When to Use Angular Signals

In this tutorial, you will learn when to use Angular Signal.

What are Angular Signals?

Signals are a reactive state management feature in Angular that automatically updates the UI when data changes.

Example: When the value changes, Angular updates the UI automatically.

import { signal } from '@angular/core';
const counter = signal(0);
function increment() {
  counter.set(counter() + 1);
}

When to Use Angular Signals

There are many reasons to use Angular Signals

1. Local Component State

Signals are perfect for small local states inside a component.

Example:

count = signal(0);

Benefit of Signal in Local Component State

1. It is very Simple.
2. It is Less boilerplate.
3. There is no need for subscriptions.

2. Derived State (Computed Values)

You can use signals in a derived state when a value depends on another value.

Example:

price = signal(100);
tax = signal(10);

total = computed(() => price() + tax());

Benefits of Signal in the Derived state

1. You can use it for auto-recalculation.
2. It is good for Cleaner logic.

3. Performance Optimization

Signals are used to improve performance because they update only the components that depend on them.

Benefits:

1. It is good for Large dashboards.
2. It is good for Data-heavy UI.
3. It is good for Real-time updates.

4. Replacing Simple RxJS Observables

If you only need basic state updates, then signals can replace simple RxJS streams.

Example:

1. Form values
2. UI state
3. Theme toggle

5. State Shared Across Components

Signals can also be used in services to share a reactive state.

Example:

@Injectable()
export class CounterService {
  count = signal(0);
}

Note: All components that use the service will respond to changes.

Angular Signals vs RxJS (Quick Comparison)

When not to Use Signals

You should avoid signals

1. When you have complex async operations.

2. When you are using WebSocket streams.

3. When you have Advanced reactive pipelines.

Conclusion

You should use Angular Signals when

1. Simple reactive state
2. Better performance
3. Cleaner component logic