Issue regards message dispaly when click on product screen about node-javascript-ecommerce HOT 1 OPEN

app.js
import HomeScreen from './screens/HomeScreen.js'
import ProductScreen from './screens/ProductScreen.js'
import { parseRequestUrl } from './utils.js';
import Error404Screen from './screens/Error404Screen.js'
const routes = {
'/': HomeScreen,
'/product/:id': ProductScreen,

};
const router = () => {
const request = parseRequestUrl();
const parseUrl = (request.resource ?
/${request.resource}:/)+ (request.id ? '/:id': '' )+
(request.verb ? /${request.verb}:'');
const screen =
routes[parseUrl]? routes[parseUrl]: Error404Screen;
const main= document.getElementById("main-container");
main.innerHTML = screen.render();
};
window.addEventListener('load',router);
window.addEventListener('hashchange',router);

from node-javascript-ecommerce.