costs and savings. I do wish that they were in color, though, because one shade of grey can be difficult to distinguish from another shade of grey.Highly recommended. The only thing I would've liked to see is a discussion on jQuery techniques because I rarely code in pure JavaScript anymore and rely heavily on jQuery and sites are increasingly dependent on this framework.

Slightly outdated

Although optimizing your javascript code generally only saves a few ms here and there, on larger scale websites and web applications you can notice a difference. I think this book covered a lot of important information especially with data/object handling.

Es muy antiguo, no me dí cuenta al comprarlo pero no entiendo por qué venden libros de este tipo sin ediciones actualizadas, no lo veo muy ético.Hay ciertas cosas que se pueden aprovechar, pero en general terminas desconfiando de todo lo que se indica porque está basado en versiones antiguas de javascript y navegadores.No sería malo, aunque tampoco maravilloso, si estuviese actualizado.

This book is (imo) for medium to advanced devs or, at least targets people who are looking for precises and strong advises in JS perfs. The metrics are old what is written in the book is still up to date.I needed to refresh my knowledges and to be able to explain to optimizations.Nice book with concrete example

Muito bom o livro, ótimo para quem já programa com javascript e quer melhorar o desempenho das suas app. Recomendo!

Delivery time and package everything is perfect :)

This is one of the rare books which actually has good advice on JavaScript performance and is written in clear, concise language which JavaScript programmers of all abilities can learn from. I was happy to learn techniques that I hadn't considered before.Some people may argue that none of the methods used in the book are required now because web browser JS engines have increased in speed, but they are wrong. Understanding basic optimisation techniques and DOM bottleneck can help both mobile and desktop JavaScript performance gains.Highly recommended.