# Angular Signals (Angular)

> Signals API, computed, effect, signal inputs, signal queries, reactivity model, migration from RxJS

- 20 interview questions
- Mid-Level
- [Interview Questions: Angular](https://sharpskill.dev/en/technologies/angular/interview-questions.md)

## 1. What is a signal in Angular?

**Answer**

A signal is a reactivity primitive introduced in Angular 16+ that wraps a value and automatically notifies consumers when that value changes. Unlike RxJS Observables, signals offer a simpler and more performant approach to managing reactive state. They are synchronous by default and integrate natively with Angular's change detection system.

## 2. How to create a signal with an initial value?

**Answer**

Use the signal() function with the initial value as parameter: signal(0) creates a signal containing 0. The returned signal is a getter function that can be called to read the value. To modify the value, use set(), update() or mutate() methods. The syntax is concise and avoids the verbosity of RxJS BehaviorSubject.

## 3. How to read the value of a signal?

**Answer**

Call the signal as a function: count() returns the current value. This syntax allows Angular to automatically track dependencies in reactive contexts (templates, computed, effect). Unlike Observables that require subscribe() or async pipe, signals offer synchronous and direct reading.

## 17 more questions available

- Which method to use to completely replace a signal's value?
- How to update a signal based on its previous value?

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## Other Angular interview topics

- [TypeScript Basics](https://sharpskill.dev/en/technologies/angular/interview-questions/typescript-basics.md): 25 questions, Junior
- [TypeScript Advanced](https://sharpskill.dev/en/technologies/angular/interview-questions/typescript-advanced.md): 20 questions, Junior
- [Angular Fundamentals](https://sharpskill.dev/en/technologies/angular/interview-questions/angular-fundamentals.md): 20 questions, Junior
- [Components & Lifecycle](https://sharpskill.dev/en/technologies/angular/interview-questions/components-lifecycle.md): 20 questions, Junior
- [Services & Dependency Injection](https://sharpskill.dev/en/technologies/angular/interview-questions/services-dependency-injection.md): 20 questions, Junior
- [Angular Modules Organization](https://sharpskill.dev/en/technologies/angular/interview-questions/modules-organization.md): 22 questions, Mid-Level
- [Angular CLI](https://sharpskill.dev/en/technologies/angular/interview-questions/angular-cli.md): 18 questions, Junior
- [Directives & Pipes](https://sharpskill.dev/en/technologies/angular/interview-questions/directives-pipes.md): 22 questions, Mid-Level
- [Routing & Navigation](https://sharpskill.dev/en/technologies/angular/interview-questions/routing-navigation.md): 24 questions, Mid-Level
- [Reactive Forms](https://sharpskill.dev/en/technologies/angular/interview-questions/forms-reactive.md): 26 questions, Mid-Level
- [Template-driven Forms](https://sharpskill.dev/en/technologies/angular/interview-questions/forms-template-driven.md): 16 questions, Mid-Level
- [RxJS Fundamentals](https://sharpskill.dev/en/technologies/angular/interview-questions/rxjs-fundamentals.md): 22 questions, Mid-Level
- [RxJS Operators](https://sharpskill.dev/en/technologies/angular/interview-questions/rxjs-operators.md): 24 questions, Mid-Level
- [HttpClient & API Calls](https://sharpskill.dev/en/technologies/angular/interview-questions/http-client.md): 22 questions, Mid-Level
- [Basic State Management](https://sharpskill.dev/en/technologies/angular/interview-questions/state-management-basics.md): 20 questions, Mid-Level
- [Change Detection](https://sharpskill.dev/en/technologies/angular/interview-questions/change-detection.md): 20 questions, Mid-Level
- [Standalone Components](https://sharpskill.dev/en/technologies/angular/interview-questions/standalone-components.md): 18 questions, Mid-Level
- [Angular Unit Testing](https://sharpskill.dev/en/technologies/angular/interview-questions/testing-unit.md): 22 questions, Mid-Level
- [End-to-End Testing](https://sharpskill.dev/en/technologies/angular/interview-questions/testing-e2e.md): 18 questions, Mid-Level
- [Build & Optimization](https://sharpskill.dev/en/technologies/angular/interview-questions/build-optimization.md): 20 questions, Mid-Level
- [NgRx Fundamentals](https://sharpskill.dev/en/technologies/angular/interview-questions/ngrx-fundamentals.md): 24 questions, Senior
- [NgRx Advanced](https://sharpskill.dev/en/technologies/angular/interview-questions/ngrx-advanced.md): 24 questions, Senior
- [Angular Architecture](https://sharpskill.dev/en/technologies/angular/interview-questions/angular-architecture.md): 22 questions, Senior
- [Performance Optimization](https://sharpskill.dev/en/technologies/angular/interview-questions/performance-optimization.md): 22 questions, Senior
- [Security & Best Practices](https://sharpskill.dev/en/technologies/angular/interview-questions/security-best-practices.md): 20 questions, Senior
- [Advanced RxJS Patterns](https://sharpskill.dev/en/technologies/angular/interview-questions/advanced-rxjs-patterns.md): 22 questions, Senior
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