search
HomeWeb Front-endJS TutorialJavaScript interview questions & answers with code

Top JavaScript Interview Questions and Expert Answers with Code Examples

Flatten a Nested Object

Question : Write a function to flatten a nested JavaScript object.

Code :

function flattenObject(obj, prefix = '', res = {}) {

** for (let key in obj) {**

** const newKey = prefix ? ${prefix}.${key} : key;**

** if (typeof obj[key] === 'object' && obj[key] !== null) {**

** flattenObject(obj[key], newKey, res);**

** } else {**

** res[newKey] = obj[key];**

** }**

** }**

** return res;**

}

console.log(flattenObject({ a: { b: { c: 1 } }, d: 2 }));

// Output: { 'a.b.c': 1, d: 2 }

2. Find Duplicates in an Array

Question : Write a function to find duplicate values in an array.

Code :

function findDuplicates(arr) {

** const counts = {};**

** return arr.filter(item => counts[item] ? true : (counts[item] = 1, false));**

}

console.log(findDuplicates([1, 2, 2, 3, 4, 4, 5]));

// Output: [2, 4]

3. Implement debounce
Question : Write a debounce function that limits the rate a function is called.

Code :

function debounce(func, delay) {

** let timer;**

** return function (...args) {**

** clearTimeout(timer);**

** timer = setTimeout(() => func.apply(this, args), delay);**

** };**

}

const log = debounce(() => console.log('Logged after 1s'), 1000);

log();

4. Reverse a String Recursively

Question : Write a recursive function to reverse a string.

Code :

function reverseString(str) {

** if (str === "") return "";**

** return reverseString(str.slice(1)) + str[0];**

}

console.log(reverseString("hello"));

// Output: "olleh"

5. Check for Palindrome

Question : Write a function to check if a string is a palindrome.

Code :

function isPalindrome(str) {

** const cleaned = str.toLowerCase().replace(/[^a-z]/g, '');**

** return cleaned === cleaned.split('').reverse().join('');**

}

console.log(isPalindrome("A man, a plan, a canal, Panama"));

// Output: true

Read more... ⇲

JavaScript interview questions & answers with code

JavaScript interview questions & answers with code

JavaScript interview questions & answers with code

JavaScript interview questions & answers with code

React interviews questions and answers with code

React interviews questions and answers with code

JavaScript interview questions & answers with code

Angular interview questions

Angular interview questions

JavaScript interview questions & answers with code

CSS Interview Questions

CSS Interview Questions along with their answers and Code

JavaScript interview questions & answers with code atharvgyan.com

The above is the detailed content of JavaScript interview questions & answers with code. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Replace String Characters in JavaScriptReplace String Characters in JavaScriptMar 11, 2025 am 12:07 AM

Detailed explanation of JavaScript string replacement method and FAQ This article will explore two ways to replace string characters in JavaScript: internal JavaScript code and internal HTML for web pages. Replace string inside JavaScript code The most direct way is to use the replace() method: str = str.replace("find","replace"); This method replaces only the first match. To replace all matches, use a regular expression and add the global flag g: str = str.replace(/fi

8 Stunning jQuery Page Layout Plugins8 Stunning jQuery Page Layout PluginsMar 06, 2025 am 12:48 AM

Leverage jQuery for Effortless Web Page Layouts: 8 Essential Plugins jQuery simplifies web page layout significantly. This article highlights eight powerful jQuery plugins that streamline the process, particularly useful for manual website creation

Build Your Own AJAX Web ApplicationsBuild Your Own AJAX Web ApplicationsMar 09, 2025 am 12:11 AM

So here you are, ready to learn all about this thing called AJAX. But, what exactly is it? The term AJAX refers to a loose grouping of technologies that are used to create dynamic, interactive web content. The term AJAX, originally coined by Jesse J

10 Mobile Cheat Sheets for Mobile Development10 Mobile Cheat Sheets for Mobile DevelopmentMar 05, 2025 am 12:43 AM

This post compiles helpful cheat sheets, reference guides, quick recipes, and code snippets for Android, Blackberry, and iPhone app development. No developer should be without them! Touch Gesture Reference Guide (PDF) A valuable resource for desig

Improve Your jQuery Knowledge with the Source ViewerImprove Your jQuery Knowledge with the Source ViewerMar 05, 2025 am 12:54 AM

jQuery is a great JavaScript framework. However, as with any library, sometimes it’s necessary to get under the hood to discover what’s going on. Perhaps it’s because you’re tracing a bug or are just curious about how jQuery achieves a particular UI

How do I create and publish my own JavaScript libraries?How do I create and publish my own JavaScript libraries?Mar 18, 2025 pm 03:12 PM

Article discusses creating, publishing, and maintaining JavaScript libraries, focusing on planning, development, testing, documentation, and promotion strategies.

10 jQuery Fun and Games Plugins10 jQuery Fun and Games PluginsMar 08, 2025 am 12:42 AM

10 fun jQuery game plugins to make your website more attractive and enhance user stickiness! While Flash is still the best software for developing casual web games, jQuery can also create surprising effects, and while not comparable to pure action Flash games, in some cases you can also have unexpected fun in your browser. jQuery tic toe game The "Hello world" of game programming now has a jQuery version. Source code jQuery Crazy Word Composition Game This is a fill-in-the-blank game, and it can produce some weird results due to not knowing the context of the word. Source code jQuery mine sweeping game

jQuery Parallax Tutorial - Animated Header BackgroundjQuery Parallax Tutorial - Animated Header BackgroundMar 08, 2025 am 12:39 AM

This tutorial demonstrates how to create a captivating parallax background effect using jQuery. We'll build a header banner with layered images that create a stunning visual depth. The updated plugin works with jQuery 1.6.4 and later. Download the

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

Hot Tools

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

MinGW - Minimalist GNU for Windows

MinGW - Minimalist GNU for Windows

This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)