In Angular, how can you optimize form submission to prevent multiple submissions of the same data?
- Disable the submit button after the first click
- Implement server-side deduplication
- Use a unique key for each form submission
- Use debouncing techniques
In Angular, you can optimize form submission to prevent multiple submissions by disabling the submit button after the first click.
You have a suite of E2E tests written using Protractor, and a particular test is flaky, occasionally failing without any code changes. What approach can you take to identify and resolve the issue?
- Debug the test
- Disable the test
- Rerun the test multiple times
- Rewrite the entire suite of tests
When encountering flaky tests in Protractor, the best approach is to debug the test to identify the root cause of the flakiness and make necessary adjustments. Rerunning the test multiple times or disabling it may not address the underlying problem. Rewriting the entire test suite is typically an overkill solution.
How can you nest one component inside another in Angular?
- Using an ng-container
- Using ng-template
- Using structural directives
- Using the @ViewChild decorator
You can nest one component inside another in Angular by using the @ViewChild decorator to reference the child component within the parent.
In an e-commerce application, you need to create a checkout form that dynamically adds input fields based on the items in the user's cart. Which Angular concept can help you achieve this?
- Dynamic Component Creation
- One-way Data Binding with [ngModel]
- Router Guards for Dynamic Routing
- Service Injection
To dynamically add input fields based on cart items, you can use Dynamic Component Creation in Angular. This allows you to generate components on the fly based on user interactions.
The _____ operator is used to catch and handle errors within an Observable sequence.
- catchError
- filter
- map
- retry
The catchError operator is used to catch and handle errors within an Observable sequence. It allows you to gracefully handle errors in your observable stream.
Using lazy loading, Angular loads additional JavaScript files when the user _______.
- Clears browser cache
- Closes a browser tab
- Logs in to the system
- Navigates
Using lazy loading, Angular loads additional JavaScript files when the user navigates to a route that is set up for lazy loading.
Why is it important to unsubscribe from observables in an Angular application?
- To ensure the observable continues emitting values.
- To prevent errors in the application.
- To save memory and prevent memory leaks.
- To simplify code and improve performance.
It's important to unsubscribe from observables in an Angular application to save memory and prevent memory leaks by cleaning up resources when they are no longer needed.
What is the purpose of using the providedIn property when creating a service in Angular?
- It specifies the service's dependencies
- It specifies the service's instance scope
- It specifies the service's name
- It specifies the service's provider
The providedIn property in Angular service metadata is used to specify the service's instance scope. By specifying a module, the service will be a singleton, providing a single shared instance.
To add a third-party library to an Angular project, you can use the _____ command of Angular CLI.
- ng add
- ng compile
- ng generate
- ng serve
To add a third-party library to an Angular project, you can use the ng add command of Angular CLI.
When an observable is hot, it means that the data is emitted regardless of whether there are any subscribers.
- buffered
- emitted
- paused
- produced
When an observable is hot, it means that the data is emitted regardless of whether there are any subscribers.