In an e-commerce application, certain routes should only be accessible after a user logs in. To check the user's authentication status before allowing them to access these routes, which Route Guard would you use?
- CanActivate
- CanActivateChild
- CanLoad
- Resolve
The CanActivate route guard is used to protect routes based on whether a user is authenticated or not. It's commonly used to restrict access to routes that require user authentication.
In template-driven forms, which directive is used to conditionally apply CSS classes based on control validity?
- *ngFor directive.
- *ngIf directive.
- *ngTemplateOutlet directive.
- ngClass directive.
The ngClass directive is used in template-driven forms to conditionally apply CSS classes based on the control's validity state. You can use it to style form controls differently depending on whether they are valid, invalid, or untouched. The other directives listed serve different purposes and are not specifically designed for controlling CSS classes based on form control validity.
Which directive in Angular is used to loop over an array and render a list?
- *ngClass
- *ngFor
- *ngIf
- *ngSwitch
In Angular, the *ngFor directive is used to loop over an array and render a list. It iterates through the elements of an array or a collection and generates HTML elements for each item in the array. This is commonly used for rendering dynamic lists, such as a list of items retrieved from an API. *ngIf is used for conditional rendering, *ngSwitch is used for switching between multiple views, and *ngClass is used for dynamically adding or removing CSS classes.
You're building a tabbed interface where only one tab content is displayed at a time, and others are conditionally hidden. Which built-in directive would be most useful to achieve this?
- ngFor Directive
- ngIf Directive
- ngShow Directive
- ngSwitch Directive
To create a tabbed interface where only one tab content is displayed at a time and others are conditionally hidden, the ngIf directive would be most useful. ngIf is a structural directive that conditionally adds or removes elements from the DOM based on a condition. You can use it to conditionally render the content of the selected tab while hiding others.
When you want to get only the first emitted value from an Observable and then complete, you should use the ________ operator.
- debounceTime
- mergeMap
- skip
- take
The take operator in RxJS is used to receive only the first 'n' values emitted by an Observable and then automatically complete the Observable. It's useful when you're interested in a limited initial set of data.
Imagine you have a modal component, and you want users to define custom header, body, and footer for each modal instance. How would you set up the modal component to achieve this?
- Use Angular Templates for Header, Body, and Footer
- Use ng-container for Header, Body, and Footer
- Use Angular Dynamic Components for Header, Body, and Footer
- Use ng-template for Header, Body, and Footer
To allow users to define custom header, body, and footer for each modal instance in Angular, you should use Angular Dynamic Components. This approach allows users to create and insert components dynamically at runtime, making it suitable for the scenario where custom content needs to be defined for each modal instance. While other options like templates, ng-container, and ng-template can be used for various purposes, they don't provide the same level of flexibility as dynamic components in this context.
How can you project content from a parent component into a child component's template?
- Using structural directives like *ngFor.
- Using input properties.
- Using the ViewChild decorator.
- Using Angular modules.
You can project content from a parent component into a child component's template using structural directives like *ngFor, *ngIf, etc. These directives allow you to conditionally render or iterate over content in the child component's template based on data passed from the parent. Input properties are used to pass data, but they don't project content in this way. The other options are not related to content projection.
You are tasked with implementing a feature where, upon clicking a button, the user should be redirected to the home page. Which method or feature of Angular's router would you utilize?
- router.navigate(['/home']);
- router.navigate(['home']);
- router.navigateByUrl('/home');
- router.to(['/home']);
To redirect the user to the home page using Angular's router, you should use the router.navigate(['/home']); method. This method navigates to the specified route, in this case, '/home', which represents the home page. The other options are either incorrect or do not exist in Angular's routing syntax.
How can you achieve nested routing (child routes) within an Angular application?
- By defining child routes in the RouterModule
- By using Angular's loadChildren feature
- By using Angular's canActivateChild guard
- By applying a deep route nesting hierarchy
To achieve nested routing (child routes) in Angular, you define child routes within the RouterModule configuration. This allows you to create a hierarchical structure of routes. The other options relate to Angular's routing features but do not specifically address the process of achieving nested routes.
What is a potential drawback of not using lazy loading in larger applications?
- Increased memory usage
- Larger initial bundle size
- Reduced component reusability
- Slower application startup
Not using lazy loading in larger applications can result in a larger initial bundle size. This means that users need to download a bigger JavaScript file when they first access the application, which can lead to slower loading times, especially on slower network connections.