You've noticed that a specific component in your application is being checked and re-rendered by Angular even though its input data hasn't changed. You want to optimize it so that Angular only re-renders it when the input data actually changes. What would you implement?
- Change Detection Strategy
- Dependency Injection
- Pure Pipe
- ngOnChanges Lifecycle Hook
To optimize re-rendering, you should implement a Change Detection Strategy, such as OnPush, to make Angular re-render the component only when its input data changes.
What is the primary purpose of using custom pipes in Angular applications?
- Create modules and services
- Handle routing and navigation
- Modify the component's class properties
- Transform and format data
The primary purpose of using custom pipes in Angular is to transform and format data before displaying it in the view. Custom pipes allow you to apply specific transformations to data.
What is the primary purpose of unit testing Angular components?
- Ensure compatibility
- Test the end-to-end flow
- Validate REST APIs
- Verify component templates
The primary purpose of unit testing Angular components is to verify component templates, ensuring they render as expected and contain the desired logic.
To test if a directive correctly updates the host element's properties, you can use the ______ method.
- debugElement
- queryHostElement
- querySelector
- updateHostProperties
To test if a directive correctly updates the host element's properties, you can use the debugElement method to inspect and manipulate the host element.
In the context of debugging, what does the term "source maps" refer to in Angular applications?
- Maps of Angular components
- Maps of geographical areas
- Maps of runtime errors and bugs
- Maps of source code
In debugging, "source maps" are mappings of the original source code to the transpiled code, allowing developers to trace errors and debug in the original source.
How can you share a directive among different modules in an Angular application?
- Import the directive in each module
- Share the directive through RxJS
- Use a service
- Use the @SharedDirective decorator
To share a directive among different modules in an Angular application, you can import the directive in each module where you want to use it. This makes the directive available in those modules, ensuring its shared usage.
What happens when you call the unsubscribe() method on a Subscription?
- Pauses the Subscription
- Resumes the Subscription
- Stops the Subscription
- Terminates the Subscription
When you call the unsubscribe() method on a Subscription, it stops the Subscription, which means it terminates the connection between the observer and the Observable.
You are building a survey application where the questions change based on the user's previous responses. Which feature of Angular forms would be best suited to create this kind of dynamic behavior?
- Both Reactive and Template-driven Forms
- Custom Form Validation
- Reactive Forms
- Template-driven Forms
To create a dynamic form that changes based on user responses, Reactive Forms are best suited. Reactive Forms offer more flexibility and control in creating dynamic forms.
In a complex application, you want to implement a global notification system that allows various components to send and receive messages. Which RxJS class would be best suited to implement this system?
- AsyncSubject
- BehaviorSubject
- ReplaySubject
- Subject
To implement a global notification system where various components can send and receive messages, Subject is a suitable choice. Subjects allow multicasting and can be used to create a central messaging hub in your application.
To handle errors within an Observable chain, you can use the _____ operator in RxJS.
- catchError
- errorHandle
- handleError
- mapError
To handle errors within an Observable chain in RxJS, you can use the catchError operator. This operator allows you to gracefully handle errors.