I develop with Sencha frameworks full time. The learning curve is on the same level as Ember, while not easy but still manageable, unlike many people want you t

I develop with Sencha frameworks full time. The learning curve is on the same level as Ember, while not easy but still manageable, unlike many people want you to believe. ExtJS component life cycle changed a lot form 4.0 to 4.2 and they refactored the code to be more like Sencha Touch. I guess this is the preamble to ExtJS 5, and it confuses a lot of people. Sencha delivers on cross browser compatibility, since their layouts are all done by JavaScript. Trying to add CSS layout on top of that will break a lot of things. This is the so called "fighting the framework" people in Sencha community calls it. ExtJS 5 lets you develop desktop/touch hybrid apps for touch laptops. With smooth scrolling driven by touch event and transition, they work on Android as well (where it doesn't have WebKit overflow scroll touch)