How do I override the action for closing a window?

I'm making an antivirus in construct, via nwjs and generic javascript and some batch files. In most antiviruses or utility apps, closing the app via clicking on the close button of the window doesn't actually close it but hides it, only to be revealed once pressing the tray icon.

I've got the tray icon settled, but how do I override the close button?

I'm making an antivirus in construct

Wow! What's next - an OS in Construct? :)

You may be able to intercept win.close event according to the documentation:

docs.nwjs.io/en/latest/References/Window