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.
You have been tasked with improving the initial load time of an Angular application. Which of the following techniques would be most effective?
- Increasing Server RAM
- Lazy Loading
- Minifying CSS and JS
- Using a Bigger CDN
Lazy Loading is a technique in Angular that loads modules only when they are needed, reducing the initial load time of an application. It's a powerful method to optimize performance by loading only what's necessary upfront.
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.
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.