Most Helpful Customer Reviews
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81 of 83 people found the following review helpful:
5.0 out of 5 stars
Wish I had this book when I first started Javascript, June 27, 2008
Do you struggle when creating objects in Javascript?
Do you find the syntax to be non-intuitive and frustrating?
Do you know the difference between using a function as an object vs using an object literal?
Do you know how using object literals can simplify your code and create something similar to namespaces?
Do you know how to augment the type system -- for example, if wanted all strings to have a trim() method?
Do you know why the "new" statement is so dangerous? Do you know an alternative that eliminates the use of "new" entirely?
These are some of the topics that the book touches upon.
This book is aimed at someone with intermediate programming experience that wants to know the best way to create and use objects, arrays, types, etc. Crockford takes his experience with Javascript to show you best practices coding techniques and styles to use with Javascript. In addition, the book provides insights into what makes Javascript so confusing and what can be done about it.
You might ask "Isn't this stuff already covered in other books that I have?" The answer is no. For one, most other books use a psuedo-classical coding style (see below) to explain objects that is a source of confusion.
Javascript can be very confusing, especially for programmers who have extensive experience in other C-based languages (like myself). Writing good Javascript that uses objects, methods, etc. is hard. In Javascript, if you want to create objects, use inheritance and create methods, you have several different ways to write your code and it's difficult to know what the strengths and weaknesses of each are.
Crockford explains the problem plainly. Other C-based languages use class inheritance (Crockford calls this classical inheritance). Javascript, on the other hand, is the only popular language that uses prototype inheritance, which does not have classes. However, the syntax which Javascript uses to create object is Java-like (Crockford calls this pseudo-classical syntax). It's confusing, because it keeps you in a class-based frame of mind while working in a language that has no concept of classes.
Clarifying what's going on with the object model is the best part of this book. Crockford also explains other parts of Javascript that can be problematic and the techniques that he prefers for handling them. I don't necessarily agree with all of them, but the important thing is that he explains his reasoning.
To effectively learn Javascript, I recommend that you buy 1) a book that covers the details of the language and can be used as a reference (e.g. Javascript, the Definitive Guide) and 2) Crockford's book. Advanced programmers might also enjoy Pro Javascript Design Patterns, which shows a number of ways to combine Javascript with some of the GoF patterns. I would avoid any cookbook style books on Javascript, because you're better off using YUI, JQuery or one of the other Javascript libraries than writing your own drag-and-drops, calendars, etc.
There are a series of Yahoo! videos by Crockford that mirror the material in this book and can be found as podcasts under YUI Theater. They contain nearly all of the material in the book and probably a little more. Those videos are:
- Douglas Crockford/An Inconvenient API: The Theory of the DOM (3 parts)
- Douglas Crockford/The JavaScript Programming Language (4 parts)
- Douglas Crockford/Advanced JavaScript (3 parts)
- Douglas Crockford/Javascript The Good Parts
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38 of 40 people found the following review helpful:
5.0 out of 5 stars
Beautiful book, May 16, 2008
This is a beautiful book.
First of all - at only 170 pages it is short. Even though some of the key points are repeated through the book it's dense with information. You don't need any JavaScript experience, but it's not a "beginning programming" book so if you haven't been programming before this is not the right book for you.
Reading this book a couple of times will give you an appreciation for the JavaScript language that you almost certainly didn't have before. It'll give you tools to write better programs that you and others will actually be able to maintain over time.
I've learned lots of little things that I maybe knew from experience, but now I _know_ and I know why.
This book will help you battle with JavaScript rather than against it.
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77 of 95 people found the following review helpful:
3.0 out of 5 stars
JavaScript: The Pretty Good Book, June 14, 2008
I'm not sure what I thought this book would be; I guess I assumed it would be along the lines of "C Traps and Pitfalls". At times, however, it seems almost more like an essay.
Certainly, parts of the book are worth five stars. I was especially pleased to see the author's treatment of how null, undefined, and NaN all relate to one another in unexpected ways -- something that has puzzled me in the past. It was also good to see a list of the reserved keywords, some of which I didn't know before, and concrete examples of the dangers of == and != versus === and !==.
An unexpected treat was to read his discussions on the technical aspects and slowness of arrays, bitwise operators, and "with" statements in JavaScript, and the origins of "switch" in FORTRAN IV, and JavaScript's similarity to Lisp, despite its outward resemblance to C.
It was also bemusing to see his example of "flight.equipment && flight.equipment.model" on page 21, as I also learned that same lesson while working on a flight-related application.
Yet, for the head Javascript guy at Yahoo, it seems that a few things are missing. For example, while he does say on page 80 that slice() creates a shallow copy of an array, he does not make it explicitly clear that array2 = array1 will effectively create a pointer, i.e., a copy by reference. To make a truly independent copy of an array, one needs array2 = array1.slice() (no arguments necessary). This caused me a day of frustration when I first learned it.
And was it not Yahoo themselves that determined that scripts should come at the end of a web page to improve load speed? Why is that not in here?
We also have nothing about compression techniques.
On the web, for free, one can read Andy King's superb 2003 article on "Optimizing JavaScript For Execution Speed". And most of the discussion on objects can be learned much more succinctly and with better examples from MDC's "Core JavaScript 1.5 Guide".
One can learn a lot about download optimization from Dean Edwards.
Chapter 4 (Functions) was good; Chapter 2 (Grammar) did nothing for me.
I was also a little disappointed with Appendix B, "The Bad Parts". Most of this dealt with undisciplined programming as opposed to flaws with the language itself. E.g., "switch" statement fall-throughs are bad. Are they? If one of your people creates an unintentional fall-through, then deal with him; don't blame the language. Does Crockford also believe that firearms should be banned because of the potential of misuse, even though they have a valid purpose? How about steak knives? This is kind of like Edsger W. Dijkstra telling us that we can never use GOTO, even though it does have its place.
Further, I've used "continue" statements effectively, albeit not so often. Maybe I'm a bad programmer?
And then, he advises against autoincrements!! (++)
Regarding style, the book is definitely filled with the usual O'Reilly collegiate pompousness that's often good, sometimes not-so-good.
In summary, there are some good parts, but as a whole this is yet another pricey programming book from which I only needed 10 pages.
If you're at the plateau of understanding that it's actually the DOM that's slow and inefficient, and that Javascript is only guilty by association, and that it's actually an elegant little language, then there's probably something in this book for you.
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