Decoded Frontend - Angular Interview Hacking %21%21top%21%21 Review

| Question | Hacker Answer | |----------|----------------| | What's a module? | "A compilation context – helps tree-shaking and lazy loading." | | Standalone components vs NgModules? | "Standalone simplifies, but modules are better for large team governance." | | How to prevent memory leaks? | "Async pipe auto-subscribes/unsubscribes. Otherwise, destroy subject + takeUntil." | | Zone.js? | "Monkey-patches async APIs to trigger change detection – can be opted out with NgZone.runOutsideAngular()." |

  • Difference between structural and attribute directives.
  • How does Angular change detection work?
  • Explain Observables vs Promises; when to use switchMap vs mergeMap.
  • Implement lazy loading in routing.
  • Write a simple custom async validator for a username (dedupe check).
  • Explain OnPush change detection pitfalls.
  • When to use trackBy in ngFor?
  • How to handle global errors and retries for HTTP?
  • How does NgRx effects work?

    • | If they ask this... | Don't answer this... | Say this (The Hack) | | :--- | :--- | :--- | | "How does DI work?" | "It's a tree of injectors." | "It's hierarchical. But with providedIn: 'root' and functional guards, I rarely think about trees. I think about inject() as a function in reactive contexts only." | | "What is a Directive?" | "It adds behavior to an element." | "It’s the forgotten secret to cross-cutting concerns. I don't put logic in components. I put it in structural directives to keep the DOM clean." | | "Angular vs React?" | "Angular is better." | "React has better marketing. Angular has better tooling (CLI, signals, forms). The only real difference is rendering model: React re-runs functions; Angular re-renders templates. I prefer Angular for enterprise scale." |

    Decoded Frontend doesn't just teach you Angular. We teach you how to hack the interview process. The keyword "Decoded Frontend - Angular Interview Hacking !!TOP!!" isn't clickbait—it is a methodology.

    Remember: The interviewer isn't looking for syntax. They are looking for architecture decisions. Show them you understand the why, not just the what.

    Stay Decoded. Stay Hacking.

    Ready for more? Download our "Angular Hacking Handbook" (PDF) for 50 more anti-pattern fixes.

    Angular Basics

  • What are the key features of Angular?
  • What is the difference between Angular and AngularJS?

    • Components and Templates

  • How do you create a new component in Angular?
  • What is a template in Angular?

    • Directives and Pipes

  • What is a pipe in Angular?

    • Services and Dependency Injection

  • How does dependency injection work in Angular?

    • Forms and Validation

  • What is the difference between template-driven and reactive forms?

    • Routing and Navigation

  • What is the purpose of the router-outlet directive?

    • State Management and Data Fetching

  • How do you fetch data from an API in Angular?

    • Testing and Debugging

  • What are some common debugging techniques in Angular?

    • Best Practices and Optimization

  • How do you optimize the performance of an Angular application?

    • Common Interview Questions

    Additional Resources

    Week 1 — Fundamentals

    Week 2 — Forms, HTTP, RxJS

    Week 3 — State, Testing, Performance

    Week 4 — Projects & interview polish

    | Topic | Rookie Mistake | The Hack | | :--- | :--- | :--- | | Change Detection | Forgetting markForCheck | Using runOutsideAngular + manual tick | | DI | Injecting everything at root | @Self() + @Optional() + multi:true | | RxJS | Subscribing in components | toSignal + async pipe | | OnPush | Pushing entire arrays | New reference + trackBy | | Structural | Using only built-in | Custom * directive with ViewContainerRef | | SSR | Ignoring hydration | ngSkipHydration + TransferState | | Standalone | Keeping NgModules | bootstrapApplication + functional guards |

    When they say, "Tell me about a time you fixed a performance bug."

    Do not say: "I optimized an ngFor."

    Say this (The Decoded Narrative):

    "We had a table with 10,000 rows. The CD was running 40 times per second. I realized Zone.js was triggering on every mouseenter event due to a third-party library.
    I migrated the table to OnPush and used trackBy with a custom signal store. Within one sprint, we went from 200ms frame drops to 16ms smooth scrolling. The key was isolating the reactive zone to only the visible viewport using @defer."