jQuery Cookbook

Preface

Rebecca Murphey and Cody Lindley

The jQuery library has taken the frontend development world by storm. Its dead-simple syntax makes once-complicated tasks downright trivial—enjoyable, even. Many a developer has been quickly seduced by its elegance and clarity. If you’ve started using the library, you’re already adding rich, interactive experiences to your projects.

Getting started is easy, but as is the case with many of the tools we use to develop websites, it can take months or even years to fully appreciate the breadth and depth of the jQuery library. The library is chock-full of features you might never have known to wish for. Once you know about them, they can dramatically change how you approach the problems you’re called upon to solve.

The goal of this cookbook is to expose you, dear reader, to the patterns and practices of some of the leading frontend developers who use jQuery in their everyday projects. Over the course of 18 chapters, they’ll guide you through solutions to problems that range from straightforward to complex. Whether you’re a jQuery newcomer or a grizzled JavaScript veteran, you’re likely to gain new insight into harnessing the full power of jQuery to create compelling, robust, high-performance user interfaces.

Who This Book Is For

Maybe you’re a designer who is intrigued by the interactivity that jQuery can provide. Maybe you’re a frontend developer who has worked with jQuery before and wants to see how other people accomplish common tasks. Maybe you’re a server-side developer who’s frequently called upon to write client-side code.

Truth be told, this cookbook will be valuable to anyone who works with jQuery—or who hopes to work with jQuery. If you’re just starting out with the library, you may want to consider pairing this book with Learning jQuery 1.3 from Packt, or jQuery in Action from Manning. If you’re already using jQuery in your projects, this book will serve to enhance your knowledge of the library’s features, hidden gems, and idiosyncrasies.

What You’ll Learn

We’ll start out by covering the basics and general best practices—including jQuery in your page, making selections, and traversing and manipulation. Even frequent jQuery users are likely to pick up a tip or two. From there, we move on to real-world use cases, walking you through tried-and-true (and tested) solutions to frequent problems involving events, effects, dimensions, forms, and user interface elements (with and without the help of jQuery UI). At the end, we’ll take a look at testing your jQuery applications and integrating jQuery into complex sites.

Along the way, you’ll learn strategies for leveraging jQuery to solve problems that go far beyond the basics. We’ll explore how to make the most of jQuery’s event management system, including custom events and custom event data; how to progressively enhance forms; how to position and reposition elements on the page; how to create user interface elements such as tabs, accordions, and modals from scratch; how to craft your code for readability and maintainability; how to optimize your code to ease testing, eliminate bottlenecks, and ensure peak performance; and more.

Because this is a cookbook and not a manual, you’re of course welcome to cherry-pick the recipes you read; the individual recipes alone are worth the price of admission. As a whole, though, the book provides a rare glimpse into the problem-solving approaches of some of the best and brightest in the jQuery community. With that in mind, we encourage you to at least skim it from front to back—you never know which line of code will provide the “Aha!” moment you need to take your skills to the next level.

jQuery Style and Conventions

jQuery places a heavy emphasis on chaining—calling methods on element selections in sequence, confident in the knowledge that each method will give you back a selection of elements you can continue to work with. This pattern is explained in depth in Chapter 1—if you’re new to the library, you’ll want to understand this concept, because it is used heavily in subsequent chapters.

jQuery’s features are organized into a handful of simple categories: core functionality, selecting, manipulating, traversing, CSS, attributes, events, effects, Ajax, and utilities. Learning these categories, and how methods fit into them, will greatly enhance your understanding of the material in this book.

One of the best practices this book will cover is the concept of storing element selections in a variable, rather than making the same selection repeatedly. When a selection is stored in a variable, it is commonplace for that variable to begin with the $ character, indicating that it is a jQuery object. This can make code easier to read and maintain, but it should be understood that starting the variable name with the $ character is merely a convention; it carries no special meaning, unlike in other languages such as PHP.

In general, the code examples in this book strive for clarity and readability over compactness, so the examples may be more verbose than is strictly necessary. If you see an opportunity for optimization, you should not hesitate to take it. At the same time, you’ll do well to strive for clarity and readability in your own code and use minification tools to prepare your code for production use.

Other Options

If you’re looking for other jQuery resources, here are some we recommend:

• Learning jQuery 1.3, by Jonathan Chaffer, Karl Swedberg, and John Resig (Packt)

• jQuery in Action, by Bear Bibeault, Yehuda Katz, and John Resig (Manning)

• jQuery UI 1.6: The User Interface Library for jQuery, by Dan Wellman (Packt)

If You Have Problems Making Examples Work

Before you check anything else, ensure that you are loading the jQuery library on the page—you’d be surprised how many times this is the solution to the “It’s not working!” problem. If you are using jQuery with another JavaScript library, you may need to use jQuery.noConflict() to make it play well with others. If you’re loading scripts that require the presence of jQuery, make sure you are loading them after you’ve loaded the jQuery library.

Much of the code in this book requires the document to be “ready” before JavaScript can interact with it. If you’ve included code in the head of the document, make sure your code is enclosed in $(document).ready(function() { ... }); so that it knows to wait until the document is ready for interaction.

Some of the features discussed in this book are available only in jQuery 1.3 and later. If you are upgrading from an older version of jQuery, make sure you’ve upgraded any plugins you’re using as well—outdated plugins can lead to unpredictable behavior.

If you’re having difficulty getting an example to work in an existing application, make sure you can get the example working on its own before trying to integrate it with your existing code. If that works, tools such as Firebug for the Firefox browser can be useful in identifying the source of the problem.

If you’re including a minified version of jQuery and running into errors that point to the jQuery library itself, you may want to consider switching to the full version of jQuery while you are debugging the issue. You’ll have a much easier time locating the line that is causing you trouble, which will often lead you in the direction of a solution.

If you’re still stuck, consider posting your question to the jQuery Google group. Many of this book’s authors are regular participants in the group, and more often than not, someone in the group will be able to offer useful advice. The #jquery IRC channel on Freenode is another valuable resource for troubleshooting issues.

If none of this works, it’s possible we made a mistake. We worked hard to test and review all of the code in the book, but errors do creep through. Check the errata (described in the next section) and download the sample code, which will be updated to address any errata we discover.

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There’s also a link to errata there. Errata gives readers a way to let us know about typos, errors, and other problems with the book. That errata will be visible on the page immediately, and we’ll confirm it after checking it out. O’Reilly can also fix errata in future printings of the book and on Safari, making for a better reader experience pretty quickly. We hope to keep this book updated for future versions of jQuery, and will also incorporate suggestions and complaints into future editions.

Conventions Used in This Book

The following typographical conventions are used in this book:

Italic

Indicates Internet addresses, such as domain names and URLs, and new items where they are defined.

Constant width

Indicates command lines and options that should be typed verbatim; names and keywords in programs, including method names, variable names, and class names; and HTML element tags, switches, attributes, keys, functions, types, namespaces, modules, properties, parameters, values, objects, events, event handlers, macros, the contents of files, or the output from commands.

Constant width bold

Indicates emphasis in program code lines.

Constant width italic

Indicates text that should be replaced with user-supplied values.

Note

This icon signifies a tip, suggestion, or general note.

Warning

This icon indicates a warning or caution.

Using Code Examples

This book is here to help you get your job done. In general, you may use the code in this book in your programs and documentation. You do not need to contact us for permission unless you’re reproducing a significant portion of the code. For example, writing a program that uses several chunks of code from this book does not require permission. Answering a question by citing this book and quoting example code does not require permission. Selling or distributing a CD-ROM of examples from O’Reilly books does require permission. Incorporating a significant amount of example code from this book into your product’s documentation does require permission.

We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: “jQuery Cookbook, by Cody Lindley. Copyright 2010 Cody Lindley, 978-0-596-15977-1.” If you feel your use of code examples falls outside fair use or the permission given above, feel free to contact us at [e-mail].

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