EaselJS is a JavaScript library that “provides a retained graphics mode for canvas including a full, hierarchical display list, a core interaction model, and helper classes to make working with Canvas much easier.” Easel’s API “is loosely based on Flash’s display list, and should be easy to pick up for both JS and AS3 developers”.
Link: http://www.easeljs.com/
To make it even easier to convert projects from Flash to JS, the makers of Easel have released Zoe, “a tool for exporting swf animations as EaselJS sprite sheets”.
Link: http://easeljs.com/zoe.html