Recs.
Updated
Webix is a JavaScript/HTML5 library for developing unique user interfaces.
There are more than 70 UI widgets and controls: charts, reports, pivots, complex tools and other components that can help you to visualize big data.
Specs
Pros
Pro A lot of widgets
Webix is one of the most extensive UI component libraries, second only to Sencha ExtJS. Not only considering the number of widgets, but also the API methods for manipulating these widgets.
Cons
Con Not very popular
Not really a reason to not recommend it. But it has still a small user base. It deserves a lot more attention.
Con Not modular
The library is not modular (except for some additional more complex widgets). If you only need a few widgets, you still need to include the entire library.
Recommendations
Comments
Flagged Pros + Cons
Pro It's a library not a framework
It doesn't nail you to a specific build tool, testing suite. It focusses solely on the GUI. Therefore it lets you implement it with the tools you like. Also, mixes very well with other GUI libs.