Detect Command+R and Command+H in Safari

I would like my webapp to do certain tasks when pressing Ctrl+R (Windows) or Command+R (Mac), just like native apps do.

It works fine in all browsers (e.g. Firefox on Windows, Chrome on Mac, …) except of Safari on Mac.

In Safari on Mac, Command+R always reloads a website. Is there a way a website can prevent it? My current code is here: https://jsfiddle.net/p45f44zb/14/ I use

Event.preventDefault(); 

but it seems like it does not help 🙁