main.js

const {app, BrowserWindow} = require('electron')
const path = require('path')

const singleInstanceLock = app.requestSingleInstanceLock();
let mainWindow;

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

  mainWindow.loadFile('index.html')
}


if (!singleInstanceLock) {
  app.quit();
} else {
  app.on('second-instance', () => {
    if (mainWindow) {
      if (mainWindow.isMinimized()) mainWindow.restore()
      mainWindow.focus();
    }
  })

  app.on('ready', () => {
    createWindow()

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

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