Understanding Angular's Lazy Loading Feature for Modules

Angular's Lazy Loading is a design pattern that is commonly used in Angular applications to improve initial load performance. It does this by splitting the application into multiple bundles that are loaded on demand, not all at once.

How it Works

Typically, an Angular application can be separated into a single bundle or multiple smaller bundles that are then loaded on demand. When a user navigates to a particular portion of the application, only the corresponding bundle for that portion is loaded. The rest of the application’s bundles are not loaded until they are requested. This approach is referred to as "Lazy Loading".

Benefits of Lazy Loading

One of the primary benefits of lazy loading is the drastic improvement in initial load performance. When a user first visits an application, the entire application doesn't need to be loaded all at once. Only the necessary bundle for the initially requested page is loaded. As a result, the time it takes for the initial application load dramatically decreases. This way, users do not need to wait for long before they can start using the application.

In addition to improved performance, lazy loading also benefits users by saving their data. Since not all data is downloaded upfront, unnecessary data usage is reduced.

Implementation of Lazy Loading in Angular

The Angular router is designed to enable lazy loading. This is typically achieved by defining a route with the loadChildren property. It points to the module that should be lazily loaded.

Below is a simple example.

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

In this example, the HomeModule is lazily loaded when the user navigates to the /home path.

Best Practices

While lazy loading offers great advantages, it is crucial to use this design pattern appropriately to ensure performance is improved rather than hampered.

Consider the following tips for the best use of lazy loading:

• Right-size your Modules: Each module should be just right in size – not too large that it slows down the initial load time, but not so small that it introduces a lot of network requests.
• Prioritize Modules: Not all modules are equally important. Modules that are hardly used can be made lower in priority to load.

In conclusion, Angular's Lazy Loading is a useful feature that improves the initial load performance of an application by splitting it into multiple bundles. Learning how to use it effectively can drastically improve the user experience of your Angular applications.