Question 1

What is Angular and how does it differ from AngularJS?

Accepted Answer

**Target Audience:** Anyone preparing for an Angular interview — assumes basic JavaScript, no Angular or AngularJS required. **Difficulty:** Easy > **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 output in section 5 was produced by compiling and running the example on Angular 22.2.3, and the default-behaviour claims in section 6 were read from the Angular 22.2.3 pa

Question 2

What does the Angular CLI provide?

Accepted Answer

**Target Audience:** Anyone preparing for an Angular interview — no Angular experience needed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Everything under "Verified" was produced by running Angular CLI 22.2.3 in a sandbox: ng new, ng generate --dry-run, ng serve, ng build, ng test and ng lint, with the real output quoted. ng add an

Question 3

What is the fixture.detectChanges() method in Angular testing, and when should you call it?

Accepted Answer

**Target Audience:** Developers writing or reviewing Angular component tests; assumes you have seen a TestBed spec but not much more. **Difficulty:** Easy to Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the vocabulary an interviewer listens for. Every behaviour quoted below was produced by running the spec in the example with Angular CLI 22.2.3 (ng test --watch=false, Vitest + jsdom), in the default zoneles

Question 4

Explain how to perform unit testing on components with Signals using TestBed.

Accepted Answer

**Target Audience:** Developers moving component tests from @Input()/@Output() to the signal APIs (input(), model(), output(), computed(), effect()). **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. All results were produced by running the example spec with Angular CLI 22.2.3 (ng test --watch=false, Vitest, the default zon

Question 5

What is the role of NgRx Effects, and why do we separate side effects from reducers?

Accepted Answer

**Target Audience:** Angular developers who know the basics of the NgRx store (actions, reducers, selectors) and want to understand where HTTP calls and other side effects belong. **Difficulty:** Medium to Hard > **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 action log in section 5, the error-handling run in section 6 and the effect test in section 7 were produce

Question 6

How do you mock services in Angular unit tests using Jasmine/Jest spies?

Accepted Answer

**Target Audience:** Developers writing component and service tests who want to isolate a unit from its dependencies. **Difficulty:** Easy to Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The Vitest spec in the example was run with Angular CLI 22.2.3 (ng test --watch=false, Vitest 5, zoneless). The Jasmine spy behaviour was run in plain Jasmine 5.13 under Node, without Angular, to check the syntax and defaults; the Jest synt

Question 7

What is ComponentFixtureAutoDetect and how does it affect unit tests?

Accepted Answer

**Target Audience:** Developers maintaining Angular test suites, especially ones migrating Zone-based specs to a zoneless Angular 22 project. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Two workspaces were used, both on Angular CLI 22.2.3 with Vitest: the default zoneless one from ng new, and a copy that loads zone.js 0.16.3 so the Zone behaviour could be run too. Every behaviour below comes from those runs

Question 8

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 9

What is provideHttpClient(withInterceptors([...])) and how does it replace legacy HTTP interceptor providing?

Accepted Answer

**Target Audience:** Developers maintaining or migrating an [NgModule](/interview-question/what-are-components-and-modules-in-angular)-era Angular app with class-based interceptors. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The deprecation notes are quoted from the installed Angular 22.2.3 typings, and every ordering result was produced by booting real class and functional interceptors (compiled with ngc)

Question 10

How do you test signal components, defer blocks, and new control flow in 2025?

Accepted Answer

**Target Audience:** Developers testing templates written with the modern Angular syntax: signals, @defer, and built-in control flow. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The title says 2025; everything here was run on the current release, Angular 22.2.3 with CLI 22.2.3 (ng test --watch=false, Vitest + jsdom, zoneless). Deep detail on signal inputs, outputs and effects is on its own page

ANGULARDECODED.

Easy