main.js

const app = require('electron').app,  // Module to control application life.
  BrowserWindow = require('electron').BrowserWindow;  // Module to create native browser window.

// Keep a global reference of the window object, if you don't, the window will
// be closed automatically when the JavaScript object is garbage collected.
let mainWindow = null;

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

// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
app.on('ready', function () {
    // Create the browser window.
    mainWindow = new BrowserWindow({width: 1000, height: 600, icon: __dirname + '/icon.ico'});

    // and load the index.html of the app.
    mainWindow.loadURL('file://' + __dirname + '/index.html');

    // Open the DevTools.
    // mainWindow.openDevTools();

    // Emitted when the window is closed.
    mainWindow.on('closed', function () {
        // Dereference the window object, usually you would store windows
        // in an array if your app supports multi windows, this is the time
        // when you should delete the corresponding element.
        mainWindow = null;
    });
});