Your choice of cross-browser javascript GUI [closed]

When considering a JavaScript library/framework for usage you should first define on your goals. I used to separate all JavaScript libraries/frameworks into three categories by their purpose and architecture:

1. I want to pimp up my page with some really "cool" features. Go for JavaScript library.

   • jQuery
   • ZenoUI
   • old: Prototype, Mootools

2. I want to build an application with a rich front-end. I like defining UI with JavaScript and I do not mind much using custom APIs of these libraries for coding my application logic. Go for JavaScript post-library/pre-framework.

   • extjs
   • kendo
   • DHTMLX
   • Dojo
   • YUI
   • Qooxdoo
   • jQuery UI
   • Bindows - generates the exact look of Windows
   • Spry (raw, suffers severely of memory leaks)

3. I want to build an application with a rich front-end. I like defining UI in XML and I would like to code my application logic against standard APIs and make use of other developer-facing standard-based technologies. Go for JavaScript framework.

   • Sproutcore
   • Backbase
   • Ample SDK

For a more detailed comparison, see the alternatives to ExtJS.

On the contrary I find qooxdoo syntax and code organization very clear. It is much like swing or gtk. I have tried Dojo as well, without much success. My no.1 choice for RIAs is qooxdoo. It is rich, coder-friendly, free and well documented.

My choice for any other (browser based) JavaScript work is jQuery. Although other libraries (prototype, mochikit etc) are all useful, jQuery is the hype now. Having an active (and big) community counts.

A lot of people on StackOverflow use jQuery, so answers will likely be biased in that direction. Additionally, jQuery will ship with ASP.Net MVC, making it the natural choice for developers using the Microsoft platform.