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JavaScript Interview Questions - Coding Interview 2026
Highest Rated
Rating: 4.8 out of 5(1,292 ratings)
11,592 students

JavaScript Interview Questions - Coding Interview 2026

Prepare for next JavaScript coding interview by doing practice questions. Learn javascript skills & concepts.
Highest Rated
Created byOleksandr Kocherhin
Last updated 2/2026
English

What you'll learn

  • Be very well prepared for any javascript programming interviews you will have
  • Excel in a wide variety of javascript interview questions that you could be asked in an interview
  • Strengthen you javascript programming skills and your knowledge of important javascript concepts
  • Learn the skills, concepts, and techniques necessary to excel in javascript coding interviews
  • Learn what programming interviews are like and what kind of questions to expect
  • Feel very confident going into any javascript programming interviews you will have

Course content

7 sections • 57 lectures • 3h 44m total length

  • What is this section about?0:05
  • Types of Interviews1:30
  • Interview and Work Are Completely Different Things1:01
  • Pdf file1:06
  • I prepared source code for you0:22
  • Mapping Users to Get Usernames9:41
  • Difference between null and undefined2:36

    Learn the difference between null and undefined in JavaScript, with examples showing unassigned variables yielding undefined and assigned null giving a null value, plus guidance on when to use each.

  • Hoisting4:45

    Explore hoisting in JavaScript, where var and function declarations bubble to the top, producing undefined or errors, while let and const do not hoist.

  • Closures6:04
  • Currying12:58
  • Adding Elements to the Array4:06
  • Concatenating Arrays3:06
  • Check if User With Such Name Exists4:12
  • Remove All Duplicates in the Array4:29

    Remove duplicates in an array by using a set as a one-line solution, or implement with forEach and includes, or with reduce to build a unique accumulator.

  • Sorting the array4:07
  • Interview Is Not What You Think2:12
  • Writing Range Function3:06
  • Writing Shuffle Function3:19

    Implement a JavaScript shuffle function by mapping each item to a random key, sorting by that key, and returning the original values, working for numbers, objects, or arrays.

  • Find the Number of Occurences of Minimum Value in List2:35
  • This5:33

    Explore how this binds in JavaScript across functions, objects, and classes, and learn how to fix incorrect this with older self-variables or arrow functions for proper context.

  • Classes5:09
  • Prototypes7:04
  • I’ve Failed Interview. What’s Next?2:19

    Recognize that failing interviews is normal and keep applying until you land your first job. After each interview, write down missed questions, google them, and seek feedback.

  • Modules9:41
  • Implement Debounce Function5:38
  • Implement Throttle Function4:19

Requirements

  • Basic Javascript knowledge

Description

This course is great preparation for any javascript programming interviews that you may have coming up. Programming interviews need a lot amount of knowledge, but the best way to prepare for interviews is a lot of practice! In this course you will complete 59 javascript interview questions that come from real javascript interviews. There are no excersises that nobody asks here. In every question we will get a task first, then you will try to solve each problem yourself, and then I will show you different solutions to each problem step-by-step for different programmer levels. We will take a deep dive into the skills, concepts, and techniques that are required to solve each problem.

When you have completed this course you will have mastered the 59 interview questions that we will cover, but you will also have learned the concepts, skills, and techniques, that are necessary for you to excel in any other interview questions you may be asked. You will feel very confident going into any javascript programming interviews you will have. On top of all this, you will strengthen your javascript programming skills and javascript fundamentals in overall.

Core topics of the course:

  • Closures

  • Hoisting

  • Currying

  • Classes & Prototypes

  • Modules

  • Working with DOM

  • Asyncronous Javascript (Callback, Promises, Async await)

  • Memoization

  • Transforming data with real world tasks

  • Creating own utility functions

Who this course is for:

  • Anyone who is looking for a job as a programmer
  • Anyone who is looking for a job as a web developer
  • Anyone who will be interviewing for a programming or web developer job
  • Anyone who wants to strengthen their javascript skills and knowledge

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