Cognizant – Angular Interview Questions

Here is the list of Angular Interview Questions which are recently asked in Cognizant company. These questions are included for both Freshers and Experienced professionals. Our Angular Training has Answered all the below Questions.

1. What is Angular 2?

Angular 2 is an open source JavaScript framework to build web applications in HTML and JavaScript. Angular 2 is not an upgrade of Angular 1 but it is completely rewritten. Angular 2 uses TypeScript which is a superset of JavaScript (It doesn't mean only TypeScript but dart also). We can say that Controllers are replaced with “Components” in Angular 2. In Angular 2, Structural directives syntax is changed.

2. List some advantages of Angular 2 over Angular1.

Angular 2 implements unidirectional-tree based change detection which, again, increases the performance. If you compare the file size, Angular 2 is 20 kb less than Angular 1 which helps in decreasing the load time for apps. Angular 2 provides more choice for languages.

3. What are the new features of Angular 2?

Important Features of Angular 2 are:

Modern, faster, and highly scalable framework.
Equally useful framework for web, mobile, and desktop apps.
Web components based architecture.
Supports Hierarchical Dependency Injection.

4. How do you define transition between two states in angular?

Transition basically means navigating from the current state to a new state. In angular, the transition is an animation-specific function which is used in angular's animation DSL language. Transition declares the sequence of animation steps that will be executed when the entered value is satisfied.

5. What is the difference between observable and promises?

Promises deal with one asynchronous event at a time, while observables handle a sequence of asynchronous events over a period of time. Emit multiple values over a period of time. Emit a single value at a time. Are lazy: they're not executed until we subscribe to them using the subscribe() method.

6. List the differences between Angular 2 components vs. directives.

Components	Directives
Component is used to break up the application into smaller components.	Directive is use to design re-usable components.
Only one component can be present per DOM element.	Many directive can be used in a per DOM element.

7. What is ECMAScript?

Angular ECMAScript is a utility library which will help you write an AngularJS app using ES6’s class system. In addition, angular-ecmascript provides us with some very handy features, like auto-injection without using any pre-processors like ng-annotate.

8. What is Traceur Compiler?

Traceur is a JavaScript compiler popularly used while developing code in AngularJS. It takes ECMAScript Edition 6 (ES6) which mainly includes classes, generators, destroying, etc. and then compiles to ECMAScript Edition 5 (ES5) which runs into the users' browser.

9. Explain Life cycle in Angular?

In Angular, every component has a life-cycle, a number of different stages it goes through from initializing to destroying. There are 8 different stages in the component lifecycle. Every stage is called life cycle hook events.

10. Diff between functional hoisting and variable hoisting

In addition to variables, hoisting applies to functions created using the function declaration syntax. Function declarations, as with the const variable, are defined and initialized in one step. However, functions are hoisted by moving the entire function, not just the declaration, to the top of the scope.

11. What are the basic rules of Decorators?

The decorator allows us to define this intent without having to actually put any code inside the class.

12. What are the new features in CSS3?

Overview of New Features

Box Shadow.
Opacity.
Rounded Corners.
Attribute Selectors.
New Colors.
More than Web-Safe Fonts.

13. What is HTML API?

The AngularJS Global API is a set of global JavaScript functions for performing common tasks like:

Comparing objects
Iterating objects
Converting data

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14. List the modern browsers supported by Angular 2.

Chrome.
Firefox.
Opera.
Safari.
IE version10 and 11.

15. When to use Ngoninit and constructor in Angular 2 ?

For the newly created instance, we can put in it some initialization processing The second one corresponds to a lifecycle hook of Angular2.

16. What is the factory method?

Angular 2 offers three ways to create a service; factory, service, and provider. The factory function allows developers to include some logic before creating the object and returns the created object.

17. Is the jQuery library used in Angular?

AngularJS can use jQuery if it's present in your app when the application is being bootstrapped. If jQuery is not present in your script path, AngularJS falls back to its own implementation of the subset of jQuery that we call jQLite.

18. Is it possible to have multiple ng-app directives on a single page in AngularJS?

The ng-app directive is used to auto-bootstrap an AngularJS application. And according to AngularJS Documentation, only one AngularJS application can be auto-bootstrapped per HTML document.

19. What is internationalization? How can it be implemented in AngularJS?

Internationalization allows you to show locale-specific information on a site. AngularJS is supporting inbuilt internationalization only for three types of filters: date, currency, and numbers. In order to implement internalization, you only need to incorporate the corresponding js as per the locale of the country.

20. What do you mean by $rootscope in AngularJS?

All applications have a $rootScope which is the scope created on the HTML element that contains the ng-app directive. The rootScope is available in the entire application. If a variable has the same name in both the current scope and in the rootScope, the application uses the one in the current scope.

21. What is bootstrapping?

Bootstrapping is a technique of initializing or loading our Angular application. let's walk through our code created in Create your First new Angular project and see what happens at each stage and how our AppComponent gets loaded and displays “app works!”.

22. What is string interpolation?

Interpolation refers to embedding expressions into marked up text. By default, interpolation uses the double curly braces {{ and }} as delimiters. Angular replaces current Customer with the string value of the corresponding component property

23. What is Prototype?

Prototype bind is a built-in function, which creates a new function with the context bound to the context given from the parameter. The major use case for this function in Angular template is the property binding ( @Input ) of function.

24. What is hoisting in JS?

Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their scope before code execution. Inevitably, this means that no matter where functions and variables are declared, they are moved to the top of their scope regardless of whether their scope is global or local.

25. Explain ngFor and ngIf?

NgIf displays the template content when the condition is true. Here, everything related to the ngFor structural directive applies to the

<ng-template>.

26. Write a syntax for ngFor with example

The syntax is *ngFor="let of " . is a variable name of your choosing, is a property on your component which holds a collection, usually an array but anything that can be iterated over in a for-of loop.

27. If you provide a service in two components "providers" section of @Component decorator, how many instances of service shall get created?

One instance can be created if we provide a service in two components because Service is a singleton object.

28. How to declare a component in Angular 2 ?

Import the Component Object. import { Component } from '@angular/core'.
Add Meta-data to our Component using TypeScript Decorators.
Export the Component.
Bootstrap our Component.

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TOP MNC's ANGULAR INTERVIEW QUESTIONS & ANSWERS

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Cognizant Angular Interview Questions