Angular Interview Questions and Answers - Part 02
Angular is a popular open-source single-page application design framework and development platform. It is a robust front-end JavaScript framework that is widely used for front-end application development. Nowadays Angular is very common as frontend technology so it is very common for the interview point as well.
Introduction
This is the Angular Interview Questions and Answers series. Here we will see 200+ Most Frequently Asked Angular Interview Questions. This is the 2nd part of the Angular Interview Questions and Answer series.
I will highly recommend that please visit the following parts before continuing to this part:
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Q013. What are the differences between AngularJS vs Angular?
Q014. What is the difference between jQuery vs Angular?
Q015. What are the advantages of Angular?
Q016. What are the disadvantages of Angular?
Q017. Why were client-side frameworks like Angular introduced?
Q018. What are the other different Client-Side SPA Frameworks available in the Market?
Q019. What is TypeScript?
Q020. What are the features of TypeScript?
Q021. Why TypeScript is developed while having JavaScript?
Q022. Why to use TypeScript? What are the advantages of TypeScript?
Q023. What is the difference between JavaScript vs TypeScript? How does TypeScript differ from JavaScript?
Q024. What is the difference between TypeScript vs ECMAScript?
Q025. What are the different data types supported by TypeScript?
Angular Interview Questions and Answers: Part 02
Q013. What are the differences between AngularJS vs Angular?
AngularJS was the very first version of Angular. The later Angular versions were a complete rewrite of AngularJS. There is nothing common between Angular and AngularJS except the core developer's team.
Q014. What is the difference between jQuery vs Angular?
The main difference between jQuery and Angular is that jQuery is a JS library, whereas Angular is a JS frontend framework.
jQuery is a feature-rich Javascript library that is primarily used for DOM manipulation whereas Angular is a front-end development framework that is used for creating single-page applications.
Jquery does not have two-way binding features, whereas Angular has critical features like routing, directives, two-way data binding, models, dependency injection, unit tests, etc.
Jquery becomes complex and challenging to maintain when the project size increases, but in the case of Angular, things are different as they are manageable at a big project size.
Q015. What are the advantages of Angular?
The AngularJS framework was re-written and called Angular or "Angular 2". At this point, "AngularJS" now referred to the 1.x versions, and "Angular" without the "JS" referred to versions 2 and up.
The following are the advantages of Angular:
SPA: Angular is used for creating Single Page Applications.
Use of TypeScript: Angular uses TypeScript as the primary programming language. TypeScript adds a lot of syntactic sugar to JavaScript. With TypeScript, we also get several productivity benefits.
MVC Architecture: Angular is a full-fledged MVC framework. It provides a firm opinion on how the application should be structured.
Dependency Injection: Dependency injection or DI is one of the most important application design patterns and Angular has its own dependency injection framework. Components dependent on other components can be easily worked around using this feature.
Lazy Loading: Instead of loading all the application code at once in the browser which may cause more loading time and a slower initial render of the web page, it loads only what is necessary. This is called lazy loading. Only the modules that are required are loaded initially and more modules or rather chunks of code are loaded as an when required.
Routing: The in-app navigation in Angular is taken care of by the Angular Router. Angular router is a very powerful and flexible navigational service. Angular Router has built-in support for lazy loading components, so the modules are loaded from the server as the user navigates within the app.
Bi-Directional Data Flow: Angular supports Two-way Data Binding and updates the real DOM dynamically.
Availability of Large Packages: There is a huge repository of open-source packages available for Angular developers. Some of these packages are maintained by the official Angular team and most of these are taken care of by the community of developers as well.
Maintained by Google: The best thing about Angular is that it is developed and maintained by Google. As it is backed by a trusted company, trust is well established within the community.
Large Community and Ecosystem: Angular is actively maintained and has a large community and ecosystem. You can find lots of material on this framework as well as many useful third-party tools.
Q016. What are the disadvantages of Angular?
Limited SEO Capabilities: Usually SPA are rendered on the client side and therefore web crawlers of search engines like Google and Bing are not able to see the complete structure and content of the individual pages of the websites.
Too Many Versions: Angular has been evolving. It started out as a JavaScript framework AngularJS and now the current version is Angular 16. There are so many miner and major releases that cause confusion, especially for beginners.
Lot of Boilerplate Code: If you are building a simple app, there is a lot of boilerplate code that the application requires. If you decide to start developing an Angular app on your system, you need to install a bunch of things and the most simple “Hello World!” application will have a lot of code that you do not care about.
Decline in Popularity: With the advent of newer frameworks like VueJS and ReactJS, Angular has seen a downfall in its popularity.
Steeper Learning Curve: Angular has its own rules that developers need to learn and follow.
Q017. Why were client-side frameworks like Angular introduced?
Angular is a TypeScript-based open-source web application framework, developed and maintained by Google. It offers an easy and powerful way of building frontend web-based applications.
Before the introduction of Angular, web developers used VanillaJS and jQuery to develop dynamic websites. Later, when the websites became more complex with added features and functionality, it was hard for them to maintain the code.
The need for a client-side framework like Angular was obvious which can make life easier for the developers by handling separation of concerns and dividing code into smaller bits of information (components).
Before client-side frameworks like Angular, the way dynamic websites worked was by taking a template that is nothing but HTML code with spaces left empty for feeding data and content into those templates. This data was usually fetched from a database. After combining the template and data, we would serve the generated HTML content back to the user.
Q018. What are the other different Client-Side SPA Frameworks available in the Market?
A client-side framework is a software development framework that focuses on executing application processes on end-user devices rather than the application's own server.
ReactJS:
ReactJS was originally developed and maintained by Facebook. It is an declarative front-end JavaScript library aimed at helping web developers build user interfaces through a "learn once, write anywhere" approach. This framework is best used with single-page or mobile apps as it is simple to use, scalable, and fast.
VueJS:
Vue is a progressive framework that developers can use to build UI. The core library is focused on the view layer only and can be easily picked up and integrated with other libraries or existing projects. When used with modern tooling and supporting libraries, Vue can power sophisticated SPA applications.
Backbone.js:
This JavaScript framework uses an MVP (Model-View-Presenter) design model that allows developers to create SPA web applications. Airbnb, Hulu, Netflix and LinkedIn Mobile all use Backbone.js, a widely used and supported framework.
The main benefit of Backbone is that it separates business logic and user interface. This means developers can easily make changes to the application logic without affecting the user interface and vice versa. Since Backbone is lightweight and flexible, it can be used with any back-end language or front-end template.
Cordova:
Cordova is an open-source mobile application development framework backed by Apache. It allows standard web languages to be wrapped and presented as native mobile applications. Cordova is widely used by companies like Oracle, SAP, and IBM. it provides web applications with Node-API that maps standard web languages to native functionality, such as a phone's GPS, camera, and accelerometer.
Bootstrap:
Bootstrap was created by Twitter. It is an HTML, CSS, and JavaScript-based open-source framework that developers can use to build responsive and native mobile websites. Bootstrap is used by companies like Lyft, Vogue, and Newsweek.
Q019. What is TypeScript?
TypeScript is a open-source, strongly-typed, object-oriented, compiled language. It was designed by Anders Hejlsberg who was the designer of C# at Microsoft. It is a typed superset of JavaScript which is compiled to JavaScript at the end. TypeScript is both a language and some additional features which act as a set of tools. Angular is written entirely in TypeScript as a primary language.
TypeScript is a strict superset of JavaScript, which means anything that is implemented in JavaScript can be implemented using TypeScript as well along with the additional enhanced features. TypeScript has optional types, classes, async/await, and many other features. TypsScript provides some syntactic sugar and makes the code base more comfortable to understand and maintain.
You can install TypeScript globally as:
npm install -g typescript
Q020. What are the features of TypeScript?
TypeScript is Nothing but a JavaScript: TypeScript starts with JavaScript and ends with JavaScript. All the TypeScript code is converted into its JavaScript equivalent for the execution.
JavaScript is also a TypeScript: This means that any valid .js file can be renamed to .ts and compiled with other TypeScript files. Whatever code is written in JavaScript can be converted to TypeScript by changing the extension from .js to .ts.
TypeScript Code is converted into Plain JavaScript Code Finally: TypeScript code can not be natively interpreted by the browsers. So the code written in TypeScript must be trans-piled into plain JavaScript code in order to be understandable by the client-side browser. With the help of JavaScript code, browsers are able to read the code and display it.
TypeScript is Portable: TypeScript is portable across all browsers, devices, and operating systems. TypeScript can run on any environment that JavaScript runs on. TypeScript doesn’t need any dedicated VM or a specific runtime environment to execute. TypeScript is not specific to any single environment.
TypeScript supports other JS libraries: Trans-Compiled TypeScript code can be consumed from any JavaScript code. TypeScript-generated JavaScript can reuse all of the existing JavaScript frameworks, tools, and libraries.
Q021. Why TypeScript is developed while having JavaScript?
When JavaScript was developed, the JavaScript development team introduced JavaScript as a client-side programming language. As people were using JavaScript, developers also realized that JavaScript could be used as a server-side programming language as well. The development of Node.js has marked JavaScript as an emerging server-side technology too.
However, as JavaScript code was growing, JavaScript code became complex and heavy. Because of this, JavaScript wasn’t even able to fulfill the requirement of an Object-Oriented Programming language. As JavaScript code grows, it tends to get messier, making it difficult to maintain and reuse the code. This prevented JavaScript from succeeding at the enterprise level as a server-side technology. So TypeScript was created by the development team to bridge this gap.
Q022. Why to use TypeScript? What are the advantages of TypeScript?
TypeScript is superior to its other counterparts like CoffeeScript and Dart programming languages in a way that TypeScript is extended JavaScript.
Ease of Use: One of the main advantages of TypeScript is its ease of use. If you are at least a little familiar with JavaScript, it will require very little effort to get started with TypeScript.
Object-Oriented Programming: TypeScript supports Object-Oriented Programming concepts like classes, interfaces, inheritance, etc. which makes it familiar with other Object-oriented programming like C++, C#, Java, etc.
Static Typing: JavaScript is not strongly typed. But TypeScript comes with an optional static typing and type inference system through the TLS (TypeScript Language Service). So the developer can get errors at compile time itself.
Portability: Actually TypeScript is nothing but JavaScript. So TypeScript code converts to JavaScript to run anywhere JavaScript runs.
Supports Type Definitions: TypeScript supports type definitions for existing JavaScript libraries. TypeScript Definition file (.d.ts extension) provides a definition for external JavaScript libraries. So, TypeScript code can contain these libraries.
Q023. What is the difference between JavaScript vs TypeScript? How does TypeScript differ from JavaScript?
JavaScript is a scripting language for building dynamic websites. It is adhered to client-side development principles i.e. runs entirely within the user’s web browser and requires no resources from the webserver. JavaScript is a loosely typed programming language developed by ECMA’s Technical Committee 39.
TypeScript is an object-oriented, open-source programming language developed and maintained by Microsoft. It is a superset of JavaScript. So every JavaScript code is valid in TypeScript. So, if you save your JavaScript programming file (.js) with a TypeScript (.ts) extension, it will execute perfectly fine.
TypeScript makes JavaScript better. TypeScript is not a competitor to JavaScript, instead, TypeScript complements JavaScript. TypeScript is not designed to replace JavaScript, instead, it's purpose is to encourage the proliferation of JavaScript-based platforms by making it easier to write, integrate, manage and maintain code.
TypeScript vs JavaScript:
i) TypeScript is an Object-oriented programming language whereas JavaScript is a Prototype-based language.
ii) TypeScript is a Staticly typed language while JavaScript is a Dynamically typed language.
iii) TypeScript supports abstraction through interfaces, while JavaScript does not. So TypeScript supports Interfaces but JavaScript does not.
iv) TypeScript allows developers to annotate code with decorators, while JavaScript does not.
v) TypeScript supports the ability to modularize and organize components through the use of namespaces, which is not supported in JavaScript.
vi) TypeScript is more expressive than JavaScript, through the use of syntax elements such as optional and named parameters.
vii) TypeScript code is easier to debug as the codebase expands because type errors can be discovered at compilation time rather than runtime.
viii) TypeScript implements additional features beyond the limited ECMAScript specification to which JavaScript complies.
ix) TypeScript is more readable and maintainable than JavaScript.
Q024. What is the difference between TypeScript vs ECMAScript?
The ECMAScript specification is a standardized specification of a scripting language. ECMAScript (ES) is a standardized scripting language developed by ECMA International. ECMAScript allows you to write less code and do more.
There are various implementations of the ES programming language, the most popular of which is JavaScript. ES was intended to bring JavaScript up to par with other programming languages. ECMAScript is mostly used by web developers for client-side scripting (WWW).
ECMAScript6 or ES6 is the sixth edition of the ECMAScript standard, which was eventually renamed ECMAScript 2015 whose codename was "Harmony". It is a significant improvement to the JavaScript programming language, which allows us to create complicated apps. Chrome and Firefox are the most popular ES6 web browsers. ES6 introduces us to many excellent features like arrow functions, template strings, class destructors, modules, and more. It makes your code more modern and more readable.
TypeScript is a JavaScript programming language. TypeScript is aligned with the ECMAScript6 specification. It can be used with Node.js or any browser that supports ECMAScript 3 or above. TypeScript adopts its basic language features from the ECMAScript5 specification, i.e., the official specification for JavaScript.
TypeScript vs ECMAScript:
i) ES6 does not support all the data types while all primitive data types are supported by TypeScript.
ii) TypeScript supports generics and type annotations, as well as Inference and Enums but ES6 does not support these features.
iii) Typescript has three scopes: Global Scope, Class Scope, and Local Scope while ES6 has only two scopes: Global Scope and Local Scope.
Q025. What are the different data types supported by TypeScript?
We know that TypeScript is a typed language. The Type System checks the validity of the supplied values before they are stored or manipulated by the program. TypeScript provides data types as a part of its optional Type System.
Any DataType:
The "any" data type is the super type of all types in TypeScript. It denotes a dynamic type. Using any type is equivalent to opting out of type checking for a variable.
Built-in DataTypes:
Number: It represents double precision 64-bit floating point values. It can be used to represent both, integers and fractions. There is no integer type in TypeScript and JavaScript.
String: It represents a sequence of Unicode characters
Boolean: It represents logical values, true and false
Void: It is used on function return types to represent non-returning functions
Null: It represents an intentional absence of an object value.
Undefined: It denotes the value given to all uninitialized variables
User-defined DataTypes:
User-defined types include enumerations (enums), classes, interfaces, arrays, and tuples.
Null vs. Undefined vs. Any:
Both null and undefined cannot be used to reference the data type of a variable. They can only be assigned as values to a variable. However, null and undefined are not the same.
A variable initialized with undefined means that the variable has no value or object assigned to it while null means that the variable has been set to an object whose value is undefined. On the other hand, any data type can store anything within it.
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