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.
In template-driven forms, which directive is utilized to implement a group of form controls?
- ngControlGroup
- formControlGroup
- ngFormGroup
- formGroup
In template-driven forms, the formGroup directive is used to implement a group of form controls. It allows you to group related form controls together, making it easier to manage their validation and state. The other options mentioned are not valid directives for implementing form control groups in template-driven forms.
Which Angular feature allows you to project different parts of content into multiple predefined slots inside a child component?
- ng-content
- ng-projection
- ng-slot
- ng-template
In Angular, the feature that allows you to project different parts of content into multiple predefined slots inside a child component is the directive. It enables you to define multiple tags with select attributes in the child component's template, and then, in the parent component, specify which content goes into each slot using the select attribute's value. The other options are not valid Angular directives or features for content projection.
If you want to serve your Angular application on a specific port other than the default (4200), which command should you use?
- ng run --port 8080
- ng serve --default-port 8080
- ng serve --port 8080
- ng start --port 8080
To serve your Angular application on a specific port other than the default (4200), you should use the ng serve --port 8080 command. This command starts the development server on port 8080, allowing you to access your application using a different port.
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.
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.