Javascript float/hover animation for HTML5 Canvas

[Jordan D.]

Hello there,
Currently working on an HTML5 banner ad. The folder of working files can be downloaded here.

At the ~7 second mark, I'd like for the "balloon cat" to gently float up and down above the button.
I've found inspiration for the floating movement here.

We need to do this with javascript so that the animation will loop infinitely. I have some code already written for the background, but am having difficulty connecting the dots on this particular piece.

I'd appreciate any help I can get.
Cheers!

[Jordan D.]

TLDR; I'm sure we'd be able to do this in pure actionscript, too. But no flash please 🙂