How can you use a different class or value in place of a service in testing or certain scenarios?
- Dependency injection
- Extending the service class
- Mocking
- Using abstract classes
You can use a different class or value in place of a service in testing or specific scenarios by mocking the service using testing libraries or creating custom mock objects.
You are building a component that fetches data from an API. However, you want to ensure that the component only triggers the API call when it's actually visible to the user. Which lifecycle hook can help you achieve this?
- ngAfterViewInit Lifecycle Hook
- ngDoCheck Lifecycle Hook
- ngOnDestroy Lifecycle Hook
- ngOnInit Lifecycle Hook
To ensure that the component triggers the API call when it's actually visible, you can use the ngAfterViewInit lifecycle hook, which is called after the component's view has been initialized.
Which RxJS operator is best suited for performing side effects in an Observable chain?
- filter
- map
- reduce
- tap
The tap operator in RxJS is specifically designed for performing side effects (such as logging, making API calls, or modifying data) in an Observable chain.
You are building a dashboard and have created a "UserCard" component to display user details. You want this component to display user details differently based on the type of user (Admin, Guest, Registered). Which feature of Angular components can help you achieve this without creating multiple components?
- Component Inheritance
- Content Projection
- Interpolation
- Structural Directives
In this scenario, Structural Directives like *ngIf and *ngSwitch allow you to conditionally render content within a single component, enabling you to display user details differently based on the type of user.
You want to track the time taken for a user to navigate from one page to another in your Angular application. Which Router Events can be useful for this purpose?
- NavigationEnd and RoutesRecognized
- NavigationStart and NavigationCancel
- NavigationStart and NavigationEnd
- NavigationStart and NavigationError
To track the time taken for navigation, you can use NavigationStart and NavigationEnd Router Events. The NavigationStart event marks the start of navigation, and NavigationEnd marks the end. Combining them allows you to measure the time taken.
To share a single subscription among multiple subscribers and turn a cold observable into a hot one, you can use the _____.
- Collect
- Connect
- Merge
- Share
To share a single subscription among multiple subscribers and turn a cold observable into a hot one, you can use the Share operator. This allows multiple subscribers to share the same execution of the observable, reducing duplicate work.
What is the purpose of Angular's built-in debugger statement?
- To debug TypeScript code
- To optimize performance
- To provide error messages
- To stop execution
The purpose of Angular's built-in debugger statement is to debug TypeScript code by pausing execution at a specific point in the code for inspection and troubleshooting.
What does the ng add command do in Angular CLI?
- Add a new component
- Add a new dependency
- Generate a service using the CLI
- Remove an existing component
The ng add command in Angular CLI is used to add a new dependency to the Angular project, such as a library or package.
What is a potential consequence of not unsubscribing from an observable in an Angular component?
- Better application responsiveness
- Improved performance
- Memory leaks
- Reduced CPU usage
Not unsubscribing from an observable in an Angular component can lead to memory leaks, as the subscription remains open, causing resources to accumulate over time.
In Jasmine, to ensure that an asynchronous operation has completed before continuing the test, you can use the _____ function.
- afterEach()
- spyOnAsync()
- tick()
- waitForAsync()
In Jasmine, to ensure that an asynchronous operation has completed before continuing the test, you can use the tick() function.