Which of the following is a push-based mechanism in JavaScript?
- Callbacks
- Observables
- Promises
- Synchronous functions
Observables are a push-based mechanism in JavaScript. They allow you to work with asynchronous data streams, where data can be emitted at any time, rather than being pulled when needed as with Promises or using callbacks.
You are tasked with creating a directive that changes the background color of an element when it's hovered over. Which type of directive would be best suited for this task?
- Attribute Directive
- Component Directive
- Service Directive
- Structural Directive
For changing the background color of an element when hovered, an Attribute Directive is the best choice. Attribute Directives are used to modify the behavior or appearance of an element. You can create an Attribute Directive that listens for the mouseenter and mouseleave events and modifies the element's style accordingly. This approach is more suitable than other types of directives for this specific task.
How can you pass data from a parent component to a child component in Angular?
- EventEmitter
- Input property
- Output property
- ViewChild
In Angular, you can pass data from a parent component to a child component by using an input property. Input properties allow you to bind a value in the parent component to a property in the child component, enabling data transfer from parent to child.
Which of the following is a benefit of using content projection in Angular?
- Easier debugging of TypeScript code.
- Enhanced security for user data.
- Faster execution of Angular applications.
- Improved component encapsulation and reusability.
Using content projection in Angular provides the benefit of improved component encapsulation and reusability. It allows you to separate the structure and content of a component, making it more flexible and easier to reuse in different contexts. This enhances the maintainability and extensibility of your Angular applications.
In which scenarios would you consider using the ChangeDetectionStrategy.OnPush for a component?
- When the component interacts with external APIs.
- When the component needs to re-render frequently.
- When the component relies on two-way data binding.
- When the component's data is immutable and only changes through input properties.
ChangeDetectionStrategy.OnPush is suitable when a component's data is immutable and only changes through input properties. This strategy optimizes performance by avoiding unnecessary change detection checks. It is not used when two-way data binding is required or when the component re-renders frequently. Interaction with external APIs is typically unrelated to the choice of change detection strategy.
How can you ensure that an Observable sequence completes after a certain number of emitted values?
- debounceTime
- distinctUntilChanged
- skip
- take
You can ensure that an Observable sequence completes after a certain number of emitted values by using the take operator. It allows you to specify how many emissions you want to take from the source Observable before it completes.
In NgRx, what would you use to handle side effects like API calls?
- Actions
- Effects
- Reducers
- Selectors
In NgRx, the "Effects" library is used to handle side effects like API calls. Effects are a way to interact with external sources such as APIs and perform asynchronous operations while maintaining the purity of reducers.
To achieve lazy loading in Angular, the loadChildren property uses the ________ syntax.
- Array
- Function
- Object
- String
To achieve lazy loading in Angular, you use the loadChildren property with a string that points to the module file to be loaded lazily. This string typically follows a specific syntax, where you specify the path to the module using a module import statement.
When content is projected into a child component, the data binding context remains that of the ________ component.
- Angular
- Child
- Host
- Parent
When content is projected into a child component, the data binding context remains that of the Parent component. This means that any data binding, variables, or properties you use in the projected content within the child component will be based on the data of the parent component that projected it. Understanding this is crucial for effective data communication in Angular.
How can you implement a custom validator that checks if a password and its confirmation are the same in a reactive form?
- Use the 'compare' method in Angular's built-in Validators.
- Create a custom validator function that compares the password and confirmation fields.
- Implement a directive for password confirmation validation.
- Utilize Angular's 'FormGroup' to compare the password and confirmation controls.
To implement a custom validator for password confirmation, you should create a custom validator function that compares the password and confirmation fields. This function should be added to the reactive form controls to ensure that the password and its confirmation are the same. Options 1, 3, and 4 are not the recommended approaches for this specific validation task.