Professional, JavaScript® for Web Developers, Second Edition

Chapter 22. The Evolution of JavaScript

With the renewed interest in web development since 2004, conversations began taking place among browser vendors and other interested parties as to how JavaScript should evolve. Work on the fourth edition of ECMA-262 began based largely on two competing proposals: one for Netscape's JavaScript 2.0 and the other for Microsoft's JScript.NET. Instead of competing in the browser realm, the parties converged back into ECMA to hammer out a proposal for a new language based on JavaScript. Initially, work began on a proposal called ECMAScript 4, and for a long time, this seemed like the next evolutionary step for JavaScript. When a counterproposal called ECMAScript 3.1 was later introduced, it threw the future of JavaScript into question. After much debate, it was determined that ECMAScript 3.1 would be the next step for JavaScript and that a further effort, code-named Harmony, would seek to reconcile some features from ECMAScript 4 into ECMAScript 3.1. To understand how this will affect JavaScript in the future, it's important to take a look at all of the steps along this process.

ECMAScript 4/JavaScript 2

The ECMAScript 4 proposal was originally scheduled to be completed by October 2008 and is still in flux at the time of this writing. There are several parts of the language that are likely to be in the final version and deserve some attention. Mozilla had taken an approach of implementing small sets of proposed ECMAScript 4 functionality through a ...