The WebKit devs are at it again, announcing a flurry of information about a new JavaScript interpreter called SquirrelFish, and revealing a little over a week later that this would set the tone for development of WebKit 4 and Safari 4.

SquirrelFish is “a register-based, direct-threaded, high-level bytecode engine, with a sliding register window calling convention”, that promises vastly improved run times. The project is almost certainly the reason for the release of WebKit’s SunSpider JavaScript benchmarking tool late last year. So far, SquirrelFish promises speeds 1.6 times that of its predecessor.

Tuesday Apple provided a developer build of Safari 4 that will be in line with 10.6 Snow Leopards mission of improving speed and stability across the OS. In addition, the team has announced plans to allow for web applications to saved and executed offline, similar to Google’s Gears project and the third part application Fluid. In terms of expected features, the browser will likely improve upon its handling of CSS and DOM Level 3 standards, and possibly begin to incorporate features outlined in the draft for the new HTML spec.

–Matthew Rosenhein