JavaScript Interview Questions & Answers

Most commonly asked JavaScript interview questions and answers. Apply confidently for a Web / Full Stack Developer jobs.
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Commonly asked Interview Questions & Answers on JavaScript
Prepare for Web Developer / JavaScript Programmer job interviews
Free Downloadable booklet of JavaScript Interview Questions & Answers
Become a Web Developer / Software Engineer / Web Programmer
Prepare for Front End Engineer jobs
Prepare for Full Stack Developer (MERN, MEAN) interviews


  • Enthusiasm and determination to make your mark on the world!


A warm welcome to the JavaScript Interview Questions & Answers course by Uplatz.

Uplatz brings you this training on the most commonly asked interview questions and answers on JavaScript.

By learning and understanding deeply the popular interview questions (with answers) of JavaScript, you can confidently apply for Web Developer / JavaScript Programmer / Full Stack or Frond End Engineer / Web Designer roles.

This course explains the solutions to common questions asked in typical JavaScript Programmer and Web Developer interviews and comes with a freely downloadable booklet on the same.

JavaScript interview questions tutorial will help you crack the job interviews which can be a turning point in your career!


JavaScript is a lightweight, interpreted programming language with object-oriented capabilities that allows you to build interactivity into otherwise static HTML pages. The general-purpose core of the language has been embedded in Netscape, Internet Explorer, and other web browsers.

JavaScript was created by Brendan Eich in 1995 to give web pages a little more pep than the <blink> tag could provide. Today it has far more powerful uses and companies like Google and Facebook use JavaScript to build complex, desktop-like web applications. With the launch of Node.js, It has also become one of the most popular languages for building server-side software. Today, even the web isn’t big enough to contain JavaScript’s versatility. I believe that you are already aware of these facts and this has made you land on this JavaScript Interview Questions article.

So, if you are planning to start your career in JavaScript and you wish to know the skills related to it, now is the right time to dive in, when the technology is in its blossoming state. JavaScript Interview Questions will provide you with in-depth knowledge and help you prepare for your interviews.

Why JavaScript

The numbers speak for themselves. According to the US Bureau of Labor Statistics, web developer jobs are targeted to grow by 40% in 2012-2022, which is much higher than any other stream. This is backed by many major publications and professional bodies listing JavaScript in their Top 10 Programming languages for 2019-2020.

So, if you’re getting interviewed for any kind of web development position, or for Android / iPhone app developer positions, you’ve got to brush up your JavaScript skills.

According to stackoverflow survey of 2019,

JavaScript is the number 1 programming language!

  • JavaScript (67.8%)

  • HTML/CSS 63.5%

  • SQL 54.4%

  • Python 41.7%

  • Java 41.1%

  • Bash/Shell/PowerShell 36.6%

  • C# 31.0%

  • PHP 26.4%

  • C++ 23.5%

  • TypeScript 21.2%

  • C 20.6%

  • Ruby 8.4%

  • Go 8.2%


Tips for JavaScript interviews

Some quick tips & tricks to crack JavaScript Developer interviews are:

1) Understand the JS functions

2) Understand bind, apply and call

3) Understand JavaScript scope well (Closures also)

4) Understand 'this' keyword (global, function and object scopes)

5) Understand objects (Object.freeze, Object.seal)

6) Understand Prototypical Inheritance

7) Understand the callbacks and promises well

8) Understand the regular expressions well

9) Understand Map, Reduce and Filter well

10) Understand Error handling patterns

11) Other things to know (Hoisting, Event Bubbling)

Who this course is for:

  • Anyone aspiring to become a Web Developer / Front End Engineer
  • JavaScript Developers
  • Full Stack Developers and Web Developers
  • Frond-end Software Engineers and Programmers
  • Application Developers
  • Mobile App Developers
  • JavaScript Developers - React & Angular
  • Full-stack JavaScript Developers
  • Working Professionals wishing to switch their jobs & roles for better prospects
  • Technical Architects
  • Newbies and Beginners


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