Angular 21 — What’s New, What’s Changed

Source: Dev.to

Standalone Components vs. NgModules

Old Way (NgModule‑based)

@NgModule({
  declarations: [UserComponent],
  imports: [CommonModule],
})
export class UserModule {}

Angular 21 Way (Standalone)

@Component({
  selector: 'app-user',
  standalone: true,
  imports: [CommonModule],
  template: `
## User Works!
`
})
export class UserComponent {}

Benefits

• Less boilerplate
• Clear dependencies
• Easier lazy loading

Signals for State Management

Replacing a BehaviorSubject

// Before (RxJS)
user$ = new BehaviorSubject(null);

// Angular 21 Signals
user = signal(null);

setUser(data: User) {
  this.user.set(data);
}

Using a signal in a template

Welcome {{ user()?.name }}

• No subscriptions, no memory leaks, clean reactivity.

Computed Signals

firstName = signal('Mridu');
lastName  = signal('Dixit');

fullName = computed(() => `${this.firstName()} ${this.lastName()}`);

### {{ fullName() }}

Angular automatically recalculates when any dependency changes.

Effects

effect(() => {
  console.log('User changed:', this.user());
});

Common Use Cases for Signals

• Analytics tracking
• API calls
• Logging
• Syncing localStorage

Zoneless Mode (Optional)

Enable zoneless change detection when bootstrapping the application:

bootstrapApplication(AppComponent, {
  providers: [provideZoneChangeDetection({ eventCoalescing: true })]
});

Result

• Faster change detection
• More predictable updates

Signals + zoneless mode provide a performance boost without additional configuration—Angular CLI handles it automatically.

What You’ll Notice

• Faster ng serve
• Faster rebuilds
• Lower memory usage (especially in large projects)

Server‑Side Rendering (SSR) Improvements

Server Component Example

@Component({
  standalone: true,
  template: `
Data loaded on server
`
})
export class ServerOnlyComponent {}

Angular 21 improves:

• Hydration mismatch handling
• Async data consistency
• Debugging experience

Result → more reliable SSR applications.

Provider Scopes

Global Provider

bootstrapApplication(AppComponent, {
  providers: [provideHttpClient()]
});

Component‑Level Provider

@Component({
  standalone: true,
  providers: [UserService]
})
export class UserComponent {}

Clearer scope and fewer surprises.

Build‑Time Checks

Angular now catches invalid template bindings at build time:

{{ user.nonExistingProp }}

• No more silent runtime bugs.

Compatibility and Migration

• Existing RxJS code continues to work.
• NgModules are still supported.
• Incremental migration to signals is possible—you don’t have to rewrite everything.

New Angular Projects

Angular 21 emphasizes clarity and confidence:

• Standalone‑first architecture
• Signals for state management
• Optional zoneless performance
• Faster builds
• Cleaner mental model

Angular is no longer “heavy”—it’s modern, reactive, and production‑ready.