Question 1

Which TypeScript primitive type represents a textual value?

Accepted Answer

The string type represents all textual values in TypeScript, whether delimited by single quotes, double quotes, or backticks for template literals. It is the appropriate type for storing text, names, messages, URLs, or any textual content in applications.

Question 2

What is a generic in TypeScript?

Accepted Answer

A generic allows creating reusable components that work with multiple types rather than a single one. Generics use type parameters (like T) to represent any type. This enables writing type-safe code without sacrificing flexibility, for example a function that manipulates arrays of any type while preserving type information.

Question 3

What is a component in Angular?

Accepted Answer

A component is a fundamental building block of an Angular application that controls a portion of the user interface. It combines an HTML template, CSS styles, and a TypeScript class with the @Component decorator. This architecture enables creating reusable and modular interfaces, promoting separation of concerns between the view and business logic.

Question 4

What is a lifecycle hook in Angular?

Accepted Answer

A lifecycle hook is a special method automatically called by Angular at key moments in a component or directive's lifecycle. These hooks allow executing code at specific stages like creation, updates or destruction. The most common hooks are ngOnInit, ngOnChanges and ngOnDestroy.

Question 5

What is a FormControl in Angular?

Accepted Answer

FormControl is the fundamental class of Angular reactive forms that represents an individual form field. It encapsulates the field's value, validation state, and provides methods to handle user interactions. Each FormControl can have validators, react to changes via observables, and maintain states like touched, dirty, or pristine. It's the basic building block for constructing complex reactive forms with FormGroup or FormArray.

Question 6

Which Angular module to import to use template-driven forms?

Accepted Answer

FormsModule is required to enable template-driven forms in Angular. It provides directives like NgModel, NgForm and enables two-way data binding with [(ngModel)]. Without this module, form directives won't work and Angular will throw errors.

Question 7

What is an Observable in RxJS?

Accepted Answer

An Observable is a lazy collection of multiple values over time. It represents a data stream that can emit zero, one, or multiple values synchronously or asynchronously. Unlike Promises which emit a single value, Observables can emit multiple values and support cancellation via unsubscribe.

Question 8

What is NgRx Store in an Angular application?

Accepted Answer

NgRx Store is a Redux pattern implementation for Angular, based on RxJS. It provides a centralized container for managing application global state in a predictable and immutable way. The Store exposes an Observable that allows components to subscribe to state changes via selectors.

Question 9

What is the main role of createEntityAdapter in NgRx?

Accepted Answer

The Entity Adapter automatically generates reducers and selectors to manage normalized collections of entities. It provides methods like addOne, addMany, updateOne, removeOne that facilitate manipulation of ID-indexed objects. This avoids manually writing collection management logic and ensures a normalized state for better performance.

Question 10

What is the main difference between a smart component and a presentational component?

Accepted Answer

Smart components (or container components) manage business logic, API calls and application state through services or state management. Presentational components focus solely on display and receive their data via @Input, emitting events via @Output. This separation improves testability and reusability of components.

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