What is the purpose of providedIn with the Injectable decorator when generating Services in Angular 6?

📝 Blog Post: Understanding the Purpose of providedIn with the Injectable Decorator in Angular 6

🤔 What does providedIn do?

When generating services in Angular, you might have come across the providedIn property in the @Injectable decorator. This property is used to control the scope of the service, determining where and how it is provided.

By default, the providedIn property is set to 'root'. This means that the service is registered at the application level and is accessible throughout the entire application.

🌐 Global Accessibility but Clean Code?

You might be wondering why this is necessary when you can simply declare the service in the providers array of the AppModule. While it is true that both approaches achieve a similar result of making the service available globally, there are some key differences to consider.

💡 The Benefit of providedIn

The providedIn property with the value 'root' offers a few advantages over declaring services in the providers array:

1️⃣ Lazy Loading Support: When you use providedIn: 'root', Angular can perform lazy loading and load the service only when it is actually required. This is particularly useful for optimizing application performance.

2️⃣ Tree Shakeability: Angular's build optimizer can properly tree shake the services when they are provided in the root scope. This means that unused services will be removed from the final bundle, reducing the overall size of your application.

3️⃣ Code Modularity: By using providedIn and letting Angular handle the service registration, your code becomes more modular and self-contained. You don't have to explicitly import and provide the service in the AppModule, keeping your module files cleaner.

🔧 Alternative Scoping Strategies

If you want to provide a service at a different level, aside from the root level, you can use other valid values for the providedIn property.

For example, if you want the service to be scoped to a specific module, you can set providedIn to the module's name:

@Injectable({
  providedIn: MyModule,
})

Similarly, if you want the service to be scoped to a specific component, you can set providedIn to the component's name:

@Injectable({
  providedIn: MyComponent,
})

📣 Call-to-Action: Engage and Share!

Now that you understand the purpose of providedIn in the @Injectable decorator, it's time to put this knowledge into practice. Experiment with different scoping strategies and see how they affect your application's performance and modularity.

If you found this blog post helpful, be sure to share it with your fellow Angular developers. And don't forget to leave a comment or reach out to us on social media to let us know your thoughts and experiences with providedIn.

Keep coding and building awesome Angular applications! ✨🚀