Security researchers have identified a Trojan which attacks a flaw in Adobe Reader's JavaScript handling to insert a backdoor - and a patch isn't due until tomorrow.

A flaw in the just-in-time compiler introduced in Firefox 3.5's new JavaScript engine can lead to code execution, with Mozilla calling the un-patched hole "critical."

The latest stable release of Google's open-source Chrome browser features a tweaked JavaScript engine that boosts performance by up to 30 percent.

Google has launched a site to host advanced JavaScript applications which showcase Chrome's engine - along with early support for extensions in its browser.

Adobe's Acrobat and Acrobat Reader packages are currently under attack from a JavaScript-based exploit, similar to one which afflicted the software back in June.

Opera has announced a new JavaScript engine for Opera 10, which should vastly improve performance - and get it closer to first place in the SunSpider benchmark tests.