A client wants the ability to deep link to specific parts of your Angular application. What would you ensure to accommodate this requirement?
- Utilizing Angular's RouterModule and configuring the application for hash-based routing.
- Disabling routing in the Angular application to prevent deep linking.
- Implementing a custom JavaScript solution for deep linking.
- Creating static HTML pages for each deep linkable section of the application.
To accommodate the client's requirement of deep linking to specific parts of your Angular application, you should use Angular's RouterModule and configure the application for hash-based routing. This approach allows for deep linking by using URL fragments. The other options are not suitable for achieving deep linking in an Angular application.
In which scenarios would you consider using ChangeDetectionStrategy.OnPush?
- When the component depends on parent component data changes.
- When the component has frequent, unrelated changes.
- When the component is rarely used in the application.
- When the component needs to check for changes on every interaction.
You would consider using ChangeDetectionStrategy.OnPush in scenarios where the component's updates depend on changes in its parent component. This strategy is beneficial when you want to optimize performance by reducing unnecessary change detection cycles. It's not typically used when a component needs to check for changes on every interaction or when it's rarely used.
What's the primary difference between the switchMap and mergeMap operators?
- switchMap and mergeMap are identical and can be used interchangeably.
- switchMap and mergeMap are used for completely different purposes and cannot be compared.
- switchMap cancels the previous inner observable when a new one arrives, while mergeMap concurrently processes all inner observables.
- switchMap processes all inner observables concurrently, while mergeMap cancels the previous inner observable when a new one arrives.
The primary difference is that switchMap cancels the previous inner observable when a new one arrives. In contrast, mergeMap concurrently processes all inner observables it receives. This behavior makes switchMap useful for scenarios where you want to ensure only the latest inner observable result is considered, while mergeMap retains all results from concurrently executing inner observables.
For which purpose might you consider using dynamic components in Angular?
- Defining application routes
- Lazy loading of modules
- Optimizing database queries by default
- Styling components dynamically
Dynamic components in Angular are often used for lazy loading of modules. This allows you to load parts of your application on-demand, improving initial loading times and overall performance. While Angular uses routes to define application navigation, dynamic components are not used for this specific purpose. They are also not primarily used for styling components dynamically or optimizing database queries.
If a service is provided both at the module level and the component level, which instance will the component receive?
- The component will receive both instances.
- The component will receive the component-level instance.
- The component will receive the module-level instance.
- The component will throw an error.
In Angular (or similar frameworks), when a service is provided both at the module and component levels, the component will receive the component-level instance. This is known as "shadowing." The component-level instance takes precedence over the module-level one. The scenario where a component receives both instances is not valid, and it will result in an error.
In multi-slot content projection, how can you differentiate between the different content slots?
- By adding custom attributes to the
elements. - By creating separate child components for each slot.
- By using Angular directives like *ngIf and *ngFor.
- By using unique CSS classes for each
tag.
In multi-slot content projection, you can differentiate between different content slots by using unique CSS classes for each tag. This approach allows you to style and target each slot individually based on the CSS class applied. Adding custom attributes or using directives like *ngIf and *ngFor do not inherently differentiate slots; they are used for other purposes. Creating separate child components for each slot is a more complex alternative.
When configuring the Angular Router for lazy loading, the loadChildren property points to a function that uses the ______ syntax to load the module.
- Import()
- fetch()
- load()
- require()
In Angular, when configuring lazy loading for the Angular Router, the loadChildren property points to a function that uses the import() syntax to load the module on-demand. This allows for efficient code splitting and loading modules only when they are needed, improving application performance.
You are working on an autocomplete feature. As a user types into a search box, you want to delay the API call until the user has stopped typing for a specific duration. Which RxJS operator would you utilize?
- debounceTime
- mergeMap
- switchMap
- throttleTime
To achieve this behavior, you should use the debounceTime operator in RxJS. It allows you to wait for a specific duration of inactivity before emitting the latest value, which is ideal for scenarios like autocomplete.
You want to test a component that has a dependency on another service, but you don't want to test the service's actual behavior. How would you approach this in Angular tests?
- Create a mock service that provides controlled responses
- Mock the component instead of the service
- Use HttpClientTestingModule to mock HTTP service
- Use the actual service for realistic testing
To isolate the component's behavior for testing, you should create a mock service that provides controlled responses. This allows you to focus solely on testing the component's interactions with the service without invoking the actual service logic.
In which scenario is it NOT recommended to use ChangeDetectionStrategy.OnPush?
- When a component has complex view logic with many nested components
- When a component is stateful and has user interactions triggering updates
- When a component relies on frequent data updates from external sources
- When optimizing for performance is a top priority
ChangeDetectionStrategy.OnPush is not recommended when a component relies on frequent data updates from external sources because it can lead to manual triggering of change detection, reducing the benefits of this strategy. It's more suitable for components with infrequent updates or performance optimization.