I would agree with Jonathan that parasitic inheritance is a powerful code reuse pattern in Javascript, although I think that calling it “inheritance” isn’t very accurate. Words like “augmentation” and “composition” fit much better. I have heard the argument that parasitic inheritance is slow, but I have never seen any statistics that show meaningful differences between it and other techniques. For me, I find it to be a clean, easy, powerful way of reusing code.

@Broofa The way to call a “super” method would look like this:

var foo = obj.foo;
obj.foo = function() {
foo();
this.onAfterFoo();
}

If you really wanted to you could use a library like Underscore and call the .wrap() method: http://documentcloud.github.com/underscore/#wrap

Overall I think this is a great post. But I would argue that in most cases a parasitic, prototypal or functional approach is more powerful than trying to retrofit Javascript with classical inheritance. Crockford has some good articles and talks on this, located here:

http://javascript.crockford.com/inheritance.html (notice the comment at the bottom of the page)
http://yuiblog.com/crockford/ (Act III is really good)

http://tinyurl.com/2fv9uqd

While instantiation was slower, the method calls were the fastest. I expected the slower instantiation because I do a mixin to preserve the constructor in a subClass’s prototype. But being faster on method calls was a nice surprise.

It variates from time to time, but if I test some rounds I see appr. this results.

@Michael .H you not?

The most important points of my implementation are:

1. User will work with constructor to create a class, not with object – private class variables and functions are possible.
2. I think at the moment when browser rendering any constructor it hasn’t to initialize all the stuff the constructor contains
3. I can use more classical order pattern inside of the constructor. (first private variables, then privileged, then public methods and then private methods)
4. access overwritten methods via _super
5. Pass any variables to constructor, so they can be used everywere in the class, without to have to map over them, like if you do it over init method

Speedtest shows that my implementation is slower than j3Class or wr Class, but it still much faster than all other famous implementations.

Probably you have some Ideas how I can impove the performance without to change the usability?

http://dev.ajaxsoft.de/classtest/