In 2005, inspired by pioneers in the field such as Dean Edwards and Simon Willison, John Resig put together a set of functions to make it easy to programmatically find elements on a web page and assign behaviors to them. By the time he first publicly announced his project in January 2006, he had added DOM modification and basic animations. He gave it the name jQuery to emphasize the central role of finding or querying parts of a web page and acting on them with JavaScript. Rapidly over the years since then, jQuery has grown in its feature set, improved in its performance, and gained widespread adoption by many of the most popular sites on the Internet. While Resig has since stepped down from his role as lead developer of the project, jQuery has blossomed, in true open source fashion, to the point where it now boasts a top-notch core team headed by Dave Methvin, as well as a vibrant community of thousands of additional JavaScript developers.

The jQuery JavaScript library can enhance your websites regardless of your background. It provides a wide range of features, an easy-to-learn syntax, and robust cross-platform compatibility in a single compact file. What's more, hundreds of plugins have been developed to extend jQuery's functionality, making it an essential tool for nearly every client-side scripting occasion.

Learning jQuery Fourth Edition provides a gentle introduction to jQuery concepts, allowing you to add interactions and animations to your pages—even if previous attempts at writing JavaScript have left you baffled. This book guides you past the pitfalls associated with Ajax, events, effects, and advanced JavaScript language features, and provides you with a brief reference to the jQuery library to return to again and again.