As you already know, your application is essentially an HTML5 stack running inside Chromium, and Electron provides all necessary integration with the underlying operating system, whether that's macOS, Windows, or Linux.
The concept of application menus is slightly different across platforms. macOS, for instance, provides a single application menu that reflects the active application and displays the corresponding menu items. The Windows system tends to provide a separate menu for each instance of the application window. Finally, Linux systems usually vary based on the window manager's implementations.
Handling every case would be quite cumbersome for developers; that is why the Electron framework provides a unified interface for building application menus from the JSON definition and takes care of integration details.
Let's take...