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.
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.
For a CanDeactivate guard, which method parameter allows you to access the current instance of the component being deactivated?
- component
- componentInstance
- currentComponent
- instance
In a CanDeactivate guard, the componentInstance parameter allows you to access the current instance of the component being deactivated. You can use this parameter to interact with the component and make decisions based on its state.
What's a key difference between Just-in-Time (JIT) and Ahead-of-Time (AOT) Compilation in Angular?
- AOT compiles at runtime
- AOT produces readable TypeScript code
- JIT compiles at runtime
- JIT produces smaller bundle sizes
JIT (Just-in-Time) compilation in Angular compiles the application's TypeScript code into JavaScript at runtime, whereas AOT (Ahead-of-Time) compilation compiles the code during the build process, producing optimized and smaller JavaScript bundles, which results in faster loading times and better performance.
For a directive to modify the value of a host property, you would use the ______ decorator.
- ElementRef
- HostBinding
- Input
- Output
For a directive to modify the value of a host property, you would use the HostBinding decorator. HostBinding allows you to bind the value of a directive property to a host element's property, effectively modifying the host element's behavior or appearance. This is useful for creating dynamic and interactive custom directives in Angular.
What does the term "Hierarchical Injector" refer to in Angular?
- A design pattern used to structure Angular components hierarchically.
- A type of dependency injection system in Angular that supports multiple hierarchies.
- An Angular feature that allows for dynamic component hierarchies.
- An Angular feature that automatically sorts components in a hierarchical order.
The term "Hierarchical Injector" in Angular refers to a type of dependency injection system that supports multiple hierarchies. In Angular, services can be provided at various levels of the application, and the hierarchical injector helps manage the scope and accessibility of these services. This is crucial for controlling how services are shared and instantiated within different parts of an Angular application.
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.