Although JavaScript is not a class-based language, it is possible to simulate classes using its prototypal structure. Ext JS 4 introduces an entirely new way of defining classes, compared with Ext JS 3. Consequently, when developing with Ext JS 4 your JavaScript's structure will be more closely in line with that of other object oriented languages. This recipe will explain how to define classes using the new system, and give some detail about the features it has to offer. We will do this by creating a custom class to model a vehicle, with a method that will alert some details about it
