50 Must-know JavaScript Interview Questions

🚀 JavaScript Objects – Interview Q&A (Frontend Focused) 1️⃣ What is an object in JavaScript? An object is a collection of key–value pairs used to store structured data. Keys are strings (or symbols), and values can be any data type. 2️⃣ How do you create an object in JavaScript? // Object literal const obj = { name: "JS" }; // Using constructor const obj2 = new Object(); // Using Object.create const obj3 = Object.create(null); 3️⃣ How do you access object properties? obj.name; // Dot notation obj["name"]; // Bracket notation 👉 Bracket notation is useful for dynamic keys. 4️⃣ Difference between dot notation and bracket notation? DotBracketStatic keysDynamic keysFaster & cleanerRequired for special characters 5️⃣ How do you loop through an object? for (let key in obj) { console.log(key, obj[key]); } Object.keys(obj).forEach(key => console.log(key)); 6️⃣ What are Object.keys(), Object.values(), and Object.entries()? Object.keys() → array of keys Object.values() → array of values Object.entries() → array of [key, value] 7️⃣ Are objects mutable in JavaScript? ✅ Yes. Objects are mutable and passed by reference. const a = { x: 1 }; const b = a; b.x = 2; // a.x is also 2 8️⃣ How do you clone an object? // Shallow copy const copy = { ...obj }; const copy2 = Object.assign({}, obj); ⚠️ Nested objects still share references. 9️⃣ Difference between shallow copy and deep copy? Shallow copy → Copies only first level Deep copy → Copies all nested levels const deep = JSON.parse(JSON.stringify(obj)); 🔟 What is this inside an object? this refers to the current object calling the method. const user = { name: "Sweta", greet() { return this.name; } }; 1️⃣1️⃣ What is object destructuring? const { name, role } = user; Used for cleaner code and readability. 1️⃣2️⃣ What is the difference between Object.freeze() and Object.seal()? freeze() → Cannot add, remove, or update properties seal() → Can update existing properties only 1️⃣3️⃣ How do you check if a property exists? "name" in user; user.hasOwnProperty("name"); 1️⃣4️⃣ Real-world use of objects? ✅ API responses ✅ Component props & state ✅ Configuration files ✅ Form handling ✅ State management (Redux / Pinia) 💡 Interview Tip: Strong understanding of objects helps you master immutability, state management, and performance optimization in React & Vue. 👍 Like • 💬 Comment • 🔁 Share if this helped #JavaScript #FrontendInterview #WebDevelopment #React #Vue #CodingInterview #LinkedInLearning

Day 31/50 – JavaScript Interview Question? Question: What is the difference between import and require()? Simple Answer: import is ES6 module syntax that's statically analyzed at compile time and supports tree-shaking. require() is CommonJS syntax used in Node.js, dynamically evaluated at runtime. import statements must be at the top level, while require() can be used conditionally. 🧠 Why it matters in real projects: Modern bundlers like Webpack and Vite use import for tree-shaking (removing unused code), significantly reducing bundle sizes. Understanding both is crucial since Node.js packages often use CommonJS while frontend code uses ES modules. 💡 One common mistake: Mixing import and require() syntax in the same file, or trying to use import conditionally inside if-statements (not allowed). Also, forgetting that require() is synchronous while dynamic import() is asynchronous. 📌 Bonus: // ES6 Modules (import) import React from 'react'; import { useState, useEffect } from 'react'; import * as utils from './utils'; import type { User } from './types'; // TypeScript // CommonJS (require) const express = require('express'); const { Router } = require('express'); // Key differences: // 1. Static vs Dynamic import { func } from './module'; // ✓ Top-level only const mod = require('./module'); // ✓ Can be anywhere if (condition) { import { func } from './module'; // ✗ SyntaxError const mod = require('./module'); // ✓ Works } // 2. Dynamic import (async ES6 feature) const module = await import('./module.js'); // ✓ Async loading // 3. Tree-shaking (import only) import { usedFunction } from 'lodash-es'; // Bundler removes unused functions ✓ const _ = require('lodash'); // Entire library included ✗ // 4. Named exports handling // ES6 export const name = 'Alice'; export default function() {} // CommonJS module.exports = { name: 'Alice' }; module.exports.name = 'Alice'; exports.name = 'Alice'; // Shorthand #JavaScript #WebDevelopment #Frontend #LearnInPublic #InterviewQuestions #Programming #TechInterviews

here's some important JavaScript questions to crack interviews 𝟭. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝘁𝗵𝗶𝘀 𝗸𝗲𝘆𝘄𝗼𝗿𝗱? - Refers to the object that is currently executing the function - In global scope, this is the window object (in browsers) - Arrow functions do not have their own this 𝟮. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝗣𝗿𝗼𝘁𝗼𝘁𝘆𝗽𝗮𝗹 𝗜𝗻𝗵𝗲𝗿𝗶𝘁𝗮𝗻𝗰𝗲? - JS objects inherit properties and methods from other objects via a prototype chain - Every object has a hidden __proto__ property pointing to its prototype - ES6 class syntax is just cleaner syntax over prototypal inheritance 𝟯. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝘁𝗵𝗲 𝗦𝗽𝗿𝗲𝗮𝗱 𝗮𝗻𝗱 𝗥𝗲𝘀𝘁 𝗢𝗽𝗲𝗿𝗮𝘁𝗼𝗿 (...)? - Spread expands an array or object: const newArr = [...arr, 4, 5] - Rest collects remaining arguments into an array: function fn(a, ...rest) {} - Same syntax, different context position determines behavior - Great for copying arrays/objects without mutation 𝟰. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝗗𝗲𝘀𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗶𝗻𝗴? - Extract values from arrays or objects into variables cleanly - Array: const [first, second] = [1, 2] - Object: const { name, age } = user - Supports default values: const { name = 'Guest' } = user 𝟱. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝗘𝘃𝗲𝗻𝘁 𝗗𝗲𝗹𝗲𝗴𝗮𝘁𝗶𝗼𝗻? - Instead of adding listeners to each child element, add one listener to the parent - Uses event bubbling events travel up the DOM tree - More memory efficient for large lists or dynamic content - Check event.target inside the handler to identify which child was clicked 𝟲. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝘁𝗵𝗲 𝗱𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝗰𝗲 𝗯𝗲𝘁𝘄𝗲𝗲𝗻 𝗰𝗮𝗹𝗹(), 𝗮𝗽𝗽𝗹𝘆()? - All three explicitly set the value of this - call() invokes immediately, passes args one by one - apply() invokes immediately, passes args as an array 𝟳. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝗠𝗲𝗺𝗼𝗶𝘇𝗮𝘁𝗶𝗼𝗻? - Caching the result of a function call so it doesn't recompute for the same input - Improves performance for expensive or repeated operations - Commonly implemented using closures and objects/Maps 𝟴. 𝗪𝗵𝗮𝘁 𝗮𝗿𝗲 𝗛𝗶𝗴𝗵𝗲𝗿-𝗢𝗿𝗱𝗲𝗿 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝘀? - Functions that take other functions as arguments or return them - Examples: .map(), .filter(), .reduce(), .forEach() - Core concept in functional programming with JavaScript 𝟵. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝘁𝗵𝗲 𝗱𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝗰𝗲 𝗯𝗲𝘁𝘄𝗲𝗲𝗻 𝗗𝗲𝗲𝗽 𝗖𝗼𝗽𝘆 𝗮𝗻𝗱 𝗦𝗵𝗮𝗹𝗹𝗼𝘄 𝗖𝗼𝗽𝘆? - Shallow copy copies only the top level nested objects are still referenced - Object.assign() and spread {...obj} create shallow copies - Deep copy duplicates everything including nested levels 𝟭𝟬. 𝗪𝗵𝗮𝘁 𝗶𝘀 𝗼𝗽𝘁𝗶𝗼𝗻𝗮𝗹 𝗰𝗵𝗮𝗶𝗻𝗶𝗻𝗴 (?.) 𝗮𝗻𝗱 𝗻𝘂𝗹𝗹𝗶𝘀𝗵 𝗰𝗼𝗮𝗹𝗲𝘀𝗰𝗶𝗻𝗴 (??)? - ?. safely accesses nested properties without throwing if something is null/undefined - user?.address?.city returns undefined instead of crashing - ?? returns the right side only if the left is null or undefined Follow the Frontend Circle By Sakshi channel on WhatsApp: https://lnkd.in/gj5dp3fm 𝗙𝗼𝗹𝗹𝗼𝘄𝘀 𝘂𝘀 𝗵𝗲𝗿𝗲 → https://lnkd.in/geqez4re

Day 35/50 – JavaScript Interview Question? Question: What is the new keyword and what happens when you use it? Simple Answer: The new keyword creates an instance of a constructor function or class. It performs four steps: creates an empty object, sets the prototype, binds this to the new object, and returns the object (unless the constructor explicitly returns another object). 🧠 Why it matters in real projects: Understanding new is fundamental to JavaScript's prototypal inheritance and OOP patterns. It's crucial when working with classes, custom data structures, and understanding how frameworks like React create component instances. 💡 One common mistake: Forgetting new when calling a constructor, causing this to refer to the global object (or undefined in strict mode) instead of creating a new instance. Also, not knowing that arrow functions can't be used as constructors. 📌 Bonus: // Constructor function function Person(name, age) { this.name = name; this.age = age; } Person.prototype.greet = function() { return `Hello, I'm ${this.name}`; }; // Using new keyword const alice = new Person('Alice', 30); // What happens behind the scenes: function Person(name, age) { // 1. const this = Object.create(Person.prototype); // 2. this.__proto__ = Person.prototype; this.name = name; // 3. Bind properties to this this.age = age; // 4. return this; (implicit) } // Common mistakes: // ✗ Forgetting new const bob = Person('Bob', 25); // undefined, this = window! console.log(window.name); // "Bob" - polluted global! // ✓ With new const charlie = new Person('Charlie', 35); // ✓ // Arrow functions can't be constructors const PersonArrow = (name) => { this.name = name; }; const dave = new PersonArrow('Dave'); // ✗ TypeError! // ES6 Classes (syntactic sugar over prototypes) class Employee extends Person { constructor(name, age, title) { super(name, age); // Must call before using this this.title = title; } } // Custom return value overrides function Custom() { this.name = 'Test'; return { custom: true }; // This is returned instead } const obj = new Custom(); console.log(obj); // { custom: true } #JavaScript #WebDevelopment #Frontend #LearnInPublic #InterviewQuestions #Programming #TechInterviews #OOP #Constructors

Last week, I shared 20 essential JavaScript interview questions. No textbook definitions. Just clarity. 1️⃣ Higher-Order Functions Functions that take another function as an argument or return one. Examples: map(), filter(), reduce() 👉 Shows strong functional programming fundamentals. 2️⃣ Destructuring Extract values from objects/arrays into variables. Cleaner, shorter, more readable code. 3️⃣ Template Literals Backticks ` ` allow embedding variables using ${}. Used for dynamic strings. 4️⃣ Spread vs Rest Operator Spread → Expands values Rest → Collects values Same syntax (...), different purpose. 5️⃣ Rest vs arguments Rest parameter is a real array. arguments is array-like and outdated. 👉 Prefer rest. 6️⃣ Object vs Array Object → Key-value structure Array → Ordered list Use arrays for lists, objects for structured data. 7️⃣ Cloning Objects/Arrays Use spread (...) for shallow copy. Use structuredClone() for deep copy. 8️⃣ Object.keys / values / entries Used to extract keys, values, or key-value pairs for iteration. 9️⃣ map() Transforms each element and returns a new array. 🔟 map() vs forEach() map() returns a new array. forEach() does not return anything. 👉 Use map() when transforming data. 1️⃣1️⃣ Event Delegation Attach one event listener to a parent instead of multiple children. Improves performance and scalability. 1️⃣2️⃣ JavaScript Modules Split code using export and import. Keeps projects clean and maintainable. 1️⃣3️⃣ Prototype Chain JavaScript uses prototypes for inheritance. Objects inherit properties from other objects. 1️⃣4️⃣ bind vs call vs apply All control this: • call() → arguments individually • apply() → arguments as array • bind() → returns a new function 1️⃣5️⃣ == vs === == allows type coercion. === is strict comparison. 👉 Always prefer ===. 1️⃣6️⃣ DOM The bridge between JavaScript and HTML. Used to read and manipulate webpage elements. 1️⃣7️⃣ preventDefault() & stopPropagation() Control event behavior and event bubbling. 1️⃣8️⃣ Sync vs Async Sync → Runs line by line. Async → Uses callbacks, promises, async/await. 1️⃣9️⃣ Event Object vs Custom Event Event object → Default event data. Custom event → Created manually for specific use cases. 2️⃣0️⃣ Performance Optimization • Debouncing / Throttling • Reduce unnecessary DOM updates • Lazy loading • Efficient loops Candidates don’t fail because they don’t know React. They fail because they can’t clearly explain JavaScript fundamentals. If you can explain these confidently with examples — you're interview ready. Save this. Share with someone preparing for frontend roles. Comment “Advanced JS” if you want the next level questions. #JavaScript #FrontendDeveloper #WebDevelopment #TechCareers #CodingInterview #Mentorship #SoftwareDevelopment

🚀 JavaScript Interview Preparation Checklist (Frontend Developers) I’ve compiled this structured JavaScript topic list for interviews. Sharing it here so it can help others who are preparing for frontend roles. 📌 Core JavaScript Concepts • Scope (global, function, block) • Execution context • this keyword (different contexts) • Hoisting • Closures • Prototype chain • Type coercion • == vs === • Primitive vs non-primitive data types 📌 ES6 & Modules • let, const • Arrow functions • Template literals • Rest parameters • Spread operator • Object & array destructuring • Classes • Default parameters • Map, Set • for…of loop • import / export • Default exports 📌 Asynchronous JavaScript • Callbacks • Promises • Async/Await • Event Loop (call stack, microtask, macrotask) • Promise.all() • Promise.allSettled() • Promise.any() • Promise.race() 📌 Advanced Concepts • Function currying • Debouncing & throttling • Shallow copy vs deep copy • Call by value vs call by reference • Polyfills • Higher Order functions • IIFE 📌 DOM Manipulation & Events • getElementById • getElementsByClassName • getElementsByTagName • querySelector • querySelectorAll • addEventListener • removeEventListener • Event propagation • Event bubbling • Event capturing • Event delegation 📌 API Calls • fetch • axios • fetch vs axios 📌 Error Handling • try • catch • finally 📌 Web Storages • sessionStorage • localStorage • cookies • IndexedDb 📌 OOP in JavaScript • Constructor functions • Prototypes • __proto__ • this • call, apply, bind • ES6 classes • Inheritance • Polyfills 📌 Functions • Function expressions • Arrow functions • Named functions • Callback functions 📌 Loops • for • for…of • for…in • forEach • while • do…while 📌 Array Methods • map • filter • reduce • join • slice • splice • push • pop • shift • unshift • find 📌 String Methods • length • charAt • split • slice • substring 📌 Object Methods • Object.keys() • Object.values() • Object.entries() 📌 Browser APIs • JSON.parse() • JSON.stringify() • setTimeout() • setInterval() • clearTimeout() • clearInterval() • fetch() If you’re preparing for frontend or React interviews, covering these topics with practical examples will give you a strong JavaScript foundation 💡. #JavaScript #FrontendDevelopment #ReactJS #WebDevelopment #InterviewPreparation #SoftwareEngineering

Top 50 JavaScript Interview Questions 1. What are the key features of JavaScript?   2. Difference between var, let, and const   3. What is hoisting?   4. Explain closures with an example   5. What is the difference between == and ===?   6. What is event bubbling and capturing?   7. What is the DOM?   8. Difference between null and undefined   9. What are arrow functions?   10. Explain callback functions   11. What is a promise in JS?   12. Explain async/await   13. What is the difference between call, apply, and bind?   14. What is a prototype?   15. What is prototypal inheritance?   16. What is the use of ‘this’ keyword in JS?   17. Explain the concept of scope in JS   18. What is lexical scope?   19. What are higher-order functions?   20. What is a pure function?   21. What is the event loop in JS?   22. Explain microtask vs. macrotask queue   23. What is JSON and how is it used?   24. What are IIFEs (Immediately Invoked Function Expressions)?   25. What is the difference between synchronous and asynchronous code?   26. How does JavaScript handle memory management?   27. What is a JavaScript engine?   28. Difference between deep copy and shallow copy in JS   29. What is destructuring in ES6?   30. What is a spread operator?   31. What is a rest parameter? 32. What are template literals?   33. What is a module in JS?   34. Difference between default export and named export   35. How do you handle errors in JavaScript?   36. What is the use of try...catch?   37. What is a service worker?   38. What is localStorage vs. sessionStorage?   39. What is debounce and throttle?   40. Explain the fetch API   41. What are async generators?   42. How to create and dispatch custom events?   43. What is CORS in JS?   44. What is memory leak and how to prevent it in JS?   45. How do arrow functions differ from regular functions?   46. What are Map and Set in JavaScript?   47. Explain WeakMap and WeakSet   48. What are symbols in JS?   49. What is functional programming in JS?   50. How do you debug JavaScript code? #JavaScript #Interview #Jobs

Day 43/50 – JavaScript Interview Question? Question: What is Event Loop, Call Stack, and Task Queue in JavaScript? Simple Answer: The Call Stack tracks function execution (LIFO). The Task Queue (Callback Queue) holds callbacks from async operations. The Event Loop continuously checks if the Call Stack is empty, then moves tasks from the queue to the stack. Microtasks (Promises) have priority over Macrotasks (setTimeout). 🧠 Why it matters in real projects: Understanding the Event Loop is crucial for debugging async behavior, preventing UI blocking, and optimizing performance. It explains why promises execute before setTimeout(0), and helps you write non-blocking code in a single-threaded environment. 💡 One common mistake: Not understanding microtask vs macrotask priority, leading to unexpected execution order. Also, creating infinite microtask loops that starve the macrotask queue and freeze the UI. 📌 Bonus:  // Example demonstrating execution order console.log('1: Sync Start'); setTimeout(() => {  console.log('2: setTimeout (Macrotask)'); }, 0); Promise.resolve().then(() => {  console.log('3: Promise 1 (Microtask)'); }).then(() => {  console.log('4: Promise 2 (Microtask)'); }); console.log('5: Sync End'); // Output: // 1: Sync Start // 5: Sync End // 3: Promise 1 (Microtask) // 4: Promise 2 (Microtask) // 2: setTimeout (Macrotask) // Event Loop phases: // 1. Execute all synchronous code // 2. Execute all microtasks (Promises, queueMicrotask) // 3. Execute one macrotask (setTimeout, setInterval, I/O) // 4. Repeat // Call Stack visualization function first() {  console.log('First');  second();  console.log('First again'); } function second() {  console.log('Second');  third(); } function third() {  console.log('Third'); } first(); // Stack: [first] → [first, second] → [first, second, third] // Output: First, Second, Third, First again // Microtask vs Macrotask setTimeout(() => console.log('Macro 1'), 0); Promise.resolve()  .then(() => {  console.log('Micro 1');  Promise.resolve().then(() => console.log('Micro 2'));  })  .then(() => console.log('Micro 3')); setTimeout(() => console.log('Macro 2'), 0); // Output: Micro 1, Micro 2, Micro 3, Macro 1, Macro 2 // All microtasks complete before next macrotask! // Blocking the Event Loop (BAD!) function blockingOperation() {  const start = Date.now();  while (Date.now() - start < 3000) {  // Blocks for 3 seconds - UI freezes!  } } // Better: Break into chunks async function nonBlockingOperation() {  for (let i = 0; i < 1000; i++) {  // Do work...  if (i % 100 === 0) {  await new Promise(resolve => setTimeout(resolve, 0));  // Yields to Event Loop every 100 iterations  }  } } // Microtask starvation (infinite loop) function starveEventLoop() {  Promise.resolve().then(() => {  starveEventLoop(); // Creates endless microtasks!  // Macrotasks never run - UI freezes  }); }

🚀 Day 14 of JavaScript Daily Series JavaScript Template Literals — Backticks, ${}, Multi-line Strings (Super Easy Hinglish + Real-Life Examples) Aaj hum JavaScript ka one of the most modern & powerful features seekhenge → 👉 Template Literals (introduced in ES6) Yeh code ko 2x clean, readable aur easy bana dete hain! 💡 What Are Template Literals? (Simple English) Template literals are special strings written using backticks (``) They allow: ✔ Multi-line strings ✔ Variables inside strings ✔ Cleaner formatting ✔ Better readability 🧠 Hinglish Explanation Pehle hum strings ko " " quotes se likhte the, aur variables ko add karne ke liye + + laga-laga ke hath dukh jaata tha. Template literals bolte hain: “Ritesh bhai, tension mat lo… sab easy bana dete hain!” 😄 🧱 1️⃣ Backticks (``) — The New & Better String Format Example: let name = "Ritesh"; let msg = `Hello ${name}, welcome to JavaScript!`; console.log(msg); ✔ No + + ✔ Automatic spacing ✔ Clean and readable 🔁 2️⃣ ${} — Variable / Expression Insert Karna Aap backticks ke andar kisi bhi variable ko easily daal sakte ho: let price = 499; console.log(`Your final price is ₹${price}`); Expressions bhi kaam karte hain: console.log(`2 + 2 = ${2 + 2}`); 📜 3️⃣ Multi-line Strings — No Need for \n Pehle hum: let msg = "Hello\nWorld"; Ab: let msg = ` This is line 1 This is line 2 This is line 3 `; ✔ Best for UI text ✔ Emails ✔ Multi-line messages ✔ Readable content 📱 Real-Life Example — Instagram Notification Message let user = "AapanRasoi"; let followers = 1200; let message = ` 🔔 New Activity! Hey ${user}, you gained ${followers} followers today! Keep growing! 🚀 `; console.log(message); Perfect for: ✔ Notification messages ✔ Email templates ✔ Chat messages ✔ JSX-style strings 🧠 Why Template Literals Are a Game-Changer? ✔ No messy string concatenation ✔ More readable ✔ Easy variable insertion ✔ Perfect for dynamic UI ✔ Used heavily in React, Node.js, APIs, everything! 🎯 Quick Summary FeatureUseBackticksCleaner strings${}Insert variables & expressionsMulti-lineCreate structured text easily

🤔 Preparing for your next JavaScript interview? Today, we're tackling one of the most crucial and misunderstood concepts in JavaScript: The Event Loop. JavaScript is single-threaded, meaning it has only one "Call Stack" and can only do one thing at a time. So, how does it handle time-consuming operations like API calls (fetch) or timers (setTimeout) without freezing the entire browser? The answer is that the JavaScript engine doesn't work alone. It gets help from the browser environment and a manager called the Event Loop. Here’s the complete system in a nutshell: 1. The Call Stack: This is where your JavaScript code is executed, one line at a time. 2. Web APIs: These are features provided by the browser (not the JS engine). When your code calls a slow operation like setTimeout, the JS engine hands it off to the Web API to handle in the background. The engine then immediately moves on to the next line of code, keeping the Call Stack free. 3.The Callback Queue (or Task Queue): Once the Web API finishes its job (the timer completes, the data arrives), it doesn't interrupt your code. Instead, it places the function you provided (the "callback") into this waiting line. This brings us to the final, critical piece. How does the function get from the waiting line back into the main code to be run? ✅ Enter the Event Loop: The Event Loop is a simple, constantly running process with one golden rule: "If the Call Stack is empty, take the first item from the Callback Queue and push it onto the Call Stack to be executed." ``` console.log('First'); setTimeout(() => { console.log('Second'); }, 0); console.log('Third'); // Output: First, Third, Second ``` Why this order? 1. `console.log('First')` goes to the Call Stack and runs. 2. `setTimeout` is handed to a Web API. JavaScript immediately continues. 3. `console.log('Third')` goes to the Call Stack and runs. 4. The `Call Stack` is now empty. 5. In the background, the timer finishes instantly (0ms) and places its callback `() => console.log('Second')` into the Callback Queue. 6. The Event Loop sees the Call Stack is empty, takes the callback from the queue, and pushes it onto the stack to run. This system is what makes JavaScript "non-blocking." The Event Loop ensures that slow tasks wait their turn without ever freezing the user interface. #javascript #eventloop #asynchronousjavascript #webdevelopment #frontenddevelopment #backenddevelopment #nodejs #v8engine #callstack #microtasks