Angular Interview Questions and Answers
Question - 81 : - What is Angular Material?
Answer - 81 : -
It is a UI component library. Angular Material helps in creating attractive, consistent, and fully functional web pages as well as web applications. It does so while following modern web design principles, including browser portability and graceful degradation.
Question - 82 : - Why prioritize TypeScript over JavaScript in Angular?
Answer - 82 : -
TypeScript is a superset of Javascript as it is Javascript and extra features like typecasting for variables, annotations, and variable scope, among other things. It is purely object-oriented programming and offers a compiler that can convert it to Javascript-equivalent code.
Question - 83 : - Define the ng-content Directive.
Answer - 83 : -
Conventional HTML elements have some content between the tags. For instance:
Now consider the following example of having custom text between angular tags:
This won’t work like HTML until you use ng-content Directive However, doing so won’t work the way it worked for HTML elements. In order to make it work just like the HTML example mentioned above, we need to use the ng-content Directive. Moreover, it is helpful in building reusable components.
Question - 84 : - Demonstrate navigating between different routes in an Angular application.
Answer - 84 : -
The following code demonstrates how to navigate between different routes in an Angular app dubbed “Some Search App”:
import from"@angular/router";
.
.
.
@Component({
selector: 'app-header',
template: `
`
})
classHeaderComponent {
constructor(private router: Router) {}
goHome() {
this.router.navigate(['']);
}
goSearch() {
this.router.navigate(['search']);
}
}
Question - 85 : - Explain the concept of scope hierarchy in Angular.
Answer - 85 : -
Angular organizes the $scope objects into a hierarchy that is typically used by views. This is known as the scope hierarchy in Angular. It has a root scope that can further contain one or several scopes called child scopes.
In a scope hierarchy, each view has its own $scope. Hence, the variables set by a view’s view controller will remain hidden to other view controllers. The following is a typical representation of a scope hierarchy:
- Root $scope
- $scope for Controller 1
- $scope for Controller 2
- …
- ..
- .
- $scope for Controller n
Question - 86 : - How do Observables differ from Promises?
Answer - 86 : -
As soon as a promise is made, the execution takes place. However, this is not the case with observables because they are lazy. This means that nothing happens until a subscription is made.
While promises handle a single event, observable is a stream that allows the passing of more than one event. A callback is made for each event in an observable.
Question - 87 : - What are the building blocks of Angular?
Answer - 87 : -
There are essentially 9 building blocks of an Angular application. These are:
- Components: A component controls one or more views. Each view is some specific section of the screen. A component contains application logic defined inside a class. This class is responsible for interacting with the view via an API of properties and methods.
- Data Binding: The mechanism by which parts of a template coordinate with parts of a component is known as data binding. In order to let Angular know how to connect both sides (template and its component), the binding markup is added to the template HTML.
- Dependency Injection (DI): Angular makes use of DI to provide required dependencies to new components. Typically, dependencies required by a component are services. A component’s constructor parameters tell Angular about the services that a component requires. So, a dependency injection offers a way to supply fully-formed dependencies required by a new instance of a class.
- Directives: The templates used by Angular are dynamic in nature. Directives are responsible for instructing Angular about how to transform the DOM when rendering a template. Actually, components are directives with a template. Other types of directives are attribute and structural directives.
- Metadata: Metadata lets Angular know how to process a class.
- Modules: Also known as NgModules, a module is an organized block of code with a specific set of capabilities. It has a specific application domain or a workflow. Like components, any Angular application has at least one module, known as the root module.
- Routing: An Angular router is responsible for interpreting a browser URL as an instruction to navigate to a client-generated view. The router is bound to links on a page to tell Angular to navigate the application view when a user clicks on it.
- Services: A very broad category, a service can be anything ranging from a value and function to a feature that is required by an Angular app. Technically, a service is a class with a well-defined purpose.
- Template: Each component’s view is associated with its companion template. A template in Angular is a form of HTML tags that lets Angular know how it is meant to render the component.
Question - 88 : - What is Data Binding? In how many ways can it be executed?
Answer - 88 : -
Data binding is used to connect application data with the DOM (Data Object Model). It happens between the template (HTML) and component (TypeScript). There are 3 ways to achieve data binding:
- Event Binding: Enables the application to respond to user input in the target environment.
- Property Binding: Enables interpolation of values computed from application data into the HTML.
- Two-way Binding: Changes made in the application state get automatically reflected in the view and vice-versa. The ngModel directive is used for achieving this type of data binding.
Question - 89 : - Draw a comparison between the service() and the factory() functions.
Answer - 89 : -
Used for the business layer of the application, the service() function operates as a constructor function. The function is invoked at runtime using the new keyword.
Although the factory() function works in pretty much the same way as the service() function does, the former is more flexible and powerful. In actuality, the factory() function is to design patterns that help in creating objects.
Question - 90 : - Explain the digest cycle in Angular.
Answer - 90 : -
The process of monitoring the watchlist in order to track changes in the value of the watch variable is termed the digest cycle in Angular. The previous and present versions of the scope model values are compared in each digest cycle.
Although the digest cycle process gets triggered implicitly, it is possible to start it manually by using the $apply() function.