MEAN Angular Components and Services 4

Question 1

Which Angular decorator is used to define a class as a service that can be injected into components?

Accepted Answer

@Injectable

Answer

@Injectable marks a class as available for dependency injection by Angular's injector.

Question 2

What is the purpose of the 'providedIn' property in the @Injectable decorator?

Accepted Answer

Determines the injector scope where the service is provided

Answer

The 'providedIn' property specifies which injector (e.g., 'root', a module, or a component) should provide the service.

Question 3

What happens when you provide a service at the component level using the 'providers' array in @Component?

Accepted Answer

A new service instance is created for each instance of that component

Answer

Component-level providers create a new service instance for each component instance, isolating state between components.

Question 4

Which lifecycle hook is called only once when the component is first created, after input properties are set?

Accepted Answer

ngOnInit

Answer

ngOnInit is called once after Angular has initialized all data-bound properties and is ideal for initialization logic.

Question 5

How do you pass data from a parent component to a child component in Angular?

Accepted Answer

Using @Input decorator on the child property

Answer

@Input() decorates a child component property so the parent can bind data to it via property binding.

MEAN - Stack Development Practice Test