Tim Anderson

Microsoft’s Internet Explorer (IE) platform architect Chris Wilson is engaged in an illuminating war of words with Brendan Eich, the creator of JavaScript who is now the chief technology officer at the Mozilla Corporation, home of FireFox. At issue is the future of JavaScript running in the web browser.

Once dismissed as just a simple scripting language, JavaScript now powers applications of considerable complexity, and plays a key role in online applications, such as Google Docs. The increasing importance of JavaScript, and close cousins such as JScript and EcmaScript, means that the language needs to evolve. A cross-industry group, including Microsoft, has come up with a new language specification called EcmaScript 4 that adds enterprise-class features, such as full object orientation and strong typing.

That sounds good, but who will implement EcmaScript 4? Adobe is keen, but mainly in the context of its proprietary Flash runtime, where it is called ActionScript. Mozilla is keen, and has plans to evolve browser applications to run at the speed of native code, through a just-in-time compiler shared with Adobe, and to blur the boundaries between browser and desktop by enabling web applications that run from desktop shortcuts and without typical browser furniture.

What about Microsoft? Rather than implementing EcmaScript 4 in IE, Microsoft would rather limit itself to a few tweaks that it calls EcmaScript 3.1. Wilson justifies this conservatism by appealing to the importance of backward compatibility and not breaking the web. As for EcmaScript 4, “In our opinion, a revolution in EcmaScript would be best done with an entirely new language,” he says, never mind that a new browser language is the last thing web developers want, and that EcmaScript 4 has good backward compatibility with earlier versions. If Microsoft presses ahead with some intermediate JavaScript variant, it will only serve to increase compatibility problems.

Eich is impatient, and gives good reasons. “When Microsoft was behind in the market [against Netscape in 1996-1997], it moved aggressively in the standards body to evolve standards. Once Microsoft dominated the market, the last edition of the standard was left to rot, and even easy-to-fix standards conformance bugs in IE JScript went unfixed for eight years. Now that the proposed fourth edition looks like a competitive threat, the world suddenly hears in detail about all those bugs, spun as differences afflicting ‘JavaScript’ that should inform a new standard,” he writes in an open letter to Wilson.

What is Microsoft’s motivation? Could it be that the prospect of browser apps that run just as sweetly as Windows apps is not one that the company relishes?

Fortunately Mozilla has a plan B, codenamed ScreamingMonkey, which would let its EcmaScript 4 implementation run in IE through ActiveX. Messy, but if Microsoft wants to hold back the web, all power to ScreamingMonkey.