Angular 101: Do you want to enable Server-Side Rendering (SSR) and Static Site Generation (SSG/Prerendering)

Yes, enabling Server-Side Rendering (SSR) and Static Site Generation (SSG/Prerendering) can bring several benefits to your Angular application, such as improved SEO, faster initial page load times, and better user experience for certain types of content. Here’s a detailed explanation to help you understand these concepts and how to implement them in Angular.

1. What is Server-Side Rendering (SSR)?

Server-Side Rendering (SSR) is a technique where the server renders the complete HTML for a page before sending it to the client. This approach has several advantages:

• Improved SEO: Search engines can easily crawl the rendered HTML, leading to better indexing.
• Faster Initial Page Load: Users see a fully rendered page more quickly because the server sends the complete HTML rather than loading it through client-side JavaScript.
• Better Performance for Slow Devices: Since the server renders the initial HTML, it reduces the processing load on client devices.

2. What is Static Site Generation (SSG/Prerendering)?

Static Site Generation (SSG) or Prerendering is a technique where HTML pages are pre-rendered at build time and served as static content:

• Faster Load Time: Static pages load faster since they don’t require JavaScript to render the initial view.
• Great for Static Content: Suitable for static content like blogs or documentation sites where content doesn’t change often.
• Reduced Server Load: Because HTML is pre-rendered, it reduces the server’s workload during runtime.

3. When to Use SSR or SSG?

• SSR is ideal for applications with dynamic content, frequent updates, or if the user experience depends on the user’s state (e.g., user authentication).
• SSG is best for static content that does not require frequent updates, such as marketing pages, blogs, or documentation.

4. How to Enable SSR and SSG in Angular?

To enable SSR and SSG in Angular, you can use the @nguniversal package. Here’s a step-by-step guide to set it up:

Step 1: Add Angular Universal

Install Angular Universal to enable SSR in your Angular project:

ng add @nguniversal/express-engine

This command will automatically set up your Angular application for server-side rendering using the express-engine.

Step 2: Build the Project for SSR

After adding Angular Universal, you need to build the application for SSR:

npm run build:ssr

Step 3: Serve the SSR Application

Once the build is complete, run the following command to serve your application with SSR:

npm run serve:ssr

Step 4: Configure SSG (Optional)

If you want to enable SSG/prerendering for some or all pages, you can modify the angular.json configuration to specify routes for prerendering:

"prerender": {
  "builder": "@nguniversal/builders:prerender",
  "options": {
    "browserTarget": "your-app:build:production",
    "routes": [
      "/",
      "/about",
      "/contact"
    ]
  }
}

Run the prerendering process with the following command:

ng run your-app:prerender

This will generate static HTML files for the specified routes and place them in the dist/browser directory.

5. Benefits of Enabling SSR and SSG

• Improved SEO: Search engines can index server-rendered or prerendered pages more effectively.
• Faster Initial Load: Users see a fully rendered page on the first request, reducing time to interactive (TTI).
• Optimized Performance: Server-side rendering offloads some of the processing from the client, making the application feel faster.

6. Common Challenges and Tips

• Handling Client-Side Interactions: SSR applications can be challenging to implement if your application heavily relies on client-side interactivity or third-party scripts.
• API Calls: Use TransferState in Angular Universal to manage API calls between the server and client.

7. Example Code Snippet for SSR Configuration

Here’s an example of how your main server module (server.ts) might look after setting up Angular Universal:

import 'zone.js/node';
import { ngExpressEngine } from '@nguniversal/express-engine';
import * as express from 'express';
import { join } from 'path';

import { AppServerModule } from './src/main.server';
import { APP_BASE_HREF } from '@angular/common';
import { existsSync } from 'fs';

const app = express();
const distFolder = join(process.cwd(), 'dist/your-app/browser');
const indexHtml = existsSync(join(distFolder, 'index.original.html')) ? 'index.original.html' : 'index';

// Configure Express to use the Angular Universal engine
app.engine('html', ngExpressEngine({
  bootstrap: AppServerModule,
}));
app.set('view engine', 'html');
app.set('views', distFolder);

// Serve static files
app.get('*.*', express.static(distFolder, {
  maxAge: '1y'
}));

// All other routes use the Universal engine to render the HTML
app.get('*', (req, res) => {
  res.render(indexHtml, { req, providers: [{ provide: APP_BASE_HREF, useValue: req.baseUrl }] });
});

// Start up the Express server
app.listen(4000, () => {
  console.log(`Node Express server listening on http://localhost:4000`);
});

8. Summary

Enabling SSR and SSG in Angular improves SEO, enhances performance, and provides a smoother user experience for certain types of content. Using Angular Universal, you can easily configure your Angular application to support both SSR and SSG techniques.

If you need further help or a detailed walkthrough for your specific use case, feel free to ask!