JavaScript 2.0: A Sneak Preview
By
As a developer and writer, part of my job is to stay informed of current trends
in the web world, whether it be company mergers, online-shopping trends, or
programming technologies. I'll admit that it's hard to keep up with everything
that's going on in the industry these days, but one tidbit of news is making
the rounds that is raising a lot of eyebrows: the drafting of the JavaScript
2.0 proposal. The new JavaScript 2.0 / EMCAScript 4.0, isn't due to be finalized
until the end of the fall of 2009, but it's already garnering lots of strong
reactions - both good and bad. Today, we'll be taking a look at some of the
proposed specifications and you can decide for yourself whether they constitute
improvements in the language or merely unnecessary standardization.
The JavaScript Story
To better understand how JavaScript standards are implemented, let's take a brief look at the language's history.
JavaScript is a dialect of the ECMAScript scripting language, which is standardized by Ecma International. The other two dialects are ActionScript (MacroMedia, Adobe) and JScript (Microsoft). JavaScript was originally developed by Brendan Eich of Netscape. It was originally called Mocha and then LiveScript, before finally being renamed to JavaScript. Sun Microsystems released Netscape Navigator 2.0 with support for JavaScript in March of 1996. Due to the widespread success of JavaScript as a client-side scripting language, Microsoft developed their own version of the language named JScript, which was included in Internet Explorer 3.0 release of August 1996. Netscape submitted JavaScript to Ecma International for standardization, in Geneva.
Ecma International is an international, membership-based, non-profit standards
organization for information and communication systems. The organization was
originally founded in 1961 to standardize computer systems in Europe. In the
40 odd years since its inception, Ecma has produced more than 370 Standards
and 90 Technical Reports, including CD-ROM volume and file structure, C++ Language
Specification, and their Open XML format. The first edition of ECMAScript (ECMA-262)
was adopted by the ECMA General Assembly of June 1997. Both JavaScript and JScript
aim to be compatible with ECMAScript, while providing additional features not
described in the ECMA specification. Even today, the JavaScript and JScript
dialects have as many differences as commonality. JavaScript was influenced
by Object-Oriented languages like Java and C++, but was meant to be easier for
non-programmers to work with.
Language Enhancements
More Object Oriented
Up until now, JavaScript used prototypical inheritance rather than the classical OOP kind for inheriting from parent classes. In fact, as the following code demonstrates, there currently exists no such thing as a "class" in JavaScript:
Functions double as object constructors along with their typical role. Prefixing
a function call with new creates a new object and calls that function with its
local this keyword bound to that object for that invocation. The function's
prototype property determines the new object's prototype. Whatever is assigned
to an object's prototype property is shared amongst all of its instances and
children. Using the prototype property, it is possible to simulate many class-based
features in JavaScript, albeit with some quirks! For instance, in the following
code, myOtherDog attempts to override the getBreed() function of parent Dog
"class". Although the myOtherDog's getBreed() function is indeed implemented,
it does not hide the parent's, giving myOtherDog two breeds!
