When a subscriber attaches to a cold observable, it gets its own independent execution of the _____.
- Observable
- Operator
- Stream
- Subscription
When a subscriber attaches to a cold observable, it gets its own independent execution of the Observable. A new instance of the observable's execution is created for each subscriber.
How can you handle conditional validation for controls within a Form Array in Angular?
- Define custom validation directives
- Use a separate Form Array for each condition
- Use the FormControl's setValidators method
- Utilize the Validators.compose function
You can handle conditional validation in Angular for controls within a Form Array by using the setValidators method of the FormControl.
Which Angular CLI command is used to create a new Angular project?
- ng create project
- ng generate project
- ng new
- ng start project
The command to create a new Angular project using Angular CLI is ng new. It sets up a new Angular project with the necessary files and dependencies.
Which Angular module must be imported to use template-driven forms?
- FormsModule
- HttpClientModule
- ReactiveFormsModule
- RouterModule
To use template-driven forms in Angular, you must import the FormsModule. This module provides the necessary directives and services for working with template-driven forms.
You are building an interactive dashboard that includes charts, graphs, and data tables. You need to ensure that the components only update when there is an actual change in the data. Which change detection strategy would be most suitable?
- Implement custom change detection logic
- Increase the polling frequency for updates
- Use OnPush change detection strategy
- Utilize the default change detection strategy
To ensure components update only when there is an actual change in data, the most suitable change detection strategy is to use the OnPush strategy.
How can you dynamically add or remove form controls in an Angular form?
- Use *ngFor Directive
- Use Angular Material Form
- Use FormGroup API
- Use Reactive Forms Module
To dynamically add or remove form controls in an Angular form, you can use the FormGroup API. It allows you to add, remove, or manipulate form controls within a FormGroup dynamically based on user interactions or other criteria.
In an e-commerce application, you want to fetch product details and customer reviews concurrently, and only update the UI when both pieces of data are available. Which RxJS operator should you use?
- combineLatest
- forkJoin
- mergeMap
- zip
To fetch data concurrently and update the UI when both are available, you should use the forkJoin operator, which waits for all observables to complete and then emits their last values as an array.
How can you prevent an expression from being re-evaluated in every change detection cycle while using interpolation in Angular?
- Use a custom pipe
- Use ngOnPush change detection strategy
- Use one-time binding ({{::expression}})
- Use trackBy with ngFor directive
In Angular, you can prevent an expression from being re-evaluated by using one-time binding ({{::expression}}).
How can you convert a cold observable into a hot observable?
- Apply the "subscribe" method
- Implement the "map" operator
- Use the "share" operator
- Utilize the "take" operator
You can convert a cold observable into a hot observable by using the "share" operator, which allows multiple subscribers to receive the same values emitted by the observable simultaneously.
In Angular, how can you ensure that your service correctly handles HTTP errors during testing?
- Mock the HttpClient responses
- Use a delay operator like debounceTime for error cases
- Use real HTTP requests with a testing server
- Wrap the service call in a try-catch block
To ensure that your Angular service correctly handles HTTP errors during testing, you should mock the HttpClient responses. This allows you to control the responses and simulate error scenarios in a controlled environment. Using real HTTP requests or delay operators like debounceTime is not recommended for testing HTTP error handling.