If a route's path is set as an empty string (''), it often represents the ________ route of the application.
- Default
- Home
- Primary
- Root
If a route's path is set to an empty string (''), it typically represents the Root route of the application. This means that when the application is accessed without any specific route, the route with an empty path ('') will be considered, often serving as the main entry point or home page of the application.
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.
When an Observable is no longer needed, it should be ________ to prevent memory leaks.
- Composed
- Pipelined
- Subscribed
- Unsubscribed
To prevent memory leaks in Angular applications when an Observable is no longer needed, it should be unsubscribed. Failing to unsubscribe from Observables can lead to resource leaks, as they may continue to emit values and hold references to objects even after the component or service that used them is destroyed. Properly unsubscribing from Observables ensures that they are cleaned up and do not cause memory issues.
Custom attribute directives can alter the appearance or behavior of an element without changing its ________.
- CSS styles.
- HTML structure.
- JavaScript code.
- Original attributes or properties.
Custom attribute directives in Angular can alter the appearance or behavior of an element without changing its HTML structure. They can manipulate the element's behavior or appearance by binding to its properties or attributes, but they typically do not modify the fundamental structure of the HTML element. This allows for greater flexibility and reusability in Angular applications.
What is the purpose of the ControlValueAccessor interface in Angular forms?
- It is used to access form control values in JavaScript code.
- It enables custom form controls to work with Angular's reactive forms.
- It provides a way to access the values of a FormGroup.
- It allows you to control the layout of form elements in Angular templates.
The ControlValueAccessor interface in Angular forms is used to enable custom form controls to work seamlessly with Angular's reactive forms. It acts as a bridge between the custom form control and Angular's form infrastructure, allowing the control to interact with form directives, template-driven forms, and reactive forms. Options 1, 3, and 4 do not accurately describe the purpose of ControlValueAccessor.
Which method is commonly used to initialize and construct a form model in Reactive Forms?
- FormBuilder.group()
- FormGroup.create()
- FormControl.initialize()
- FormModel.construct()
In Reactive Forms, the commonly used method to initialize and construct a form model is FormBuilder.group(). This method is part of the FormBuilder service and is used to create an instance of FormGroup, which represents the form model. The other options are not standard methods for initializing form models in Angular's Reactive Forms.