Q: What is trackBy in ngFor and why use it?

**Target Audience:** Developers working with *ngFor lists, especially lists refreshed from an API, and anyone preparing for the classic Angular performance question. **Difficulty:** Easy to Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The row-creation counts, the this behaviour and the deprecation notes below were produced on Angular 22.2.3: the example was AOT-compiled with ngc (strict templates)

Q: What are ng-container and ng-template?

**Target Audience:** Developers who have seen ng-container and ng-template in templates and want a precise picture of what each does and what ends up in the DOM. **Difficulty:** Easy to Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The DOM markup quoted below is the real innerHTML printed after compiling the templates with ngc (strict templates) on Angular 22.2.3 and running them in jsd

Question 1

What is standard content projection vs. Multi-Slot Content Projection?

Accepted Answer

**Target Audience:** Developers who already use and need to build components with several distinct content areas, such as cards, dialogs and page layouts. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every slot assignment quoted below was produced on Angular 22.2.3 by compiling the components with ngc (strict templates), rendering them in jsdom, and printing what landed in eac

Question 2

Explain the difference between Shadow DOM, Emulated, and None View Encapsulation with compile output.

Accepted Answer

**Target Audience:** Developers who know the three encapsulation modes by name and want to see what the compiler and the runtime actually produce — comfortable with CSS selectors and attributes. **Difficulty:** Hard > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the vocabulary an interviewer expects. The compiled code in section 3 is real ngc output from Angular 22.2.3, and the runtime CSS and DOM in sections 4 and 5 were printe

Question 3

What is trackBy in ngFor and why use it?

Accepted Answer

**Target Audience:** Developers working with *ngFor lists, especially lists refreshed from an API, and anyone preparing for the classic Angular performance question. **Difficulty:** Easy to Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The row-creation counts, the this behaviour and the deprecation notes below were produced on Angular 22.2.3: the example was AOT-compiled with ngc (strict templates)

Question 4

What is the difference between component styling using :host, :host-context, and ::ng-deep?

Accepted Answer

**Target Audience:** Developers who style Angular components and have met these three selectors in a codebase — CSS selectors and specificity assumed, encapsulation basics helpful. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the vocabulary an interviewer expects. The compiled selectors below are real ngc output from Angular 22.2.3, and the computed styles were produced by running the example on 22.2.3 i

Question 5

What are ng-container and ng-template?

Accepted Answer

**Target Audience:** Developers who have seen ng-container and ng-template in templates and want a precise picture of what each does and what ends up in the DOM. **Difficulty:** Easy to Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The DOM markup quoted below is the real innerHTML printed after compiling the templates with ngc (strict templates) on Angular 22.2.3 and running them in jsd

Question 6

What is the critical render path and how does Angular handle font and style optimization?

Accepted Answer

**Target Audience:** Developers who have seen "render-blocking resources" in Lighthouse and want to know what the browser waits for, and what Angular's build already optimises. **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 index.html snippets were produced by ng build with Angular CLI 22.2.3 on Node 24, once as a

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