prerender.ts

// Load zone.js for the server.
import 'zone.js/dist/zone-node';
import 'reflect-metadata';
import { readFileSync, writeFileSync, existsSync, mkdirSync } from 'fs';
import { join } from 'path';

import { enableProdMode } from '@angular/core';

// Faster server renders w/ Prod mode (dev mode never needed)
enableProdMode();

// Express Engine
import { ngExpressEngine } from '@nguniversal/express-engine';
// Import module map for lazy loading
import { provideModuleMap } from '@nguniversal/module-map-ngfactory-loader';
import { renderModuleFactory } from '@angular/platform-server';
import { ROUTES } from './static.paths';

// * NOTE :: leave this as require() since this file is built Dynamically from webpack
const { AppServerModuleNgFactory, LAZY_MODULE_MAP } = require('./dist/server/main.bundle');

const BROWSER_FOLDER = join(process.cwd(), 'browser');

// Load the index.html file containing referances to your application bundle.
const index = readFileSync(join('browser', 'index.html'), 'utf8');

let previousRender = Promise.resolve();

// Iterate each route path
ROUTES.forEach(route => {
	var fullPath = join(BROWSER_FOLDER, route);

	// Make sure the directory structure is there
	if(!existsSync(fullPath)){
		mkdirSync(fullPath);
	}

	// Writes rendered HTML to index.html, replacing the file if it already exists.
	previousRender = previousRender.then(_ => renderModuleFactory(AppServerModuleNgFactory, {
		document: index,
		url: route,
		extraProviders: [
			provideModuleMap(LAZY_MODULE_MAP)
		]
		})).then(html => writeFileSync(join(fullPath, 'index.html'), html));
	});