Menu
Coddy logo textTech
START LEARNING
flag En iconEnglishdown icon
PopularJourney

Learn JavaScript

A free, interactive online JavaScript course. You write JS on every lesson, with AI hints when you get stuck and a certificate when you finish.

START LEARNING(it's free)
View syllabusJavaScript playground

268,541+ codders enrolled

271 lessons220 challenges1,458 quiz questions

  • Beginner friendly
  • sparkles iconAI-assisted coding help
  • hint iconHands-on interactive lessons
  • volume On iconAudio narration on every lesson
  • quiz iconQuizzes to test your knowledge
  • certificate iconFree certificate of completion

Syllabus

4 sections10 projects271 lessons220 challenges1,458 quiz questions
  1. Section 1

    Fundamentals

    Start sectionStartExpandCollapse    Build a strong foundation with essential concepts and basic skills77 lessons102 challenges391 questions3 projects

    Introduction

    4 lessons323

    Variables

    7 lessons1247

    Operators Part 1

    6 lessons1037

    Operators Part 2

    5 lessons831

    Decision Making

    5 lessons729

    Basic IO

    6 lessons931

    Bill Split Calculator

    Project4 lessons1

    Loops

    7 lessons1345

    Functions

    8 lessons1250

    FizzBuzz with a Twist

    Project4 lessons1

    Arrays Part 1

    6 lessons1037

    Arrays Part 2

    8 lessons1254

    Grocery List Tracker

    Project4 lessons1

    Final Challenges

    3 lessons37
  2. Section 2

    Logic & Flow

    Start sectionStartExpandCollapse    Develop problem-solving skills and create dynamic, interactive programs65 lessons60 challenges325 questions2 projects

    Strings In Depth

    5 lessons630

    Multi-dimensional Arrays

    9 lessons1452

    JSON Part 1

    7 lessons944

    JSON Part 2

    6 lessons530

    Sets Part 1

    8 lessons749

    Sets Part 2

    6 lessons637

    Library Management System

    Project5 lessons1

    Arrays Interesting Topics

    4 lessons422

    Advanced Array methods

    9 lessons761

    Manage Festival System

    Project6 lessons1
  3. Section 3

    Introduction To TypeScriptDedicated page

    Start sectionStartExpandCollapse    Introduction to typescript after learned about javascript73 lessons58 challenges438 questions2 projects

    Getting Started with TS

    5 lessons232

    Core Types

    7 lessons748

    Data Structure: Arrays & Tuple

    9 lessons862

    Working with Functions

    8 lessons855

    Types: Aliases, Unions & Inter

    7 lessons751

    Typing Objects and Interfaces

    8 lessons757

    Project: A Simple Task List

    Project6 lessons18

    Enums

    6 lessons638

    Generics: A First Look

    6 lessons537

    Project: Inventory Management

    Project5 lessons18

    Advanced Topics

    6 lessons642
  4. Section 4

    Object Oriented Programming

    Start sectionStartExpandCollapse    Discover how to organize code with classes, objects, and reusable structures56 lessons49 challenges304 questions3 projects

    Objects & The this Keyword

    6 lessons642

    Organizing Code

    4 lessons434

    Classes & Objects

    4 lessons426

    Methods & Managing State

    2 lessons218

    Encapsulation & Access

    4 lessons426

    Project: A Simple Bank Account

    Project3 lessons1

    Inheritance & The extends Key

    6 lessons645

    Organizing OOP Code

    1 lesson19

    Static Methods & Properties

    4 lessons425

    Polymorphism

    4 lessons425

    Project: A Shape Renderer

    Project4 lessons1

    Getters & Setters

    4 lessons426

    Composition vs. Inheritance

    3 lessons328

    Library Management System

    Project3 lessons1

    Final Challenges

    4 lessons4

JavaScript courses

Hands-on JavaScript courses, free to start in your browser.

Interview PreparationData StructuresGraph Algorithms Courses

Beginner Challenges - Practice Basic Concepts

Popular

Put your beginner coding knowledge to test and try to solve this programming challenges, use any language you want, Happy Coding!

certificate icon

Certificate on completion

  • 20
  • 20

Coding Problems

Popular

Put your programming problem solving skills to the test using the exercises with different difficulties in this course. Designed for coders with some prior knowledge of the basic syntax in any programming language.

certificate icon

Certificate on completion

  • 32
  • 31

Stack - Data Structures Series #1

In this course, you will learn about the Stack data structure, create a Stack from zero using your preferred language, and practice coding challenges with it!

Data Structures
  • 13
  • 6
  • 1

Coding Problems: Volume 2

Put your programming problem solving skills to the test using the exercises with different difficulties in this course. Designed for coders with some prior knowledge of the basic syntax in any programming language. This course is an extension of the first Coding Problems

certificate icon

Certificate on completion

  • 25
  • 24

Hash Tables - Data Structures Series #4

In this course, you will learn about the Hash Table data structure, create a Hash Table from zero using your preferred language, and practice coding challenges with it!

Data Structures
certificate icon

Certificate on completion

  • 14
  • 12

Linked List - Data Structures Series #5

In this course, you will learn about the Linked List data structure, create a Linked List from zero using your preferred language, and practice coding challenges with it!

Data Structures
certificate icon

Certificate on completion

  • 14
  • 6
  • 1
See all 47 JavaScript courses →
What you get
Everything you'll use to learn to code

Learn by Doing

Write real code, query databases, build websites, and master AI prompts. Our interactive lessons cover every skill modern developers need.

playground.js
Code Editor
1const greeting = "Hello, Coddy!"
2function sayHi(name) {
3    return greeting + " " + name
4}
5
bottombar Collapse icon
Test #1test Case Success icon
Test #2test Case Success icon
Test #3test Case Failure icon
Input
"Alex"
Output
"Hello, Coddy! Alex"

Build Your Coding Streak

Stay consistent and watch your progress grow! Track your daily coding habit, protect your streak with freeze days, and earn rewards for showing up every day.

12 days streak

Return tomorrow to keep your streak!

fire Filled icon
left icon

January 2026

right icon

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

21

22

23

24

25

26

27

28

29

30

product Double Or Nothing icon

Double or Nothing

Day 5 of 7

fire Freeze icon

Streak Freeze

2 left

Code Anywhere, Anytime

Take your coding journey on the go! No setup, no downloads - just open and start coding. Available on iOS, Android and Web with 4.9 star ratings.

Python
7Streak
250Score
5Energy
Variables
journey Hex Done Base iconjourney Hex Done Shadow iconjourney Hex Done Top iconjourney Lesson Done icon
journey Path Right Done icon
journey Hex Done Base iconjourney Hex Done Shadow iconjourney Hex Done Top iconjourney Lesson Done icon
journey Path Left Done icon
journey Hex Active Base iconjourney Hex Active Shadow iconjourney Hex Active Top iconjourney Lesson Theory Challenge icon
CONTINUE
journey Path Right icon
journey Hex Locked Base iconjourney Hex Locked Shadow iconjourney Hex Locked Top iconjourney Lesson Theory Challenge icon
journey Path Left icon
journey Hex Locked Base iconjourney Hex Locked Shadow iconjourney Hex Locked Top iconjourney Lesson All icon
Journey
Goals
Leaderboard
Profile
4.9
StarStarStarStarStar
Rating

You're Not Alone in This

Compete on global leaderboards, invite friends to earn rewards, and celebrate each other's wins. Coding is better with friends!

Challenger League
Challenger LeagueTop 7 advance
leaderboard First icon1
avatar 1 icon
fire Filled icon
Alex7+ Days
2840
leaderboard Second icon2
avatar 2 icon
fire Filled icon
Jordan7+ Days
2650
leaderboard Third icon3
avatar 3 icon
fire Filled icon
Sam7+ Days
2420
4
avatar 4 icon
Casey
2180
5
avatar placeholder icon
fire Filled icon
Morgan7+ Days
1950
leaderboard Arrow Up iconPromotion zoneleaderboard Arrow Up icon

Every way to learn

Read, listen, test yourself, ask the AI, or look up anything you've already covered. Every lesson meets you where you are.

Intro to Variables
Audio

A variable is a named container that stores a value you can reference later in your program.

In Python, you create one by writing the name, an equals sign, then the value you want to store.

The value can change over time - reassigning the name simply points it to a new value.

1xSarah

Prove Your Skills

Earn certificates for every course you complete. Add them to your LinkedIn profile and resume to showcase your coding expertise to employers.

CoddyCertificate of Completion
This certifies thatJohn Doehas successfully completed
PythonPython Fundamentals
Verified
DateJan 2026
LinkedInAdd to LinkedIn

Why learn JavaScript with Coddy

  • Run JavaScript instantly in your browser. No Node.js install, no IDE setup. The editor and output sit side-by-side, so the JavaScript feedback loop is short.
  • Modern JavaScript: ES6+ syntax, arrow functions, promises, async/await, destructuring, modules - the JavaScript you'd write on the job, not legacy patterns.
  • AI hints help you debug an exercise without spoiling the solution, so you build the mental model that makes future JS code easier to write.
  • Free JavaScript certificate of completion when you finish the course - a credible proof point alongside any portfolio projects or GitHub repos.

Frequently asked questions about learning JavaScript

Is JavaScript hard to learn?

JavaScript is one of the easier programming languages to start with. The syntax is forgiving, you can run code directly in any browser, and basic interactivity (button clicks, alerts) gives instant visual feedback. The trickier parts - asynchronous code, closures, this-binding - come later, and the course introduces them gradually with hands-on examples.

How long does it take to learn JavaScript?

Plan on one to two weeks of daily practice for the JavaScript basics - variables, functions, conditionals, loops, arrays. Reaching a comfortable level with the DOM, ES6+, and asynchronous JavaScript usually takes two to four months. Going further into React or Node.js is a separate journey on top of that.

Should I learn HTML and CSS before JavaScript?

It helps. JavaScript becomes much more concrete once you can change a real page - hide an element, update text, react to a click. The HTML and CSS courses are short and feed directly into the JavaScript lessons that touch the DOM, but you can also start with pure JavaScript logic.

Can I learn JavaScript online for free?

Yes. The interactive JavaScript course is free - full lessons, coding exercises, quizzes, and a certificate. The editor runs in your browser, so you don't need to install Node.js or any other tooling to start writing JS.

What's the difference between JavaScript and Java?

Despite the name, they're unrelated languages. Java is a statically-typed, class-based language used heavily on servers and Android. JavaScript is dynamically typed and runs in browsers and on Node.js. For the web, learn JavaScript; for Android or large enterprise backends, learn Java.

Do I get a certificate after the JavaScript course?

Yes. Finishing the JavaScript course gives you a free certificate of completion you can share on LinkedIn or include on your resume. A verifiable signal that you've worked through a structured, interactive course, not just watched tutorials.
Coddy programming languages illustration

Learn JavaScript with Coddy

GET STARTED