JavaScript Example

javascript

const lesson = "Learn by building"
const completed = true

if (completed) {
  console.log("Ready for next chapter")
}

Guided tutorial track

JavaScript Tutorial

Learn JavaScript from scratch with practical examples covering variables, functions, arrays, objects, DOM manipulation, events, and browser scripting.

Start learning

Tutorial overview

Start here, then move through the chapters

This tutorial is designed to be followed in order. Read the chapter, practice with the editor, test your understanding, and move toward completion.

Lessons

207

Sections

Access

Free

Level

beginner

Ready to begin?

Start with lesson one and follow the tutorial step by step.

Open first lesson

This tutorial teaches JavaScript from a first variable to code that reacts to a click, fetches data and updates the page - the language itself first, then the browser APIs that make it useful.

Values, a condition, and output

javascript

const name = "Ada"
const visits = 3

if (visits > 1) {
  console.log(`Welcome back, ${name}`)
} else {
  console.log(`Hello, ${name}`)
}

What JavaScript actually is

JavaScript is the language that makes a page do something. HTML describes what is there, CSS decides how it looks, and JavaScript decides what happens when someone interacts with it.

Unlike HTML and CSS it is a real programming language: variables, conditions, loops, functions and data structures. That makes it harder, and also the reason it is worth the time.

Where it runs

In every browser, with no install and no build step. Open the console on this page and you are already in a JavaScript environment.

It also runs on servers through Node, which is why it is the one language that can cover a whole product. This tutorial stays in the browser, because that is where the feedback is immediate.

What this tutorial covers

The basics - variables, types, operators, conditions and loops.
Functions and scope - parameters, return values, closures and this.
Data - arrays, objects, Maps and Sets, and the methods worth knowing by heart.
The DOM - finding elements, changing them, and responding to events.
Asynchronous code - callbacks, promises, async/await and fetching data.
Modern JavaScript - modules, classes, destructuring, generators and error handling.

Each chapter is short and runnable, and the order is deliberate: nothing uses an idea you have not met yet.

Reacting to a click

javascript

const button = document.querySelector("#go")
const output = document.querySelector("#out")

button.addEventListener("click", () => {
  output.textContent = "Clicked at " + new Date().toLocaleTimeString()
})

The part that makes it click

Five lines, and the page responds to a person. Most of what you will write professionally is a longer version of exactly this shape: find something, listen for something, change something.

Frameworks like React exist to manage that pattern at scale - but they are JavaScript underneath, and they make far more sense once this is second nature.

What you need before you start

Basic HTML, and enough CSS to recognise a class selector. You need to know what an element is before you can ask JavaScript to find one.

No maths beyond arithmetic, and no prior programming. If this is your first language, expect the first few chapters to be slower than the rest - that is normal and it passes.

How long this takes

The basics - variables, conditions, loops, functions - take a week or two of evenings, and they transfer to every other language you will ever learn.

The DOM is quick and immediately satisfying, because every change is visible. Asynchronous code is the wall most people hit, and it is worth going slowly there rather than pushing on.

You will not remember every method, and you do not need to. Knowing that something exists and what it is called is most of the skill; the exact arguments are a search away.

Common questions

JavaScript. React is a JavaScript library, and starting with it means every problem looks like a React problem when most of them are language problems wearing a costume.

The learning path

Work through these in order. Each part builds on the one before it, and every part lists what it covers and roughly how long it takes.

Part 1Beginner

JavaScript Introduction

6 lessons36 min

What is JavaScript · JavaScript Features · JavaScript Syntax …

JavaScript Tutorial

Start here, then move through the chapters

What JavaScript actually is

Where it runs

What this tutorial covers

The part that makes it click

What you need before you start

How long this takes

Common questions

Should I learn JavaScript or React first?

Is JavaScript the same as Java?

Do I need to learn TypeScript too?

Why does my code run in the wrong order?

Is it still worth learning with AI writing code?

The learning path

What You Will Learn

Practice Live

Tutorial Features

Code examples inside chapters

Practice with the Try It Editor

Quiz for self-check

Certificate after completion

How to Use This Tutorial

Learn the chapter

Practice the example

Test your understanding

Finish with proof

Complete the tutorial with confidence

Why Learn JavaScript

Easy to Learn

Essential Skill

Build Real Websites