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.
In an e-commerce application, you want to implement a feature to undo the last action (like adding an item to the cart). Which feature of NgRx would you leverage for this?
- Actions
- Effects
- Selectors
- Time-travel debugging
To implement an undo feature in NgRx, you would leverage "Time-travel debugging." This feature allows you to step backward and forward through the state changes, effectively enabling undo and redo functionality in your application.
The routerLink directive can be bound to an array, allowing you to pass ________ to the route.
- arrays
- data
- parameters
- queries
The routerLink directive can be bound to an array, allowing you to pass parameters to the route. This is useful for passing dynamic data to routes, such as route IDs or other contextual information. While the routerLink can also be bound to other types of data, like arrays or queries, it's primarily used for passing parameters.
If two modules provide the same service and are imported into a third module, the service from the ________ module will be used.
- 'first'
- 'second'
- 'third'
- 'third-party'
When two modules provide the same service and are imported into a third module in Angular, the service from the 'first' module will be used. Angular's dependency injection system follows a hierarchical order for providing services. The first module providing the service takes precedence over the second module, and so on. This ensures that the service is consistent and predictable in its usage.
Which method in the TestBed is used to create an instance of a component or service for testing?
- createComponent()
- createService()
- getComponent()
- getService()
In Angular, you use the createComponent() method provided by TestBed to create an instance of a component for testing. This method allows you to set up and configure the component in a controlled testing environment.
What is the primary purpose of the RouterOutlet directive in Angular?
- To define routes in the application
- To display the contents of routed components
- To define route guards for route protection
- To configure authentication settings
The primary purpose of the RouterOutlet directive in Angular is to display the contents of routed components. It acts as a placeholder where the routed component's view is rendered when the corresponding route is activated. It is an essential part of Angular routing and ensures that the correct component is displayed based on the route configuration. The other options do not accurately describe the purpose of RouterOutlet.
You notice that certain components in your application are re-rendered even when their input data remains unchanged. What could be a potential solution to optimize this behavior?
- Use ChangeDetectionStrategy.OnPush in component metadata
- Increase the max zone.js event listeners
- Use the EventEmitter class to emit events for input changes
- Enable the ViewEncapsulation.None option in component metadata
To optimize the behavior of components that re-render unnecessarily, you can use the ChangeDetectionStrategy.OnPush in the component's metadata. This strategy triggers change detection only when the component's input properties change or when an event is fired, reducing unnecessary re-renders. The other options are not directly related to this issue. Increasing the max zone.js event listeners may not solve the problem.