main.js

const electron = require('electron');
const url = require('url');
const path = require('path');

const {app, BrowserWindow, Menu, ipcMain} = electron;

//Set environment
process.env.NODE_ENV = 'production';

let mainWindow;
let addWindow;

//Listen for the app to be ready
app.on('ready', function(){
    //Create new window
    mainWindow = new BrowserWindow({
        webPreferences: {
            nodeIntegration: true,
            contextIsolation: false
        }
    });
    //Load html into the window
    mainWindow.loadURL(url.format({
        pathname: path.join(__dirname, 'mainWindow.html'),
        protocol: 'file:',
        slashes: true
    }));

    //Quit app on close
    mainWindow.on('closed', function(){
        app.quit();
    });

    //Build the menu from template
    const mainMenu = Menu.buildFromTemplate(mainMenuTemp);

    //Insert menu
    Menu.setApplicationMenu(mainMenu);
});

//Add item handler
function createAddWindow(){
    //Create new window
    addWindow = new BrowserWindow({
        width: 300,
        height: 200,
        title: 'Add Item',
        webPreferences: {
            nodeIntegration: true,
            contextIsolation: false
        }
    });
    //Load html into the window
    addWindow.loadURL(url.format({
        pathname: path.join(__dirname, 'addWindow.html'),
        protocol: 'file:',
        slashes: true
    }));
    //Handle garbage collection
    addWindow.on('close', function(){
        addWindow = null;
    });
}

//Catch item:add
ipcMain.on('item:add', function(e, item){
    mainWindow.webContents.send('item:add', item);
    addWindow.close();
});

//Create menu template
const mainMenuTemp = [
    {
        label:'File',
        submenu: [
            {
                label: 'Add Item',
                click(){
                    createAddWindow();
                }
            },
            {
                label: 'Clear Items',
                click(){
                    mainWindow.webContents.send('item:clear');
                }
            },
            {
                label: 'Quit',
                accelerator: process.platform == 'darwin' ? 'Command+Q' : 'Ctrl+Q',
                click(){
                    app.quit();
                }
            }
        ]
    }
];

//If mac add empty object to menu so file isnt renamed to electron.
if(process.platform == 'darwin'){
    mainMenuTemp.unshift({});
}

//Add dev tools when not in production.
if(process.env.NODE_ENV !== 'production'){
    mainMenuTemp.push({
      label: 'Developer Tools',
      submenu:[
        {
          role: 'reload'
        },
        {
          label: 'Toggle DevTools',
          accelerator:process.platform == 'darwin' ? 'Command+I' : 'Ctrl+I',
          click(item, focusedWindow){
            focusedWindow.toggleDevTools();
          }
        }
      ]
    });
  }