In this section, we will quickly discuss responsive design. Since it is not the primary topic of this book, we will implement a very simple example that will give us an idea of what we need to do if we need to develop a responsive application with Ext JS. And speaking of responsive design, we know Ext JS is great to develop desktop applications (that will be executed from a desktop computer or a laptop), but mobiles have now become a very integral part of our lives. We will figure out the means to run the same application running on a desktop and also on a mobile device. We will also discuss how to enable touch support in our application as well.

The major difference between running an application on a desktop and a mobile device is the events, among other details. On a desktop, when the user clicks on a button, we listen to the click event. On a touch mobile device, there is no click event; there is the tap event, because we are touching the screen and not working...