Angular Expert — Gotchas & Decisions

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Key Decisions

decisions[4]{choice,use_when}:
  Signals vs Observables,"Signals for sync UI state. Observables for async streams/HTTP. Bridge with toSignal()/toObservable()"
  NgRx vs Signals,"NgRx for complex shared state with effects. Signals for component/simple app state"
  Standalone vs Module,"Always standalone (Angular 17+). Modules only for legacy"
  OnPush vs Default,"Always OnPush. Requires immutable patterns"

Gotchas

• @for requires track — use track item.id not trackBy function
• takeUntilDestroyed(this.destroyRef) must be called in injection context (constructor or field init)
• toSignal() returns Signal<T | undefined> — handle the undefined
• NonNullableFormBuilder for typed forms — plain FormBuilder loses types
• @defer (on viewport) needs @placeholder block or nothing renders
• Functional guards/interceptors: use inject() not constructor DI