Name: Angular
Author: ivangdavila

When to Use

User needs Angular expertise — component architecture, RxJS patterns, change detection, dependency injection, routing, and forms.

Quick Reference

| Topic | File |

|-------|------|

| Components & change detection | components.md |

| RxJS & subscriptions | rxjs.md |

| Forms & validation | forms.md |

| Dependency injection | di.md |

| Routing & guards | routing.md |

| HTTP & interceptors | http.md |

OnPush with mutated objects won't trigger change detection — always create new reference: {...obj} or [...arr]
@ViewChild is undefined in constructor/ngOnInit — access in ngAfterViewInit or later
*ngFor without trackBy re-renders entire list on any change — add trackBy returning stable ID
Manual subscribe() without unsubscribe leaks memory — use async pipe, takeUntilDestroyed(), or unsubscribe in ngOnDestroy
HttpClient returns cold Observable — each subscribe() fires new HTTP request
setTimeout/setInterval outside NgZone — change detection won't run, use NgZone.run() or signals
Circular DI dependency crashes app — use forwardRef() or restructure services
ElementRef.nativeElement direct DOM access breaks SSR — use Renderer2 or @defer
Route params via snapshot miss navigation changes — use paramMap Observable for same-component navigation
setValue() on FormGroup requires ALL fields — use patchValue() for partial updates