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Top 100 JavaScript Interview Questions And Answers
January 6, 2022
JavaScript is, without a doubt, the most famous and widely used programming language in the world. It is also
abbreviated as JS but notes that Java and JavaScript are totally different programming languages.
JavaScript is a high-level programming language and easy to learn as well; however, you need a clear understanding
of fundamental concepts in order to proceed to become a better programmer.
When you apply for a job, you need to go through an interview where mixed types of questions are asked from basic
to advance. Therefore, we have bundled together with the top 100 JavaScript questions that are frequently asked.
Below is the list which contains basic JavaScript interview questions to JavaScript advanced interview questions
which will help you clear an interview round. Below JavaScript, interview coding questions are helpful for freshers as
well as experienced programmers because we have divided the questions into multiple parts.
Table of Contents
JavaScript Developer Interview Questions
Following are the most often asked JavaScript basics interview questions which will help the newcomers to clear the
interviews. The great part about this bundle is, we have also added the HTML, CSS, JavaScript interview questions,
JavaScript algorithm interview questions, and so many other particular topic-related questions. Here we go!
,Basic JavaScript Interview Questions
Here are some vanilla JavaScript interview questions which will help freshers who don’t have experience in any JS
frameworks. Vanilla JavaScript is often called a core JavaScript, don’t be confused!
These JavaScript fundamentals interview questions should be known to every fresher before attending an interview.
Q1. What Is Javascript? What Is The Use Of It?
Ans- This is one of the most basic JavaScript programming interview questions. JavaScript is a client side scripting or
programming language which is used to implement complex operations in web pages. JavaScript is present
everywhere, presenting timely content updates, interactive maps, dynamic 2D/3D visuals, scrolling video jukeboxes,
and so on, you name it.
JavaScript is also used for DOM manipulation, which includes dynamically adding, updating, and deleting HTML
elements and CSS properties. Apart from this, JavaScript is also used for desktop application development, and
nowadays, we can use JavaScript as a server-side programming language using nodeJS, which is a JavaScript
runtime.
Q2. Tell The Actual Name Of Javascript.
,Ans- JavaScript was started as Mocha, and then it became a LiveScript. Then it became JavaScript. It is among the
most famous and widely used programming languages; however, it has nothing to do with Java programming
language. It is said that, because of the popularity of Java, LiveScript became JavaScript to go with Java, with the
compiled language.
Q3. Whether Javascript Is Case Sensitive Or Not?
Ans- Yes, JavaScript is case sensitive programming language. This means the keywords, function names, class
names, variables, and other identifiers should be written by considering the case sensitivity. For e.g., JavaScript and
JavaScript are two different variables, and they will be interpreted differently by JavaScript. Utmost care should be
taken while declaring variables and functions.
Q4. Whether Javascript Is Compiled Or Interpreted Language?
Ans- JavaScript is a programming language that is interpreted instead of compiled. Programming languages like C++
or Java are compiled first before running. The original code is run through a compiler, which converts it to bytecode
that the machine can understand and execute.
Whereas JavaScript does not require any compilation. Instead, a browser interpreter reads the JavaScript code,
interprets each line, and then executes it.
, Modern browsers like Google Chrome, Mozilla Firefox, apple safari use just-in-time compilation technology to compile
the JavaScript code and convert it to executable bytecode.
Q5. State The Features Of Javascript.
Ans- JavaScript is a programming language that can achieve absolutely anything; website, mobile app, desktop app,
server side programs, you guess it. It has some special kinds of features which make complex tasks easier than you
think, and that is what makes it a most popular programing language. Here are some amazing features of JavaScript:
Input validation- Not surprising, but this is among the most useful features of JavaScript. JavaScript is very
useful for form validations like validating emails or phone numbers.
Platform independent- You don’t need to install a separate compiler for JavaScript. Almost all browsers
support JavaScript, and code runs in a web browser on any platform like Windows, Mac, or Linux.
DOM manipulation- Using JavaScript, you can have control over the HTML document. You can add, update
and delete the HTML elements and CSS properties.
Object-oriented language- you can have an object-oriented structure rather than functional or monolithic
programing.
Q.6 Which Data Types Does Javascript Support?
Ans- In JavaScript, there are six basic data types that can be classified into three groups: primitive, composite, and
special data types. The primitive data types are String, Number, and Boolean. Composite data types include Object,
Array, and Function (which are all sorts of objects). On the other hand, Null and Undefined are special types of data.
Top 100 JavaScript Interview Questions And Answers
January 6, 2022
JavaScript is, without a doubt, the most famous and widely used programming language in the world. It is also
abbreviated as JS but notes that Java and JavaScript are totally different programming languages.
JavaScript is a high-level programming language and easy to learn as well; however, you need a clear understanding
of fundamental concepts in order to proceed to become a better programmer.
When you apply for a job, you need to go through an interview where mixed types of questions are asked from basic
to advance. Therefore, we have bundled together with the top 100 JavaScript questions that are frequently asked.
Below is the list which contains basic JavaScript interview questions to JavaScript advanced interview questions
which will help you clear an interview round. Below JavaScript, interview coding questions are helpful for freshers as
well as experienced programmers because we have divided the questions into multiple parts.
Table of Contents
JavaScript Developer Interview Questions
Following are the most often asked JavaScript basics interview questions which will help the newcomers to clear the
interviews. The great part about this bundle is, we have also added the HTML, CSS, JavaScript interview questions,
JavaScript algorithm interview questions, and so many other particular topic-related questions. Here we go!
,Basic JavaScript Interview Questions
Here are some vanilla JavaScript interview questions which will help freshers who don’t have experience in any JS
frameworks. Vanilla JavaScript is often called a core JavaScript, don’t be confused!
These JavaScript fundamentals interview questions should be known to every fresher before attending an interview.
Q1. What Is Javascript? What Is The Use Of It?
Ans- This is one of the most basic JavaScript programming interview questions. JavaScript is a client side scripting or
programming language which is used to implement complex operations in web pages. JavaScript is present
everywhere, presenting timely content updates, interactive maps, dynamic 2D/3D visuals, scrolling video jukeboxes,
and so on, you name it.
JavaScript is also used for DOM manipulation, which includes dynamically adding, updating, and deleting HTML
elements and CSS properties. Apart from this, JavaScript is also used for desktop application development, and
nowadays, we can use JavaScript as a server-side programming language using nodeJS, which is a JavaScript
runtime.
Q2. Tell The Actual Name Of Javascript.
,Ans- JavaScript was started as Mocha, and then it became a LiveScript. Then it became JavaScript. It is among the
most famous and widely used programming languages; however, it has nothing to do with Java programming
language. It is said that, because of the popularity of Java, LiveScript became JavaScript to go with Java, with the
compiled language.
Q3. Whether Javascript Is Case Sensitive Or Not?
Ans- Yes, JavaScript is case sensitive programming language. This means the keywords, function names, class
names, variables, and other identifiers should be written by considering the case sensitivity. For e.g., JavaScript and
JavaScript are two different variables, and they will be interpreted differently by JavaScript. Utmost care should be
taken while declaring variables and functions.
Q4. Whether Javascript Is Compiled Or Interpreted Language?
Ans- JavaScript is a programming language that is interpreted instead of compiled. Programming languages like C++
or Java are compiled first before running. The original code is run through a compiler, which converts it to bytecode
that the machine can understand and execute.
Whereas JavaScript does not require any compilation. Instead, a browser interpreter reads the JavaScript code,
interprets each line, and then executes it.
, Modern browsers like Google Chrome, Mozilla Firefox, apple safari use just-in-time compilation technology to compile
the JavaScript code and convert it to executable bytecode.
Q5. State The Features Of Javascript.
Ans- JavaScript is a programming language that can achieve absolutely anything; website, mobile app, desktop app,
server side programs, you guess it. It has some special kinds of features which make complex tasks easier than you
think, and that is what makes it a most popular programing language. Here are some amazing features of JavaScript:
Input validation- Not surprising, but this is among the most useful features of JavaScript. JavaScript is very
useful for form validations like validating emails or phone numbers.
Platform independent- You don’t need to install a separate compiler for JavaScript. Almost all browsers
support JavaScript, and code runs in a web browser on any platform like Windows, Mac, or Linux.
DOM manipulation- Using JavaScript, you can have control over the HTML document. You can add, update
and delete the HTML elements and CSS properties.
Object-oriented language- you can have an object-oriented structure rather than functional or monolithic
programing.
Q.6 Which Data Types Does Javascript Support?
Ans- In JavaScript, there are six basic data types that can be classified into three groups: primitive, composite, and
special data types. The primitive data types are String, Number, and Boolean. Composite data types include Object,
Array, and Function (which are all sorts of objects). On the other hand, Null and Undefined are special types of data.
