JavaScript has come a long way from its humble beginnings in 1995 as part of the Netscape browser, to the high-performance JIT interpreters of today. Even just five years ago developers were blown away by Ajax and the yellow fade technique; now, complex JavaScript apps run into the hundreds of thousands of lines.

In the last year, a new breed of JavaScript applications has appeared, giving an experience people were used to on the desktop, but that was unheard of on the Web. Gone are the slow page requests every time a user interacts with an application; instead, JavaScript engines are now so powerful we can keep state client side, giving a much more responsive and improved experience.

It’s not just JavaScript engines that have improved; CSS3 and HTML5 specs haven’t finished the drafting stage, but they are already widely supported by modern browsers such as Safari, Chrome, Firefox, and—to some extent—IE9. Beautiful interfaces can be coded in a fraction of the time previously required, and without all that notorious image cutting and splicing. Support for HTML5 and CSS3 is getting better every day, but you’ll need to decide—based on your client base—whether to use these technologies.

Moving state to the client side is no simple task. It requires a completely different development approach to server-side applications. You need to think about structure, templating, communicating with the server, frameworks, and much more. That’s where this book comes in; I’ll take you through all the steps necessary to create state-of-theart JavaScript applications.