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JavaScript

Make websites interactive: from variables and functions to the DOM, APIs and real projects.

All (36) Beginner (14) Intermediate (10) Advanced (12)

🌱 Beginner 14 lessons

Start here. No experience needed.

Lesson 1

What is JavaScript? — The Language That Makes Websites Interactive

JavaScript brings web pages to life. Learn what JavaScript is, what it can do, and run your first script in un...

Beginner 2 min

Lesson 2

JavaScript Variables — var, let, and const Explained

Variables store data in JavaScript. Learn the difference between var, let, and const, when to use each, and ho...

Beginner 2 min

Lesson 3

JavaScript Data Types — Strings, Numbers, Booleans and More

JavaScript has 8 data types. Learn strings, numbers, booleans, null, undefined, and how to check what type a v...

Beginner 3 min

Lesson 4

JavaScript Operators — Arithmetic, Comparison & Logical

Operators are the building blocks of logic in JavaScript. Learn arithmetic, comparison, logical, and assignmen...

Beginner 3 min

Lesson 5

Strings: Working with Text and Template Literals

Learn to create, join, search, cut and format text in JavaScript with template literals and string methods, an...

Beginner 11 min

Lesson 6

Numbers and Math: Bills, Discounts and Rounding

Learn how JavaScript handles numbers, rounding, random values and text to number conversion, and build a resta...

Beginner 10 min

Lesson 7

JavaScript Conditionals — if, else, and switch

Conditionals let your code make decisions. Learn if, else if, else, switch statements, and build real features...

Beginner 3 min

Lesson 8

JavaScript Loops — for, while, and for...of

Loops repeat a block of code. Learn for, while, for...of, and for...in loops with real examples like rendering...

Beginner 2 min

Lesson 9

JavaScript Functions — Writing Reusable Code Blocks

Functions let you write code once and reuse it anywhere. Learn function declarations, arrow functions, paramet...

Beginner 2 min

Lesson 10

JavaScript Arrays — Working with Lists of Data

Arrays store multiple values in one variable. Learn how to create, access, and manipulate arrays using push, p...

Beginner 3 min

Lesson 11

JavaScript Objects — Key-Value Pairs and Methods

Objects store related data together in key-value pairs. Learn how to create, access, update, and work with obj...

Beginner 3 min

Lesson 12

DOM Manipulation — Changing HTML with JavaScript

The DOM is the live representation of your HTML. Learn how to select, modify, create, and delete elements usin...

Beginner 3 min

Lesson 13

Events: Responding to Clicks, Typing and Forms

Make web pages react to clicks, typing, keys and form submissions with addEventListener, and build a canteen f...

Beginner 15 min

Lesson 14

Debugging: Finding and Fixing Bugs with the Console and DevTools

Learn to read JavaScript error messages, inspect values with console.log, typeof and console.table, and pause ...

Beginner 11 min

⚙️ Intermediate 10 lessons

You know the basics. Build real skills.

Lesson 15

Array Methods: map, filter, reduce, find and sort

Use forEach, map, filter, reduce, find, some, every and sort to work with lists in JavaScript, and build a gro...

Intermediate 12 min

Lesson 16

Scope and Hoisting: Where Your Variables Live

Understand global, function and block scope, why let and const replace var, shadowing, hoisting and the tempor...

Intermediate 10 min

Lesson 17

Arrow Functions and Closures

Write short arrow functions and understand closures: functions that remember. Build a clinic token machine wit...

Intermediate 10 min

Lesson 18

Destructuring, Spread and Rest: Cleaner Code with Objects and Arrays

Unpack arrays and objects with destructuring, copy and merge them with spread, collect values with rest, and h...

Intermediate 12 min

Lesson 19

Dates and Time: Countdowns, Ages and Formatting

Create and change dates, find the days between two dates, format dates the Indian way and handle IST and UTC. ...

Intermediate 13 min

Lesson 20

JSON: Sending and Saving Data as Text

Learn what JSON is and why servers use it. Turn objects into text with JSON.stringify, read server data with J...

Intermediate 11 min

Lesson 21

Error Handling: try, catch and Friendly Error Messages

Catch errors with try, catch and finally, throw your own errors, create a custom PaymentError class and show f...

Intermediate 12 min

Lesson 22

Form Validation with JavaScript: Instant, Friendly Feedback

Validate a sign-up form with JavaScript: handle submit, check email, Indian mobile numbers and passwords, show...

Intermediate 18 min

Lesson 23

localStorage: Remembering Data in the Browser

Save data in the browser with localStorage so it stays after the page is closed. Store arrays with JSON, read ...

Intermediate 13 min

Lesson 24

Modules: Splitting Code into Files with import and export

Split a shop app into small files with JavaScript modules. Learn named and default exports, import with as, sc...

Intermediate 13 min

🚀 Advanced 12 lessons

Go deeper, write professional code and build projects.

Lesson 25

Callbacks and Promises: Waiting Without Freezing the Page

Learn how JavaScript waits for slow tasks without freezing the page. Simulate a food delivery order with setTi...

Advanced 13 min

Lesson 26

async and await: Asynchronous Code That Reads Like a Story

Write asynchronous JavaScript that reads top to bottom with async and await. Handle errors with try and catch,...

Advanced 12 min

Lesson 27

Fetch API: Getting Live Data from the Internet

Use fetch to show live weather for Indian cities and load posts from a practice API. Handle status codes, load...

Advanced 14 min

Lesson 28

The Event Loop: How JavaScript Does One Thing at a Time

See how JavaScript runs one thing at a time with the call stack, Web APIs, the task queue and the microtask qu...

Advanced 13 min

Lesson 29

Classes and Objects: Building a Bank Account in JavaScript

Build a bank account with JavaScript classes: constructors, methods, getters and setters, static members and p...

Advanced 13 min

Lesson 30

The this Keyword Explained Simply

Understand the JavaScript this keyword with one simple idea: like the word I, it means whoever is calling. Fix...

Advanced 11 min

Lesson 31

Regular Expressions: Checking PIN Codes, Mobile Numbers and More

Learn JavaScript regular expressions by validating a KYC form: PIN codes, mobile numbers, PAN and vehicle numb...

Advanced 13 min

Lesson 32

Debounce and Throttle: Smarter Search Boxes and Scroll Events

Stop sending a request on every key press. Write your own debounce and throttle functions with setTimeout and ...

Advanced 15 min

Lesson 33

Project: Build a Study Planner To-do App

Build a study planner to-do app step by step with plain JavaScript: add, tick, delete and filter tasks, count ...

Advanced 35 min 🔨 Project

Lesson 34

Project: Build a Quiz App with Score and Timer

Build a general knowledge quiz app step by step: one question at a time, right and wrong highlights, a score, ...

Advanced 36 min 🔨 Project

Lesson 35

Project: Build a Weather App with a Live API

Build a live weather app step by step with fetch and async/await: search a city, show the current weather and ...

Advanced 43 min 🔨 Project

Lesson 36

Project: Build a Monthly Expense Tracker

Build a monthly expense tracker step by step: add and delete expenses, total them with reduce, format rupees w...

Advanced 46 min 🔨 Project