You're developing an e-commerce application and want to create a shopping cart service that maintains the state of the cart across different components. What would be the best approach to ensure that all components refer to the same instance of the service?
- Using 'ngIf' directive
- Using separate instances for each component
- Using the 'providedIn' property
- Using the 'singleton' pattern
The best approach to ensure that all components refer to the same instance of a service is to use the 'singleton' pattern, which allows a single instance of the service to be shared among multiple components.
In Angular testing, the _____ function is used to simulate user interactions on elements.
- expect
- mock
- query
- trigger
In Angular testing, the trigger function is used to simulate user interactions on elements, such as clicks, inputs, and other events.
The RxJS operator _____ is used to delay the emissions from an Observable.
- debounceTime
- filter
- mergeMap
- skip
The RxJS operator debounceTime is used to delay the emissions from an Observable. It's often used for scenarios like handling user input and performing searches with a delay.
The _____ strategy in Angular's change detection checks the component and its children only when an event is fired.
- Always
- CheckOnce
- Default
- OnPush
The OnPush strategy in Angular's change detection checks the component and its children only when an event is fired, optimizing performance.
How would you implement cross-field validation in a reactive form?
- Create a new form module
- Define custom validators
- Use the FormArray class
- Utilize Angular templates
To implement cross-field validation in a reactive form, you would typically define custom validators that check and enforce validation rules involving multiple fields.
Which feature in Angular allows you to create custom HTML elements that can be used outside Angular applications?
- Angular Components
- Angular Elements
- Angular Modules
- Angular Services
The feature in Angular that allows you to create custom HTML elements usable outside Angular applications is Angular Elements.
You are tasked with optimizing an Angular application's load time. One strategy is to minimize the number of services that are eagerly loaded. Which technique can help achieve this?
- Using 'ngFor' directive
- Using 'ngIf' directive
- Using the 'async' pipe
- Using the 'providedIn' property
To minimize the number of services that are eagerly loaded in an Angular application, you can use the 'providedIn' property to specify that a service should be lazily loaded, which can improve load time.
When you want to execute a side effect for every emission on the source Observable, but return an Observable that is identical to the source, you can use the _____ operator.
- finalize
- reduce
- subscribe
- tap
When you want to execute a side effect for every emission on the source Observable, but return an Observable that is identical to the source, you can use the tap operator.
When testing a directive, which testing utility can be used to interact with a directive's host element?
- ComponentFixture
- DebugElement
- TestBed
- TestHostDirective
In Angular testing, you can use the DebugElement to interact with a directive's host element, query elements, and trigger events.
In an Angular application, how can you optimize a component to be checked only once by Angular's change detection mechanism?
- Use the Default change detection strategy
- Use the EventEmitter to trigger change detection
- Use the OnPush change detection strategy
- Use the Renderer2 to skip change detection
To optimize a component to be checked only once by Angular's change detection, you should use the OnPush change detection strategy. This strategy reduces unnecessary checks.