Lazy Loading Techniques in Angular for Enterprise Applications

In enterprise applications, it’s common to have a large codebase with multiple feature modules. Loading all these modules at once can slow down the application’s initial load time and negatively impact its performance. Lazy loading is a technique used in Angular to load feature modules on-demand when needed. In this blog post, we’ll discuss lazy loading techniques in Angular for enterprise applications.

What is Lazy Loading?

Lazy loading is a technique used in web development to defer the loading of non-critical resources until they are needed. In Angular, lazy loading is implemented using the LoadChildren property in the routing configuration. When a user navigates to a route that has a lazy-loaded module, Angular will load the module on-demand.

Advantages of Lazy Loading in Enterprise Applications:

• Faster initial load time: Lazy loading enables the application to load only the required modules when the application is initially loaded, reducing the load time.
• Better performance: Lazy loading improves performance by reducing the amount of data that needs to be loaded initially, thereby improving the application’s overall speed.
• Better code organization: Lazy loading promotes better code organization by allowing developers to break the application into smaller, more manageable feature modules.

Lazy Loading Techniques in Angular

Here are some techniques for implementing lazy loading in Angular for enterprise applications:

• Route-level lazy loading: This technique involves defining a lazy-loaded module in the routing configuration. When the user navigates to a route that has a lazy-loaded module, Angular will load the module on-demand. Here’s an example:

const routes: Routes = [
  { path: 'home', component: HomeComponent },
  {
    path: 'products',
    loadChildren: () => import('./products/products.module').then(m => m.ProductsModule)
  },
  { path: '**', component: PageNotFoundComponent }
];

In this example, the products route is lazy-loaded using the LoadChildren property.

• Component-level lazy loading: This technique involves lazy-loading a component when it is needed. Angular provides a ComponentFactoryResolver class that can be used to dynamically load components. Here’s an example:

@Component({
  selector: 'app-product-list',
  template: '<div #container></div>'
})
export class ProductListComponent implements OnInit, AfterViewInit {
  @ViewChild('container', { read: ViewContainerRef }) container: ViewContainerRef;

  constructor(private componentFactoryResolver: ComponentFactoryResolver) {}

  ngOnInit() {}

  ngAfterViewInit() {
    import('./product-item.component').then(m => {
      const factory = this.componentFactoryResolver.resolveComponentFactory(m.ProductItemComponent);
      this.container.createComponent(factory);
    });
  }
}

In this example, the ProductItemComponent is lazy-loaded when the ProductListComponent is initialized.

• Preloading modules: Preloading is a technique used to load modules in the background after the initial load. This improves the user experience by reducing the time required to load modules when they are requested. Angular provides a PreloadAllModules strategy that preloads all the lazy-loaded modules in the background. Here’s an example:

@NgModule({
  imports: [
    RouterModule.forRoot([
      { path: 'home', component: HomeComponent },
      { path: 'products', loadChildren: () => import('./products/products.module').then(m => m.ProductsModule) },
      { path: '**', component: PageNotFoundComponent }
    ], { preloadingStrategy: PreloadAllModules })
  ],
  exports: [RouterModule]
})
export class AppRoutingModule {}

In this example, the PreloadAllModules strategy is used to preload all the lazy-loaded modules in the background.

conclusion

Lazy loading is an essential technique in Angular for improving the performance of enterprise applications. By loading modules on-demand, it reduces the initial load time of the application and provides better performance to the end-users. In this blog post, we discussed various lazy loading techniques such as route-level lazy loading, component-level lazy loading, and preloading modules. Implementing these techniques in enterprise applications can significantly improve their performance and enhance the user experience.