>A UI framework is only as good as the widgets it ships with
Completely wrong. A UI framework is only as good as the widgets it lets you build, and how much it helps you while building them. I have never yet worked on a project where I could piece together all the widgets from one library that perfectly fit every use case.
jQuery UI made a few smart decisions in how to build their API. They kept it extremely jQuery-like, so if you are familiar with jQuery coding style you will be right at home. Everything is tied into the jQuery enhanced set object, built for chaining whenever possible, and relies on no external objects.
Instead of opting to build 40 widgets, 90% of which you won't need for your project and the other 10% which will only fit some of your needs, the pattern you will see is behavior enhancement. This is what gives you the power to build something more powerful than a cookie cutter widget, with only a few short declarations. You can make something draggable, then sortable, then droppable. You can make something else resizable, draggable, and selectable. You can tie all of these things together with the powerful event and method system, and make something that is greater than the sum of its parts. Then you get the bonus of everything being easily themeable with Themeroller.
I feel like web designers are too often stuck in the mindset of imitating desktop UI's, saying "I need this exact kind of treeview" or "This should be a grid, and this a combobox, and these have to be tabs" when they could be considering all the ways that JavaScript, jQuery, and CSS let you step completely out of this box and make something fresh. Things that have become mini-trends in website UIs like the expandy horizontal accordions or Apple's product scroller are what happens when you apply familiar behaviors to new things. In my experience, jQuery UI has allowed me to be the most creative out of any UI framework, and is the best suited for getting interesting stuff done.
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.
Completely wrong. A UI framework is only as good as the widgets it lets you build, and how much it helps you while building them. I have never yet worked on a project where I could piece together all the widgets from one library that perfectly fit every use case.
jQuery UI made a few smart decisions in how to build their API. They kept it extremely jQuery-like, so if you are familiar with jQuery coding style you will be right at home. Everything is tied into the jQuery enhanced set object, built for chaining whenever possible, and relies on no external objects.
Instead of opting to build 40 widgets, 90% of which you won't need for your project and the other 10% which will only fit some of your needs, the pattern you will see is behavior enhancement. This is what gives you the power to build something more powerful than a cookie cutter widget, with only a few short declarations. You can make something draggable, then sortable, then droppable. You can make something else resizable, draggable, and selectable. You can tie all of these things together with the powerful event and method system, and make something that is greater than the sum of its parts. Then you get the bonus of everything being easily themeable with Themeroller.
I feel like web designers are too often stuck in the mindset of imitating desktop UI's, saying "I need this exact kind of treeview" or "This should be a grid, and this a combobox, and these have to be tabs" when they could be considering all the ways that JavaScript, jQuery, and CSS let you step completely out of this box and make something fresh. Things that have become mini-trends in website UIs like the expandy horizontal accordions or Apple's product scroller are what happens when you apply familiar behaviors to new things. In my experience, jQuery UI has allowed me to be the most creative out of any UI framework, and is the best suited for getting interesting stuff done.