Angular load time performance

Angular Load Time Performance Optimization

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Load time is a crucial factor in delivering a seamless user experience. In our previous blog post on performance optimization, we discussed the importance of optimizing various aspects of Angular applications. Today, we continue our exploration by diving deeper into load time performance optimization. In this blog post, we will build upon the foundational knowledge and explore effective techniques and best practices specifically tailored to Angular development. By optimizing load time, we can ensure that our applications captivate users from the moment they land on our sites. So, let’s continue our journey of enhancing Angular performance and discover the secrets of load time optimization!

Minimizing Bundle Size

One of the primary contributors to slow load times is a large bundle size. Angular applications are bundled with JavaScript, CSS, and HTML files, which collectively determine the size of the bundle. To minimize the bundle size, consider the following strategies:

Eliminate Unused Code

Identifying and removing unused code is a powerful strategy to reduce your bundle size. By eliminating unnecessary code, you can significantly trim down the size of your application. Here are a few examples:

  • Tree Shaking: Suppose your Angular application has a library imported but only a small portion of it is actually used. By leveraging tree shaking, you can eliminate the unused parts during the build process. For instance, if you’re using a large utility library like Angular Material, but only require a few specific functions, tree shaking will remove the unused functions, resulting in a smaller bundle size. I will dive deeper into tree shaking in another post.
  • Conditional Imports: Angular allows you to conditionally import modules based on runtime conditions. This technique is useful when you have modules or features that are only required in specific scenarios. By importing these modules conditionally, you prevent them from being included in the main bundle, reducing its size. For example, if you have a debugging module that is only needed in development mode, you can conditionally import it using Angular’s environment configuration.

Optimize Dependencies

Reviewing and optimizing your application’s dependencies can significantly impact the bundle size. By selecting smaller, more lightweight alternatives and removing unnecessary dependencies, you can achieve substantial size reductions. Consider the following examples:

  • Replace Heavy Libraries: Suppose you have been using a large, feature-rich library for a specific functionality in your Angular application. If you only require a subset of those features, consider replacing it with a smaller, more focused library. For instance, if you’ve been using Moment.js for date manipulation but only need basic date formatting, consider using a lighter alternative like date-fns.
  • Custom Implementations: In some cases, you may find that writing custom functions or components is more efficient than relying on external libraries. Assess your application’s requirements and consider building custom solutions where feasible. This approach allows you to eliminate dependencies altogether, resulting in a leaner bundle size, e.g. I’ve showed here how you can implement your own SVG loading service instead of using external libraries,

Code Splitting

Implementing code splitting enables you to load specific parts of your application on-demand, reducing the initial bundle size. Angular provides various mechanisms to achieve code splitting. Here are a couple of examples:

  • Lazy Loading Modules: Angular’s lazy loading feature allows you to load modules only when they are required. This technique is particularly useful for large applications with distinct feature modules. For instance, if you have an e-commerce application, you can lazily load the shopping cart module when the user navigates to the cart page. This way, the cart module is fetched separately, reducing the initial load time of your application. Lazy loading is also topic for another post.
  • Dynamic Imports: With dynamic imports, you can asynchronously load components, services, or libraries when they are needed. This approach enables you to split your code into smaller chunks and load them dynamically, reducing the initial bundle size. For example, you can leverage dynamic imports to load specific charting libraries only when the user visits a dashboard page.

Optimizing the bundle size of your Angular application is crucial for achieving fast load times and delivering exceptional user experiences. By eliminating unused code, optimizing dependencies, and leveraging code splitting techniques, you can significantly reduce the bundle size. Implement these strategies in your Angular projects and unlock the full potential of your application’s performance. Remember, a smaller bundle size not only enhances load times but also improves overall user satisfaction.

Lazy Loading

Lazy loading is a technique that defers the loading of specific parts of an application until they are required. Traditionally, Angular loads the entire application upfront, including all modules, components, and assets. However, with lazy loading, you can split your application into smaller, more manageable chunks that are loaded on-demand as users navigate through your application.

Benefits of Lazy Loading

  • Improved Initial Load Time: By lazily loading modules, you can significantly reduce the initial load time of your application. Instead of loading the entire application at once, only the necessary modules are fetched, resulting in faster rendering and improved user experience.
  • Optimal Resource Utilization: Lazy loading allows you to load modules and components only when they are needed. This optimizes the utilization of system resources, ensuring that your application remains lightweight and responsive.
  • Faster Subsequent Page Loads: Once the initial module is loaded, subsequent navigation within your application becomes faster since the required modules are already available. This seamless transition between pages enhances the overall user experience.

Route-based Lazy Loading

Angular provides a straightforward way to implement lazy loading at the route level. By configuring your application’s routing module, you can specify which modules should be lazily loaded when a particular route is accessed.

Let’s consider an e-commerce application with multiple routes. We can implement lazy loading for specific routes that are not frequently accessed. Here’s an example:

const routes: Routes = [
  { path: '', loadChildren: () => import('./home/home.module').then(m => m.HomeModule) },
  { path: 'products', loadChildren: () => import('./products/products.module').then(m => m.ProductsModule) },
  { path: 'cart', loadChildren: () => import('./cart/cart.module').then(m => m.CartModule) },
  // ...
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

In this example, we have the AppRoutingModule where the routes are defined. Each route is configured with lazy loading by using the loadChildren property. The loadChildren property takes a function that returns a dynamically imported module using the import() function.

Now, let’s take a look at how to use lazy loading in the module itself:

// products-routing.module.ts
const routes: Routes = [
  { path: '', component: ProductsComponent },
  { path: 'details/:id', component: ProductDetailsComponent },
  // ...
];

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule]
})
export class ProductsRoutingModule { }

In the ProductsModule, we have the ProductsRoutingModule where the routes specific to the products feature module are defined. Similarly to the AppRoutingModule, lazy loading is applied using the forChild method from RouterModule.

By using lazy loading in both the AppRoutingModule and feature module routing modules, you ensure that the respective modules are loaded only when their routes are accessed. This helps optimize the initial loading time of the application and improves performance.

Remember to configure the necessary components, services, and other dependencies within each lazily loaded module as needed.

Preloading

Angular provides various preloading strategies to fetch non-critical modules in the background while users interact with the initial parts of the application. Preloading improves UX by loading parts of your application in the background. You can preload modules, standalone components or component data.

@NgModule({
  imports: [
    RouterModule.forRoot(routes, { preloadingStrategy: PreloadAllModules }),
    // ...
  ],
  // ...
})
export class AppModule { }

By specifying PreloadAllModules as the preloading strategy in the RouterModule, all modules defined with lazy loading will be preloaded in the background while users explore the initial parts of the application. This ensures a seamless user experience when navigating to other routes.

You can also create custom preloading strategies tailored to your application’s needs. Here’s an example of a custom preloading strategy that prioritizes preloading based on user behavior:

export class CustomPreloadingStrategy implements PreloadingStrategy {
  preload(route: Route, load: () => Observable<any>): Observable<any> {
    if (route.data && route.data.preload) {
      // Perform logic to determine if the module should be preloaded based on user behavior.
      // If true, return the load() function to preload the module.
    }
    return of(null); // Return `of(null)` for modules that should not be preloaded.
  }
}

You can then specify this custom preloading strategy in the RouterModule configuration:

@NgModule({
  imports: [
    RouterModule.forRoot(routes, { preloadingStrategy: CustomPreloadingStrategy }),
    // ...
  ],
  // ...
})
export class AppModule { }

With this custom preloading strategy, you have full control over which modules should be preloaded based on specific criteria, such as user preferences or previous interactions.

By utilizing route-based lazy loading and preloading strategies, you can optimize the loading process of your Angular application and provide a smoother user experience. Choose the appropriate lazy loading strategy for each module or route based on their usage patterns and priorities.

Best Practices for Lazy Loading

  • Module Organization: Properly organize your modules based on their functionality and usage patterns. Identify feature modules that are self-contained and can be loaded independently. This modular structure will make lazy loading more effective and maintainable.
  • Shared Modules: Be cautious with shared modules. Shared modules contain common components, services, and directives used across multiple feature modules. Carefully analyze the dependencies and determine whether a shared module should be lazily loaded or eagerly loaded to avoid duplication or potential conflicts. Generally you should avoid shared modules with all commons inside, instead use standalone components and smaller modules with more specific functionalities.

Lazy loading summary

Lazy loading is a powerful technique that allows Angular developers to optimize the loading process of their applications, resulting in faster load times and improved user experiences. By deferring the loading of modules until they are needed, you can achieve optimal resource utilization and seamless page transitions.

Optimizing Asset Loading

Optimizing the loading of assets such as images, fonts, and stylesheets can have a substantial impact on load times. By employing strategies to minimize asset size and optimize their delivery, you can significantly improve load times and enhance the user experience.

Asset Optimization Techniques

  • Image Compression: Large image files can significantly impact load times. Optimize your images by compressing them without compromising visual quality. Tools like ImageOptim, TinyPNG, or Squoosh offer convenient ways to reduce image file sizes. Additionally, consider using modern image formats like WebP or AVIF, which provide superior compression compared to traditional formats like JPEG or PNG.
  • SVG Usage: Whenever possible, use Scalable Vector Graphics (SVG) for icons, logos, and other graphics. SVG images are resolution-independent and have smaller file sizes compared to raster images. They can be easily optimized and scaled without loss of quality, resulting in faster loading times.
  • Minification and Compression: Minify and compress your JavaScript, CSS, and HTML files to reduce their size. Angular CLI automatically performs minification during the build process using tools like UglifyJS and Terser. Similarly, enable Gzip or Brotli compression on your web server to further reduce file sizes during transmission.

Lazy Loading of Assets

  • Lazy Loading Images: Load images lazily, especially those below the fold or outside the initial viewport. Angular provides the ngSrc directive that allows you to implement lazy loading without external libraries. You can conditionally bind the src attribute of an image based on whether it is in the viewport or not. By doing so, the image will only load when necessary, reducing the initial page load time.
<img [ngSrc]="isVisible ? 'path-to-image.jpg' : null" (isVisible)="isVisible = true">
  • Lazy Loading Fonts: Fonts can contribute to significant initial load times. Utilize font-display CSS property to control how fonts are rendered. Set the font-display property to swap to display fallback fonts immediately while the custom font loads asynchronously in the background.

Asset Delivery Optimization

  • Resource Prioritization: Prioritize critical assets to ensure they are loaded and rendered quickly. Use techniques like preloading and prefetching to inform the browser about assets needed for future navigation. For example, you can preload critical CSS or JavaScript files to ensure they are available when subsequent pages are loaded.
  • Content Delivery Network (CDN): Utilize a CDN to distribute your static assets geographically closer to your users. CDNs cache and deliver assets from servers strategically located worldwide, reducing the latency and improving the overall loading speed for users accessing your application from different regions.
  • Cache Control Headers: Configure proper cache control headers for your assets to enable browser caching. Set appropriate cache durations for static assets that rarely change. This allows subsequent visits to your application to load assets from the user’s local cache, resulting in faster page loads.

Optimizing asset loading is a crucial step in maximizing the performance of your Angular application. By employing techniques like image compression, lazy loading of assets, and leveraging CDNs, you can significantly enhance load times and improve user experience. Experiment with these techniques and analyze the performance impact to fine-tune your asset optimization strategy. Remember, every byte matters in delivering a fast and responsive application.

Conclusion

Efficiently optimizing the loading process of your Angular application is vital for delivering a fast, responsive, and engaging user experience. In this blog post, we explored various strategies and techniques to optimize load times, ranging from minimizing bundle sizes and lazy loading to asset optimization and leveraging CDNs. By implementing these practices, you can significantly improve the performance of your application and keep your users satisfied.

Remember, optimization is an ongoing process. Regularly analyze your application’s performance, monitor network requests, and assess user experience to identify areas for further improvement. Experiment with different techniques, measure their impact, and fine-tune your optimization strategies based on the specific needs and requirements of your application.

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