electron/docs/fiddles/features/macos-dock-menu/main.js

const { app, BrowserWindow, Menu } = require('electron/main')

function createWindow () {
  const win = new BrowserWindow({
    width: 800,
    height: 600
  })

  win.loadFile('index.html')
}

const dockMenu = Menu.buildFromTemplate([
  {
    label: 'New Window',
    click () { console.log('New Window') }
  }, {
    label: 'New Window with Settings',
    submenu: [
      { label: 'Basic' },
      { label: 'Pro' }
    ]
  },
  { label: 'New Command...' }
])

app.whenReady().then(() => {
  if (process.platform === 'darwin') {
    app.dock.setMenu(dockMenu)
  }
}).then(createWindow)

app.on('window-all-closed', () => {
  if (process.platform !== 'darwin') {
    app.quit()
  }
})

app.on('activate', () => {
  if (BrowserWindow.getAllWindows().length === 0) {
    createWindow()
  }
})