After mentioning Prototype’s inheritance model the other day, one rather important thing struck me about it. I was going to borrow their model for some of my own work when I realised that, if you use Prototype’s $super feature, your code will break if you compress it using a variable-shrinking algorithm (all the decent compressors do this). Prototype inspects the argument names of your functions and determines whether to use Function#wrap to pass in a reference to the overridden function.

So, what to do? We use YUI at work, but their inheritance model is so cumbersome as to be almost totally useless. I needed something better. Taking a few leaves out of Prototype’s model, and out of Alex Arnell’s Inheritance.js, I’ve come up with something that does just what I want. Basic features:

• Simple, elegant single-inheritance model, including inheritance of class (static) methods
• Clean, intuitive access to the class hierarchy from within instance methods, as well as through class interfaces
• Automated inheritance: adding class/instance methods to a class after its initial definition instantly updates all its subclasses and their instances
• Mixins, like in Ruby (this is essentially Ruby-ish syntax masking a trivial JavaScript feature)
• super, with arguments optional
• is_a support (JavaScript trivially supports has-a relationships itself)

Although this takes much of its syntax ideas from Ruby (that being the classical inheriting language I know best), it should be intelligeable to users of other classical OO languages such as Java (we are a Java shop where I work).

So, without further ado, go check out JS.Class.