A client asks for a feature where certain parts of the application should only be accessible to authenticated users. Which feature of Angular would you use to implement this?
- Angular Directives
- Data Binding
- Dependency Injection
- Route Guards
In Angular, you can implement access control for certain parts of the application by using Route Guards. Route Guards allow you to protect routes based on conditions, such as whether the user is authenticated. Data Binding, Dependency Injection, and Angular Directives are not specifically designed for access control.
For a router link to get an "active" CSS class when the link's route is active, you can use the ________ directive.
- [activeLink]
- [routerDirective]
- [routerLinkActive]
- [routerStyle]
To ensure that a router link receives an "active" CSS class when its associated route is active, you can use the [routerLinkActive] directive in Angular. This directive allows you to define CSS classes that should be applied when the link's route is active, providing visual feedback to users.
A client wants certain fields in a form to be auto-populated based on the value of another field. How would you achieve this in Angular?
- Implementing custom validation for auto-population
- Using pipes to manipulate the form data
- Using reactive forms with value changes observables
- Using template-driven forms with ngModel
To auto-populate fields based on another field's value, you'd typically use reactive forms in Angular along with valueChanges observables. This allows you to reactively update form fields based on changes in other fields. While template-driven forms with ngModel can achieve some level of auto-population, reactive forms provide more control and flexibility. Using pipes or custom validation may not be the most suitable approach for this requirement.
Which decorator is used to declare a class as an Angular component?
- @Component
- @Directive
- @Injectable
- @NgModule
The @Component decorator is used to declare a class as an Angular component. Components are the fundamental building blocks of Angular applications, representing user interface elements. NgModule is used to define modules, @Directive is used for custom directives, and @Injectable is used for dependency injection, but they are not used to declare components.
When dealing with a custom component that doesn't naturally fit into Angular's form ecosystem, which strategy can be employed to ensure it works with ngModel and formControl directives?
- Creating a separate service for form control interactions.
- Implementing a custom directive to handle ngModel and formControl.
- Modifying Angular's core source code to accommodate custom components.
- Using custom event emitters for data binding.
To make a custom component work with ngModel and formControl in Angular, you should implement a custom directive that uses ControlValueAccessor. This allows the component to interface with Angular's form system seamlessly, enabling data binding and validation. Modifying Angular's core source code is not a recommended approach.
What is the primary use of the @Input() decorator in a component?
- To declare a component
- To declare a service
- To declare a variable
- To declare an Angular module
The primary use of the @Input() decorator in a component is to declare a variable as an input property. This allows data to be passed into the component from its parent component. Input properties enable communication between components, making it possible to send data from a parent component to a child component. It is not used to declare services, components, or Angular modules.
What's the main advantage of using HttpInterceptor over handling errors directly in the component or service?
- Better performance
- Centralized error handling
- Easier testing
- Improved code readability
The main advantage of using HttpInterceptor for error handling is centralized error handling. It allows you to intercept and handle HTTP errors in a single location, making error management more consistent and maintainable across the entire application.
Which state management library in Angular uses concepts like Actions, Reducers, and Effects?
- MobX
- NgRx
- Redux
- RxJS
NgRx is a popular state management library for Angular that employs concepts like Actions, Reducers, and Effects. These concepts help manage the application's state, handle actions, and manage side effects in a predictable manner.
When implementing a CanDeactivate guard, what should be considered if the component does not have a canDeactivate method?
- The component will be deactivated
- The guard will throw an error
- The guard will use a default canDeactivate method
- The navigation will proceed without confirmation
When implementing a CanDeactivate guard, if the component does not have a canDeactivate method, the navigation will proceed without confirmation. The guard relies on this method to determine whether to allow or prevent the user from leaving the component with unsaved changes.
When dynamically creating components, it's often necessary to handle their lifecycle events. The ______ method can be used to detect when the component's view has been initialized.
- ngAfterViewInit()
- ngDoCheck()
- ngOnChanges()
- ngOnInit()
In Angular, when dynamically creating components, you can use the ngAfterViewInit() method to detect when the component's view has been initialized. This lifecycle hook is called after the component's view is fully initialized, and it's a suitable place to perform operations that depend on the view being ready. ngOnInit() is called when the component is initialized, but the view might not be ready at that point.