main.js

// Modules to control application life and create native browser window
const {app, BrowserWindow, screen, dialog} = require('electron')
const path = require('path')

function createWindow () {
  // Create the browser window.
  const mainWindow = new BrowserWindow({
    width: 800,
    height: 600,
    webPreferences: {
      preload: path.join(__dirname, 'preload.js')
    }
  })

  // and load the index.html of the app.
  mainWindow.loadFile('index.html')

  // Open the DevTools.
  // mainWindow.webContents.openDevTools()
}

// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.whenReady().then(() => {
  createWindow()


  // https://www.electronjs.org/docs/api/screen More info here
  let displays = screen.getAllDisplays();
  console.log(displays)

  let externalDisplay = displays.find((display) => {
    return display.bounds.x !== 0 || display.bounds.y !== 0
  })

  console.log(externalDisplay)

  if (externalDisplay) {
    const options = {
      type: 'info',
      buttons: [ 'Okay'],
      defaultId: 2,
      title: 'Message',
      message: 'External Display Detected!',
      detail: 'Now we can do some action here!',
    };
  
    dialog.showMessageBox(null, options, (response, checkboxChecked) => {
      console.log(response);
      console.log(checkboxChecked);
    });
  }

  
  app.on('activate', function () {
    // On macOS it's common to re-create a window in the app when the
    // dock icon is clicked and there are no other windows open.
    if (BrowserWindow.getAllWindows().length === 0) createWindow()
  })
})

// Quit when all windows are closed, except on macOS. There, it's common
// for applications and their menu bar to stay active until the user quits
// explicitly with Cmd + Q.
app.on('window-all-closed', function () {
  if (process.platform !== 'darwin') app.quit()
})

// In this file you can include the rest of your app's specific main process
// code. You can also put them in separate files and require them here.