Most Common Top Angular Interview Questions And Answers to a successful interview

Angular is gaining popularity among experienced and new developers. The well-paying jobs and businesses it can land you are the key factors in its popularity. Let us look at the most common angular interview questions nowadays.

Angular is a powerful front-end JavaScript framework that is frequently utilized in the creation of apps. There is a huge need for Angular developers due to the platform’s growing popularity.

In this article on Angular Interview Questions, we’ll go through some frequently asked questions and how to respond to them.

1. What Exactly Is Angular?

Google developed the open-source Angular framework for building web applications. It is used to create frontend, single-page JavaScript apps. It is a complete framework that handles numerous front-end web application components, including HTTP requests, validation, layout, routing, forms, reactivity, etc.

2. How Does An Angular Application Function?

Angular’s components provide the foundation of how it functions. The configuration file angular.json is where the Angular application gets to operate. The main file, configurations, and paths are all located in this file, which the builder reads.

Soon, the process will start. Following that is the main.ts file, which serves as the configuration file’s entry point. Basically, it aids in developing the browser environment needed for the program to execute. The Angular application is currently bootstrapped using the app. module.ts.

The APP.COMPONENT.TS file now contains the app component that is bootstrapped. To request that Angular load the application component, the INDEX.HTML file is now called. The APP.COMPONENT.HTML file shows the component’s content after it has loaded. The components we’ve spoken about here help make the Angular application function this way.

3. Describe Metadata

We instruct Angular on how to handle a class by using metadata. Unless we explicitly notify Angular that a component is being used, which we do with the support of metadata, a component behaves as a class when it is used.

A decorator is used in TypeScript to attach metadata. To simplify, decorators can be defined as functions familiar with the setup of classes and how they should operate.

4. Define TypeScript

The majority of front-end developers prefer the TypeScript capability that Angular offers. By automatically filling in, TypeScript makes efficient error detection and simple compilation possible. Additionally, it provides robust interfaces, access restrictions, hybrid types, etc. When combined, all of these result in a shorter development period.

5. What Function Does The Async Pipe Serve?

The async pipe aims to mark the default parts of a program that need to be inspected for changes. It returns the most recent value it has emitted and subscribes to a Promise or Observable. The async pipe identifies the components after this new value has been emitted.

The async pipe automatically disconnects or unsubscribes if any component is deleted. Similar to this, the async pipe unsubscribes from the previous Promise or Observable and subscribes to the new one if the expression reference of the component changes.

6. What Does The ngFor Directive Do?

The ngFor directive is used as and when necessary. Its primary function is to repeat a section or parts of an HTML template, repeating each item at least once in a collection. In short, it uses the ngFor directive to construct individual templates for each iteration as it gets simpler.

7. What Does The ngIf Directive Do?

The ngIf directive’s goal is to destroy or reconstruct a section of the DOM tree using an expression. The element is deleted from the tree if the ngIf directive determines whether or not the evaluated expression is false. If the given expression is fake, it is replaced with a matching element from the DOM tree.

8. What If Script Tag Is Used Within Template?

When a script tag is used inside a template, Angular flags it as an unsafe value and initiates the sanitization process on its own. This eliminates the script tag while protecting the text element’s content. This way, the tag eliminates the possibility of an attack during the entire procedure.

9. Define Template Expressions

An expression that generates a value and is enclosed in double curly brackets is known as a template expression in Angular. Angular executes the template expression and applies it to a binding target property. Any of these—an HTML element, a directive, or even a component—can now be the binding target.

10. What Do You Mean By Template Statements?

Template statements in Angular refer to the operations or elements utilized in HTML tags generated in response to user events. These statements are general templates that enable the application to attract users via activities like presenting dynamic information or completing forms.

11. Should I Bootstrap Custom Elements?

The answer is no! No matter the type of development in question, bootstrapping a  custom element is not advised. They are generally done when introduced to the DOM. Additionally, Angular’s custom elements are immediately deleted when they are removed from the DOM.

12. How Are Typings For Custom Elements Defined?

Using NgElement and WithProperties exported from @angular/elements, Angular developers may define the typings for custom elements. The component below is a simple container with an input property:

@Component(…)
class MyDialog {
@Input() content: string;
}

13. What Do You Mean By Custom Elements?

You can design a tag whose content is generated and managed by JavaScript code using a custom element to expand HTML.

14. What Exactly Is A Bootstrapping Module?

The “Bootstrapping Module” in Angular can be expressed as a root module leveraged for launching or bootstrapping the application. Every Angular project contains a Bootstrapping Module, which is kept in the AppModule class. The AppModule is another name for the Bootstrapping module.

15. What Is Content Projection?

The term “content projection” in the context of Angular is a technique where you may project the content you wish to utilize within another component. Consider a Card component, for instance, which may take content from another component.

16. What Does Data Binding Mean, Exactly?

One of the most significant and effective aspects that helps in creating communication between the component and DOM is data binding. Since there is no longer a need to worry about data pulling or pushing between the template and the component. The ultimate purpose of binding is to simplify the development of interactive applications.

17. What Distinguishes An Angular Decorator From An Annotation?

Decorators in Angular are design patterns that allow modifying or enhancing the relevant classes without altering the real source code.

On the other side, Angular uses annotations to create an annotation array. They are a set of metadata for the specified class and use the Reflective Metadata library.

18. What Does Angular’s AOT Compilation Mean?

The Angular AOT (ahead-of-time) compiler transforms TypeScript and Angular HTML and code into JavaScript coding while following the development process, greatly speeding up rendering. This compilation procedure is necessary because Angular employs HTML and TypeScript code. The compiler transforms the code into JavaScript so that the application’s browser may use it.

19. What Are The AOT’s Three Phases?

The three phases are:

1. Code generation
2. Template type checking
3. Code analysis

20. What Exactly Does String Interpolation Mean?

The mustache syntax, commonly known as string interpolation, in Angular only permits one-way data binding. Double curly brackets are used in a particular syntax for this purpose so that the component data may be shown.

The JavaScript expressions that Angular must run to acquire the result are included within the brackets and may be put into the HTML code. Additionally, these expressions are consistently updated and saved as part of the digest cycle.

21. What Do You Mean By Dynamic Components?

The Angular framework’s Dynamic Components are components that simplify the process of developing complex apps. Typically, the runtime is when dynamic components are created and added to the program.

22. What Does The Base HREF Tag Do?

All the related URLs on a given page need to have a base URL specified by the href attribute. The base href tag is a base path to the module files, components, and templates during navigation via the Angular router.

23. What Is DOM?

The Document Object Model, or DOM in its full name, is in charge of expressing changes in an application’s architecture as well as the content of a web page. The document can only be readily edited, altered, and accessed with the aid of APIs in this case since all the objects are arranged in the shape of a tree.

24. What Are Templates?

Angular-specific elements and attributes are used in the HTML to create Angular templates. The user may be presented with a dynamic view by combining the templates with the controller and model data, which can then be displayed.

25. What Exactly Are The Angular Components?

 In Angular, components serve as the fundamental building blocks of the UI (User Interface). A component for a particular user interface area is made up of HTML, CSS, and JavaScript. These may be compared to unique HTML elements that only Angular can comprehend.

As the compiler namespacing them, these components are isolated, so code and styles from one component do not influence the others in the program. The Angular framework then assembles these parts to create the user interface that the browser will display.

26. What Does The Term “Angular Material” Mean?

A UI component framework called Angular Material enables experts to create consistent, aesthetically pleasing, and fully functioning online apps, websites, and web pages. It can do so by adhering to contemporary web design concepts like gentle browser and degradation probability.

27. Describe RxJS

The word RxJS means Reactive Extensions for JavaScript and refers to a library. It is utilized so that we may implement reactive programming in our JavaScript project by using observables.

As it enables us to combine our callback-based or asynchronous code into a sequence of actions executed on a data stream that emits values from a publisher to a subscriber, RxJS is utilized in several well-known frameworks, including Angular. Libraries exist for Java, Python, and other languages that enable the creation of reactive programming utilizing observables.

28. What Does Angular’s Digest Cycle Process Involve?

The digest cycle in Angular is the procedure via which developers observe a watch list to keep track of changes in the value of the watch variable. Comparing the current and prior versions of the scope model values occurs in each digest cycle.

29. What Does Rxjs’s Term “Subscribing” Mean?

In RxJS, to access the data that passes via an observable, we must subscribe to that observable. This information is produced by a publisher and used by a subscriber. When we subscribe to an observable, we pass in a function for the data and a separate function for errors so that, in the event of an error, we may show some message or process the message in some way.

30. What Is REST?

Representational State Transfer is known as REST in Angular. It is an API that responds to HTTP requests. So, the requested URL leads to the data that needs to be processed, and an HTTP function is then utilized to determine which operation must be carried out on the provided data. RESTful APIs are the name given to the APIs that use this approach.

31. What Is The Scope?

In Angular, a scope is an object that alludes to the application model. It is a setting in which expressions can be used. These scopes are arranged in a hierarchical manner that resembles the DOM structure of the application. A scope aids in observing expressions and spreading various occurrences.

32. Describe Angular CLI.

The acronym Angular CLI stands for Angular command-line interface. Professionals may utilize Angular’s CLI tools to create components, deploy them immediately, test them, and execute various other tasks.

33. How Can You Make Directives With The CLI?

The steps below are used to build a directive using Angular CLI:

1. Using Angular CLI, run the following command to launch a new project:

‘ng new [application-name]’

• Use the following command to now transform the directory into a new directory:

 ‘cd [application-name]’

• Use the following command to create a new directive after changing the directory:

‘ng generate directive [path-to-directives/my-directive]’

34. What Is Schematic?

Schematics are code generators that use templates to allow complicated logic. It is typically bundled into collections and set up using npm. Schematics are used to change a software project by creating or altering codes.

35. What Does A Rule In Schematics Mean?

In Schematic, the term “Rule” refers to a set function that accepts a Tree, modifies it, and outputs a fresh Tree.

36. What Is Schematics CLI?

Projects for web-based apps are transformed using the Schematics CLI.

37. What Is HttpClient & What Advantages Does It Offer?

An Angular module called HttpClient is used to interact with a backend service via the HTTP protocol. We often utilize the fetch API in front-end apps to send requests. The fetch API, however, makes use of promises. Although promises are helpful, they lack the extensive functionality that observables provide.

Because HttpClient delivers the data as an observable that we can subscribe to, unsubscribe from, and perform a number of actions on using operators, we utilize it in Angular. Both promises and observables may be derived from one another. Promises can be turned into observables.

38. What Does Angular’s Multicasting Mean?

The HttpClient module in Angular allows us to interface with a backend service and retrieve data. Once the data has been retrieved, we may broadcast it to numerous subscribers in a single execution. Multicasting is the process of broadcasting data to several subscribers. It is very helpful when several components of our apps are awaiting data.

We must utilize an RxJS topic to use multicasting. Observables do not support multiple subscribers because they are unicast. Subjects do, however, support many subscribers and are multicast.

39. What Does An Angular Directive Mean?

In Angular, a directive is used to expand the syntax and functionality of a typical HTML view. The Angular compiler comprehends and gives particular meaning to Angular directives.

Angular searches the whole code base for a directive that has been registered before starting to combine the TypeScript, CSS, and HTML files into a single JavaScript file. If a match is discovered, the compiler modifies the HTML view accordingly.

Angular comes with a large number of directives. To ensure that the compiler is aware of them and uses them during the compilation stage, we can build our directives and communicate their functions to Angular.

40. What Will Happen If You Don’t Provide The Observer With A Handler?

The observer automatically ignores notifications of that type when a handler is not provided for them, and the observer instance only publishes value when it is subscribed to.

41. What Are Angular Elements?

Angular components, a web standard for defining new HTML elements bundled as custom elements, are referred to as angular elements. “Web Components” is another name for these unique elements. When added to the DOM tree, the Angular custom elements bootstrap themselves automatically.

42. What Browsers Does Angular Elements Support?

Through polyfills, angular elements are supported by Chrome, Edge (Chromium-based), Firefox, Opera, Safari, and other modern browsers because Angular is built on the most recent web platform standards. Full Angular apps can run thanks to polyfills.

43. What Function Does SPA Serve In Angular?

“Single Page Application” is what it stands for. Even though the URL changes often, this technology simply keeps track of one page, index.html. Compared to conventional web technology, SPA technology is quick to develop and relatively simple.

44. Describe The Various Angular Directive Types.

1. Components: A directive with a template is all that a component is. With the use of TypeScript code, CSS styles, and an HTML template, it is used to define a single element of the user interface. When defining a component, we send an object with a selector property and utilize the component denoted by the @ symbol. The selector property informs the Angular compiler of the HTML element that the component belongs to, allowing it to know to replace that tag with the component template when it comes across it in HTML.

• Structural: To alter a view’s structure, use structural commands. For example, the ngIf directive may be used to show or conceal data based on a property. Similarly, the *ngFor directive can be used to add a list of data to the markup. These directives are known as “structural directives” because they alter the template’s structure.

• Attribute: An attribute directive can alter an element, component, or another directive’s look or behavior. They serve as an element’s characteristics. Aspect directives include things like ngClass and ngStyle.

45. What Function Does Angular’s Common Module Serve?

The common module in Angular is a module that contains all the frequently used elements of Angular, such as services, pipes, directives, etc. It is accessible under the package @angualr/common.

Additionally, it contains a few sub-modules, including the HttpClientModule from the @angular/common/http package. Due to Angular’s modular design, its capabilities are kept in manageable, self-contained modules that can be imported and added to our applications as needed.

46. What Distinguishes JavaScript Expressions From Angular Expressions?

JavaScript expressions and Angular expressions are very different since Angular allows us to write JavaScript in HTML, but plain JavaScript does not. Additionally, all Angular expressions are localized.

However, these JavaScript expressions only apply to the global window object. But when the Angular compiler takes the Angular code we’ve written and turns it into normal JavaScript, which a web browser can subsequently understand and utilize, these discrepancies are resolved.

47. What Does Angular’s Server-Side Rendering Entail?

In a typical Angular application, JavaScript manages all user interactions while the browser runs our application. Due to this, our page’s load time can occasionally be significantly slowed down if we have a massive application with a large bundle size since it must download all the necessary files, parse the JavaScript, and execute it.

We can utilize server-side rendering to get around this delay, which enables us to deliver a completely drawn page from the server that the browser can display and then let the JavaScript code handle any further user interactions.

48. What Distinguishes The Content Assigned To A Dom Element’s InnerHTML Property From Content That Has Been Interpolated?

When we enter a JavaScript expression inside double curly braces, such as “someExpression(),” Angular interpolation takes place. Using this, dynamic content may be added to a web page. However, we may achieve the same result by supplying some dynamic content to a DOM element’s innerHTML attribute.

The difference between the two is that the compiler always escapes the interpolated content in Angular, preventing HTML from being interpreted. The browser shows the code with brackets and symbols rather than the result of the interpreted HTML. In contrast, innerHTML interprets the content as HTML code if it is HTML.

49. What Do Angular’s Httpinterceptors Do?

HttpInterceptors are used to analyze and alter HTTP requests and HTTP responses. They are a component of the @angular/common/HTTP module. These interceptors are designed to conduct checks on a request, alter the answer, and carry out cross-cutting tasks like logging requests, user authentication via requests, response compression using gzip, etc.

50. What Is Folding?

When Angular generates the code, it’s conceivable that some of the non-exported members get folded. This procedure, known as folding, in which the collector evaluates an expression and records the outcome in the.metadata.json file, is known as folding.

51. Describe Angular’s Authorisation And Authentication Processes

A user’s login information is sent to a server-based authenticate API. After validating the credentials, the server delivers a JSON web token (JWT), which contains the current user’s properties and data. Additionally, JWT makes it simple to identify the user; this procedure is known as authentication.

Users have different sorts and levels of access after logging in; some may have unrestricted access to all resources, while others may not. The level of access for these users is determined by authorization.

52. Describe NoopZone

NoopZone helps Angular in determining and understanding when to initiate the change detection. However, the NoopZone also be defined if Angular is to be used without a zone.

Conclusion

By reading through these commonly asked questions, you may better understand the types of interview questions and their answers, which will also help you understand Angular interviews and Angular as a framework.

These Angular interview questions and responses may have piqued your curiosity about the framework. You can count on them to make your next job interview a success.

Remember, Angular happens to be one of the most prominent platforms that are often upgraded. Stay updated!

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