1.What is Angular?
Angular is a popular open-source JavaScript framework for building web applications. It is maintained by Google and offers features for building dynamic, single-page applications (SPAs).
2.What are the key features of Angular?
Key features of Angular include:
- Two-way data binding
- Dependency injection
- Templating
- Component-based architecture
- Routing
- Reactive forms
- Testing support
- Code generation with Angular CLI
3.What is the difference between AngularJS and Angular?
AngularJS (version 1.x) is an older JavaScript framework, while Angular (versions 2 and above) is a complete rewrite of AngularJS. Angular is more modular, performs better, has improved features, and uses TypeScript as the default language.
4.What is TypeScript?
TypeScript is a superset of JavaScript that adds optional static typing, classes, interfaces, and other features to JavaScript. Angular is written in TypeScript and encourages its use for better tooling and developer experience.
5.What are directives in Angular?
Directives are markers on a DOM element that tell Angular to attach a specific behavior or functionality to that element. They can be classified as component directives, structural directives, or attribute directives.
6.What is data binding in Angular?
Data binding is the automatic synchronization of data between the model and the view. Angular offers different types of data binding, including one-way binding ({{expression}}), property binding ([property]=”expression”), and event binding ((event)=”expression”).
7.What is Angular CLI?
Angular CLI (Command Line Interface) is a command-line tool used to create, build, test, and deploy Angular applications. It provides a scaffolding mechanism and simplifies various development tasks.
8.What is dependency injection in Angular?
Dependency injection is a design pattern used in Angular to manage the dependencies of an application. It allows components to request dependencies from an injector rather than creating them directly, making components more modular and testable.
9.What is a module in Angular?
A module is a mechanism to group related components, directives, pipes, and services together. It provides a context for the components to share common functionality and dependencies.
10.What is the purpose of the NgModule decorator in Angular?
The NgModule decorator is used to define and configure an Angular module. It specifies the module’s metadata, such as imports, declarations, providers, and exports.
11.What are Angular templates?
Angular templates are HTML files with additional syntax that allows for dynamic rendering and data binding. They define the structure and layout of the view in an Angular application.
12.What is the Angular component lifecycle?
The Angular component lifecycle consists of several phases: creation, rendering, change detection, and destruction. The lifecycle hooks, such as ngOnInit and ngOnDestroy, allow developers to tap into these phases and perform specific actions.
13.What is Angular routing?
Angular routing is a mechanism to navigate between different components/views in an application. It allows for the creation of multiple pages or views within a single-page application.
14.What are services in Angular?
Services are singleton objects in Angular that provide functionality and data to components throughout an application. They can be used to share data, perform HTTP requests, handle business logic, and more.
15.What are Angular Forms?
Angular Forms are a set of classes and directives that enable capturing and validating user input in forms. Angular offers two types of forms: Template-driven forms and Reactive forms.
16.What is the difference between Template-driven forms and Reactive forms in Angular?
Template-driven forms rely on directives in the template to create and manage the form. They are suitable for simple forms with less complex validation requirements. Reactive forms, on the other hand, are built programmatically using form control objects and provide more flexibility and control over form validation and handling complex scenarios.
17.What is a resolver in Angular?
A resolver is a service in Angular that pre-fetches data before activating a route. It ensures that the required data is available before loading a component, helping to avoid the flickering of empty or incomplete views.
18.How do you handle HTTP requests in Angular?
Angular provides the HttpClient module to make HTTP requests. You can import the module, inject the HttpClient service into your component or service, and use its methods like get(), post(), put(), etc., to interact with APIs.
19.What is Angular CLI and how do you use it?
Angular CLI (Command Line Interface) is a powerful tool for developing Angular applications. It provides a command-line interface to generate components, services, modules, and other Angular artifacts, as well as building, testing, and deploying the application.
20.What is Angular Material?
Angular Material is a UI component library for Angular applications that provides a set of pre-built, reusable UI components following the Material Design principles. It includes components like buttons, forms, dialogs, tables, and more.
21.What is lazy loading in Angular?
Lazy loading is a technique in Angular that loads modules and components only when they are required, rather than loading them all at once. It helps to improve the initial loading time and optimize the performance of large applications.
22.What are Angular guards?
Angular guards are used to control access to routes in an Angular application. They allow developers to implement authentication, authorization, and other custom logic to protect certain routes or perform actions before navigating to a route.
23.What is Angular testing and how do you write unit tests in Angular?
Angular testing involves writing and executing tests to ensure that components, services, and other parts of the application work as expected. Unit tests in Angular can be written using frameworks like Jasmine and tools provided by Angular such as TestBed and ComponentFixture.
24.How do you share data between components in Angular?
Data can be shared between components in Angular using various techniques such as input and output properties, template references, services, and state management libraries like NgRx or RxJS.
25.What is Angular Universal?
Angular Universal is a server-side rendering (SSR) solution for Angular applications. It allows the application to be rendered on the server and sent as HTML to the client, improving performance, SEO, and initial load time.
26.What is Angular change detection and how does it work?
Angular change detection is the process of identifying changes in the application’s data and updating the DOM accordingly. It uses a hierarchical tree structure to track changes and triggers the necessary updates efficiently.
27,What are Angular directives?
Angular directives are instructions in the DOM that Angular uses to manipulate and control the behavior of elements or components. Directives can be structural (like *ngIf and *ngFor) or attribute-based (like ngModel and ngClass).
28.What is the Angular ngFor directive used for?
the ngFor directive is used for rendering a template for each item in an iterable collection. It is commonly used to display lists or tables based on data in the component.
29.What is Angular ngIf directive used for?
The ngIf directive is used for conditionally rendering elements or components based on a boolean expression. It allows you to control the visibility of elements in the DOM dynamically.
30.What is the purpose of Angular decorators?
Angular decorators are used to enhance and modify the behavior of classes and their members. They provide metadata that Angular uses for various purposes, such as component configuration, dependency injection, and routing.
31.What is Angular interpolation?
Angular interpolation is a way to display dynamic data in the HTML template using double curly braces {{}}. It allows you to bind values from the component’s properties or expressions to the view.
32.What is Angular event binding?
Angular event binding is a way to handle DOM events, such as button clicks or input changes, and trigger corresponding actions in the component. It uses parentheses () to bind event handlers to component methods.
33.What is Angular property binding?
Angular property binding is a way to set the value of an HTML element’s property based on a value in the component. It uses square brackets [] to bind component properties to element properties.
34.What are Angular pipes?
Angular pipes are used to transform and format data in the template. They take input values, apply transformations, and display the transformed values in the view. Angular provides built-in pipes like DatePipe and UpperCasePipe, and you can also create custom pipes.
35.What is Angular dependency injection and why is it important?
Angular dependency injection is a design pattern that allows you to provide dependencies to a class without creating them manually. It promotes modularity, testability, and reusability by decoupling components and services.
36.What is Angular ViewChild?
ViewChild is a decorator in Angular used to get a reference to a child component, directive, or DOM element from the parent component. It allows the parent component to access and interact with the properties and methods of the child element.
37.What is Angular ContentChild?
ContentChild is a decorator in Angular used to get a reference to a projected content child component, directive, or element inside a parent component. It allows the parent component to access and manipulate the content projected inside its template.
38.What are Angular forms validators?
Angular forms validators are functions that are used to validate the user input in forms. They can be built-in validators like required or minLength, or custom validators created by developers.
39.How do you handle form submission in Angular?
Form submission in Angular can be handled using the (submit) event or the ngSubmit directive. By binding a method to the form’s submit event or using ngSubmit, you can perform actions like form validation, data submission, or navigation.
40.What is the purpose of ngZone in Angular?
ngZone is an Angular service that provides a wrapper for browser APIs and enables efficient change detection. It helps to execute code in the Angular zone, triggering change detection and ensuring UI updates occur correctly
41.What are Angular directives ngClass and ngStyle used for?
- ngClass: The ngClass directive is used to conditionally apply CSS classes to elements based on certain conditions or expressions in the component. It allows dynamic styling of elements.
- ngStyle: The ngStyle directive is used to conditionally apply inline CSS styles to elements based on expressions in the component. It allows dynamic styling of elements
42 What is Angular interpolation vs. property binding?
- Angular interpolation: Interpolation is used to display the value of a component property or an expression in the template. It uses double curly braces {{}} and evaluates the expression within them.
- Property binding: Property binding is used to set the value of an HTML element’s property based on a component property or expression. It uses square brackets [] and binds the component property to the element property.
43.What is Angular router outlet?
The router outlet is a directive in Angular used to mark the location in the template where the router should render the components corresponding to the current route. It acts as a placeholder for the dynamically loaded components.
44.What is the purpose of Angular HttpClient and how do you use it?
The Angular HttpClient module is used to make HTTP requests to a server. It provides methods like get(), post(), put(), delete(), etc., to interact with APIs. HttpClient returns an Observable, which can be subscribed to for handling the response.
45.What is Angular ng-template?
The ng-template is a directive in Angular used to define reusable templates that can be conditionally rendered using structural directives like ngIf or ngFor. It allows you to define and reuse complex HTML structures in your templates.
46.What is Angular animation and how do you use it?
Angular animations allow you to add visual effects and transitions to elements in your application. You can use the @angular/animations package to define animation states, triggers, and transitions. Animations can be applied to components, directives, or individual elements.
47.What is Ahead-of-Time (AOT) compilation in Angular?
Ahead-of-Time (AOT) compilation is a process in Angular that converts Angular templates and components into efficient JavaScript code during the build process. It helps to improve the application’s performance and load time.
48.What is Angular ng-container?
The ng-container is a structural directive in Angular that provides a logical container in the template without creating an additional element in the DOM. It is useful for grouping elements or applying structural directives to multiple elements.
49.What is Angular ng-content?
The ng-content directive is used for content projection in Angular. It allows you to pass content into a component from its parent component, providing a way to create reusable components with customizable content.
50.What is Angular CLI ng serve command used for?
The ng serve command is used to start the development server for an Angular application. It compiles the application, watches for changes in the source files, and automatically reloads the browser when changes are detected.