A Beginner’s Guide to Angular Signals 🌟

Signals in Angular are a fast, simple, and powerful way to manage state. They allow Angular to track changes and update your application automatically, making your app more dynamic and responsive. This guide walks you through the basics of Angular Signals and how to use them effectively.

What Are Signals?

A signal is a reactive state management tool in Angular. It tracks values and automatically triggers updates where necessary, making it a faster and more efficient way to handle dynamic data compared to traditional methods.

Creating a Signal

Use the signal() function to create a signal.

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

// Create a signal
const firstName = signal('Morgan');

// Read the signal value
console.log(firstName()); // Outputs: Morgan

// Update the signal value
firstName.set('Jaime');
console.log(firstName()); // Outputs: Jaime

// Update the value based on the previous state
firstName.update(name => name.toUpperCase());
console.log(firstName()); // Outputs: JAIME

Why Are Signals Faster?

Unlike traditional change detection, signals rely on fine-grained reactivity. Angular tracks exactly where a signal is used, meaning it updates only the necessary parts of the DOM instead of checking the entire application. This results in blazing-fast updates.

Computed Signals

A computed signal derives its value from other signals. It’s read-only and updates automatically whenever its dependent signals change.

Creating a Computed Signal

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

const firstName = signal('Morgan');
const firstNameCapitalized = computed(() => firstName().toUpperCase());

console.log(firstNameCapitalized()); // Outputs: MORGAN

// Update the original signal
firstName.set('Jaime');
console.log(firstNameCapitalized()); // Outputs: JAIME

Using Signals in Components

Signals are perfect for managing state in Angular components.

Example: Trial Management Component

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

@Component({
  selector: 'app-user-profile',
  template: `
    <div>
      <button (click)="activateTrial()">Activate Trial</button>
      <p *ngIf="showTrialDuration()">Trial is active!</p>
    </div>
  `,
})
export class UserProfile {
  isTrial = signal(false);
  isTrialExpired = signal(false);

  showTrialDuration = computed(() => this.isTrial() && !this.isTrialExpired());

  activateTrial() {
    this.isTrial.set(true);
  }
}

Benefits:

• Signals make UI updates faster by only re-rendering when specific values change.
• Computed signals simplify derived state management.

Why Use Signals?

1. Performance: Signals update specific parts of the DOM, reducing overhead and boosting speed.

2. Simplicity: Less boilerplate code compared to traditional state management tools.

3. Reactivity: Angular tracks changes automatically, streamlining updates.

4. Efficiency: Eliminates the need for manual change detection or complex state management patterns.

Next Steps

Now that you understand the power of Angular Signals, learn how to integrate them into templates and build even faster, more dynamic applications.

👉 Dive deeper into signals with the In-depth Angular Signals Guide.