Currently, we can zoom-in and zoom-out as much as we want. I wanted to limit the zoom-in and zoom-out for the user. We wanted to know if it is this possible in GoJS and how we can achieve that?
Try setting Diagram.maxScale and minScale.
Also, you might want to read GoJS Coordinate Systems-- Northwoods Software if you want to limit the Diagram.scale values that the user can zoom to.