A client asks for a feature where a child component should be able to inform its parent component when a button inside the child component is clicked. How would you implement this interaction?
- Use the @Output decorator to emit an event from the child component and bind to it in the parent component.
- Use the @ViewChild decorator to access the child component's method directly from the parent component.
- Use the @Input decorator to pass a callback function from the parent to the child component.
- Use the @HostListener decorator to listen for events in the child component and trigger a method in the parent component.
To implement communication from child to parent in Angular, you can use the @Output decorator to emit an event from the child component, and the parent component can bind to this event to listen for changes. This allows the child to inform the parent when the button is clicked. The other options are not the typical approach for this scenario.
Which module should you import to use the HttpClient in an Angular application?
- @angular/common/http
- @angular/core
- @angular/forms
- @angular/router
To use the HttpClient in an Angular application, you should import the @angular/common/http module. This module provides the HttpClient service for making HTTP requests.
To project specific content into a designated slot, you would use the select attribute of with a ________ selector.
- Class
- Slot
- Name
- Tag
When using content projection in Angular with , you typically use the select attribute with a CSS class selector to specify where the content should be projected. This allows you to target specific slots in the child component's template. Options 1, 3, and 4 are not commonly used in this context.
What is the primary use of in Angular?
- To define a new component in Angular.
- To display data from an API.
- To project content from a parent component into a child component.
- To style Angular components using CSS.
The primary use of in Angular is to project content from a parent component into a child component. This allows you to pass content or HTML elements from a parent component to a designated location in a child component, facilitating component reusability and flexibility. It's a fundamental concept in Angular for creating dynamic and customizable components.
When you want to disable a form control conditionally based on some logic, you would use the ______ attribute.
- [conditionalControlDisable]
- [controlToggle]
- [disable]
- [ngControlDisabled]
When you want to disable a form control conditionally based on some logic in Angular template-driven forms, you would use the [disable] attribute. This attribute allows you to bind a condition to the disabled state of a form control, making it either enabled or disabled based on the provided logic. It's a crucial feature for creating dynamic and responsive forms.
What is the primary purpose of the ng serve command in the Angular CLI?
- To build the production-ready application
- To deploy the application
- To run a development server
- To test Angular components
The ng serve command in Angular CLI is primarily used to run a development server. This server serves your Angular application, provides hot module reloading for rapid development, and enables you to view changes in real-time as you code.
Which providedIn value ensures that a service instance is shared across the entire application?
- 'app'
- 'global'
- 'root'
- 'shared'
The 'root' providedIn value ensures that a service instance is shared across the entire Angular application. When a service is provided with 'root', it becomes a singleton service, and there is only one instance of it created and shared throughout the entire application. This is commonly used for services that should have a single, shared state across components.
What allows you to dynamically load and render components in Angular?
- Angular dynamic component loader.
- Angular modules.
- Angular services.
- Angular templates.
To dynamically load and render components in Angular, you can use Angular's dynamic component loader. This feature allows you to programmatically load and render components at runtime. Angular templates and modules are part of the Angular framework but don't directly enable dynamic component loading. Angular services provide functionality but aren't specifically for dynamic component loading.
How would you implement asynchronous validation for checking if an email is already registered?
- Use the 'asyncValidator' property of the FormControl to call an asynchronous API.
- Implement a synchronous validator function that checks email registration status.
- Utilize Angular's built-in 'EmailValidator' for asynchronous checks.
- Create a custom directive to handle email registration validation asynchronously.
To implement asynchronous validation for checking if an email is already registered, you should use the 'asyncValidator' property of the FormControl to call an asynchronous API or service. This allows you to perform an asynchronous check on the email's registration status. Options 2, 3, and 4 do not provide the correct approach for asynchronous validation.
In template-driven forms, the ______ directive is used to bind an input field to a property in the component's class.
- ngBinding
- ngDirective
- ngModel
- ngTemplate
In template-driven forms in Angular, the "ngModel" directive is used to bind an input field to a property in the component's class. This directive establishes two-way data binding between the form control and the component class property, allowing changes in the input field to be reflected in the component and vice versa.
You are building a dynamic form where users can add or remove input fields. Which feature or approach in Angular would be best suited for this requirement?
- FormArray
- Reactive Forms
- Template-driven Forms
- ngFor Directive
To allow users to add or remove input fields dynamically, you would typically use the FormArray feature in Angular. FormArray allows you to create arrays of form controls dynamically, making it ideal for scenarios where the number of input fields can change. Reactive Forms provide a more robust way to manage form data compared to Template-driven Forms, and ngFor is a directive used for rendering lists but doesn't handle form controls.
You're building a layout component that should allow users to inject custom content for the header, sidebar, and main content area. What approach would you take to enable this functionality in the layout component?
- Use ng-template with ng-container to define placeholders for header, sidebar, and main content.
- Use Angular Directives to inject content into the layout component.
- Use Angular Dynamic Components to create header, sidebar, and main content dynamically.
- Use Angular Pipes to transform content for the header, sidebar, and main content areas.
To enable users to inject custom content for the header, sidebar, and main content area in an Angular layout component, you can use ng-templates with ng-containers to define placeholders. Users can then fill these placeholders with their custom content. This approach provides flexibility and is a common pattern for creating layouts with dynamic content. While other options like directives, dynamic components, and pipes have their use cases, they are not the most suitable choice for this specific scenario.