Is there a way to do a shape tween in javascript? Using canvas maybe...
If you will be doing graphics on the HTML 5 canvas element, you may want to check the Processing.js library. There is a tweening library, but you will probably find it helpful for many other things.
Processing.js uses JavaScript to draw shapes and manipulate images on the HTML 5 Canvas element. The code is light-weight, simple to learn and makes an ideal tool for visualizing data, creating user-interfaces and developing web-based games.
For tweening, you may want to have a look at the following: