Angular

Angular Lazy Loading: A Complete Guide


One effective approach through which an Angular application can be optimized in terms of loading speed is lazy loading. Lazy loading is wherein modules or components load only when they need to be loaded rather than having all the content loaded at once. This reduces the initial load time and gives a better experience to a user.

What is Lazy Loading?

Lazily loading refers to deferring the loading of non-critical resources at the first time of load. When a visitor arrives at your website, Angular does not load the whole application but loads the required parts for the initial view. The rest of the modules and components are loaded as demanded by the user while using the application.

Advantages of Lazy Loading in Angular

  1. Improved Initial Load Time: Since not every module needs to be loaded, the application's initial loading time is greatly reduced.

  2. Better User Experience: This happens because the users can interact with the application much sooner without waiting for unneeded resources to load.

  3. Resource Optimization: The application loads the components only when required so that resources are utilised in a very optimized manner.Scalability: Lazy Loading makes it much easier to scale large applications because you can easily break them up into smaller, more manageable chunks of modules.

How Angular Implements Lazy Loading

Angular provides built-in support for lazy loading via its NgModules and the Angular Router. You can configure the router to load modules lazily based on the routes that users visit.

Implementing lazy loading in Angular Step-by-step

Let's walk through the process of implementing lazy loading in an Angular application.

1. Create Feature Modules

To take advantage of lazy loading, you need to break your application into feature modules. Each module should represent a specific feature of your app.

For example, let's create a ProductModule that will be loaded la

ng generate module product --route products --module app.module

2. Configure Lazy Loading in the Router

In app-routing.module.ts, configure the lazy loading for your module:

3. Create Feature Module Components

Within the ProductModule, you can now create components that will be part of this module. For instance, you might have a ProductListComponent that displays a list of products:

-ng generate component product/product-list

then add

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

4. Verify Lazy Loading with Network Tab

You can verify that lazy loading is in effect by opening the Developer Tools for your browser, and going to the Network tab. When you run the application the first time, it should not download a product.module.js file, but when you navigate to the /products route, it should download that module dynamically.

Evitate the Common Mistakes

  1. Not Using loadChildren Properly: Ensure you use the correct syntax for lazy loading in your routing configuration. Forgetting the import() function can lead to errors.

  2. Not Organizing Modules Correctly: Be mindful of how you structure your application. Too many small lazy-loaded modules can increase the number of HTTP requests, while too few can defeat the purpose of lazy loading.

  3. Failure to handle routes properly: In case your configuration of routes is performed incorrectly, you will find such messages like "Cannot match any routes" when you try to navigate into modules with lazy loading.

Conclusion

This is one of the most powerful features of Angular. Lazy loading can dramatically improve the performance and scalability of your application. Modules are loaded only when needed to decrease the amount of initial loading time thereby giving a superior user experience.

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