main.electron.js

const {app, BrowserWindow, ipcMain, dialog} = require('electron');
const path = require('path');
const url = require('url');
const process = require('process');


// 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 win;

function createWindow() {
    // Create the browser window.
    win = new BrowserWindow({width: 800, height: 600});

    const startUrl = process.env.ELECTRON_START_URL || url.format({
        pathname: path.join(__dirname, 'build/index.html'),
        protocol: 'file:',
        slashes: true
    });

    win.loadURL(startUrl);

    // Open the DevTools.
    win.webContents.openDevTools();

    // Emitted when the window is closed.
    win.on('closed', () => {
        // 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.
        win = null
    })
}

// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.on('ready', createWindow);

// Quit when all windows are closed.
app.on('window-all-closed', () => {
    // On macOS 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()
    }
});

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 (win === null) {
        createWindow()
    }
});

ipcMain.on("fromWebToNative", (event) => {
    dialog.showMessageBox(win, {message: "I am electron!"})
});