How to Implement Zoneless Change Detection in Angular 19: Performance Guide

Why Should You Care About Zoneless Angular?

Angular 19 makes your apps faster - much faster. By removing Zone.js, your app can run up to 40% quicker. Think of Zone.js as a watchdog that constantly checks for changes in your app. Now, we can tell Angular exactly when to check for updates, making everything smoother.

Angular 19 brings game-changing performance improvements

Quick Setup Guide (5 Minutes)

Want better performance? Let's set up a zoneless Angular project:

1. Create a Fresh Project

ng new my-fast-app
# Choose your preferred options when prompted

2. Power Up Your App Open app.config.ts and add the zoneless magic:

import { provideExperimentalZonelessChangeDetection } from "@angular/core";

export const appConfig = {
  providers: [
    provideExperimentalZonelessChangeDetection(), // This is the secret sauce!
    provideRouter(routes),
    provideClientHydration(),
  ],
};

3. Remove the Training Wheels Update your angular.json - find the "polyfills" section and remove Zone.js:

{
  "polyfills": [
    // "zone.js" is now commented out
  ]
}

How to Know It Worked?

Open your browser's console (press F12) and type window.Zone. If you see "undefined", congratulations! You're now running Zone-free!

Your console should show undefined for the Zone object

Making Things Change with Signals

Signals are Angular's new way of handling updates. They're like smart variables that tell Angular when something changes. Here's a simple example:

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

@Component({
  selector: "app-counter",
  template: `
    <h2>Count: {{ count() }}</h2>
    <button (click)="increment()">Add One</button>
  `,
})
export class CounterComponent {
  count = signal(0);

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

Signals Quick Start

Signals are wrappers around values that notify Angular when they change. Here's what you need to know:

Basic Signal Usage

@Component({
  selector: "app-counter",
  template: `
    <h2>Count: {{ count() }}</h2>
    <button (click)="increment()">+1</button>
  `,
})
export class CounterComponent {
  count = signal(0);
  increment() {
    this.count.update((n) => n + 1);
  }
}

Computed Values

@Component({
  template: `<p>Total: ${{ total() }}</p>`
})
export class PriceComponent {
  price = signal(10);
  quantity = signal(2);
  total = computed(() => this.price() * this.quantity());
}

Effects for Side Effects

export class ThemeComponent {
  theme = signal("light");

  constructor() {
    effect(() => {
      document.body.classList.toggle("dark", this.theme() === "dark");
    });
  }
}

RxJS Integration

@Component({
  template: `<p>Time: {{ time() }}</p>`,
})
export class ClockComponent {
  time = toSignal(interval(1000), { initialValue: 0 });
}

Tips for Success

• Use signals for values that change over time
• Prefer computed() for derived values
• Use effects sparingly, mainly for side effects
• Remember: signals are synchronous

Want to Learn More?

• Check out the official Angular Signals guide
• Join the Angular Discord community

Next Steps

Now that you're running zoneless, explore Signals and start building faster apps! Keep an eye on our blog for more Angular tips and tricks.

Last updated: December, 2024

Tags: #Angular19 #WebDevelopment #JavaScript #Performance #Frontend