Alex @ Net

JavaScript is a trademark of Sun Microsystems and it was used for technology implemented by Netscape Communications and introduced in the Netscape Communicator Web browser in December 1995.

The first JavaScript language specification, described in ECMA-262 standard, was adopted by the ECMA General Assembly of June 1997 and the “ECMAScript” name means this standard. There are three editions of this standard, known as ES1, ES2 and ES3, and fourth edition is currently under development. The fourth edition is known as JavaScript 2 or ES4 and it describes several very important language enhancements such as classes, packages and namespaces and other features that aid developers in their work. ES4 is expected to be finished by October 2008.

The widely used JavaScript implementation that is closest to ES4 is ActionScript language, which is part of Adobe Flash platforms. In November 2006 Adobe donated 135,000 lines of code of its ActionScript Virtual Machine (AVM) to the Mozilla project. So, Mozilla FireFox 4 may be the first browser that will have ES4.

Another known partial ES4 implementation is JScript.NET, but there is no information on when Microsoft add its support into browser.

Safari and Opera support ES2 and ES3 and there is no official information on when they will support ES4.

See also:
http://en.wikipedia.org/wiki/JavaScript
http://en.wikipedia.org/wiki/Ecmascript
http://en.wikipedia.org/wiki/ActionScript
http://en.wikipedia.org/wiki/Tamarin_(JIT)