The jQuery JavaScript framework is a rising star in the world of web development. JavaScript frameworks in general have grown to become immensely popular in the past few years in parallel with the ever-increasing presence of JavaScript-driven, so-called Web 2.0 websites that make heavy use of technologies like AJAX and JavaScript in general for slick graphical enhancements that would be impossible or much more cumbersome to incorporate without JavaScript.

jQuery’s mission as a JavaScript library is simple — it strives to make the lives of web developers easier by patching over certain portions of cross-browser development and by making other tasks commonly needed by developers much easier. jQuery has the real, proven ability to reduce many lines of plain-vanilla JavaScript to just a few lines, and, in many cases, just a single line. jQuery strives to remove barriers to JavaScript development by removing redundancy wherever possible and normalizing cross-browser JavaScript development in key areas where browsers would otherwise differ, such as Microsoft’s Event API and the W3C Event API, and other, more remedial tasks like getting the mouse cursor’s position when an event has taken place.

jQuery is a compact, lightweight library that currently works in Microsoft’s Internet Explorer browser from version 6 on, Firefox from version 1.5 on, Safari from version 2.0.2 on, Opera from version 9 on, and Google’s new Chrome browser from version 0.2 on. Getting started with jQuery is very easy — all you have to do is include a single link of markup in your HTML or XHTML documents that includes the library. Throughout this book, I demonstrate jQuery’s API (Application Programming Interface) components in detail and show you how all the nuts and bolts of this framework come together to enable you to rapidly develop client-side applications.

I also cover the jQuery UI library, which makes redundant user-interface (UI) tasks on the client side ridiculously easy and accessible to everyday web developers who might not have much JavaScript programming expertise. Have you ever wondered how websites make virtual pop-up windows using JavaScript, HTML, and CSS? The jQuery UI library provides the ability to create these pop-up windows and includes the ability to animate transitions like fading the window on and off, or having it re-size from very small to full sized. The jQuery UI library gives you the ability to use animations and transitions using JavaScript, markup, and CSS that you may have thought previously could only have been done with Adobe’s Flash player.

What This Book Covers

This book covers the jQuery JavaScript framework and the jQuery UI JavaScript framework and demonstrates in great detail how to use the jQuery framework to get more results more quickly out of JavaScript programming. I cover each method exposed by jQuery’s API, which contains methods to make common, redundant tasks go much more quickly in less code. Some examples are methods that help you to select elements from a markup document through the DOM and methods that help you to traverse through those selections and filter them using jQuery’s fine-grained controls. This makes working with the DOM easier and more effortless. I also cover how jQuery eliminates certain cross-browser, cross-platform development headaches like the event model; not only does it eliminate these headaches, but it also makes it easier to work with events by reducing the amount of code that you need to write to attach events. It even gives you the ability to simulate events.

Later in the book, I cover how you can leverage the jQuery UI library to make graphically driven UI widgets. jQuery gives you the ability to break content up among multiple tabs in the same page. You have the ability to customize the look and feel of the tabs, and even to create a polished look and feel by providing different effects that come in when you mouse over tabs and click on them. The jQuery UI library also makes it easy to create accordion sidebars, like the one on Apple’s Mac website. These sidebars have two or more panels, and when you mouse over an item, one pane transitions to another via a smooth, seamless animation wherein the preceding pane collapses and the proceeding pane expands.

The jQuery UI library also gives you the ability to make any element draggable with the mouse; by clicking and holding and moving the mouse, you can move elements around on a page. It also makes it really easy to create drag-and-drop user interfaces. This can be used to make a dropping zone where you take elements from other parts of the page and drop them in another, as you would in your operating system’s file manager when you want to move a folder from one place to another. You can also make lists that are sortable via drag-and-drop, rearranging elements based on where you drop them. You can also have a user interface where you drag the mouse cursor to make a selection, as you would in your operating system’s file manager when you want to select more than one file. Then jQuery UI also exposes the ability to re-size elements on a page using the mouse. All of those neat things that you can do on your computer’s desktop, you can also do in a web browser with jQuery UI.

jQuery UI also provides a widget for entering a date into a field using a nice, accessible JavaScript-driven calendar that pops up when you click on an input field.

You can also make custom pop-up dialogues that are like virtual pop-up windows, except they don’t open a separate browser window — they come up using markup, CSS, and JavaScript.

Another widget that jQuery UI provides is a graphical slider bar, similar to your media player’s volume control.

As jQuery has done for JavaScript programming in general, jQuery UI strives to do for redundant graphical user interface (GUI) tasks. jQuery UI gives you the ability to make professional user-interface widgets with much less development effort.

This book is for anyone interested in doing more with less code! You should have a basic understanding of JavaScript. I review some basic JavaScript programming concepts, such as the Event API, but I do not go into great detail about the JavaScript language itself. You’ll want to have at least a basic grasp of the Document Object Model, or DOM, and basic JavaScript programming syntax. Additionally, you’ll need to know your way around CSS and HTML, since knowledge of those technologies is also assumed. A complete beginner might be able to grasp what is taking place in the examples in this book but might not understand certain terminology and programming concepts that would be presented in a beginner’s JavaScript guide, so if you are a beginner and insist with pressing forward, I recommend doing so with a beginning JavaScript book on hand as well. Specifically, I recommend the following Wrox books for more help with the basics:

• Beginning Web Programming with HTML, XHTML, and CSS, 2nd ed. (2008), by Jon Duckett
• Beginning CSS: Cascading Style Sheets for Web Design, 2nd ed. (2007), also written by yours truly.
• Beginning JavaScript, 3rd ed. (2007), by Paul Wilton and Jeremy McPeak

For further knowledge of JavaScript above and beyond what is covered in this book, I recommend Professional JavaScript for Web Developers, 2nd ed. (2009), by Nicholas C. Zakas.