Making custom ExtJS components using panels

One of the principles of the object–oriented programming says that the functionality should be encapsulated into a component and handled by the component. It helps to keep the functionality in one place and modify it easily or rewrite/replace it completely without affecting other parts of an application.

Since ExtJS is an object–oriented JavaScript framework, the same principle should be used there.

Recently I had to create a numerous ExtJS components for one project. There are numerous ExtJS examples on the web, which show complex...