Which option is NOT a valid view encapsulation mode in Angular?
- Emulated
- Shadow DOM
- None
- Native
In Angular, the valid view encapsulation modes are Emulated (default), Shadow DOM, and Native. The "None" option is not a valid view encapsulation mode. View encapsulation modes determine how Angular styles are applied and scoped in a component. "None" is not a recognized mode for Angular view encapsulation.
In the context of state management in Angular, what is the role of "selectors"?
- Selectors are responsible for dispatching actions
- Selectors are used to derive data from the store
- Selectors handle side effects
- Selectors provide routing functionality
In Angular state management, "selectors" play a crucial role in deriving and transforming data from the store. They allow you to compute and return specific slices of the application state, making it easier to access and display relevant data in components.
You have a service that makes an HTTP request. You want to test this service without actually hitting the endpoint. How would you achieve this in Angular testing?
- Mock the HTTP service using HttpClientTestingModule
- Use a real HTTP request for accurate testing
- Use a testing library like ng-mocks to mock the HTTP service
- Utilize ng-test-bed to simulate HTTP requests
In Angular testing, you can use a testing library like ng-mocks to mock the HTTP service, allowing you to isolate and control the behavior of the service without making actual network requests. This is essential for unit testing to avoid external dependencies.
You notice that a particular component in your application re-renders too often, causing performance issues. What steps can you take to optimize it?
- Implement shouldComponentUpdate()
- Increase the component's complexity
- Use more inline styles
- Ignore the issue and focus on other components
To optimize a component that re-renders too often and causes performance issues in a React application, you can implement the shouldComponentUpdate() lifecycle method. This allows you to control when the component should update and re-render, potentially improving performance. The other options are not effective ways to address this issue.
What is the main purpose of Angular's ChangeDetectionStrategy.OnPush?
- To enable two-way data binding.
- To improve change detection performance.
- To disable change detection altogether.
- To increase the framework's size.
The main purpose of Angular's ChangeDetectionStrategy.OnPush is to improve change detection performance. When you use this strategy, Angular will only perform change detection when input properties of a component change or when certain events are triggered, leading to better performance in applications with complex component trees. The other options are not the main purpose of this strategy.
Why would you use the ViewContainerRef in Angular?
- To manage the DOM elements where dynamic components are inserted.
- To create Angular services.
- To handle form submissions in Angular.
- To define Angular component templates.
ViewContainerRef in Angular is used to manage the DOM elements where dynamic components are inserted. It provides a reference to the container where you can dynamically add or remove components. This is useful for scenarios where you need to render components based on user interactions or application logic. The other options are not the primary purpose of ViewContainerRef.
If you have an application where some modules are loaded on-demand, and you want to restrict this based on user roles, which Route Guard should you implement?
- CanActivate
- CanActivateChild
- CanDeactivate
- CanLoad
To restrict loading of modules based on user roles in a lazy-loaded scenario, you should implement the CanLoad guard. It allows you to check conditions before the module is loaded, ensuring that only authorized users can access certain parts of the application.
What method of HttpClient would you use to send a GET request?
- delete()
- get()
- post()
- put()
To send a GET request using HttpClient, you would use the get() method. This method is used to perform HTTP GET requests to retrieve data from a specified URL.
In Angular's dependency injection, what is the difference between a service provided in 'root' and one provided in a module?
- Services provided in 'root' are lazy-loaded, while those in a module are eager-loaded
- Services provided in 'root' are singletons, while those provided in a module are scoped to that module
- Services provided in 'root' cannot have dependencies, while those in a module can
- Services provided in 'root' have wider accessibility, while those in a module are private
When a service is provided in the 'root' of an Angular application, it becomes a singleton. This means there's only one instance of the service for the entire application. Services provided in a module are scoped to that module, creating a new instance for each module that imports it.
You're building a tab component system where each tab can have custom content. Which Angular feature would be most appropriate to allow users to define content for each tab?
- Content Projection (ng-content)
- Dependency Injection (DI)
- Input Properties (Bindings)
- Output Properties (Events)
In Angular, Content Projection (ng-content) is the most appropriate feature to allow users to define custom content for each tab. It allows users to pass in content that will be inserted into designated placeholders within your component. Input properties allow data binding, output properties handle events, and Dependency Injection is used for providing services, making Content Projection the correct choice for this scenario.