main.js

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

let win

function createWindow () {
  win = new BrowserWindow({width: 800, height: 600})
  win.loadURL(
    url.format({
      pathname: path.join(__dirname, 'index.html'),
      protocol: 'file:',
      slashes: true
    })
  )

  win.on('closed', () => {
    win = null
  })
}

app.on('ready', createWindow)