of course it goes without saying that a framework should have an extension mechanism that allows you to build custom widgets (and Ext does). It's also nice when you don't have to build a treeview or grid with pagination and sorting and editing etc.etc. Personally I like being able to plug and play someone else's code - There's nothing more wasteful than reinventing the wheel.
There's a good reason people build UIs that mimic desktop applications - it's because a user should be able to sit down at an unfamiliar application and know instantly what each widget does - you don't get that when each app reinvents UI elements to create interesting stuff hehe
Obviously no one is comparing JQueryUI with ExtJS - that would be apples to oranges.
JQueryUI is light and designed for enhancing web pages
ExtJS is a ~600kb framework designed for web applications.
There's a good reason people build UIs that mimic desktop applications - it's because a user should be able to sit down at an unfamiliar application and know instantly what each widget does - you don't get that when each app reinvents UI elements to create interesting stuff hehe
Obviously no one is comparing JQueryUI with ExtJS - that would be apples to oranges.
JQueryUI is light and designed for enhancing web pages
ExtJS is a ~600kb framework designed for web applications.
Both are designed for different use cases.