This chapter introduces and defines the Ext JS plugins and extensions, the differences between them, and finally shows how to develop a plugin and an extension.

In this chapter we will cover:

In this modern world of JavaScript, Ext JS is the best JavaScript framework that includes a vast collection of cross-browser utilities, UI widgets, charts, data object stores, and much more.

When developing an application, we mostly look for the best functionality support and components that offer it to the framework. But we usually face situations wherein the framework lacks the specific functionality or component that we need. Fortunately, Ext JS has a powerful class system that makes it easy to extend an existing functionality or component, or build new ones altogether.