After the fourth edition of JavaScript: The Definitive Guide was published, the Document Object Modelthe fundamental API for client-side JavaScript™ programmingbecame widely, if not completely, implemented in web browsers. This meant that web developers had a stable, mature language (JavaScript 1.5) and a common API for manipulating web pages on the client. Several years of stability followed.
But things have started to get interesting again. Developers are now using JavaScript to script HTTP, manipulate XML data, and even draw dynamic graphics in a web browser. Many JavaScript developers have also started to write longer programs and use more sophisticated programming techniques, such as closures and namespaces. This fifth edition has been fully revised for the new world of Ajax and Web 2.0 technologies.