Just one week ahead of the planned final release of Microsoft's IE 8, the long-delayed third beta version of Firefox 3.1 web browser was officially released by Mozilla, on Thursday. The Firefox 3.1 beta 3, which was delayed due to bugs in the JavaScript engine TraceMonkey, was released for developers and testers for evaluation and feedback.

Mozilla stated that the Firefox 3.1 beta 3, based on the Gecko 1.9.1 rendering platform, was released with a number of improvements. 

According to Mozilla, the Firefox 3.1 beta 3 features improvements in the new JavaScript engine, private browsing tools including a "forget this site" function in the history sidebar, and its Gecko layout engine. It offers new native JSON parsing support to protect Firefox against code execution, and provides better stability in TraceMonkey. It also offer support for video and audio functions like W3C Geolocation API, JavaScript query selectors, CSS 2.1 and 3 properties, SVG transforms and offline applications.

In an entry to the company's developer blog, Mike Beltzner, director of Firefox, said, "Firefox 3.1 Beta 3 is a public preview release intended for developer testing and community feedback. This is pre-release software: you may encounter compatibility problems with some Web sites and add-ons."

The Firefox 3.1 beta 3 was released as the Mozilla executives, two weeks ago, promised that the Beta 3 would be rolled out with or without patching the bug in the new TraceMonkey JavaScript engine, which according to Mozilla's Bugzilla problem-tracking database, hasn’t been fixed yet.

Mozilla announced that in order to fix the bug in the new TraceMonkey JavaScript engine permanently, the Beta 4 will be rolled out on April 14. The company confirmed that the Beta 4 will be followed by a release candidate, and finally the Firefox 3.5, which is codenamed as Shiretoko, will be released. The company however did not announce any final release date for Firefox 3.5.

Beltzer, said, "The increase in version number is proposed due to the sheer volume of work which makes Shiretoko feel like much more than a small, incremental improvement over Firefox 3. Bugs will be filled to ensure that systems like addons.mozilla.org, bugzilla.mozilla.org, tinderbox.mozilla.org [and] crash-stats.mozilla.org will continue to work with minimal disruption, and we will coordinate with those systems' administrators to coordinate the work."

The open-source Firefox browser is presently the second-most popular Web browser in terms of market share. It has an edge over Apple Safari and Google Chrome, but still lags behind Microsoft’s Internet Explorer.