A Guide to Angular Signals With Practical Use Cases (Part 1)

Welcome! If you’re reading this, you’re probably curious about Angular Signals, the latest gem in the Angular framework’s treasure trove. Known for its streamlined approach to state management, Angular Signals can be a game-changer. But where does it truly shine in real-world applications? Let’s embark on a detailed exploration, touching on three use cases and their practical applications.

1. Form Management

Angular Forms, whether Reactive or Template-Driven, are essential for capturing user input.

Instead of manually subscribing to form control value changes or using valueChanges, Signals can represent form control values. This ensures that only relevant components or parts of your application react to changes in form values, making form handling more efficient.

Angular’s Forms module, be it Reactive or Template-Driven, is a core part of many applications, ensuring seamless user data input. With the introduction of Angular Signals, developers can further enhance the efficiency and simplicity of form handling.

Reactive Form Handling with Signals

Consider a typical reactive form setup; with Angular Signals, you can use the toSignal function to represent form control values as signals. This ensures that only relevant components or parts of your application react to changes in form values.

Let’s create an example component with a form that uses Angular Signals:

Angular component with form utilizing Signals

In the example above, firstNameSignal is created using the toSignal function. It represents the value of the 'firstName' form control. Now, instead of manually subscribing to the valueChanges of the form control, we directly use the signal in our template. The div containing the compliment message for the first name will only be rendered or updated when the first name changes. More than that, we can have computed signals that would have an effect on our template. For example, we can have a form field with the date of birth, which is converted to a writable signal using toSignal. And another computed signal that would calculate and show the age based on the date of birth signal.

Benefits Unveiled:

• Selective Rendering: Only the parts of your application that rely on a specific signal will update when its value alters. While not a virtual DOM like React, it does offer focused template updates.
• Smart Subscription Handling: The toSignal function has got your back! It subscribes when a component starts and unsubscribes upon its demise, safeguarding against memory leaks.
• Crystal-clear Code: No more murky waters! With Signals, dynamic values within Angular templates become straightforward and intuitive.

In essence, integrating Angular Signals with forms amplifies their performance and paves the way for a more organized, maintainable coding experience.

2. Dynamic Theming

Changing the visual theme of an application based on user preferences or system settings is a common requirement.

A signal can represent the current theme. When a user switches themes, the signal updates, and only components that depend on the theme need to re-render, instead of the whole application.

Dynamic theming enables users to switch between different color schemes or designs on the fly, enhancing user experience. Using Angular Signals, we can achieve efficient and reactive theming solutions that are both scalable and maintainable.

Dynamic Theming with Angular Signals

Traditionally, you might have handled dynamic theming with ngClass and a service that is using BehaviorSubject to store the state. Using Angular Signals, we can streamline this process:

Theme service with Signals

App component that is consuming the theme service

Here’s what we achieved:

• Simplified Service: With Angular Signals, we use the signal function to create a signal for the theme, removing the need for the BehaviorSubject.
• Reactive Theme Switch: In the component, we can directly access the theme using the signal. This ensures that our component template reacts instantly to theme changes.
• Synchronized State Access: By using themeService.themeSignal(), we can access the current theme directly, ensuring that the theme state is always synchronized.

Bottom line: Angular Signals crafts a path for dynamic theming that’s intuitive, efficient, and free from excessive coding.

3. Live Data Streams

Applications like stock trading platforms or live sports scoreboards require real-time data updates.

By integrating with RxJS through the toSignal function, Angular Signals can directly represent these data streams. This means that as new data is streamed in, only the affected components get updated, ensuring optimal performance.

Modern web applications often deal with dynamic data that constantly updates in real-time. Such live data streams are typically used in stock trading platforms, sports scoreboards, live chat applications, and more. Angular Signals can be incredibly effective in these scenarios, ensuring that data remains reactive and synchronizes with the UI seamlessly.

Handling Live Data with Angular Signals

Traditionally, managing live data streams might involve services, observables, and complex subscription logic. Now, let’s reimagine this using Angular Signals:

Chat Service with Signals

Chat Component with Signals

Notable Enhancements:

• Message Management: Gone are the days of BehaviorSubject. Now, the Signal takes the stage, ensuring on-the-fly updates.
• Reactive Templates: Signals directly in templates react instantly to live data changes, all without the need for async pipes or subscription hassles.
• Trimmed Down Code: Less is more! Reducing manual work enhances clarity and maintenance.

To wrap it up, Angular Signals is revolutionizing how we manage live data streams, offering a method that’s simpler and more efficient.

Enough for now.

Stay tuned for more in our next part, where we’ll delve into User Profiles, E-commerce Cart Management, and Notification Systems. Remember, the world of Angular Signals is vast, and as more developers dive in, its horizons will only expand. Happy coding!

Also published here.