I get you. I think you’re right - if you have a page which does make heavy use of JS, it can be difficult if not.impossible to replicate the same behaviour without it. HOWEVER: you can often get something close enough!

To go back to my shop example: yes, you can use JS to show a richer shopping experience, with pop-up windows, filtering, and the ability to add to cart without leaving the page. Graceful degradation would be to show the same listings, but without the more convenient features that use JS - so without popups, with filtering that refreshes the page, and a completely separate cart.

Some apps really can’t function without JS, because they are… well, apps.