Angular Signals: A Modern Approach to Reactivity

Angular Signals: A Modern Approach to Reactivity

Angular Signals introduce a new reactive primitive that simplifies state management and improves change detection performance. Instead of relying heavily on RxJS or manual change detection strategies, Signals provide a more predictable and fine-grained reactivity model.

1. What Are Signals?

A Signal is a reactive value that notifies Angular when it changes.

import { signal } from '@angular/core';
const count = signal(0);
count.set(1);
console.log(count()); // 1

Signals behave like reactive variables. When their value changes, Angular knows exactly which parts of the UI should update.

2. Computed Signals

Computed signals allow you to derive values from other signals.

import { signal, computed } from '@angular/core';
const count = signal(0);
const double = computed(() => count() * 2);
console.log(double()); // 0
count.set(2);
console.log(double()); // 4

Angular automatically tracks dependencies, so computed values update whenever their source signals change.

3. Effects

Effects run side effects when signals change.

import { signal, effect } from '@angular/core';
const count = signal(0);
effect(() => {
  console.log('Count changed:', count());
});
count.set(1);

Effects are useful for logging, API calls, or synchronizing external state.

4. Why Signals Improve Performance

Signals enable fine-grained reactivity:

• Angular updates only the components that depend on a signal
• Reduced unnecessary change detection cycles
• Simpler state management compared to complex RxJS chains

This makes Angular applications more predictable and efficient, especially in large-scale projects.

Conclusion

Angular Signals represent a major shift in Angular's reactivity model. They provide a simpler and more efficient way to manage state while improving rendering performance. As Angular continues to evolve, Signals are becoming a core tool for building modern, high-performance applications.