You're developing an e-commerce application and want to create a shopping cart service that maintains the state of the cart across different components. What would be the best approach to ensure that all components refer to the same instance of the service?
- Using 'ngIf' directive
- Using separate instances for each component
- Using the 'providedIn' property
- Using the 'singleton' pattern
The best approach to ensure that all components refer to the same instance of a service is to use the 'singleton' pattern, which allows a single instance of the service to be shared among multiple components.
In Angular testing, the _____ function is used to simulate user interactions on elements.
- expect
- mock
- query
- trigger
In Angular testing, the trigger function is used to simulate user interactions on elements, such as clicks, inputs, and other events.
The RxJS operator _____ is used to delay the emissions from an Observable.
- debounceTime
- filter
- mergeMap
- skip
The RxJS operator debounceTime is used to delay the emissions from an Observable. It's often used for scenarios like handling user input and performing searches with a delay.
The _____ strategy in Angular's change detection checks the component and its children only when an event is fired.
- Always
- CheckOnce
- Default
- OnPush
The OnPush strategy in Angular's change detection checks the component and its children only when an event is fired, optimizing performance.
Which Router Event is fired when navigation is canceled?
- NavigationCancel
- NavigationEnd
- NavigationError
- NavigationStart
The NavigationCancel event is fired when navigation is canceled in Angular. It can be used to perform actions when navigation is interrupted.
In Angular, the _____ Guard checks whether a route can be deactivated.
- CanActivate
- CanActivateChild
- CanDeactivate
- CanLoad
In Angular, the CanDeactivate Guard checks whether a route can be deactivated, allowing you to confirm or prevent the user's navigation away from the current route.
For debugging and profiling Angular applications, developers can use the _____ browser extension.
- AngularDebugger
- AngularDevTools
- Augury
- Redux DevTools
For debugging and profiling Angular applications, developers can use the Augury browser extension. It provides insights into an Angular app's structure and behavior.
In an Angular application, how can you optimize a component to be checked only once by Angular's change detection mechanism?
- Use the Default change detection strategy
- Use the EventEmitter to trigger change detection
- Use the OnPush change detection strategy
- Use the Renderer2 to skip change detection
To optimize a component to be checked only once by Angular's change detection, you should use the OnPush change detection strategy. This strategy reduces unnecessary checks.
You're building a type-ahead search feature in an Angular application. The user input should trigger API calls, but you want to avoid making unnecessary calls for every keystroke. Which RxJS operators can help optimize this?
- filter and reduce
- mergeMap and throttleTime
- switchMap and debounceTime
- take and pluck
To optimize the type-ahead search feature, you can use switchMap to cancel previous API calls and only return the latest result, and debounceTime to delay the API call until the user stops typing, avoiding unnecessary calls for every keystroke.
What language is used to write E2E tests in Protractor?
- Java
- JavaScript
- Python
- TypeScript
JavaScript is the language used to write E2E tests in Protractor, making it compatible with Angular applications, as Angular also uses JavaScript.