Agent skill

angular-performance

Angular performance: NgOptimizedImage, @defer, lazy loading, SSR. Trigger: When optimizing Angular app performance, images, or lazy loading.

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npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/angular-performance-gutierrezp22-administracion-depar-2

Metadata

Additional technical details for this skill

author
gentleman-programming
version
1.0

SKILL.md

NgOptimizedImage (REQUIRED for images)

typescript
import { NgOptimizedImage } from '@angular/common';

@Component({
  imports: [NgOptimizedImage],
  template: `
    <!-- LCP image: add priority -->
    <img ngSrc="hero.jpg" width="800" height="400" priority>
    
    <!-- Regular: lazy loaded by default -->
    <img ngSrc="thumb.jpg" width="200" height="200">
    
    <!-- Fill mode (parent needs position: relative) -->
    <img ngSrc="bg.jpg" fill>
    
    <!-- With placeholder -->
    <img ngSrc="photo.jpg" width="400" height="300" placeholder>
  `
})

Rules

  • ALWAYS set width and height (or fill)
  • Add priority to LCP (Largest Contentful Paint) image
  • Use ngSrc not src
  • Parent of fill image must have position: relative/fixed/absolute

@defer - Lazy Components

html
@defer (on viewport) {
  <heavy-component />
} @placeholder {
  <p>Placeholder shown immediately</p>
} @loading (minimum 200ms) {
  <spinner />
} @error {
  <p>Failed to load</p>
}

Triggers

Trigger When to Use
on viewport Below the fold content
on interaction Load on click/focus/hover
on idle Load when browser is idle
on timer(500ms) Load after delay
when condition Load when expression is true
html
<!-- Multiple triggers -->
@defer (on viewport; on interaction) {
  <comments />
}

<!-- Conditional -->
@defer (when showComments()) {
  <comments />
}

Lazy Routes

typescript
// Single component
{
  path: 'admin',
  loadComponent: () => import('./features/admin/admin').then(c => c.AdminComponent)
}

// Feature with child routes
{
  path: 'users',
  loadChildren: () => import('./features/users/routes').then(m => m.USERS_ROUTES)
}

SSR & Hydration

typescript
bootstrapApplication(AppComponent, {
  providers: [
    provideClientHydration()
  ]
});
Scenario Use
SEO critical (blog, e-commerce) SSR
Dashboard/Admin CSR
Static marketing site SSG/Prerender

Slow Computations

Solution When
Optimize algorithm First choice always
Pure pipes Cache single result
Memoization Cache multiple results
computed() Derived signal state

NEVER trigger reflows/repaints in lifecycle hooks (ngOnInit, ngAfterViewInit).


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