How to Build SPAs With Angular Router Lazy Loading

Single Page Applications (SPAs) have gained immense popularity due to their ability to provide a seamless user experience. When building SPAs using Angular, one of the essential concepts to understand is lazy loading. In this article, we will explore how to effectively implement lazy loading with Angular Router to enhance the performance of your applications.

What is Lazy Loading?

Lazy loading is a design pattern that postpones the loading of non-essential resources until they are actually needed. In the context of Angular applications, this means loading modules only when the user navigates to a specific route, which significantly improves load time and performance.

Setting Up Your Angular Application

Before diving into lazy loading, ensure you have a basic Angular application set up. If you haven’t created an Angular application yet, you can easily create one using the Angular CLI:

ng new my-lazy-loading-app

Navigate to your project directory:

cd my-lazy-loading-app

Creating Feature Modules for Lazy Loading

The first step in implementing lazy loading is to create feature modules. Let’s say you want to create a feature module for a blog section of your application:

ng generate module blog --route blog --module app.module

This command generates a new module called 'BlogModule' and automatically configures it for lazy loading in the app routing module.

Configuring Routes for Lazy Loading

Open your `app-routing.module.ts` file. You will see a newly added route configuration for the blog module. It should look something like this:

const routes: Routes = [
  { path: 'blog', loadChildren: () => import('./blog/blog.module').then(m => m.BlogModule) }
];

Here, the `loadChildren` property defines that the `BlogModule` should be loaded only when the '/blog' route is accessed.

Creating Components within the Feature Module

Next, let’s create a component within the `BlogModule`:

ng generate component blog/blog-list

This will create a new component named `BlogListComponent`. Modify your blog module's routing to include this component:

const routes: Routes = [
  { path: '', component: BlogListComponent }
];

Adding Navigation Links

To navigate to the lazy-loaded blog section, you should add a link in your main application component, typically found in `app.component.html`:

<a routerLink="/blog">Go to Blog</a>

This router link will allow users to navigate to the blog section, thus triggering the lazy loading of the `BlogModule`.

Building and Running the Application

Once everything is set up, you can run your application to see lazy loading in action. Use the following command:

ng serve

Open your browser and navigate to http://localhost:4200. Click on the "Go to Blog" link, and you will notice that the blog module gets loaded only when you access it, reducing the initial load time of your main application.

Benefits of Lazy Loading in Angular SPAs

Improved Performance: Only necessary modules are loaded, which speeds up the initial loading time.
Better User Experience: Delivers a smoother experience as users navigate through the application.
Efficient Resource Management: Reduces the amount of code loaded at the start, optimizing performance for users with slower internet connections.

Conclusion

Implementing lazy loading with Angular Router is a powerful way to enhance the performance of your Single Page Applications. By loading feature modules only when they are needed, you can significantly improve the user experience and lower load times. Incorporate lazy loading into your Angular projects to deliver faster, more efficient applications.

How to Build SPAs With Angular Router Lazy Loading