27 ES6 Interview Questions (With A Few Example Answers)

By Indeed Editorial Team

Published 25 September 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

ES6 or ECMAScript 6, also referred to as ECMAScript 2015, is the sixth edition of ECMA-262 standards, where ECMA is short for the European Computer Manufacturers Association. Through ES6, developers have access to more robust programming concepts, like practical object-oriented code. During an ES6 interview, hiring managers can ask various questions to assess your knowledge of ECMAScript programming language or to determine if you know why developers consider ES6 an essential part of JavaScript. In this article, we list 27 ES6 interview questions and share example answers to seven of them to help you prepare well for your interview.

7 ES6 Interview Questions And Sample Answers

Below are ES6 interview questions and their example answers to help you create your own responses:

1. Define ES6 and also tell us if it is the latest edition of ECMAScript

Recruiters interviewing developers who use ES6 may often start the interview with this question to assess your basic understanding of the scripting language. If they ask you about the latest ECMAScript, then they intend to see if you are aware of the ECMAScript version history. In your explanation, clearly define ES6 and mention when Ecma International standardised it, along with the number of the present ECMAScript editions.

Example answer: 'ES6, also referred to as ECMAScript 6 or ECMAScript 2015, is a scripting language that is the sixth major release of ECMAScript language. ES6 has a lot of new features and syntaxes for writing web applications in JavaScript. It helps standardise the JavaScript language and has multiple implementations. It supports large applications and library creation and offers various enhancements like classes, modules, lexical block scoping, iterators, generators and native language support for promises. ES6 is certainly not the latest edition, as ECMA finalised it in 2015.

After that, ECMA released five more editions, with the 12th edition or the ECMAScript 2021 being the latest one. The technology news outlets that I follow recently published a news article, mentioning that ECMA has approved the ECMAScript 2022 specification for this year to add to the JavaScript family. It is going to be the 13th edition and some of its features that the community is waiting for are static class initialisation blocks, static class fields and methods and top-level await.'

Related: How To Prepare For A Job Interview

2. Can you list some features of ES6?

With this question, interviewers evaluate how well you know ES6. Giving an appropriate answer to this question may prove beneficial, as it may help you show hiring managers your level of familiarity with the client-side scripting language. When preparing a response to this question, consider including the features that developers utilise the most, along with the features that are new in this edition of ECMAScript.

Example answer: 'ES6 has a lot of new features. Some of these new features include support for constants; block-scope support for variables, constants and functions, arrow functions, extended parameter handling, template literals, extended literals, modules, classes, iterators and generators, promises, meta-programming, internationalisation and localisation; enhanced regular expression; destructuring assignment and enhanced object properties. When ECMA released it initially, developers had to convert ES6 into compatible JavaScript code, but now it is one of the most widely supported ECMAScript.'

Related: Interview Question: "Tell Me About Yourself"

3. Can you tell us what functional programming is?

When interviewers ask this question, they intend to see how passionate you are about programming. Many interviewers may often ask this question since JavaScript is an implementation of ES6. To give an impressive answer, briefly include the history of functional programming and clearly tell the interviewers what is its relationship with JavaScript. You may also include a few examples of functional languages.

Example answer: 'Functional programming is an important JavaScript concept. The aim of such languages is to create programs by applying mathematical functions. Programmers have been utilising various functional programming languages, like Lisp, Haskell and Clojure since the 1950s. Higher-order functions, functions as arguments or values and first-class functions are some of the JavaScript features that support functional programming. It is also interesting to note that ES6 offers many features to JavaScript, such as with the help of new syntaxes programmers may write the code more expressively. Some of these features together even complete the functional programming toolkit of JavaScript.'

Related: Video Interview Guide: Tips For A Successful Interview

4. Tell us about some pros and cons of functional and object-oriented programming

A thorough answer to this question may help interviewers to appreciate your functional programming and object-oriented programming knowledge. They ask this question to determine if you know that both these programming techniques employ different methods for storing and manipulating data. To give an impressive answer, clearly explain the advantages and disadvantages of both, along with their application that is based on the situation.

Example answer: 'With functional programming, developers can avoid the bugs that are caused by multiple functions seeking access to the same resources. Functions too are more simple compared to object-oriented programming. With functional programming, programmers can optimise their work better, as it focuses on the overall view instead of detailing each step. Compared to object-oriented programming, functional programming can be challenging to learn. When programmers overuse functional programming, they are more likely to produce less readable code. Object-oriented programming also helps programmers to follow specific instructions, but it may be time-consuming to optimise it.'

Related: How To Succeed In Your First Interview

5. What is Webpack? Can you list some benefits of using it?

With the help of this question, interviewers evaluate your understanding of the JavaScript module bundler. For an excellent response, you may talk about its various functions, along with clearly defining this type of application. To list its benefits, consider concentrating on the major ones or those that you take advantage of routinely.

Example answer: 'Webpack is a type of application that allows programmers to run an environment that hosts Babel. This open-source JavaScript module bundler accepts modules with dependencies and produces static assets that represent those modules. Its first major benefit is that it bundles several modules and packs them into a single .js file. Second, it has an integrated dev server for local development, which I use to include a JavaScript tag in the server and update the live code efficiently, along with managing assets.'

Related: Interview Question: "What Are Your Strengths And Weaknesses?"

6. What makes functions first-class objects?

Your answer to this question shows the interviewers your knowledge of value, variables and methods. When you mention in your response how functions may be properties of an object, you tell recruiters you possess the knowledge of arrays as well. Keep your answer brief and focus on the key factors that make functions in JavaScript first-class objects.'

Example answer: 'A programmer may assign functions to variables. Functions are object properties, also referred to as methods. These functions may also be an item in the array. A programmer may also choose to pass them as arguments to a function. A programmer may even receive the functions in return as values of functions.'

Related: 9 Common Mistakes To Avoid In An Interview

7. What is the significance of Babel in ES6 and how do you install it?

An interviewer asking this question intends to assess your JavaScript transpiler knowledge. In your answer, mention what is the outcome of using Babel. Before listing the steps involved in Babel installation, you may also share with interviewers the prerequisite for the installation.

Example answer: 'A JavaScript transpiler, Babel helps programmers to transpile new features into old standards. This allows the features to run both on old and latest browsers easily. The many features of BabelJS include plug-ins, presets and polyfills. It is a robust tool that programmers employ to give post-ECMAScript 2015 code backwards compatibility. For its installation, you require Node.js and Node Package Manager (npm). The installation process is successful only when the server has Node.js installed on it. Finally, executing a short and simple command on a terminal allows programmers to install Babel command-line interface (CLI) locally.'

Related: 23 Interview Tips: How To Get The Job

20 Additional ES6 Interview Questions

Here are some other questions that interviews may ask candidates during their ES6 interview:

  1. How do you declare a variable in JavaScript?

  2. Can you list a few major differences between var and let?

  3. Expand DOM and BOM and briefly share their definitions.

  4. Is it possible to create a JavaScript class in ES6? If yes, then how?

  5. Discuss some use cases of let, const and var.

  6. Tell us about the different types of ES6 comments.

  7. What new features in ES6 make it more efficient than ES5?

  8. Can you list all the data types that JavaScript supports?

  9. Can you share with us what a web storage system is?

  10. What is the generator function in ES6?

  11. What is your understanding of the states of promises in ES6?

  12. Can you define callback and callback hell in JavaScript?

  13. What are some array methods that are present in ES6?

  14. What is the role of new string methods that developers have introduced in ES6?

  15. Can you tell us what constants are in ES6?

  16. In ES6, what is the role of template literals?

  17. What is your understanding of WeakMap in ES6?

  18. Can you define what hoisting is in JavaScript?

  19. What is the role of the spread operator in ES6?

  20. Explain map and set.

Please note that none of the companies, institutions or organisations mentioned in this article are associated with Indeed.

Explore more articles