Web 2.0 has seen the resurrection of JavaScript. This is quite surprising when you consider how it was misused, as animated GIFs or Java applets were previously.

Many of today’s key Web 2.0 sites have lots of Javascript links for a fancy presentation. Some JavaScript effects almost rival Flash in their complexity and aesthetic appeal.

Software vendors, and in particular Mozilla, Apple, and Google, go to great lengths to make sure that their particular browsers (Firefox, Safari, and Chrome) provide the best Javascript performance.

The recent version of Firefox included the TraceMonkey JavaScript engine and that made 3.5 twice as fast as version 3 and more than ten times faster than version 2.

Google’s Chrome is currently the champion Javascript-enabled browser, with the latest version scoring 709 ms on the Sunspider Javascript benchmark, beating Safari 4 with 910 ms and Firefox, Opera and Internet Explorer trailing behind.

This excellent performance will trickle down to regular users as developers will build more complex Javascript applications and sites to take advantage of the new technology.

Regular users will also notice the difference in their email clients, which will load much faster than before.

For front-end developers, the advent of the JQuery Javascript library has taken hold across the industry and is just as revolutionary as the introduction of CSS. The whole concept of JQuery is based on the undeniable premise of web design: ‘separate content, behavior and presentation’; and this concept drastically simplifies development and maintainability.

Other popular Javascript frameworks and libraries include Prototype, Yahoo! User Interface Library (YUI) and MooTools.

You’re no doubt also familiar with the term AJAX, which has been as ubiquitous as the term Web 2.0 for the past five years. AJAX is short for Asynchronous JavaScript and XML, with the client-side scripting language being used as the glue to bind HTML and XML together. This technique for data presentation has been widely used in recent times and has given the web community yet another reason to use Javascript.

Google’s crawler has also gotten much better at reading the language, whereas before it had trouble following links written with Javascript.

However, there are still accessibility issues with this script, and as a general rule, all essential features used on a site should work just as well if disabled in the browser.

However, it remains true that the main reason anyone should use Javascript is for form validation. Using a client-side script for this purpose reduces the load on server resources, but also provides a more user-friendly approach than using a server-side script and CSS alone.

So if you’re a web designer, it’s really worth thinking about learning Javascript, as it will undoubtedly be a vital element of online creativity for years and decades to come.