In my honest opinion Dojo is a better choice than ExtJS. As was mentioned elsewhere, ExtJS abstracts you away from the HTML quite a bit, that being said for rea

In my honest opinion Dojo is a better choice than ExtJS. As was mentioned elsewhere, ExtJS abstracts you away from the HTML quite a bit, that being said for really large apps, ExtJS and Dojo are really the only two games in town. I have built some extremely large apps with Require/Backbone/jQuery/Underscore etc. and while it can be done, Dojo and ExtJS provide more uniform ways of doing it, think of them as more akin to Java where the other way is more akin to Perl one provides a well tested and integrated toolkit for building large apps. While the other allows you to add features from different libraries as you realize you need them, sometimes that leads to less constancy in the code base. But with good conventions and design you can build and app with Backbone/etc. that is just as maintainable and scalable as ExtJS or Dojo. There are all, after-all just Javascript when you strip it all away. When I use Dojo, I also use Backbone as the two are compatible and Backbone provides a far better design pattern for Hash management and routing.