Your application has a dynamic form where fields can be added or removed based on user input. Which feature of Angular's Reactive Forms would you leverage to accomplish this?
- Create a separate component for each dynamic form field.
- Implement dynamic forms using Angular's template-driven approach.
- Use the ngIf directive to conditionally render form fields.
- Utilize form arrays to dynamically add or remove form controls.
In Angular's Reactive Forms, you would leverage form arrays to dynamically add or remove form controls based on user input in a dynamic form. The ngIf directive is more suitable for conditionally rendering existing elements in the DOM, not for dynamically managing form controls. Creating a separate component for each dynamic form field is not the recommended approach for dynamic forms, and Angular's template-driven approach is less flexible in handling dynamic forms than Reactive Forms with form arrays.
You're creating a feedback form where users can rate a product. You want to ensure users provide a rating between 1 to 5. How would you validate the input to ensure values are within this range?
- Use client-side JavaScript to restrict input to values between 1 and 5.
- Implement server-side validation to check the rating before storing it.
- Utilize Angular's Validators to create a custom validation rule for the rating field.
- Allow users to enter any value and provide an error message if it's not within the range after submission.
To validate user input for a rating between 1 to 5 in an Angular form, you would use Angular's Validators to create a custom validation rule (Option 3). This ensures the validation occurs on the client side. Server-side validation (Option 2) is important but doesn't prevent invalid values from being submitted. Option 1 restricts input but doesn't provide feedback, and Option 4 is less user-friendly.
You have a shared service that maintains user settings. You notice that different parts of the application have different instances of this service. What could be a possible reason?
- Different parts of the application are using different configurations, which require separate instances of the service.
- The application is not using a proper dependency injection framework.
- The shared service is being loaded with lazy loading modules, leading to multiple instances.
- There is a bug in the shared service causing it to create multiple instances.
Different parts of the application may require different configurations or data, which necessitates separate instances of the shared service. This allows each part of the application to have its own instance with specific settings or configurations. It's not a bug or dependency injection issue but rather a design choice to accommodate varying requirements.
How does Akita differ in its approach to state management compared to NgRx?
- Employs Redux-style pattern with actions and reducers
- Favors a component-based state management approach
- Uses a simpler, more declarative approach
- Utilizes MobX for reactive state management
Akita differs from NgRx by using a simpler and more declarative approach to state management. It provides a straightforward way to manage state in Angular applications without the boilerplate associated with Redux-style patterns.
You have a multi-step registration process where each step is its own route. A user should not proceed to the next step without completing the previous one. How would you enforce this in Angular?
- Implementing route guards to prevent navigation to the next step until the current step is completed.
- Using conditional statements to hide the next step until the current step is completed.
- Storing step completion status in a browser cookie and checking it during navigation.
- Reloading the page after each step to ensure step completion.
In Angular, you can enforce the requirement that a user should not proceed to the next step without completing the previous one by implementing route guards. Route guards are Angular's way of protecting routes and can be used to prevent navigation until certain conditions, such as step completion, are met. The other options are not recommended practices for enforcing this requirement in an Angular application.
For handling multiple values over time in Angular, you would use ________ instead of Promises.
- Components
- Decorators
- Modules
- Observables
In Angular, when you need to handle multiple values over time, you should use Observables instead of Promises. Observables are more versatile and allow you to work with asynchronous data in a more flexible manner. They can emit multiple values, making them ideal for scenarios like handling streams of data from HTTP requests or user interactions.
When using , which lifecycle hook is ideal for accessing projected content inside the child component?
- ngAfterContentInit()
- ngAfterViewInit()
- ngOnChanges()
- ngOnInit()
When using , the ideal lifecycle hook for accessing projected content inside the child component is ngAfterContentInit(). This hook is triggered after content projection has taken place, allowing you to work with the projected content effectively. ngOnInit() is too early in the component lifecycle, and ngOnChanges() and ngAfterViewInit() are not specifically related to content projection.
In Jasmine, the ______ function is used to define expectations for a test.
- beforeEach
- describe
- expect
- it
In Jasmine, the expect function is used to define expectations (assertions) for a test. It is used within an it block to specify what should happen during the test and what should be verified as correct behavior.
Which is NOT a lifecycle hook in Angular?
- ngOnInit
- ngRender
- ngAfterViewInit
- ngOnDestroy
ngRender is not a standard lifecycle hook in Angular. The other options (ngOnInit, ngAfterViewInit, ngOnDestroy) are all valid Angular lifecycle hooks. These hooks allow developers to tap into various stages of a component's lifecycle to perform actions like initialization, cleanup, and interaction with the DOM. Understanding these hooks is crucial for managing component behavior and interactions in Angular applications.
In Jasmine, which function is used to create spies that can track calls, arguments, and return values?
- createSpy
- spyOn
- trackSpy
- watchSpy
In Jasmine, the spyOn function is used to create spies. Spies are functions that can replace existing functions or be standalone, and they allow you to track function calls, arguments passed to them, and even control their behavior, including returning specific values.
When creating a custom form control in Angular, which interface should it implement to work seamlessly with Angular's form directives?
- ControlValueAccessor
- FormControl
- FormGroup
- FormControlDirective
When creating a custom form control in Angular, it should implement the ControlValueAccessor interface to work seamlessly with Angular's form directives. This interface provides methods for connecting custom form controls with Angular's forms API, enabling the control to interact correctly with form directives like ngModel, formControl, and formGroup. The other options (FormControl, FormGroup, FormControlDirective) are related to form handling but do not specifically enable custom form control integration.
In Angular's reactive forms, the method used to mark a control as touched is called ______.
- markAsDirty()
- markAsTouched()
- setDirty()
- setTouched()
In Angular's reactive forms, the method used to mark a control as touched is called markAsTouched(). This method is used to indicate that a form control has been interacted with by the user. It's commonly used for validation and to show error messages for untouched controls.