What's the purpose of the FormBuilder service in Angular's reactive forms?
- It's used for styling forms with CSS.
- It's used to create form controls manually.
- It's used to handle HTTP requests in forms.
- It's used to simplify the creation of form controls.
The FormBuilder service in Angular's reactive forms is used to simplify the creation of form controls and form groups. It provides a more concise and readable way to define form structures compared to manually creating controls. While Angular also uses HTTP for handling HTTP requests in forms, this is not the primary purpose of FormBuilder. It's primarily focused on form control management.
Which Angular CLI command is used to generate a new service?
- ng create service
- ng generate service
- ng make service
- ng new service
To generate a new service in an Angular application, you should use the ng generate service command. This command creates the service file, sets up the necessary imports, and registers the service with the Angular dependency injection system.
A backend API endpoint occasionally fails, and you want to implement a strategy to retry the request three times before giving up. How would you achieve this in Angular?
- Implement a custom retry mechanism in a service
- Set the maxRetries configuration option in Angular HTTP Client
- Use a timeout for three retries in the catch block
- Use the RxJS retry operator with a count of 3
To implement a strategy to retry an HTTP request three times before giving up in Angular, you should use the RxJS retry operator with a count of 3. This operator allows you to specify the number of retry attempts for a failed request, helping you achieve the desired retry behavior.
To define specific styles that apply only to a component and do not affect any external elements, you'd set the component's encapsulation property to ViewEncapsulation.______.
- None
- ShadowDom
- Emulated
- Native
In Angular, the encapsulation property determines how styles are scoped for a component. Setting it to Emulated (or None for no encapsulation) ensures that styles apply only to the component and its descendants, not affecting external elements. This is often used to create encapsulated styles for Angular components. The other options (ShadowDom and Native) represent different encapsulation methods, but Emulated is the correct option for this scenario.
Which command or flag should you use with Angular CLI if you want to analyze the size of your bundles?
- "ng analyze"
- "ng build --stats-json"
- "ng bundle-analysis"
- "ng size-check"
To analyze the size of your bundles in an Angular application, you should use the "ng analyze" command. This command provides detailed information about the size of your application's bundles, including dependencies and modules.
A service provided at the component level will create a new instance for each ________ of the component.
- 'child component'
- 'function'
- 'instance'
- 'module'
A service provided at the component level will create a new instance for each 'instance' of the component. This means that every time a new instance of the component is created, a new instance of the service will also be created, ensuring that each component instance has its own isolated instance of the service.
Which operator is best suited for handling multiple click events in rapid succession with RxJS in Angular?
- debounceTime()
- filter()
- map()
- switchMap()
The debounceTime() operator in RxJS is best suited for handling multiple click events in rapid succession. It allows you to specify a time window during which it will ignore subsequent events, which is ideal for scenarios where you want to debounce click events to avoid processing them too quickly. The other operators have different use cases and are not specifically designed for this scenario.
You are building an e-commerce application. On the product page, you want to have tabs for "Details", "Reviews", and "Related Products", each being a separate route. How would you structure this in Angular?
- Create child routes for each tab within the product page route
- Create separate components for each tab and load them dynamically
- Use one route and manage tab switching with ngIf
- Use route guards to load content on demand
In this scenario, it's best to create child routes for each tab within the product page route. This approach allows you to have separate components and templates for each tab while maintaining a clean URL structure.
The process of retrieving previous navigation details, such as the previously visited route, can be achieved using router.________ in Angular.
- router.events
- router.history
- router.previousRoute
- router.snapshot
In Angular, the process of retrieving previous navigation details, including the previously visited route, can be achieved using router.events. This is because router.events emits events related to route navigation, including NavigationEnd events, which can be used to access the previous route or URL and implement custom logic based on it.
You have a component that receives a large list of items as an input. You notice performance degradation when items within this list are updated frequently. Which change detection strategy would be most appropriate to address this?
- OnPush Change Detection
- Default Change Detection
- CheckAlways Change Detection
- Detached Change Detection
In this scenario, when dealing with frequent updates to a large list of items, using the OnPush change detection strategy is most appropriate. It allows the component to only re-render when its input properties change or when explicitly triggered, which can significantly improve performance by reducing unnecessary updates. Default change detection (Option 2) checks for changes on every digest cycle, leading to performance issues in this scenario. CheckAlways (Option 3) and Detached (Option 4) are not recommended for typical use cases.