For a form control that has both synchronous and asynchronous validators, how does Angular handle validation?
- Angular only runs either synchronous or asynchronous validators based on configuration.
- Angular runs asynchronous validators first and then synchronous validators.
- Angular runs both types of validators simultaneously.
- Angular runs synchronous validators first and then asynchronous validators.
Angular handles validation for a form control with both synchronous and asynchronous validators by first running the synchronous validators and then the asynchronous ones. This ensures that immediate validation checks occur before potentially asynchronous checks, providing a smooth user experience.
At which lifecycle hook is it best to make an HTTP request in an Angular component?
- constructor
- ngAfterViewInit
- ngOnDestroy
- ngOnInit
In Angular, it's best to use the ngOnInit lifecycle hook to handle any additional initialization tasks, including making HTTP requests. The constructor is mainly used for dependency injection and not for logic.
In the context of Angular's router, what is the significance of the pathMatch property?
- It defines the priority of route matching.
- It determines the parent route of a child route.
- It specifies how to match a URL path to a route.
- It controls the route's access permissions.
In Angular's router, the pathMatch property is significant because it specifies how to match a URL path to a route. It has two values: 'prefix' (default) and 'full.' 'Prefix' means the route will match if the URL starts with the path, while 'full' requires an exact URL match. The other options do not accurately describe the purpose of pathMatch.
Which directive in Angular is used to add or remove an element from the DOM based on a condition?
- *ngFor
- *ngIf
- *ngInclude
- *ngSwitch
The *ngIf directive is used in Angular to conditionally add or remove an element from the DOM based on a given condition. If the condition evaluates to true, the element is rendered; otherwise, it is removed from the DOM. It's a fundamental directive for handling conditional rendering in Angular templates.
To ensure high performance when dealing with large datasets in Angular, one should avoid data ________ and instead use immutable operations.
- Compilation
- Injection
- Mutation
- Serialization
To ensure high performance with large datasets in Angular, developers should avoid data mutation and instead use immutable operations. Mutating data can lead to frequent change detection cycles and performance issues, as Angular may not detect changes in mutated objects. Using immutability ensures that each change results in a new object, making change detection more efficient.
When dealing with an Observable, which method is used to start its execution?
- combineLatest
- filter
- map
- subscribe
To start the execution of an Observable and receive values from it, you need to call the subscribe method on the Observable instance. This method takes one or more callback functions to handle emitted values, errors, and completion.
What is the behavior of the ViewEncapsulation.None mode?
- Styles defined in the component affect all elements in the application, and global styles can affect the component's elements.
- Styles defined in the component are scoped to the component and do not affect other parts of the application.
- Styles defined in the component do not have any impact, and all styling must be done in external CSS files.
- Styles defined in the component are isolated and cannot be overridden.
In ViewEncapsulation.None mode, styles defined in the component can affect all elements in the application, and global styles can affect the component's elements. This mode effectively removes the shadow DOM boundary and makes the component's styles global. The other options describe the behavior of different encapsulation modes (such as ViewEncapsulation.Emulated, ViewEncapsulation.ShadowDom, and ViewEncapsulation.Native) but not the specific behavior of ViewEncapsulation.None.
When using OnPush change detection strategy, what can cause a component to be checked, besides changes to its input properties?
- Asynchronous HTTP requests.
- Changes in the component's internal state.
- Changes in the global application state managed by Redux.
- Events triggered by user interactions.
In Angular, when using the OnPush change detection strategy, a component will be checked for updates not only when its input properties change but also when events triggered by user interactions occur. This is because user interactions can lead to changes in a component's view, and OnPush checks for such changes to provide more efficient and responsive updates.
For handling complex state transitions in Ngxs, one would utilize ________.
- Actions
- Effects
- Entities
- Selectors
To handle complex state transitions in Ngxs (a state management library for Angular), one would utilize "Effects." Effects are used to manage side effects, such as HTTP requests, that can change the state in response to dispatched actions.
When creating a service using the Angular CLI, which command would you use?
- ng serve
- ng generate service
- ng create service
- ng build service
When creating a service in Angular using the Angular CLI, you would use the command ng generate service. This command generates the necessary files and boilerplate code for an Angular service, making it a convenient way to create services in an Angular project. The other options (ng serve, ng create service, ng build service) are not the correct commands for creating a service.