If you are interested check out his post, the example and the implementation. The code only runs on Firefox 2 since it is the only browser that supports Javascript 1.7.

Although I have only programed with languages that provide class based object models I believe that that prototype based object models are very easy to understand if you know the primitives of object oriented programming.

Prototype based object models are an interesting idea that suits very well with dynamic languages like Javascript. The only thing that I don’t really like is the syntax. For example creating a new “class” that inherits from an Employee “class” looks like this in Javascript:

function Manager () {
  this.reports = [];
}
Manager.prototype = new Employee;

And in Java:

public class Manager extends Employee {
  public Employee[] reports;
  public Manager () {
    this.reports = new Employee[0];
  }
}

I prefer the Java version because the whole definition is included in one syntactic unit (a class definition), instead two in Javascript (a function definition and an assignment).

If I am correct, Ruby (BTW I don’t know Ruby and Javascript) has a class based object model but also has most of the features of languages that are prototype based. For example in Ruby, you can add or modify, at runtime, methods of classes and instances.

Now that Javascript and asynchronous web user interfaces are beginning to be more and more important in web application development I think that Sarissa might be a good solution for more portable Javascript code.

BTW did you know that Javascript has a unit testing framework (ECMAUnit) and a lint program (jslint).