Electron doesn't seem to support it (and even if it did, I suspect most electron developers wouldn't pay it any mind) but...
NSApplicationDelegate's -(BOOL)applicationShouldTerminateAfterLastWindowClosed:(NSApplication *)sender; method exists so an application can, uhh, automatically terminate after the last window closes.
https://developer.apple.com/documentation/appkit/nsapplicati...
It's not 100% consistent but if you look at Apple's applications based on single window (calculator, system preferences, etc), closing the window quits the app.
Electron doesn't automatically exit when the last window is closed, and the Electron getting started guide (https://www.electronjs.org/docs/latest/tutorial/tutorial-fir...) recommends this code:
app.on('window-all-closed', () => {
if (process.platform !== 'darwin') app.quit()
})
The function has been available for a while, but auto-closing system apps is a relatively recent change.
I can’t find obvious reference or when Apple started changing this, but it seems related to background app killing that is done now as well. I’m still not sure how I feel about it, but historically that wasn’t common for Mac apps.
The ability for an app to keep running without a window was a godsend back in the days when we were all running on hard drives and large apps had splash screens to amuse you during their multi-second launch process. If you were done with a particular document but not done with the application as a whole, you could simply close the window and next time you needed to open a document in that app you wouldn't have to sit through the splash screen again. Unless it was an app with a cross-platform GUI that didn't support this model.
Nowadays, apps closing themselves or being closed by the OS automatically is reasonable in a lot of cases, but Electron apps tend to hit the cases where it still is valuable to operate with the classic NeXT/OS X document-based app paradigm.