JavaScript Coding Interview Questions & Solutions 2025, Get Sample Questions

JavaScript Coding Interview Questions & Solutions 2025 | JavaScript Coding Interview Questions | JavaScript Coding Interview Questions and Answers | JavaScript Coding Interview Questions Pdf

JavaScript Coding Interview Questions & Solutions 2025: Some of the Coding questions helps to get more marks in your examinations or test. Aspirants focussed to prepare the Coding Questions for easy to crack the examinations. In the may organisation is released the hiring every month for various JavaScript qualified candidates. The candidates who applied the JavaScript Hiring, they must attend the selection process. Every Company will ask the questions in the JavaScript Programming Language. Candidates eagerly prepare for the JavaScript Language. The JavaScript Language one of the Competitive langugae in the private sector. Those who will be selected in the JavaScript Coding Test, they will be move on further selection process. The JavaScript Coding Interview Questions is helping to achieve the selection round. Continuous practising of the JavaScript Coding Questions and answers, it gives idea and got a repeated asked question. JavaScript Coding Questions and Answers will be uploaded in the official website. JavaScript Coding Interview questions contains post wise coding questions. More questions about the JavaScript Coding Question and Answers, JavaScript Coding Interview Questions etc., Kindly use this page to get Basic JavaScript coding questions and JavaScript Coding Questions and Answers for Freshers .

Basic JavaScript coding questions: 

1. Write a JavaScript function to calculate the sum of two numbers.

When managers ask this question, they are looking for the candidate’s basic understanding of JavaScript. They assess their understanding of basic syntax along with problem-solving skills. This also helps evaluate the candidate’s coding style and attention to detail.

Sample Answer: 

I would take two parameters and the following function can be used to calculate the sum of any 2 numbers that are passed as arguments.

function sumOfTwoNumbers(a, b) {

return a + b;

}

2. Write a JavaScript program to find the maximum number in an array.

A hiring manager asks this question to analyze the candidate’s ability to write clear and efficient code. It’s crucial for candidates to explain the code step-by-step while demonstrating bug-free code.

Sample Answer: 

function findMaxNumber(arr) {

return Math.max(…arr);

}

3. Write a JavaScript function to check if a given string is a palindrome.  

The interviewer is looking for the candidate’s familiarity with loop constructs, JavaScript string methods, and other basic JavaScript syntax. They will evaluate the candidate’s skills based on the approach used to solve the palindrome problem. 

Sample Answer: 

function isPalindrome(str) {

return str === str.split(”).reverse().join(”);

}

4. Write a JavaScript program to reverse a given string. 

Hiring managers are expecting an accurate solution that demonstrates the interviewee’s proficiency in JavaScript programming.

const reverseString = (str) => str.split(”).reverse().join(”);

5. Write a JavaScript function that takes an array of numbers and returns a new array with only the even numbers. 

Interviewers are looking for candidates who can not only clearly explain the solution along with the code, but also show the ability to think logically and articulate their thought processes. 

Sample Answer: 

By using the filter method on the array, I can check if each element is even or not by using the modulus operator (%) with 2. The element is even if the result is 0. This can be included in the new array.

function filterEvenNumbers(numbers) {

return numbers.filter(num => num % 2 === 0);

}

Advanced JavaScript coding interview questions

1. Implement a debounce function in JavaScript that limits the frequency of a function’s execution when it’s called repeatedly within a specified time frame. 

Interviewers expect the candidate to showcase their ability to clearly explain the purpose of the debounce function and its usage in scenarios where function calls need to be controlled. They are looking for the person’s ability to articulate technical concepts clearly. 

Sample Answer:

By delaying the execution of the debounce function until the specified time frame has passed, the frequency can be limited.

function debounce(func, delay) {

let timer;

return function() {

clearTimeout(timer);

timer = setTimeout(func, delay);

};

}

2. Write a function that takes an array of objects and a key, and returns a new array sorted based on the values of that key in ascending order. 

By asking this question, hiring managers analyze how well the candidate can discuss the sorting algorithm and its time complexity. It’s also crucial for candidates to demonstrate their code’s robustness. 

Sample Answer: 

The following function takes an array of objects and a key to sort the array based on the values in ascending order.

function sortByKey(arr, key) {

return arr.sort((a, b) => a[key] – b[key]);

}

3. Implement a deep clone function in JavaScript that creates a copy of a nested object or array without any reference to the original. 

Hiring managers want to assess the interviewee’s skill to handle complex coding tasks and understand the concept of avoiding reference issues while cloning. 

Sample Answer: 

By using two methods together and creating a deep clone, I can serialize the object to a JSON string. I would then parse it back into a new object, thereby removing any reference to the original object.

function deepClone(obj) {

return JSON.parse(JSON.stringify(obj));

}

4. Write a recursive function to calculate the factorial of a given number. 

Interviewers expect the candidate to write a concise recursive function that handles edge cases. Candidates must show their understanding of how recursion works to avoid infinite loops or stack overflow errors.

Sample answer: 

function factorial(num) {

if (num <= 1) return 1;

return num * factorial(num – 1);

}

5. Implement a function that takes two sorted arrays and merges them into a single sorted array without using any built-in sorting functions. 

When interviewers ask this question, they seek to assess the knowledge of algorithms and efficiency in handling sorted data. They also look for the ability to think of and execute a correct solution. 

Sample Answer: 

I can implement a function that can efficiently merge two sorted arrays.

function mergeSortedArrays(arr1, arr2) {

return […arr1, …arr2].sort((a, b) => a – b);

}

Common JavaScript coding interview questions 

1.Write a function that determines if a given number is prime or not. 

By asking this question, interviewers can understand how good the candidate is proficient in math operations and JavaScript logic. The interviewee should excute a clean and optimized solution that is efficient. 

Sample Answer: 

function isPrime(num) {

if (num <= 1) return false;

for (let i = 2; i <= Math.sqrt(num); i++) {

if (num % i === 0) return false;

}

return true;

}

2. Implement a function to find the sum of all the numbers in an array. 

Such a question helps understand if the interviewee can manipulate arrays and handle numeric values. This also helps managers assess problem-solving capabilities and ability to pay attention to code efficiency. 

Sample Answer: 

I would use the reduce method to implement the following function:

function findSum(arr) {

return arr.reduce((sum, num) => sum + num, 0);

}

3. Given a string, write a function to count the occurrences of each character in the string. 

Hiring managers expect the candidate to be familiar with string manipulation and loop constructs. When they ask this question, they can evaluate whether the candidate knows data structures. 

Sample Answer: 

function countCharacterOccurrences(str) {

const charCount = {};

for (let char of str) {

charCount[char] = (charCount[char] || 0) + 1;

}

return charCount;

}

4. Implement a function to remove duplicates from an array. 

When interviewers present the candidate with this question, they can gauge the level of understanding a candidate has regarding array methods and different approaches to solve the problem. 

Sample Answer:  

The following function duplicates from an array by converting it into a Set. This automatically removes duplicates. Next, the function converts the Set back into an array.

function removeDuplicates(arr) {

return Array.from(new Set(arr));

}

5. Write a function that sorts an array of numbers in ascending order. 

Interviewees must show their knowledge of bubble sort, merge sort, sorting algorithms, and other approaches. The HR manager aims to measure the capability to execute strong algorithms and handle edge cases. 

Sample Answer:

I can solve this by using JavaScript’s built-in sort method.

function ascendingSort(numbers) {

return numbers.sort((a, b) => a – b);

}

JavaScript Coding Interview Questions and Answers

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