Live demo: http://tommikaikkonen.github.io/rbtree/
This application helps demonstrate red-black tree node insertion cases. If you want to look at the code, I suggest starting from js/tree.js to see the data structures, moving onto js/treeView.js to see presentation-related data and finally js/ui.js and js/main.js for user interface code and the main program start.
The live application was made for a teaching video produced in an Algorithms & Data Structures class. The video can be seen here.
The application has only been tested on Google Chrome 40 (Mac OS X) and may not work correctly on older browsers.