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.
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.
In an Angular reactive form, how can you dynamically add a validator to a form control at runtime?
- Create a new FormControl instance with the validator
- It's not possible to add validators at runtime
- Use the 'Validators' service
- Use the 'setValidators' method
To dynamically add a validator to a form control in an Angular reactive form, you should use the 'setValidators' method to set the validators for the form control, allowing you to change the validation rules at runtime.
You have an Observable that fetches user data from an API. However, the API occasionally fails. You want to implement a mechanism that retries the API call up to 3 times before handling the error. How would you achieve this?
- catch(error)
- repeat(3)
- retry(3)
- retryWhen
To retry an observable up to a specified number of times, you can use the retry(3) operator. It retries the source observable up to 3 times before emitting an error if it still fails.
In a large Angular application, you want to ensure that the build process is optimized for production, with minimized bundle size and improved performance. Which Angular CLI command or option would you use?
- ng build --development
- ng build --prod --aot
- ng build --watch
- ng build --optimize
To optimize a large Angular application for production with minimized bundle size and improved performance, you would use the "ng build --prod --aot" command (option b). This enables Ahead-of-Time (AOT) compilation and produces optimized bundles.
You are building an e-commerce application and want to create a route that shows product details based on the product ID passed in the URL. How would you set this up in your Angular application?
- Define a route with a parameter like /product/:productId and access the productId using ActivatedRoute.
- Define a route with a wildcard route that matches /product/* and parse the product ID from the URL.
- Set up an HTTP interceptor to extract the product ID from the URL and fetch the details.
- Use Angular Guards to fetch the product details before activating the route.
To show product details based on the product ID in the URL, you should define a route with a parameter like /product/:productId and access the productId using the ActivatedRoute to retrieve the product details.