In large applications, frequent change detection cycles can lead to performance issues, especially if the application does not use the ________ change detection strategy.
- CheckOnce
- Default
- OnPush
- Push
In large Angular applications, frequent change detection cycles can indeed lead to performance issues. By default, Angular uses the Default change detection strategy, which checks all components in each cycle. To address this, developers can use the ChangeDetectionStrategy.OnPush strategy, which limits change detection to components that receive input changes or manually trigger detection, significantly improving performance for large applications.
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.
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 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.
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.
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 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.
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.
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 apply styles scoped to a particular component and prevent them from affecting other elements outside the component, you would use _____.
- ::ng-deep
- ViewEncapsulation.Emulated
- ViewEncapsulation.None
- ng-deep
To apply styles scoped to a particular component in Angular and prevent them from leaking out and affecting other elements, you would use the ::ng-deep selector. This is used to pierce through the view encapsulation and apply styles to specific components.
When dynamically creating a component, which object is responsible for providing the factory to create an instance of the component?
- ComponentFactoryResolver
- ElementRef
- NgModule
- ViewChild
The ComponentFactoryResolver is responsible for providing the factory to create an instance of a component dynamically in Angular. It's a crucial part of dynamic component creation, allowing you to create components on the fly based on specific conditions or requirements in your application. NgModule deals with module-level configuration, ViewChild is used for querying child components, and ElementRef is used for accessing the DOM element of a component, but none of these directly provide a factory for dynamic component creation.
Which directive is utilized to switch between multiple views, but only one view can be displayed at a time?
- *ngFor
- *ngIf
- *ngModel
- *ngSwitch
The *ngSwitch directive in Angular is used to switch between multiple views, but only one view can be displayed at a time based on a specified condition. It's commonly used for rendering different templates or components depending on the value of an expression. The other directives listed, such as *ngFor, *ngIf, and *ngModel, have different purposes and don't provide the same view-switching behavior.