How do Angular Signals differ from RxJS, and What is an advanced use case for them?

Signals and RxJS are both for handling reactivity, but they serve different primary purposes.

 RxJS: Best for handling asynchronous events and complex event streams (e.g., HTTP requests, WebSockets, complex user input sequences). RxJS comes with a great set of operators to orchestrate these streams.

Signals: Optimized for synchronous state management. They provide a simple, efficient way to represent state that can change over time and automatically notify dependents when it does, enabling fine-grained, zoneless change detection.

Advanced Use Case (Combining Signals and RxJS):

A common pattern is to use RxJS to handle the “event” and then feed the result into a signal to manage the “state.” This combines the benefits of RxJS for async operations and the performance of Signals for UI updates.

import { Component, signal, inject } from '@angular/core';
import { toSignal } from '@angular/core/rxjs-interop';
import { DataService } from './data.service';
import { catchError, of } from 'rxjs';
@Component({ selector: 'app-user-profile', template: `	<div *ngIf="user()">Welcome, {{ user().name }}</div><div *ngIf="error()">{{ error() }}</div> `
})
export class UserProfileComponent { private dataService = inject(DataService); private user$ = this.dataService.getUser().pipe(	catchError(err => of({ error: 'Failed to load user' })) ); // Convert the Observable stream to a Signal private userData = toSignal(this.user$); // Use computed signals to derive state user = computed(() => this.userData()?.name ? this.userData() : null); error = computed(() => this.userData()?.error);
}

Final Words

Signals are great for managing app state, while RxJS handles async data like API calls. When you combine both, you get smooth UI updates with powerful data control. To do this right, it helps to hire Angular developers who know when and how to use each one.