Name: YUI (The Yahoo! User Interface Library)
URL: http://developer.yahoo.com/yui/
Native Server Environment: none
Included Widgets: AutoComplete, Button, Calendar, Color Picker, Container, DataTable, Logger, Menu, Rich Text Editor, Slider, TabView, TreeView
Download Size: 6.5 mb (build directory)

YUI or the Yahoo! User Interface Libary. Is one of the most used toolkits on the market today. Because free hosting for the toolkit is provided by Yahoo on its content distribution network, download times can be dramatically reduced for end users. This is especially true if the user already has a copy of the toolkit cached from visiting one of the myriad of Yahoo or third party sites that use the library.

The library itself is capable and easy to work with. It doesn’t go to great effort to abstract away core javascript functionality. It also does a remarkable job of providing complex capabilities with a reasonably simple and fine grained approach. The library doesn’t rely on monolithic JS files or complex syntax and there for is highly approachable for the novice developer.

Some Highlights

• CSS resources empowering css-resets, fonts, & layout grids
• Effects & animation tools
  
• Rapidly Growing Widget Set
  
• Dramatic bandwidth and caching improvements due to Yahoo!’s hosting of library files
  
• Powerful server communication tools including asset management functions
• Big name industry backing
• Cached library can be utilized between sites.
• Yahoo uses its own library
  

Some Drawbacks

• Skinning System still in its infancy
• Many Widgets still in beta
• Large library size on initial download
• Lack of compressed download requires dependence on Yahoo hosting for efficiency in many situations