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Angular Services: A Beginner’s Guide

Seamless and responsive experience is, more often than not, made possible by Angular services. Working behind the scenes. So how does it all work?
Daniel Zacharias

Code Power Team

August 4, 2023

Online shopping is an almost unavoidable part of 21st-century living. Of course, everyone wants it to be as smooth as possible. The changes made by the user should appear instantaneous and be clearly visible at all times.

Let’s say you’ve added a few items to your cart. The web app will display the total price you need to pay. Remove one item, and the app will automatically recalculate the price. But aren’t endless paragraphs of code needed for this to work? Not quite.

This sort of seamless and responsive experience is, more often than not, made possible by Angular services. Working behind the scenes, they can perform the above-described task, help with user authentication, and so much more. So how does it all work?

The world of Angular

For all the beginners out there first discovering Angular, we can promise you one thing, you’re going to be pleasantly surprised. This open-source JavaScript framework serves to build truly dynamic web apps. Some of its features include data binding, component-based architecture, and dependency injection. All of these make the life of a junior developer easier.

What are Angular services?

Within this little universe, we now dip into the realm of services. They are objects belonging to the Angular framework. We can also define them as typescript classes with the @injectible decorator. This means their implementation happens through dependency injection, which, in turn, makes them available to any other component within the app.

Services do, however, remain separate, a category unto themselves. Components are primarily used for data binding, exposing methods and properties. They act as mediators between the application logic and the user interface presented to the end user. In contrast, services encapsulate business logic and perform tasks that are independent of both the view and the application logic.

Why do you need them?

A narrow, well-defined purpose allows Angular services to perform specific operational tasks in an efficient and prompt manner. We’re talking about fetching data from the server, validating user input, establishing network connections, etc. They can also help with database management.

Basically, these single pieces of code can be any feature, function, or variable that your app needs. Services deal with this so components themselves don’t have to. They won’t rewrite your code, they’ll just do their thing and recede into the background.

The benefits

It’s not difficult to assume that there are multiple advantages to this approach.

Single responsability. Component responsibilities are kept separate from data manipulation and business logic. The code remains cleaner and easier to manage.

Code reusability. Services you are able to share across multiple components reduce code duplication. This, in turn, improves the modularity and scalability of your code.

Ease of testing. Both of the above points allow easy maintenance and straightforward testing. Fixing errors and debugging are practically streamlined.

Dependency injection and sharing data. Services are easily injected into components. The process has no dependency on the parent-child relationship and can flow in any direction. A great thing for both synchronous and asynchronous operations.

It’s no wonder the future of Angular development seems bright.

Where should you use them?

Angular services offer countless possibilities. There are, however, five categories in which their potential is fully realized.

Authentication service. It handles user authentication, makes sure the login is truly secure, and takes care of session management. It tends to be easy on the resources.

Data service. Enables efficient data retrieval and manipulation. Connects the front with the back end. A great solution for data catching, filtering, sorting, pagination, etc.

Logging service. Lets developers track app performance, events, and errors. Offers valuable insights for monitoring and debugging.

Notification service. Keeps the users informed through the implementation of real-time alerts and notifications.

Localization service. Deals with translation, localization, and implementation of multi-language support.

The way of providing services

Before you start employing Angular services, remember to register at least one provider. You can embed it in the service’s own metadata. Alternatively, providers can remain attached to specific modules or even individual components.

The former option is somewhat more efficient. Register the provider in the @Injectable() decorator metadata. Once it’s done its duty, Angular can optimize the app by removing the service. JavaScript pros call this process tree-shaking. It helps keep the code clean.

So how do you create a service then?

Remember that this little piece of code is nothing more than a JavaScript function. You only need to follow a few simple steps to get things going.

  1. Decide on a descriptive name. This will help you find your service in a sea of other code. Nothing worse than being unable to locate something in your project.
  2. Create your typescript file. Don’t forget to add the .service.ts extension. It won’t work without it.
  3. Open the above-mentioned file and import the necessary modules. For example, you can employ the injectable from @angular/core. Use said injectable decorator to mark the service class.
  4. Next, implement the functionality your project requires. This can include performing calculations, making API calls, etc.
  5. Save the file and always keep it in your services folder.

Built-in services

Of course, you won’t have to create all of them from scratch. Angular comes with quite a few built-in services available to the developer. We’ll only mention the most common ones you can use in your future projects. They include:

$http. Used to handle HTTP server responses and send and retrieve data.

$log. A simple yet secure logging mechanism.

$timeout. Delays code execution.

$interval. Repeatedly runs code at predetermined intervals.

$filter. Applies filters and format data inside your templates and controllers.

$translate. Lets you manage language-specific content by providing internationalization (i18n) and localization (l10n) capabilities.

$q. Handles asynchronous operations and manages their outcomes.

Just keep building

As a developer, you will always want to create a robust and maintainable app. Even better if it’s scalable, sustainable, and easy to test. Angular services are simple bits of code that make these goals more attainable. They serve to trigger events or as intermediaries through which components can communicate and share info.

You can use ready-made ones or code your own from scratch. Either way, they’ll help you build complex apps efficiently, avoid redundant code, and keep things well organized.

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