Angular Signals vs RxJS – Which One Should You Use?

Introduction

Signals are used to simplify state management and improve performance. Traditionally, developers used RxJS.

In this tutorial, we will compare Angular Signals vs. RxJS features and when to use each.

What are Angular Signals?

Angular Signals are a reactive state management feature that automatically tracks dependencies. Angular automatically updates the UI whenever the value changes.

Example 1:

import { signal } from '@angular/core';
const counter = signal(0);

counter.set(5);

console.log(counter());

Output:

Note: Signals are synchronous, lightweight, and designed primarily for application state.

Example 2:

import { Component, signal } from '@angular/core';

@Component({
    selector: 'app-root',
    standalone: true,
    template: `<button (click)="increment()">Increment</button>
        <h2>{{ count() }}</h2>`
})
export class AppComponent {

    count = signal(0);

    increment() {
        this.count.update(value => value + 1);
    }

}

Note: The UI updates automatically whenever the signal changes.

What is RxJS?

RxJS is a library, and it is used to handle asynchronous data streams using Observables.

Example 1:

import { of } from 'rxjs';

of(1,2,3).subscribe(value => console.log(value));

Note: RxJS is used for HTTP requests, event streams, and async operations.

Example 2:

TypeScript File:

import { BehaviorSubject } from 'rxjs';

count = new BehaviorSubject(0);

increment() {
    this.count.next(this.count.value + 1);
}

Template:

{{ count | async }}

Note: The AsyncPipe subscribes and unsubscribes automatically.

How Signals Work?

Signals keep track of which components use them. Whenever a Signal changes, Angular updates only the affected parts of the UI. The UI refreshes automatically.

name = signal('John');

name.set('Tom');

Template:

{{ name() }}

How RxJS Works?

RxJS uses Observables that emit values over time.

this.http.get('/api/users')
    .subscribe(users => {
        console.log(users);
    });

The Observable completes after returning data.

Signals vs RxJS Comparison

When should you use Signals?

Now, you will see when we should use Signals

1. When you need to manage local component state.
2. When you need to build UI state like counters or toggles.
3. When you need to create derived values with computed().
4. When you need to optimize performance.

When should you use RxJS?

Now, you will see, when we should use RxJS

1. You should use RxJS when working with HTTP requests.
2. You should use RxJS when working with WebSocket streams.
3. You should use RxJS when working with Event streams.
4. You should use RxJS when working with Complex async workflows.

Can Signals Replace RxJS?

No, Signals cannot fully replace RxJS.

Both have different purposes

1. Signals → It is used for UI state management.

2. RxJS → It is used for asynchronous data streams.

In Modern Angular App, you should use both based on the requirement.

Conclusion

Both Signals and RxJS are important in Angular.

Signals is used for state management.

RxJS is used to handle complex asynchronous streams.

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