Google’s latest version of Chrome has claimed the lead in my JavaScript speed tests, but Apple’s new Safari 4 beta is the first browser to challenge it on Google’s own performance benchmark. JavaScript is a programming language that powers not just innumerable ordinary Web sites, but also many Web-based applications such as Google Docs. With the computing industry’s major push to cloud computing, Web application performance is increasingly important, and there’s a race on to see who’s got the best JavaScript engine. JavaScript engines even have become a named feature, with Chrome’s V8, Firefox’s TraceMonkey, Opera’s Futhark and upcoming Carakan, and now the Safari’s newly branded Nitro, which is Apple’s version of WebKit’s Squirrelfish.