Quitting

A set of windows keeps a session. The windows open at quit reopen at the next start.

Which windows stay

A window that closes leaves the session, so closing one of three windows opens two next time. A window closed by a quit stays in it. Off macOS the last window, which quits the app, stays in the session too.

Asking first

An app that asks before quitting, or must finish something first, passes confirmQuit to attach in its AttachOptions. It runs once per quit, before any window closes, and the quit waits for it. true lets the quit go ahead and false cancels it. A throw lets the quit go ahead, so a broken check never traps the app. On false, a window that already closed for the quit (the last one off macOS) reopens.

windows.attach(app, {
    confirmQuit: async ({ update }) => {
        if (!update && (await workIsRunning()) && !(await askToStopWork())) {
            return false;
        }

        await server.close();

        return true;
    }
});

The argument is a QuitRequest. Its update is true for a quit an update install started. A test can replace the timer that restarts the quit after a yes with setTimeout in the WindowsOptions.

Deciding in your own listener

Without confirmQuit, an app that decides in its own before-quit listener calls windows.quit() once the quit goes ahead and windows.resume() when it is cancelled. A listener that only calls event.preventDefault(), for example to hide the app, needs neither.

An update install

electron-updater closes the windows before the app's before-quit runs. Pass windows.quitForUpdate as the updater's onQuit, so the windows the install closes stay in the session and reopen if the install fails:

const updater = createUpdater({
    // ...
    onQuit: windows.quitForUpdate
});

Updater covers the install itself.