Decoded Frontend - Angular Interview Hacking %21%21top%21%21 __exclusive__ May 2026

In the modern JavaScript ecosystem, Angular interviews have shifted. They no longer test documentation memory. They test , Reactive performance , and Dependency Injection magic .

"Write a directive that conditionally renders a template except twice." Decoded Frontend - Angular Interview Hacking %21%21TOP%21%21

"RxJS is for streams (WebSockets, debounced searches). Signals are for state (Component store, UI flags). Using async pipe with RxJS is still superior for HTTP requests because of switchMap cancellation." 4. The OnPush Grand Slam – Memoization & async Pipe Deep Dive The Scenario: "My view isn't updating after I change an array property. Why?" In the modern JavaScript ecosystem, Angular interviews have

If you use OnPush , Angular only checks inputs that change by . Hacking the Array Mutability // This WON'T work with OnPush this.items.push(newItem); // This WILL work (New reference) this.items = [...this.items, newItem]; The Secret Weapon: ChangeDetectorRef.detectChanges() When you have a setTimeout inside a third-party library that Zone.js misses, force a local check: "Write a directive that conditionally renders a template

@Directive( selector: '[appTwice]' ) export class TwiceDirective implements OnChanges { @Input() appTwice: any; constructor( private templateRef: TemplateRef<any>, private viewContainer: ViewContainerRef ) {}

DI isn't just about getting a service. It’s about overriding and multi-providing . Hack #1: The multi: true flag You can have multiple services implementing the same InjectionToken.