Mochikit JS Toolkit

Mochikit

Pros
  • simple AJAX
  • Drag 'n Drop
  • Visual Effects
  • Event handling
  • Widgets
    • Sortable Tables
    • Color Wheel
  • Good documentation
  • Well-design API
  • Developer tools (debug console, logging)
Cons
  • Not many widgets
  • Medium footprint (80-115KB)
  • Small developer community

Differentiators

(plus) Good Documentation
(plus) Developer tools
(plus) Well-design API (modeled after Python)
(minus) Not many widgets
(minus) Heavy footprint

DEMO: http://www.mochikit.com/demos.html