Angular Basic Interview Questions : most asked interview Question and answer for Freshers

Angular Basic Interview Questions : A well-liked JavaScript framework for creating dynamic web apps is called Angular. Because of its component-based architecture, the application is broken up into more manageable and interchangeable parts. Large-scale application management and maintenance are facilitated by this.

A software developer with expertise in creating web apps with the Angular framework is known as an Angular developer. They are in charge of Angular application development, testing, and design. Angular developers usually know a lot about HTML, CSS, and JavaScript. They must also be conversant with the best practices of the Angular framework.

here are some Angular Basic Interview Questions : most asked interview Question and answer for Freshers

1.What are Directives in Angular?

Using reusable HTML elements, directives in Angular allow you to build new elements or expand the functionality of existing ones, giving you the ability to alter the behavior of the Document Object Model (DOM) in your online application.

Building reusable and adaptable Angular applications is made possible with the help of directives. Developers may construct dynamic and interactive user interfaces by learning how to use directives efficiently.

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2.What is an AOT compilation?

In Angular, an operation known as “Ahead-of-Time” compilation occurs when TypeScript code is compiled straight into JavaScript during the build phase, prior to the deployment of the application. As a result, there is no need for the browser to build the code dynamically, which leads to quicker initial load times and better performance.

By analysing the entire application at build time when utilizing AOT compilation, Angular’s compiler improves code efficiency and finds possible issues earlier in the development cycle. This may result in a development workflow that is more simplified and effective.

Larger applications or situations where performance is crucial benefit greatly from AOT compilation. It’s crucial to consider the trade-offs between quicker runtime performance and longer build times, though, as it can lengthen build times.

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3.What are Pure Pipes? 

In Angular, pure pipes are functions that solely undergo automatic reevaluation in response to changes in their input values. Compared to impure pipes, which undergo reevaluation each time the component’s change detection cycle completes, they are therefore more efficient.

For straightforward data changes like formatting dates, currencies, or integers, pure pipelines are frequently utilized. They work best in situations when the output can be cached and the input values are fixed. DecimalPipe, DatePipe, and CurrencyPipe are a few instances of pure pipes.

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4.What are Impure Pipes?

In Angular, impure pipes are functions that are evaluated again each time the component’s change detection cycle completes. This makes them less efficient than pure pipes, which are evaluated only when their input values change. Impure pipes are frequently used for side effects, like HTTP requests and external service access, as well as complex transformations that cannot be cached or situations in which the output depends on variables other than the input values. However, usage of impure pipes should be limited to avoid performance problems.

5.What is an ngModule?

In Angular, ngModules function as building pieces that arrange and compose your application into harmonious sections. They give you a means to organize directives, pipelines, services, and other related components into groups, which helps you manage and scale your code. Consider them as containers that delineate a particular functional segment of your application.

The @NgModule decorator is used by NgModules to define their settings. This decorator accepts a metadata object that instructs Angular on how to build and execute the code within the module. It specifies which directives, pipes, and other elements belong to the module and which ones other modules may use. Furthermore, NgModules can offer services to the dependency injection system of the application, opening them up to other modules.

6.What are controllers?

Classes called controllers in Angular manage the data and logic related to a particular view or component. They serve as a bridge between the application’s data model and user interface (UI). Consider them to be the programmers’ brains, altering the user interface (UI) in response to user input and the status of the application.

Typically, attributes and methods that describe the information and capabilities of the component they govern are found in controllers. They could respond to user-initiated events, including button clicks or form submissions, and modify the user interface (UI) appropriately. In addition, controllers can communicate with other parts of the program and engage with services to retrieve or alter data.

7.What is String Interpolation in Angular?

Angular’s string interpolation capability is a strong point that lets you dynamically add values to HTML templates. It offers a clear and simple method for attaching data from your components to the page’s elements.

String interpolation allows you to easily include data into your templates without the need for manual string and value concatenation in your HTML code. In your HTML, you can directly access component properties or method calls by enclosing expressions in double curly braces {{ }}. Your templates become easier to read and update as a result.

8.Why were client-side frameworks like Angular introduced?

The shortcomings of conventional web development techniques were addressed with the introduction of client-side frameworks like Angular. To create dynamic HTML pages in the early days of the web, the majority of apps mostly relied on server-side scripting languages like PHP or ASP.NET. Due to the need to refresh the entire page for every user input, this method frequently resulted in delayed page loading, especially for sophisticated applications.

In contrast, client-side frameworks use JavaScript’s capabilities to handle a large portion of the logic and rendering of the application within the browser. As a result, users can enjoy more engaged and responsive user experiences because only the essential portions of the website require updates. Furthermore, client-side frameworks frequently offer an organized method of managing and organizing code,

9.What are the advantages of Angular over React?

10.What are Single Page Applications (SPA)?

Web applications known as Single Page Applications (SPAs) load a single HTML page and then dynamically change its content without necessitating page loads in complete. With each user interaction, classic multi-page applications (MPAs) load a new page; in contrast, SPAs use JavaScript and AJAX to retrieve and present content instantly.

Numerous benefits come with this strategy, including less server load, enhanced performance, and enhanced user experience. SPAs have the ability to handle complicated interactions more effectively, load pages more quickly, and offer a more seamless navigation experience. However, they might necessitate a larger initial development investment and pose problems with browser history management and SEO.

11.What are templates in Angular?

Templates in Angular are just HTML files that specify the organization and design of the user interface (UI) for your application. They act as guides for how elements including as text, graphics, and interactive controls should be presented in the browser for various components.

Written using a particular syntax, templates enable you to manage user interactions, provide dynamic information, and tie data from your components to the user interface. They frequently have unique Angular directives and syntax that allow for conditional rendering, data binding, and data looping. You may construct dynamic and rich web applications by assembling components and their logic with templates.

12.What is data binding in Angular?

Angular’s data binding feature is a robust way to link the data of your component to the elements in your templates. It creates a dynamic connection between the values shown in the user interface and the data kept in the properties of your component. This guarantees that your user interface (UI) always reflects the status of your application and removes the need for manual DOM manipulation.

Property binding and event binding are the two main forms of data binding offered by Angular. By using property binding, you may update the user interface (UI) in response to modifications made to the properties of your component. Alternatively, you can manage user interactions in your template and update the component’s data accordingly by using event binding. You may design engaging and responsive user interfaces that flawlessly represent the underlying data in your application by mastering the technique of data binding.

13.What are Decorators and their types in Angular?

In Angular, decorators are specialized functions that are used to change the behavior of classes, properties, methods, and parameters. They offer a potent means of enhancing and personalizing the capabilities of Angular pipes, services, directives, and components.

Many built-in decorators, including @Component, @Directive, @Pipe, @Injectable, and @NgModule, are available with Angular. These decorators specify these entities’ fundamental setup and structure. The selector, template, styles, and other metadata of the component, for instance, are specified by the @Component decorator. You can also write your own decorators to provide reusable functionality across your application or to encapsulate common patterns.

14.How does Angular handle routing?

With the help of angular routing, you may move between sections of your online application without having to reload the entire page. It offers an organized method for creating routes and assigning them to particular parts, so users can move between views in your application with ease.

Angular configures routing inside your application using the RouterModule. The components that should be rendered for each route as well as the URL URLs are specified when you define a route in a configuration file. Angular intercepts the request and loads the relevant component into the relevant area of the page when a user navigates to a specified URL. This allows for quick and seamless navigation without requiring a page reload.

15. Explain Angular’s change detection mechanism.

Angular’s change detection mechanism is in charge of automatically changing the user interface (UI) whenever data in the program changes. It functions by routinely examining the expression values in your templates and contrasting them with their initial values. Angular refreshes the necessary DOM elements to reflect the updated data whenever a change is detected.

Zone-based methodology is employed by Angular to initiate change detection. This means that the zone system in Angular recognizes changes and initiates a change detection cycle whenever specific asynchronous events take place, including user interactions, HTTP requests, or timer callbacks. This guarantees a responsive user experience and keeps the UI in line with the underlying data.

16. What is Lazy Loading in Angular, and why is it important?

In Angular, lazy loading is an approach that waits to load some modules until they are really needed. This shortens the time it takes for your application to load initially by loading only the modules that the user is currently using. Modules are loaded on demand as the user moves through the application.

The efficiency of your Angular application can be greatly enhanced by lazy loading, which is crucial for larger applications with several modules. Your user experience can be made faster and more responsive by cutting down on the initial load time. Furthermore, because only the modules that are actively being used are loaded into memory, lazy loading can help you get the most out of the memory that your application uses.

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