Angular Web Framework Angular Advanced Practice 3

Question 1

In Angular's Router, what is the role of a `CanDeactivate` guard?

Accepted Answer

Prevents leaving a route, useful for unsaved-changes warnings

Answer

CanDeactivate lets you intercept an attempt to leave a route and prompt the user (e.g., 'You have unsaved changes, are you sure?') before allowing navigation away.

Question 2

Which lifecycle hook should you use to perform cleanup such as unsubscribing from Observables to prevent memory leaks?

Accepted Answer

ngOnDestroy

Answer

ngOnDestroy is called just before Angular destroys the component, making it the correct place to unsubscribe, clear timers, and release other resources.

Question 3

What does the `async` pipe do when it receives a new Observable or Promise?

Accepted Answer

Unsubscribes from the old Observable and subscribes to the new one automatically

Answer

When the bound reference changes, the async pipe unsubscribes from the previous stream and subscribes to the new one, always displaying the latest emitted value.

Question 4

Which Angular testing utility creates a synchronous test environment where you can interact with a compiled component?

Accepted Answer

TestBed

Answer

TestBed configures and compiles a test module that mimics an Angular module, allowing you to create component instances in an isolated test environment.

Question 5

In a reactive form, what class represents a group of form controls that can be validated as a unit?

Accepted Answer

FormGroup

Answer

FormGroup aggregates multiple FormControl instances into a single object, exposing the combined valid/invalid state and value as a plain JS object.

Angular Web Framework Practice Test

Angular Web Framework Practice Test

Angular Web Framework Angular Advanced Practice 3