MEAN Angular Components and Services 5

Question 1

What is the role of Angular's ChangeDetectionStrategy.OnPush?

Accepted Answer

Limits change detection to run only when inputs change or an observable emits

Answer

OnPush optimizes performance by only triggering change detection when the component's @Input references change or an async pipe resolves.

Question 2

Which method would you call on a service's Subject to both store the current value and emit it to new subscribers?

Accepted Answer

BehaviorSubject

Answer

BehaviorSubject holds the current value and immediately emits it to any new subscriber upon subscription.

Question 3

What is the correct Angular template syntax for two-way data binding on an input element?

Accepted Answer

[(ngModel)]='name'

Answer

[(ngModel)] is the 'banana in a box' syntax that combines property binding and event binding for two-way data binding.

Question 4

In Angular, what does the async pipe do when used in a template?

Accepted Answer

Subscribes to an Observable or Promise and returns the latest value, unsubscribing on component destroy

Answer

The async pipe automatically subscribes to Observables/Promises in templates and unsubscribes when the component is destroyed, preventing memory leaks.

Question 5

What is the purpose of ng-content in Angular component templates?

Accepted Answer

It creates a placeholder where parent components can project external content

Answer

ng-content enables content projection, allowing parent components to pass HTML content into designated slots of a child component's template.

MEAN - Stack Development Practice Test

MEAN - Stack Development Practice Test

MEAN Angular Components and Services 5