I've been thinking about this sometimes, I don't understand why there hasn't been any editor suite to generate HTML5 + JS animations like Macromedia Flash did. On the foundation it's basically the same concepts: a canvas that can draw vectors and a scripting language based on ECMAScript. The editor then has a timeline control and can render the appropriate assets for animating it: vectors and scripts that animate those vectors based on the timeline information.

Is there some technical limitation I haven't figured out? Or is it simply a matter that no one has done it yet?