Understand ext.application():

In previous chapter, we have started with Ext.application() in app.js. Ext.application() is a gateway of Ext JS 4 application. All Ext JS 4 applications start with a call to Ext.application method in app.js file. Ext is a singleton class and application() is a method of it that loads Ext.app.Application class and starts it up with the supplied configuration after the page is ready.

Ext.app.Application class represents an Ext JS 4 application, which is mostly a single page application using viewport.

Ext.app.Application has following features:

Visit Sencha documentation for more information on Ext.app.Application.