Jaws is a 2D game lib powered by HTML5. It started out only doing canvas but is now also supporting ordinary DOM based sprites through the same API.
Jaws is well suited for “classic” side/top scrolling games (tile based or not) where you have a number of sprite-sheet-animated sprites. Jaws comes with basic rect-vs-rect/circle-vs-circle collision detection that works well in most cases. If you have tons of sprites (for example, a bullet hell schmup) you probably want to use a physicslib like Box2D or spatial hashing like quad trees to speed things up. Jaws use of canvas makes pixel perfect collisions and worms-style terrain relatively easy to develop. If your game is very GUI-heavy you might want to base your game on pure HTML-elements instead of canvas-sprites.