this is mainjs

const { app, BrowserWindow } = require('electron')
const path = require('path')
const Store = require('electron-store');

Store.initRenderer();
const createWindow = () => {
// Create the browser window.
const mainWindow = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
contextIsolation:true,
nodeIntegration:true,
preload: path.join(__dirname, 'preload.js')
}
})

and this is render
const Store = require('electron-store');
const store = new Store();
document.getElementById("btnSave").addEventListener("onClick", Save);

function Save() {

store.set('unicorn', "1");
var BnbBalance = document.getElementById("Balance");

BnbBalance.innerHTML = store.get('unicorn');

}
i do like tutorial but function cant run, but node xxx.js work verywell