GenCon provides a simple text-based display with a curses-like interface. GenCon does not use HTML5's canvas, as most libraries like this do. I figure, if it's text, why not implement it using text? This may be used for roguelikes, or geeky niche applications of any sort.
Every function is documented fairly thoroughly in the code in gencon.js.
An example that tests out most available functionality is located in examples/test.html