To begin with this is not a book for the person new to JavaScript. The authors assume some knowledge of JavaScript and object oriented programming right from the start. This is more of an advanced text for those who already can get things done in JavaScript and want to advance their knowledge, write code that is easier to maintain, and exploit the flexibility of JavaScript to its fullest extent.

For each pattern discussed they provide background information on the problem to be resolved, example coding, and when to use it. I appreciated this detail in helping me to fully understand not only when a pattern could be used to benefit a project but also when it might not be the most appropriate way. While JavaScript has always been known for its flexibility these authors show how a creative person can exploit the language's flexibility.. The patterns themselves represent pretty common ones in other languages but the way they were implemented in JavaScript was enlightening.

This is an excellent guide and reference for high-level JavaScript programming on large projects maintained by multiple programmers. Pro JavaScript Design Patterns is highly recommended for experienced object oriented programmers who want to add this to their knowledge base.

it's a great book to learn more.....it's missing practical examples for real life.....lot of theory. If you don't know Object Oriented Principles, it will be (very) hard(er). (ActionScript 3.0 book can help, or Java book ).

It's not begginer book........It's great for large projects, applications.
This is great for frontend engineers and software engineers.
I would recommend JavaScripts Good Parts in addition to this, it could help with coding standards....

Unfortunatelly, there is no single Javascript book.

Many of them are old and lousy......

As UI/Front End Developer, it's nice to have a book like this. it's very helpfull for sure.

What's missing, HOW TO - the connection to real Javascript frameworks, like YUI, JQuerry, Mootools, Prototype, Dojo, etc, etc, etc.

Back in the early days Design Patterns examples mostly used C++ as language. This day Java is the typical choice, with an increasing amount of C#. Usually if you are familiar with any of those languages, porting the sample code to a different platform isn't that hard. Unfortunately JavaScript is quite a different beast, first of all is not class based, it's loosely typed, it doesn't support interfaces etc. JavaScript has a whole bunch of peculiarities that make it really hard to translate those Java/C# samples. That's why this book is really welcomed. The authors stick with mainstream, well-know patterns, nothing new, but they "translate" those patterns in JavaScript, offering working samples. I tend to disagree with them whenever they pretend to add interface-like functionality to JavaScript; yet, I think they made an excellent job, a book that can be really valuable if you do non-trivial work with JavaScript

The authors of this book, being recognized web experts in Google and Yahoo circles, are sharing an array of javascript design patterns that will empower your applications and widen horizons of all web developer levels.

Harmes and Diaz bend, twist, fold and stretch the Javascript language in ways that it wasn't probably intended to ever be used and, in doing so, demonstrate just how flexible and dynamic Javascript is. They actually cover topics such as Interfaces, encapsulation, inherittance, the singleton pattern, the factory pattern, the bridge pattern, the composite pattern, the adapter pattern, the proxy pattern, the lightweight pattern and the command pattern.

Early on in the book when looking at the interface pattern, when it was suggested an implementation of this pattern with comments, I actually thought that this just wasn't going to work for me. They do, however, show a much more credible implementation of this and other patterns and, in the process, cover some of the deeper and more powerful features of the language. The examples are highlighted against specific applications. For instance, the benefits of the singleton pattern are explained through the process of creating an XHR object (an instance of the XMLHttpRequest).

I haven't finished the book yet, but it is clear that this is one to keep going back to. As someone else has already mentioned, this is not a showcase of UI tricks and will be appreciated by someone developing or extending web development frameworks or someone who just wants to write better and more extensible Javascript.

I would have liked to have seen some examples of how the patterns are used in frameworks such as Prototype/Scriptaculous and jQuery in the same vein that Olsen's "Design Patterns in Ruby" (an excellent book if you are into Ruby) illustrates patterns with code used in Rails, Ruby and other applications in the wild. Also, I found that I needed to brush up on my Javascript (bigtime) in order to keep up with this one (Resig's "Pro Javascript Techniques" and Crockford's "JavaScript: The Good Parts" are highly recommenced to that end). Then again, the Authors might have then struggled to keep this at just under 270 pages.

Highly recommended!

"Pro JavaScript Design Pattens"is a useful read regardless of whether you have a JavaScript or server side language background. An advanced topic that appeals to such varied audiences is tough to do, but the authors succeed admirably. In fact, I can't do such a job, so read the chapter that applies...

For JavaScript developers:
The book covers how to write good clean object oriented code in JavaScript. It introduces concepts that are not present in JavaScript along with how to simulate them. The sections on when to use a given pattern are well written.

For server side language developers:
The book covers how to implement in JavaScript the design patterns we are accustomed to. Before getting to this, there are several chapters on JavaScript idioms which are very useful. There were also a couple patterns that a server side developer might not have encountered because the server side is not so memory constrained.

For everyone:
The book also covers tradeoffs of using the patterns. I appreciated where they mention the slight performance hit and how to check/profile if it is a problem for you. All patterns were described clearly and succinctly. There were some real examples as well. At times, it is a bit code heavy - one example had 1.5 pages of implementation details that had nothing to do with the topic at end. Overall, I think the book was great. If you have a significant amount of JavaScript code, the concepts in this book are critical.

This book is a "JavaScript for Programmers" book. It's very detailed and advanced. I wouldn't classify it as a "JavaScript for Web Weenies" or a "JavaScript for Stupid UI Tricks" book at all. If you don't know OOP concepts in another language already, this book really might be too much for you and could frustrate you. This book is good if you are a server-side programmer and you want to know how to push JavaScript about as far as it can go (at this point). If you are a web programmer/designer with a light understanding of OOP concepts and you want to "go deep", this book could be ok, but I would try to learn OOP from another language first because this book would read better with that background knowledge. Also, I am recommending that you already know OOP from another language because you can really shoot yourself in the foot with JavaScript because it's *so* flexible and the authors prove this well! I think it's probably a good idea to know when you're going off in the weeds and JavaScript really doesn't provide many boundaries where other languages have stricter controls on what you can do.

This book shows that when used by an experienced person, JavaScript is no joke. Seriously.

This book provides one of the more thorough treatments of some of the more advanced javascript idioms/concepts - it's not aimed at the beginner - and it does have some typos (for e.g defining functions as obj.fun() { } vs obj.fun = function() {...} - and while i haven't completed reading it (it is a design patterns book after all) - I have been quite impressed with it's initial chapters (encapsulation, inheritance, singletons etc.)
And as you would expect, this book does make it easier to follow library code written using the class-based OO pattern (such as extjs).

A bit hard to read unless you have the detailed knowledge of JavaScript and design patterns. Lack of figures to represent how things work and the idea behind all these.

Other than that, this is one of the GREATEST books about JavaScript you can find in the market, especially for those who want to know more about the JavaScript and design pattern.

Design patterns, and particularly their application in dynamic languages can be a controversial topic, and every now and again another round of blog posts bubbles up appalled at the way a new group of programmers have become infatuated with design patterns. Applied without care design patterns can quickly lead to over-engineered code that seems designed as much to draw on as many of the established patterns as possible as to solve the intended problem. But if applied with care, and with consideration of how a pattern applies in the context of your chosen language they can be a helpful way to draw on the wisdom of the coders that came before you, and make your code easier to understand to those who may inherit it.

Written by Dustin Diaz (of Google) and Ross Harmes (of Yahoo), Pro Javascript Design Patterns builds on experience of building complex, high profile javascript applications. That experience shows as each pattern is introduced with solid examples and sample code and then refined to provide looser-coupling, more flexibility and/or better performance.

Early on in the book I was concerned that some of the solutions could become too heavy and the early introduction of interfaces hinted at something akin to the early approaches to pattern usage in PHP, which often looked more like an attempt to turn PHP into Java than a way to use PHP's own features better. As the book goes on the usefulness of those interfaces, particularly for large development teams, becomes clear and most of those concerns are allayed, especially as the authors offer pros and cons for the use of each pattern and are clearly focussed on how these patterns can help produce more robust solutions.

Most of the patterns will have a fairly immediate impact for developers new to them, and even for those who have used them in other contexts it is helpful to see how they have been applied in JavaScript. Most modern JavaScript libraries rely on several of these patterns to abstract out handling of different browser quirks or adding new event types, and even if you rely heavily on one or more of the major libraries this guide may well help you understand their internals better.

I've sometimes been skeptical of books claiming to be targeted at an advanced target. Labels like "pro" are often handed out far too easily. But in this case it seems deserved. While the book does a good job of quickly introducing approaches to object-oriented programming in JavaScript, that's based on an assumption of a solid knowledge of the language and of OO development in at least one language. If you're a newcomer to JavaScript or just looking for a way to add a few fancy features to your web pages this isn't be book for you. But if you have some serious JavaScript development experience and are needing a way to tighten up your code to make it more modular and more maintainable, this book is well worth your time.

Disclaimer: I was sent a copy of this book for review by the publisher.