Most Commonly Asked Angular Interview Questions

Software Development | Design, Digital, Technology | Oct 27,2021 | By Shashvathi G

As a framework for constructing front-end web applications, Angular has gained in popularity. During your interview, this collection of Angular interview questions will surely come in helpful.

1.What kind of DOM does Angular support?

ANS:The DOM (Page Object Model) views an XML or HTML content as a tree structure, with each node representing a different portion of the document. Angular makes use of the standard DOM. This updates the entire HTML tag tree structure until it reaches the data to be updated. Angular, on the other hand, employs Change Detection to guarantee that speed and performance are not jeopardised. This brings us to the end of the article. We strongly advise you to review the key ideas for an interview. It's always a plus to write code in the locations where it's needed.

2.What is the difference between eager and lazy loading?

ANS:The default module-loading approach is eager loading. Eager loading feature modules are loaded before the programme starts. This is usually reserved for applications that aren't too large. When there is a demand, lazy loading dynamically loads the feature modules. This speeds up the application. It's utilised in larger projects where all of the modules aren't required right at the start.

3.What exactly is Bootstrap? How does it integrate with Angular?

ANS:Bootstrap is a robust framework. It's a set of HTML, CSS, and JavaScript tools for generating and developing responsive web pages and apps. The bootstrap library may be included into your programme in two ways. CDN Angular Bootstrap - Bootstrap A Content Delivery Network (CDN) is a public network that distributes content to users. It allows you to load CSS and JavaScript files from its servers remotely. Angular Bootstrap through NPM - Another option for incorporating Bootstrap into your Angular project is to use NPM to install it into your project folder (Node Package Manager). install bootstrap using npm install jquery using npm

4. What exactly is ngOnInit?

ANS:Angular uses the ngOnInit lifecycle hook and callback method to indicate that a component has been created. It doesn't take any arguments and returns a void type.

5.In Angular, what are Promises and Observables?

ANS:While both concepts in Angular deal with asynchronous events, Promises deal with one at a time, whereas observables deal with a series of events over time. Promises are objects that emit just one value at a time. They go into effect right once they're created and can't be stopped. They are Promises to the kid Push Errors. Observables are only performed when the subscribe() method is used to subscribe to them. Over a period of time, they emit several values. They aid in the execution of tasks such as forEach, filter, and retry, among others. Subscribers receive errors as a result of their actions. The listener is stopped when the unsubscribe() function is used.

6.In Angular, what are Services?

ANS:Angular Services are utilised by several components to execute operations. Data and picture retrieval, network connectivity, and database administration are examples of these jobs. They handle all of the component's operating functions and prevent rewriting code. A service may be created once and then injected into all of the components that need it.

7.Describe how to use the @Component Decorator.

ANS:Components are created using the TypeScript class. The "@Component" decorator is then applied to this class genre. The decorato's function is to take a metadata object containing pertinent component information.

8.I'm not sure what the difference is between AOT and JIT.

ANS:Ahead of Time (AOT) compilation translates your code as it is being built, rather than when it is downloaded and run by the browser. This guarantees that the browser renders content more quickly. Include the —aot option with the ng build or ng serve commands to indicate AOT compilation. The Just-in-Time (JIT) compilation technique converts computer code to machine code as it is being executed or performed. Dynamic compilation is another name for it. When you use the ng build or ng serve CLI commands, JIT compilation is used by default.

9.What are Template statements and how do I use them?

ANS:In HTML, template statements are properties or methods that respond to user actions. With these template declarations, the application you design or are working on may engage users by allowing them to submit forms and view dynamic information.

10.In Angular, what is String Interpolation?

ANS:String interpolation is a one-way data binding method that delivers data from TypeScript code to an HTML display. Double curly braces are used to indicate it. This template expression allows the data from the component to be shown in the view.

11.In Angular, what do you mean by scope?

ANS:In Angular, the scope connects the HTML, or view, and the JavaScript, or controller. It is, as expected, an object with the methods and attributes that are provided. Both the view and the controller have access to the scope. In Angular, you supply the $scope object as a parameter when creating a controller.

12.What are controllers and how do they work?

ANS:The data in AngularJS apps is controlled by AngularJS controllers. They're just ordinary JavaScript Objects. The application controller is defined using the ng-controller directive.

13.In Angular, what is view encapsulation?

ANS:View encapsulation determines whether a component's template and styles may impact the entire programme or vice versa.

14.In Angular, what are filters?

ANS:Filters are used to show an expression to the user after it has been formatted. View templates, controllers, and services may all benefit from them.

15.What is a ngModule, exactly?

ANS:NgModules are containers that assign a section of code to a certain application domain or workflow. @NgModule receives a metadata object that explains how to build a component's template and produce an injector at runtime. It also uses the export property to identify the module's components, directives, and pipes, making some of them public so that external components can utilise them.

16.Impure Pipes are what they sound like.

ANS:Angular calls an impure pipe for every change detection cycle, independent of the change in the input fields. For these pipes, several pipe instances are produced. The inputs to these pipes can be changed.

17.What are Pure Pipes, exactly?

ANS:These are pipelines with just pure functions. As a result, a pure pipe uses no internal state, and the output remains constant as long as the parameters provided remain constant. When Angular detects a change in the arguments being given, it invokes the pipe. Throughout all components, a single instance of the pure pipe is used.

18.What is the PipeTransform interface and what does it do?

ANS:The convert() function gets an input value and changes it into the appropriate format, as the name implies. It's commonly used to create bespoke pipelines.

19.What exactly is an AOT collection? What are the benefits?

ANS:During the build step, before the browser downloads and runs the code, the AOT compiler turns the Angular HTML and TypeScript code into JavaScript code. The following are some of its benefits. Rendering that is faster There will be fewer asynchronous queries. The download size of the Angular framework has been reduced. Errors in templates are detected quickly. Better security

20.In Angular, what are components?

ANS:Components are the fundamental building pieces of an Angular application's user interface. Every component is a subset of directives and is coupled with a template. An Angular application usually starts with a root component, the AppComponent, and then branches out into various components to form a hierarchy.

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