In this column we showed you how to take advantage of JavaScript's object-oriented capabilities using constructors, methods, and prototypes. We started with extending both intrinsic and user-defined classes of objects with the prototype property. We demonstrated this capability with JavaScript's Array and String objects. We then explained you how to use object extension in order to differentiate between instances of the same class, practically giving you two types of objects that inherit their essence from a base class. Finally, we described a true inheritance mechanism, implemented by extending two different objects with a common third one. We used our animation scripts from Column 19 to demonstrate the inheritance concept.

In this column you have learned:

• How to boost JavaScript performance with prototypes.
• How to extend a class of objects.
• How to extend a particular instance of an object.
• How to inherit a common object.

We have shown you the code of the simple animation script, the nested animation script, and the shared animation library. You can also download the zipped version of the library.