The easiest thing to do when writing a software application is to switch into programmer mode—to focus on the code, and not on the end user experience. The architecture of a system is extremely important, but if the user is not satisfied with their interactions with the system, then the project can only be seen as a failure.
Ext JS contributes to solving this issue by providing many slick components that react well to user input and maintain a consistent look and feel across the entire framework. "Feel" is a very fuzzy word when it comes to software design; the way a link acts when you hover over it or the way in which a window appears onscreen can be the difference between a pleasurable experience and a confusing one.
Many of Ext JS's components have transitional animations built in by default, allowing you to smoothly expand a treenode
rather than suddenly pop it open, or to shrink down a window to a specified button that can be used to...