Tips for optimizing the build process of an Angular application.

Introduction

Angular is a popular and powerful framework for building web applications, but as your project grows, it can become challenging to maintain optimal performance. In this blog, we will explore strategies to optimize Angular applications, and we'll provide real-world examples to illustrate these concepts. Let's dive in!

1. Lazy Loading Modules

Lazy loading is a fundamental technique for optimizing Angular applications. It allows you to load modules and components only when they are needed, reducing the initial loading time and improving user experience.

Example: Suppose you have a large e-commerce site with multiple feature modules like product listing, cart, and checkout. By lazy loading these modules, you can ensure that only the necessary code is loaded when a user visits a specific page.

const routes: Routes = [
  { path: 'products', loadChildren: () => import('./product/product.module').then(m => m.ProductModule) },
  { path: 'cart', loadChildren: () => import('./cart/cart.module').then(m => m.CartModule) },
  { path: 'checkout', loadChildren: () => import('./checkout/checkout.module').then(m => m.CheckoutModule) },
];

2. Tree Shaking

Tree shaking is a technique to eliminate unused code from your application. In Angular, this can be achieved by configuring your build tools and using ES6 modules effectively.

Example: When you import third-party libraries or modules, only import the parts of the library that you actually use. For example:

// Bad practice - importing the entire library
import * as moment from 'moment';

// Good practice - importing only what you need
import { format, parse } from 'moment';

3. Minify and Compress

Minifying your JavaScript code and enabling compression can significantly reduce the size of your application bundles, leading to faster loading times.

Example: Use tools like UglifyJS for minification and enable Gzip or Brotli compression on your web server to serve compressed assets. You can configure this in your server settings or use a CDN that offers compression.

4. Lazy Loading Images

Lazy-loading images can dramatically improve initial page load times. Images outside the viewport are only loaded when the user scrolls down, reducing the initial page weight.

Example: In your HTML, use the loading="lazy" attribute for images to enable native browser lazy loading:

<img src="image.jpg" alt="Lazy-loaded image" loading="lazy">

5. Service Workers for Offline Support

Service workers can cache your application assets, allowing your Angular app to work offline or in low-network conditions. This improves user experience and reduces the load on your server.

Example: Implement a service worker using libraries like @angular/service-worker or Workbox to cache your app's assets. This allows users to access your application even when they are offline.

6. Route Guards

Route guards can prevent unnecessary loading of modules and components. By using guards, you can control access to specific routes based on user roles or other criteria.

Example: Create an authentication guard to protect routes that require authentication. This ensures that unauthorized users don't load unnecessary components or data.

import { CanActivate } from '@angular/router';

export class AuthGuard implements CanActivate {
  canActivate(): boolean {
    // Check if the user is authenticated
    return true; // Or implement your logic here
  }
}

7. Minify and Bundle CSS and JavaScript

Minifying and bundling CSS and JavaScript files can reduce the number of requests made to the server, improving load times.

Example: You can configure the Angular CLI to extract styles into separate CSS files, minify them, and generate source maps for debugging using the --extract-css and --source-map options when building your application:

ng build --extract-css --source-map

8. Optimize Bundle Splitting

Bundle splitting is crucial for efficient loading. Angular CLI allows you to configure and optimize your application's bundle splitting strategy.

Example: In your Angular CLI configuration (angular.json), you can customize your build options. For example, you can configure the optimization.splitChunks section to fine-tune how your application's code is split into chunks.

"optimization": {
  "splitChunks": {
    "chunks": "all",
    // Add more options as needed
  }
}

Conclusion

Optimizing Angular applications is essential for delivering a fast, responsive, and user-friendly web experience. By implementing techniques like lazy loading, tree shaking, minification, lazy loading images, service workers, and route guards, Minify and Bundle CSS and JavaScript, Optimize Bundle Splitting you can significantly enhance the performance of your Angular app. These optimizations not only benefit your users but also reduce your server load and hosting costs. Start applying these strategies today to make your Angular application shine.

Comments

[Melroy van den Berg]

--aot is by default. right? So no need to give this flag.

[Melroy van den Berg]

Also.. ng build --prod, the --prod flag doesn't exists anymore. I think it's just ng build now.

[Balaji]

Yes, you're correct. As of Angular 8, the --aot flag is enabled by default for production builds, so there's no need to provide it explicitly.

And starting from Angular 12, the --prod flag has been deprecated. Can now use ng build for a production build. The Angular CLI understands that it's a production build based on the configuration in your angular.json file.

Updated now Thank you!.