February 8, 2025
As Angular continues to innovate, the upcoming Angular 18 release promises to take web application performance and developer experience to the next level. In this post, we’ll explore some of the exciting features anticipated in Angular 18 based on release candidate notes and community previews, including resumability, an enhanced signals API, and a new hydration system.
1. Resumability: Faster Page Loads by Avoiding Re-rendering
One of the biggest challenges in server-side rendered (SSR) apps is the cost of rehydrating the page on the client — essentially re-executing all the component logic to make the page interactive.
Angular 18 introduces resumability, a technique where the client picks up the server-rendered UI exactly where it left off without full re-rendering or running lifecycle hooks again.
Why Resumability Matters
- Instant interactivity: The app becomes interactive almost immediately after the HTML loads.
- Reduced CPU usage: Avoids expensive reconciliation and change detection on startup.
- Improved SEO and user experience: Server pre-rendering still works but with seamless client takeover.
2. Enhanced Signals API: Fine-Grained Reactivity
Building on the experimental signals introduced earlier, Angular 18 plans to ship an enhanced Signals API with more capabilities:
- Derived signals for creating reactive computed values.
- Signal batching to optimize multiple updates efficiently.
- Better integration with existing Angular APIs for smoother developer experience.
Example: Using a derived signal
import { signal, computed } from '@angular/core';
@Component({
selector: 'app-profile',
template: `<p>{{ fullName() }}</p>`
})
export class ProfileComponent {
firstName = signal('Jane');
lastName = signal('Doe');
fullName = computed(() => `${this.firstName()} ${this.lastName()}`);
}Here, fullName automatically updates when either firstName or lastName changes, without triggering unnecessary change detection cycles elsewhere.
3. New Hydration System: Smarter and More Efficient
Angular 18’s new hydration system complements resumability by offering:
- Smarter DOM diffing that skips static parts.
- Selective hydration of interactive components.
- Support for lazy hydration to prioritize above-the-fold content.
This system works hand-in-hand with Angular Universal to create blazingly fast SSR experiences.
4. Developer Experience Enhancements
Beyond core features, Angular 18 aims to improve DX with:
- Better tooling for debugging signals.
- Improved error messages and warnings around hydration.
- Streamlined APIs for SSR configuration.
Summary
Angular 18 is set to revolutionize how Angular apps handle SSR and reactivity:
- Resumability eliminates client-side re-render overhead.
- The enhanced signals API offers powerful reactive primitives.
- The new hydration system makes server-client transitions seamless.
If you’re excited to build ultra-fast Angular apps with these next-gen features, keep an eye on the official Angular RC announcements and start experimenting with the latest previews!
