When creating hierarchical injectors, child injectors can ________ services from parent injectors.
- 'access'
- 'inherit'
- 'isolate'
- 'override'
When creating hierarchical injectors, child injectors can 'access' services from parent injectors. This means that components or services in the child injector can access and use services provided in the parent injector, allowing for hierarchical sharing of services while maintaining encapsulation and isolation.
What would be a primary reason to use a Subject over a standard Observable in RxJS?
- To create Observables from scratch
- To debounce user input
- To handle async operations
- To multicast emissions to multiple subscribers
A primary reason to use a Subject over a standard Observable in RxJS is to multicast emissions to multiple subscribers. Subjects are both an Observable and an Observer, making them suitable for scenarios where multiple subscribers need to receive the same values.
You notice that styles defined in a component are affecting other components throughout the application. Which view encapsulation mode might the component be using?
- None (ViewEncapsulation.None)
- Shadow DOM (ViewEncapsulation.ShadowDom)
- Emulated (ViewEncapsulation.Emulated)
- Native (ViewEncapsulation.Native)
When styles defined in a component affect other components, it's likely that the component is using the "Emulated" (ViewEncapsulation.Emulated) mode. In this mode, Angular emulates the shadow DOM, and styles are scoped to the component, but they can leak out and affect other components. The other options (None, Shadow DOM, Native) have different encapsulation behaviors.
To ensure a single instance of a service is available throughout the app, set the providedIn property to ________.
- 'app'
- 'root'
- 'shared'
- 'singleton'
To ensure a single instance of a service is available throughout the app, you should set the providedIn property to 'root'. This means that the service is provided at the application level, and there will be only one instance of the service for the entire app, making it a singleton service that can be injected into multiple components.
You are developing an Angular application where a child component needs to notify its parent component about certain events. Which mechanism would you use?
- @Input and @Output
- EventEmitter
- Subject
- ngModelChange Event
To have a child component notify its parent in Angular, you typically use the @Input and @Output decorators. The child component can send data or events to the parent component using @Output, creating a custom event emitter. EventEmitter can be used, but it's often associated with custom events. Subjects are used for more complex scenarios. The ngModelChange event is used for form input changes, not parent-child communication.
What is the primary benefit of using lazy loading in Angular applications?
- Better performance in data binding
- Enhanced security
- Faster initial loading
- Improved SEO
The primary benefit of using lazy loading in Angular applications is faster initial loading. Lazy loading allows you to load only the necessary modules and components when they are needed, reducing the initial bundle size and improving the application's loading speed.
You're building a dashboard that fetches and displays data from multiple API endpoints simultaneously. To ensure that all data is loaded before rendering the dashboard, which RxJS technique would you employ?
- combineLatest
- forkJoin
- merge
- zip
To ensure that all data from multiple API endpoints is loaded before rendering the dashboard, you should use the forkJoin operator in RxJS. It combines the results of multiple observables and emits only when all observables complete.
How can you pass data to a dynamically created component?
- Using Angular's data binding with @Input().
- By directly modifying the component's internal state.
- Through a centralized data store like Redux.
- By using Angular services and injecting data.
To pass data to a dynamically created component in Angular, you can use Angular's data binding with @Input() decorators. This allows you to bind properties of the dynamic component to the parent component's properties, enabling seamless data communication between them. The other options may be possible in certain scenarios but are not the standard approach for passing data to dynamically created components.
Your application requires a custom directive that modifies the structure of the DOM based on user roles. Which type of directive should you consider creating?
- Attribute Directive
- Component Directive
- Service Directive
- Structural Directive
When you need to modify the structure of the DOM based on user roles, a Structural Directive is the most appropriate choice. Structural Directives, such as ngIf and ngFor, can conditionally add or remove elements from the DOM, allowing you to customize the view based on user roles or conditions. This flexibility makes them well-suited for this scenario.
An Observable that can emit multiple values over time is different from a Promise, which can resolve only ________.
- multiple times
- never
- once
- twice
An Observable can emit multiple values over time, whereas a Promise can resolve only once. This fundamental difference makes Observables suitable for handling asynchronous streams of data, while Promises are used for handling single asynchronous operations.