Electron Multiple Windows

main.dev.js

const windows = new Set();

export const createWindow = async () => {
  if (
    process.env.NODE_ENV === 'development' ||
    process.env.DEBUG_PROD === 'true'
  ) {
    await installExtensions();
  }

  let x, y;

  const currentWindow = BrowserWindow.getFocusedWindow();

  if (currentWindow) {
    const [currentWindowX, currentWindowY] = currentWindow.getPosition();
    x = currentWindowX + 24;
    y = currentWindowY + 24;
  }

  let newWindow = new BrowserWindow({
    show: false,
    width: 1200,
    height: 812,
    x,
    y,
    webPreferences: {
      nodeIntegration: true
    }
  });

  newWindow.loadURL(`file://${__dirname}/app.html`);

  newWindow.webContents.on('did-finish-load', () => {
    if (!newWindow) {
      throw new Error('"newWindow" is not defined');
    }
    if (process.env.START_MINIMIZED) {
      newWindow.minimize();
    } else {
      newWindow.show();
      newWindow.focus();
    }
  });

  newWindow.on('closed', () => {
    windows.delete(newWindow);
    newWindow = null;
  });

  newWindow.on('focus', () => {
    const menuBuilder = new MenuBuilder(newWindow);
    menuBuilder.buildMenu();
  });

  windows.add(newWindow);
  return newWindow;
};

app.on('activate', () => {
  // 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 (windows.size === 0) createWindow();
});