jQuery UI in Action

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Brief Table of Contents

Copyright

Brief Table of Contents

Table of Contents

Foreword

Preface

Acknowledgments

About this Book

About the Cover Illustration

1. Meet jQuery UI

Chapter 1. Introducing jQuery UI

Chapter 2. Enhancing UIs with widgets

2. jQuery UI Core

Chapter 3. Building complex web forms with jQuery UI

Chapter 4. Enhancing interfaces with layout and utility widgets

Chapter 5. Adding interaction to your interfaces

Chapter 6. Creating rich animations with effects

Chapter 7. Theming and styling applications with jQuery UI

3. Customization and advanced usage

Chapter 8. Using the widget factory to build stateful plugins

Chapter 9. Extending widgets with the widget factory

Chapter 10. Preparing your application for production

Chapter 11. Building a flight-search application

Chapter 12. Under the hood of jQuery UI

Appendix A. Learning jQuery

Appendix B. How jQuery UI tests jQuery UI

Appendix C. Using jQuery UI with Backbone

Appendix D. Creating decimal, currency, and time pickers with Globalize

Appendix E. Contributing to jQuery UI

Appendix F. Polyfilling HTML5 with jQuery UI

Index

List of Figures

List of Tables

List of Listings

Table of Contents

Copyright

Brief Table of Contents

Table of Contents

Foreword

Preface

Acknowledgments

About this Book

About the Cover Illustration

1. Meet jQuery UI

Chapter 1. Introducing jQuery UI

1.1. What is in jQuery UI?

1.2. The benefits of using jQuery UI

1.2.1. Cohesive and consistent APIs

1.2.2. Comprehensive browser support

1.2.3. Open source and free to use

1.2.4. Thorough documentation

1.2.5. Powerful theming mechanism

1.2.6. Emphasis on accessibility

1.2.7. Stable and maintenance friendly

1.3. The limitations of jQuery UI

1.3.1. Lack of widgets

1.3.2. jQuery UI and mobile devices

1.4. Getting started with the library

1.4.1. Versions of the library

1.4.2. Downloading from the jQuery UI website

1.4.3. Downloading from CDNs

1.5. The first example

1.6. Using an online testing tool

1.7. Summary

Chapter 2. Enhancing UIs with widgets

2.1. Creating widgets

2.2. Customizing widgets with options

2.3. Modifying widgets with methods

2.3.1. Invoking methods

2.3.2. Using option() to modify widgets

2.3.3. Using dialogs to edit lists

2.4. Responding to widget changes with events

2.4.1. Subscribing to widget events

2.4.2. Event handlers vs. callbacks

2.4.3. Event parameters

2.5. Summary

2. jQuery UI Core

Chapter 3. Building complex web forms with jQuery UI

3.1. The challenges of building modern web forms

3.2. Autocomplete: suggesting input options to users

3.2.1. Using local data

3.2.2. Loading from a remote source

3.2.3. Using autocomplete with third-party services and APIs

3.3. Button: enhancing native buttons, inputs, and links

3.4. Selectmenu: enhancing native elements

3.5. Datepicker: selecting dates from a pop-up calendar

3.5.1. Parsing and formatting dates

3.5.2. Handling date globalization

3.6. Spinner: enhancing native elements to collect numeric data

3.7. Completing the appointment form

3.8. HTML5 elements vs. jQuery UI widgets

3.9. Summary

Chapter 4. Enhancing interfaces with layout and utility widgets

4.1. Accordion: creating toggleable content panels

4.1.1. Configuring the accordion widget

4.1.2. Adding and removing panels

4.2. Tabs: toggling between content areas

4.2.1. Loading remote content

4.2.2. Loading movie information in a tabs widget

4.3. Menu: creating web menus with semantic markup

4.4. Dialog: displaying content in a pop-up container

4.5. Progressbar: displaying the progress of a task

4.6. Slider: selecting a value using moveable handles

4.6.1. Building range sliders

4.6.2. Adding a font size range

4.7. Tooltip: enhancing native tooltips with a customizable control

4.7.1. Using custom tooltip content

4.7.2. Displaying a preview in a tooltip

4.8. Summary

Chapter 5. Adding interaction to your interfaces

5.1. Draggable: allowing users to move elements

5.2. Droppable: creating containers that accept draggables

5.2.1. Building a drag-and-drop game

5.2.2. Building a shopping cart

5.3. Sortable: rearranging elements in a list

5.3.1. Building connected lists

5.3.2. Building a fruit and vegetable sorting game

5.4. Resizable: allowing users to change the size of elements

5.4.1. Using custom resize handles

5.4.2. Building an appointment scheduler

5.5. Selectable: allowing users to select elements from a group

5.6. Creating multidevice interactions: the importance of touch

5.6.1. Why doesn’t jQuery UI support touch events?

5.6.2. Introducing jQuery UI Touch Punch

5.7. Summary

Chapter 6. Creating rich animations with effects

6.1. Using effects and the effect() method

6.1.1. Customizing effects with easings

6.1.2. Making visual associations with the transfer effect

6.2. Animating visibility changes

6.2.1. Building form validation messages

6.2.2. Building portlets with jQuery UI

6.3. Using effects with the jQuery UI widgets

6.3.1. The show and hide options

6.3.2. Showing a message in a dialog

6.4. Animating CSS class name changes

6.4.1. Enhancing addClass(), removeClass(), and toggleClass()

6.4.2. Building an off-canvas navigation menu for mobile

6.5. Effects vs. CSS3 animations and transitions

6.5.1. CSS3 transitions vs. the jQuery UI class name methods

6.5.2. CSS animations vs. effects

6.6. Summary

Chapter 7. Theming and styling applications with jQuery UI

7.1. Using built-in and custom themes

7.2. Using the jQuery UI CSS framework to customize applications

7.2.1. Styling widget containers

7.2.2. Styling interaction states

7.2.3. Styling interaction cues

7.2.4. Building a styled confirmation dialog

7.3. Styling with widget class names

7.3.1. Building vertical tabs

7.3.2. Building a mobile-friendly datepicker

7.3.3. Adding arrows to tooltips with CSS

7.4. Summary

3. Customization and advanced usage

Chapter 8. Using the widget factory to build stateful plugins

8.1. Building a widget

8.1.1. Constructing widgets with $.widget()

8.1.2. Choosing a markup structure

8.1.3. Overriding _create() to initialize widgets

8.1.4. Making widgets themeable

8.1.5. Listening for events with _on()

8.2. Customizing widgets with options, methods, and events

8.2.1. Making widgets configurable with options

8.2.2. Changing the widget’s state with methods

8.2.3. Triggering widget events with _trigger()

8.3. Enabling, disabling, and destroying widgets

8.3.1. Enabling and disabling a widget

8.3.2. Undoing a widget’s effects with _destroy()

8.4. Summary

Chapter 9. Extending widgets with the widget factory

9.1. Building widget extensions

9.1.1. Changing existing and adding new options to a widget

9.1.2. Redefining widgets with the widget factory

9.1.3. Extending a custom widget

9.2. Customizing widgets with extension points

9.2.1. Using undocumented extension points

9.2.2. Adding your own extension points

9.3. Extending the datepicker widget

9.3.1. Building a mobile-friendly datepicker extension

9.4. Summary

Chapter 10. Preparing your application for production

10.1. The problem with third-party CDNs

10.2. Downloading jQuery UI from Download Builder

10.3. Managing JavaScript dependencies with AMD

10.3.1. Setting up RequireJS for development

10.3.2. Loading jQuery UI components with RequireJS

10.4. Building your application’s assets with the optimizer

10.4.1. Optimizing JavaScript assets

10.4.2. Optimizing CSS dependencies

10.5. Supporting AMD in custom widgets

10.6. Summary

Chapter 11. Building a flight-search application

11.1. Structuring your application

11.2. Collecting user input

11.2.1. Building an airport code autocomplete

11.2.2. Polyfilling HTML5 inputs with jQuery UI

11.2.3. Validating user input with HTML5

11.3. Connecting to a RESTful API

11.3.1. Looking up flights with $.ajax()

11.3.2. Parsing XML with jQuery

11.4. Displaying the results on the screen

11.4.1. Storing and resolving templates with RequireJS

11.4.2. Showing a processing indicator while data loads

11.5. Adding a responsive design

11.6. Preparing the application for production

11.7. Getting the optimal performance with almond

11.8. Summary

Chapter 12. Under the hood of jQuery UI

12.1. Positioning elements with the position utility

12.1.1. Building a UI walkthrough with the position utility and dialog widget

12.1.2. Handling collisions elegantly

12.1.3. Controlling the collision detection

12.2. Using the utility functionality in jQuery UI Core

12.2.1. Generating unique ids

12.2.2. Using key code constants

12.3. Accessing and managing widget instances

12.3.1. Detecting widget instances with :data()

12.4. Advanced widget prototype methods and properties

12.4.1. A widget’s prototype chain explained

12.4.2. Using a widget’s default element to streamline initialization

12.4.3. Supporting embedded-window use in widgets

12.4.4. Displaying elements with _show() and _hide()

12.4.5. Customizing options on the fly

12.5. Using autoinitialization to remove boilerplate code

12.5.1. How jQuery Mobile’s autoinitialization works

12.5.2. jQuery Mobile’s widget extension

12.5.3. Autoinitializing jQuery UI widgets

12.6. Summary

Appendix A. Learning jQuery

A.1. Experimentation

A.1.1. Try jQuery (try.jquery.com)

A.1.2. Online testing tools

A.1.3. The browser’s developer tools

A.2. Reading

A.2.1. jQuery Learning Center (learn.jquery.com)

A.2.2. Books

Appendix B. How jQuery UI tests jQuery UI

B.1. Testing options

B.2. Testing methods

B.3. Testing events

Appendix C. Using jQuery UI with Backbone

C.1. Building a Backbone view

C.2. Adding jQuery UI to the view

C.3. Using declarative widgets

Appendix D. Creating decimal, currency, and time pickers with Globalize

D.1. Building decimal pickers

D.2. Building currency pickers

D.3. Building time pickers

Appendix E. Contributing to jQuery UI

E.1. Help others on the forums, Stack Overflow, and IRC

E.2. Triage bugs

E.3. Write documentation and maintain the websites

E.4. Write code

E.5. Ask for help

Appendix F. Polyfilling HTML5 with jQuery UI

F.1. Using polyfills

F.1.1. Using Modernizr

F.2. Polyfilling date> with datepicker

F.3. Polyfilling number> with spinner

F.4. Polyfilling range> with slider

F.5. Polyfilling with progressbar

F.6. Polyfilling

Index

List of Figures

List of Tables

List of Listings

Foreword

jQuery has taken the web development community by storm. It has done this by building an API that is approachable for designers and new developers while simultaneously providing the power and extensibility desired by the most advanced and experienced developers. jQuery is easy to learn, easy to extend, and paves over browser differences, making it the go-to choice for millions of developers.

jQuery UI takes the same philosophies used to build jQuery and applies them to various aspects of UI creation. Building elegant interfaces with powerful, customizable widgets should be just as easy as showing and hiding elements. jQuery UI delivers on this promise while addressing often ignored issues such as accessibility and extensibility.

jQuery UI has built a solid base over the past seven years and the number of users is growing steadily. But the web is evolving at a rapid pace and new JavaScript libraries and UI toolkits are popping up left and right. Choosing the right tools for your next project can be quite daunting. jQuery UI in Action shows how to leverage jQuery UI to quickly build an application or just add an extra touch of interaction on an existing page.

This book will serve as a fantastic resource for anyone interested in getting started with jQuery UI. As always, TJ has done a great job of walking through tasks in detail and pointing out potential pitfalls. TJ’s dedication and desire to help others has been an invaluable asset, not just to jQuery UI, but to the web development community as a whole. I’m sure you’ll feel the same way after reading this book.

SCOTT GONZÁLEZ

PROJECT LEAD, JQUERY UI

Preface

In 2013 Manning contacted me about writing a book on jQuery UI. Because I had been an enthusiastic user of the library for five years, and had been a member of the jQuery team for approximately two years, I had a lot of experience and knowledge that I wanted to share with the world. I said Yes!

From the start, I made it clear that I wanted to take a different tack with this book: rather than reprinting the library’s API documentation in a book, which is something I think far too many tech books do, I wanted to write about how to use the jQuery UI components in real-world usage scenarios and applications. I also wanted to tackle the tough questions for jQuery UI users. Why should you use the jQuery UI datepicker instead of the native date picker included in HTML5? How do you use jQuery UI on mobile devices, especially in low bandwidth situations?

From start to finish the book took about a year and a half to complete, and although it was an exhausting amount of work, I’m extremely happy with the result. jQuery UI is a stable library that helps you write robust, accessible, and cross-browser friendly web applications today. This book represents my attempt to share the knowledge I’ve gained from building countless projects with jQuery UI, and from working as a member of the jQuery team. I hope you enjoy it.

Acknowledgments

I never thought that I would be writing one of these ... I feel like I’m at the Oscars or something. Although I hate to list specific names, as it will force me to exclude people I should thank and it’ll be totally awkward the next time I see them, I’ll do it anyway ... otherwise this section would be kind of boring.

I’ll start with Scott González, who brought me into the jQuery project, walked me through countless jQuery concepts, and has always been around to help with any problem I run into. In addition to helping me with all things jQuery UI over the last few years, Scott also contributed the foreword to this book.

Next I’ll thank Jörn Zaefferer, whose expertise has made me a better developer during my time with jQuery UI. I asked Jörn to perform the technical review of this book because I felt he was the most qualified person for the job (he is the original author of a good chunk of the jQuery UI source), and I wasn’t disappointed. The book is unquestionably better because of Jörn.

The entire jQuery UI team has either directly or indirectly helped make this book a reality, so I’d also like to thank Kris Borchers, Felix Nagel, Corey Frang, Mike Sherov, Rafael Xavier, and Alexander Schmitz.

The people at Manning have been great through the long and arduous process of writing a technical book. My development editor, Sean Dennis, not only provided great feedback throughout, but also took care of managing the various tedious processes involved in writing and publishing a book. Robin de Jongh was the one who asked me to write this book and was a great guy to talk to throughout the process. Without him there would be no book.

The following peer reviewers also provided invaluable insights, reading the manuscript a number of times during its development and I’d like to acknowledge them here: Linda Carver, A. Krishna Chaitanya, Alain Couniot, Jürgen De Commer, Dave Corun, Cole Davisson, Mark Elston, Peter Empen, Ed Griebel, Al Scherer, Natalia Stavisky, Philip Taffet, and Gregor Zurowski.

But without question, the lion’s share of thanks goes to my beautiful and talented significant other, Trish. In addition to providing desperately needed moral support throughout the harrowing journey that was the writing of this book, Trish also helped shape the structure and flow of the chapters with her own development expertise (as well as her brutally honest criticism). And because she has a wizard-like ability to bend CSS to her will, she may even have had her hand in the book’s examples directly.

Thank you, Trisha. I love you.

About this Book

jQuery UI in Action’s primary purpose is to teach you how to use the jQuery UI library to build rich, user-friendly web applications. The book starts with the basics of creating and modifying widgets, and moves on to a series of complex examples, such as building widgets from scratch, optimizing your applications for production, and even building a complete flight-search application.

This book assumes that you have basic knowledge of CSS, JavaScript, and jQuery. If you’re not an expert don’t despair—when intermediate- and advanced-level concepts are brought up, they’re explained. If you’re finding yourself a bit overwhelmed, appendix A discusses resources for getting up to speed. On the flip side, if you’re an expert don’t despair either. You’ll build a number of real-world examples and discuss advanced aspects of the library throughout the book.

Roadmap

This book is organized into three parts.

Part 1 provides an introduction to jQuery UI. Chapter 1 introduces the library itself, with an explanation of what is in the library, what the library does well, and what it doesn’t do well. Chapter 2 explains the ins and outs of widgets, the core building blocks of jQuery UI.

Part 2 walks through the core components of jQuery UI, starting with its widgets. Chapter 3 introduces the five jQuery UI form widgets, uses them to build a complete form, and compares the widgets to their HTML5 counterparts. Chapter 4 discusses the three jQuery UI layout widgets and the four utility widgets. Chapter 5 introduces the five interaction widgets, and uses them to build a series of real-world interfaces, as well as a few games. Chapter 6 contains a thorough discussion of the jQuery UI effects and chapter 7 explains everything about jQuery UI themes.

Part 3 builds upon the core knowledge taught in part 2 to show a series of advanced topics. Chapter 8 shows how to build your own widgets from scratch, using the same mechanism jQuery UI uses. Chapter 9 shows how to customize the behavior of any widget using widget extensions. Chapter 10 teaches how to prepare a jQuery UI application for production usage, including applying several performance optimizations. Chapter 11 builds upon all this knowledge to explain how to build a complete flight-search application. And finally, chapter 12 looks under the hood of the library, to show the tools that jQuery UI uses to make jQuery UI work.

There are 6 appendixes. Appendix A covers the best ways to learn jQuery. How jQuery UI tests its own widgets (jQuery UI tests jQuery UI!) is the focus of appendix B. Appendix C focuses on using jQuery UI with Backbone. Appendix D is about globalization. Ways to contribute to jQuery UI are explained in appendix E, and polyfilling HTML5 with jQuery UI is touched on in appendix F.

Code conventions

jQuery UI in Action provides copious examples that show how you can make use of each of the topics covered. Source code in listings or in text appears in a fixed-width font like this to separate it from ordinary text. In addition, class and method names, object properties, and other code-related terms and content in text are presented using the same fixed-width font.

Code annotations accompany many of the listings, highlighting important concepts. In some cases, numbered cueballs link to additional explanations that follow the listing.

Getting the source code

You can access the source code for all examples in the book from the publisher’s website at www.manning.com/jQueryUIinAction. All source code for the project is also hosted at GitHub, a commercial Git hosting firm, at https://github.com/tjvantoll/jquery-ui-in-action-demos. We will maintain the current URL via the publisher’s website. The source is maintained by chapter, so, for example, you can download /source-code/ch06 and you will have a full copy of the source code up to that point in the book.

Author Online

Purchase of jQuery UI in Action includes free access to a private web forum run by Manning Publications where you can make comments about the book, ask technical questions, and receive help from the author and from other users. To access the forum and subscribe to it, point your web browser to www.manning.com/jQueryUIinAction. This page provides information on how to get on the forum once you’re registered, what kind of help is available, and the rules of conduct on the forum.

Manning’s commitment to our readers is to provide a venue where a meaningful dialog between individual readers and between readers and the author can take place. It’s not a commitment to any specific amount of participation on the part of the author, whose contribution to the AO forum remains voluntary (and unpaid). We suggest you try asking the author some challenging questions lest his interest stray!

The Author Online forum and the archives of previous discussions will be accessible from the publisher’s website as long as the book is in print.

About the author

TJ VanToll is a developer advocate for Telerik and a jQuery team member. He has over a decade of web development experience—specializing in performance and the mobile web. TJ speaks about his research and experiences at conferences around the world, and has written for publications such as Smashing Magazine, HTML5 Rocks, and MSDN Magazine.

About the Cover Illustration

The figure on the cover of jQuery UI in Action is captioned a Man from Imotski, Croatia. The illustration is taken from the reproduction, published in 2006, of a nineteenth-century collection of costumes and ethnographic descriptions entitled Dalmatia by Professor Frane Carrara (1812–1854), an archaeologist and historian, and the first director of the Museum of Antiquity in Split, Croatia. The illustrations were obtained from a helpful librarian at the Ethnographic Museum (formerly the Museum of Antiquity), itself situated in the Roman core of the medieval center of Split: the ruins of Emperor Diocletian’s retirement palace from around AD 304. The book includes finely colored illustrations of figures from different regions of Dalmatia, accompanied by descriptions of the costumes and of everyday life.

Imotski is a small town situated on the northern side of the Biokovo massif in the Dalmatian hinterland, close to the border of Croatia with Bosnia-Herzogovina. The man on the cover is wearing an embroidered vest over a white linen shirt and white woolen trousers, a suede jacket is thrown over his shoulder, and he is carrying a musket. The rich and colorful embroidery on his costume is typical for this region of Croatia.

Dress codes have changed since the nineteenth century, and the diversity by region, so rich at the time, has faded away. It is now hard to tell apart the inhabitants of different continents, let alone different towns or regions. Perhaps we have traded cultural diversity for a more varied personal life—certainly for a more varied and fast-paced technological life.

At a time when it is hard to tell one computer book from another, Manning celebrates the inventiveness and initiative of the computer business with book covers based on the rich diversity of regional life of two centuries ago, brought back to life by illustrations from collections such as this one.

Part 1. Meet jQuery UI

These first two chapters serve as an introduction to jQuery UI. As you’ll learn in chapter 1, jQuery UI is a collection of plugins and utilities that build on jQuery, supported by the jQuery Foundation. You can count on them to be officially supported and maintained throughout the life of your application.

In chapter 1 you’ll learn about the library itself—what’s in it, who maintains it, what it does well, and even what it doesn’t do well.

In chapter 2 you’ll build on that knowledge to learn the ins and outs of widgets, the core building blocks of jQuery UI. The focus here is on three mechanisms the widget factory provides for customization: options, methods, and events. Options are configurable properties of widgets, methods let you perform actions on widgets, and events let you to respond to changes on the widgets.

What you learn about the library, and about the jQuery UI widgets, will give you the foundation you need to build more complex interfaces in part 2.

Chapter 1. Introducing jQuery UI

This chapter covers

What jQuery UI includes

Whether jQuery UI is for you

How to get started using the library

Let’s take a trip back to early 2006. The term AJAX had been coined, the second beta of Internet Explorer 7 was released, and John Resig announced a small library he called jQuery. jQuery would soon become wildly popular, thanks in part to how easy it was to extend its core functionality through plugins.

Months passed, and thousands of plugins were created by the jQuery community. Although the abundance of plugins provided variety, they were scattered around the internet, had inconsistent APIs, and often had little or no documentation. Because of these problems, the jQuery team wanted to provide an official set of plugins in a centralized location. In September 2007 they created a new library with these plugins—jQuery UI.

From a high level, jQuery UI was, and still is, a collection of plugins and utilities that build on jQuery. But dig deeper and you find a set of consistent, well-documented, themeable building blocks to help you create everything from small websites to highly complex web applications.

Unlike jQuery plugins, the plugins and utilities in jQuery UI are supported by the jQuery Foundation. You can count on them to be officially supported and maintained throughout the life of your application.

The stability and ease of use of jQuery UI led to continuous growth in the library’s popularity. The library is now used in 19% of the top 10,000 sites on the web, and has been incorporated into WordPress core and Drupal.

In this book you’ll learn how to use the pieces of jQuery UI to create powerful and interactive websites and applications. In this chapter you’ll start by taking a thorough look at what the jQuery UI library is, why you’d want to use it, and how to download the library and get it up and running. Let’s get started!

Who is this book for?

This book assumes that you have basic knowledge of CSS, JavaScript, and jQuery. If you’re not an expert don’t despair—when intermediate- and advanced-level concepts are brought up, they’re explained. If you’re finding yourself a bit overwhelmed, appendix A discusses resources for getting up to speed. On the flip side, if you’re an expert don’t despair either. We’ll build a number of real-world examples and discuss advanced aspects of the library throughout the book.

1.1. What is in jQuery UI?

The plugins and utilities in jQuery UI are divided into four categories—widgets, interactions, effects, and utilities (the structure of the library is presented in figure 1.1):

Figure 1.1. The pieces of the jQuery UI library, categorized into widgets, interactions, utilities, and effects

Widgets are jQuery plugins used to create UI elements such as datepickers and menus. As of version 1.11, the library has 12 widgets, shown in figure 1.2. The widgets in jQuery UI adhere to the library’s CSS framework, and therefore have a consistent look and feel. We’ll cover the jQuery UI widgets in chapters 2, 3, and 4 and the CSS framework in chapter 7.

Figure 1.2. An example of all 12 jQuery UI widgets. Because of the jQuery UI CSS framework, each widget has a consistent look.

Interactions are jQuery plugins that give the user the ability to interact with DOM elements. The draggable interaction allows users to drag elements around the screen, and the sortable interaction allows users to sort items in a list. We’ll cover interactions in chapter 5.

Effects are a full suite of custom animations and transitions for DOM elements. They’re built on the animations provided in jQuery Core, and enhance a number of Core’s methods such as show() and hide(). We’ll cover effects in chapter 6.

Utilities are a set of modular tools the library uses internally. The widget factory is the mechanism all jQuery UI widgets are built with; we’ll cover it in chapters 8 and 9. The position utility provides an easy and precise means of positioning elements on the screen. We’ll cover position and the rest of the utilities in jQuery UI in chapter 12.

The pieces of jQuery UI work well together, but they were also designed with modularity in mind. Although the widget factory and position utility are heavily used in the library, they’re also standalone plugins that can be used outside of jQuery UI; their only dependency is jQuery Core.

Now that we’ve seen what jQuery UI includes, let’s see what jQuery UI can be used for, and how it might be a good fit for your next project.

Who is jQuery UI?

Development on jQuery UI (as well as all jQuery projects) is coordinated by the jQuery Foundation—a nonprofit association funded by community contributions of time and money.

The jQuery UI team is a group of eight individuals (I am one of them) scattered throughout the world. I became enthralled with jQuery UI after I discovered the amazing number of things the library could do with a small amount of code. I started submitting bug fixes and documentation and haven’t looked back.

I hope you become as excited about the library as I am. The jQuery UI project is primarily community and volunteer driven, and there’s always plenty to do!

1.2. The benefits of using jQuery UI

Any website or application that uses jQuery almost certainly has a use for jQuery UI. jQuery Core is powerful, but it’s a small library that doesn’t do everything you need to build modern web applications. If you’ve been frustrated by searching the internet and piecing together jQuery plugins, then jQuery UI provides an appealing alternative. Let’s look at the advantages of using the library.

1.2.1. Cohesive and consistent APIs

Because jQuery plugins have different authors, they often have wildly inconsistent APIs. jQuery UI has also faced this problem. The jQuery UI library started as a collection of popular plugins by numerous authors with a variety of programming styles. This resulted in years of refactoring to present a consistent API to end users. Throughout the process, common patterns emerged and were abstracted into utilities like the widget factory.

Because jQuery UI provides consistent APIs, users can move from one part of the library to another without constantly needing to refer to online documentation.

1.2.2. Comprehensive browser support

When using jQuery UI, you can feel confident that your code works in all major browsers. As of version 1.11, jQuery UI supports Internet Explorer versions 7 and up, as well as the latest two versions of Chrome, Firefox, Safari, and Opera. With jQuery UI, you write your code once and it runs everywhere.

Note

Internet Explorer 6 support was dropped in version 1.10 of jQuery UI due to low global usage. If you still need Internet Explorer 6 support, you can use version 1.9 of jQuery UI.

1.2.3. Open source and free to use

Everything in jQuery UI is open source. The library’s source files are publicly available at https://github.com/jquery/jquery-ui. Not only are the source files open source but the project’s home page and API documentation are as well (see https://github.com/jquery/jqueryui.com and https://github.com/jquery/api.jqueryui.com, respectively).

All development is done in the open, and the community is encouraged to participate. If you find a bug in the library, you can submit a patch for it. If you’re confused by the documentation, you can ask for clarification. If you find a typo, you can submit a patch that fixes it. The development of all jQuery projects is community driven, and contributions are always welcome. For more information on contributing to jQuery, see appendix E.

jQuery UI is also free. The use of jQuery UI (and all jQuery projects) is under the terms of the MIT license. All jQuery projects are free to use in any project (including commercial ones), as long as the copyright headers are preserved.

1.2.4. Thorough documentation

One of the major pain points with jQuery plugins is the difficulty of finding up-to-date and accurate documentation. All pieces of jQuery UI are thoroughly and consistently documented at http://api.jqueryui.com/. By default, the APIs for the latest version are shown, but previous versions are available as well. For example, http://api.jqueryui.com/1.10/ shows the APIs for 1.10 and http://api.jqueryui.com/1.9/ shows the APIs for 1.9.

1.2.5. Powerful theming mechanism

Another challenge of working with plugins is creating a consistent look. Although some plugins provide a way to theme the elements they create, the conventions used are often wildly different. jQuery UI solves this with a CSS framework that all its widgets use; therefore, all widgets look the same out of the box, but you still have the flexibility to create your own custom look and feel.

To make this process easier, the jQuery UI ThemeRoller allows you to visually play with the widgets’ displays and generate a CSS file with your theme. Not a designer? No worries. jQuery UI also provides 24 themes you can use or build on top of. ThemeRoller is available at http://jqueryui.com/themeroller/ and is shown in figure 1.3.

Figure 1.3. Using jQuery UI ThemeRoller, you can configure a custom theme by playing with CSS properties and seeing their effect on the jQuery UI widgets live.

1.2.6. Emphasis on accessibility

Accessibility is an important consideration when building anything for the web, but making even simple applications accessible to all audiences can be a difficult task. Documentation is scarce, screen readers can be tricky to test on, and specifications such as Accessible Rich Internet Applications (ARIA) can be complex and difficult to understand.

All jQuery UI widgets are designed with accessibility in mind. You can add widgets to your site and feel confident that everyone can use them. The jQuery UI widgets are keyboard accessible, use ARIA roles appropriately, and use proper markup to optimize user experiences on screen readers.

Note

ARIA is a technical specification published by the World Wide Web Consortium (W3C). It aims to improve the accessibility of web pages—specifically pages with dynamic content and UI components. It specifies a number of HTML attributes that can be applied to elements to help assistive technologies such as screen readers interpret web pages.