Question 1

How does catchError work in RxJS, and how do you return a fallback value?

Accepted Answer

**Target Audience:** Angular developers handling HTTP failures in RxJS pipelines, especially inside search boxes, effects and other long-lived streams. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. Every behaviour in sections 3 to 6 was produced by running RxJS 7.8.2, and the component in section 7 was compiled and clicked through on Angular

Question 2

How do you handle errors and retries globally with interceptors?

Accepted Answer

**Target Audience:** Developers who know the basics of interceptors and RxJS and want a production-grade global error and retry strategy. **Difficulty:** Medium to Hard > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every attempt count, ordering result and test outcome below was produced by running the code on Angular 22.2.3 and RxJS 7.8.2 (compiled with ngc, booted in jsdom with an exported appConfig, a fake backend in

Question 3

What is the difference between Observables and Promises?

Accepted Answer

**Target Audience:** Anyone preparing for an Angular interview who has used async/await — assumes basic JavaScript, no RxJS required. **Difficulty:** Easy to Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every ordering claim below was produced by running a Node script against RxJS 7.8.2, and the component example was compiled with ngc on Angular 22.2.3 and clicked in jsdom. Execution order is the to

Question 4

What is an InjectionToken?

Accepted Answer

**Target Audience:** Developers who have injected services and now need to inject something that is not a class: config, a string, a function. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. The outputs below were produced by compiling and running the code on Angular 22.2.3, and the API notes come from the 22.2.3 typings. ## 1. Why This Even M

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Medium

How does catchError work in RxJS, and how do you return a fallback value?

How do you handle errors and retries globally with interceptors?

What is the difference between Observables and Promises?

Hard

What is an InjectionToken?