How to add a "Reset" button

Hi there,

I've implemented "Zoom out" / "Zoom in" buttons with dragscroll modeled off of [this example] (https://stackoverflow.com/questions/47635341/zooming-in-out-an-image-by-clicking-zoom-buttons-javascript) and I'd like to add a third "Reset" button that brings the image back to initial scale and position.

Any ideas on how to accomplish this?