MEAN Angular Routing and Forms 4

Question 1

Which Angular guard interface should you implement to prevent navigation away from a component with unsaved changes?

Accepted Answer

CanDeactivate

Answer

CanDeactivate guards are used to intercept navigation away from a route, allowing you to prompt the user about unsaved changes.

Question 2

In Angular reactive forms, what does the `patchValue()` method do differently than `setValue()`?

Accepted Answer

patchValue() updates only specified controls while setValue() requires all controls to be provided

Answer

patchValue() allows partial updates by only setting the controls you specify, while setValue() throws an error if you omit any controls.

Question 3

What is the purpose of the `RouterLinkActive` directive in Angular?

Accepted Answer

It adds a CSS class to an element when its linked route is active

Answer

RouterLinkActive automatically adds a specified CSS class to the host element when the associated RouterLink's route is currently active.

Question 4

Which operator is recommended to use with route parameter observables to avoid memory leaks in Angular components?

Accepted Answer

takeUntil with a destroy Subject

Answer

Using takeUntil with a Subject that emits on ngOnDestroy ensures the subscription is automatically cleaned up when the component is destroyed.

Question 5

In Angular, what does setting `runGuardsAndResolvers: 'always'` on a route configuration do?

Accepted Answer

Runs guards and resolvers every time the route is activated, even with the same URL

Answer

Setting runGuardsAndResolvers to 'always' ensures guards and resolvers execute on every navigation to the route, including when query params or fragments change.

MEAN - Stack Development Practice Test

MEAN - Stack Development Practice Test

MEAN Angular Routing and Forms 4