Learning path

JavaScript

The language that makes web pages interactive, from your first variable to working with the DOM.

Start with lesson 1

1

JavaScript Introduction

What JavaScript is, what it can do in the browser and beyond, how it relates to HTML and CSS, and your first lines of code.
4 min read
2

Where to Put JavaScript

Add JavaScript with script elements and external .js files, understand why placement matters, and load scripts correctly with defer.
4 min read
3

JavaScript Output (console.log)

Show results with console.log and its relatives, write into the page with textContent, use alert sparingly, and debug with the browser console.
4 min read
4

JavaScript Variables (let and const)

Store values in variables with let and const, learn naming rules, when to use each keyword, and why to avoid the old var.
4 min read
5

JavaScript Data Types

Strings, numbers, booleans, undefined, null, objects and arrays; checking types with typeof; and how JavaScript converts between types.
4 min read
6

JavaScript Operators

Arithmetic, assignment, comparison and logical operators, why to use === instead of ==, the ternary operator, and nullish coalescing.
4 min read
7

JavaScript Strings

Create and combine strings, read characters, and use the essential string methods to search, slice, change case, trim, split and replace text.
4 min read
8

JavaScript Numbers

Work with numbers: rounding, fixed decimals, converting from strings, NaN checks, the Math object, random numbers and formatting prices.
4 min read
9

JavaScript If/Else

Make decisions with if, else if and else, combine conditions, use truthy checks, write guard clauses and avoid deeply nested code.
4 min read
10

JavaScript Switch

Choose between many exact values with switch, understand break and fall-through, use default, and know when an object lookup is cleaner.
3 min read
11

JavaScript Loops (for, while)

Repeat code with for, while, do...while, for...of and for...in loops, control them with break and continue, and avoid infinite loops.
4 min read
12

JavaScript Arrays

Store ordered lists in arrays: create them, read and change items by index, add and remove with push, pop, shift, unshift and splice, and copy with spread.
4 min read
13

JavaScript Array Methods

Transform and search data with forEach, map, filter, find, some, every and reduce, and chain them together to process lists in a few readable lines.
5 min read
14

JavaScript Objects

Group related data with objects: create them, read and update properties with dot and bracket notation, loop over them, copy them, destructure them and add methods.
4 min read
15

JavaScript Functions

Write reusable code with functions: declarations, parameters and arguments, return values, default and rest parameters, and functions as values.
4 min read
16

JavaScript Arrow Functions

Write short functions with the arrow syntax, learn implicit returns and returning objects, and understand how arrow functions treat this differently.
4 min read
17

JavaScript Scope

Global, function and block scope explained, why let and const beat var, how shadowing works, and a first look at closures.
4 min read
18

DOM: Selecting Elements

What the DOM is, and how to find elements with getElementById, querySelector and querySelectorAll, loop over results, and move around the element tree.
5 min read
19

DOM: Changing Content

Change text, HTML, attributes, classes and styles, create and insert new elements, remove elements, and render a list from data.
5 min read
20

JavaScript Events

Respond to clicks, typing and keys with addEventListener, use the event object, prevent default actions, and handle many elements with event delegation.
5 min read
21

JavaScript Forms and Validation

Read form values, handle submit, validate input with clear error messages, combine HTML validation with JavaScript, and use FormData.
6 min read
22

JavaScript Local Storage

Save data in the browser with localStorage and sessionStorage, store objects with JSON, handle errors, and remember a user's theme between visits.
5 min read
23

JavaScript Fetch and JSON

Load data from APIs with fetch, understand JSON and HTTP status codes, handle errors, send data with POST, and show results on the page.
5 min read
24

JavaScript Async/Await

Understand asynchronous JavaScript, Promises and the event loop, then write clear async code with async/await, try/catch, and parallel requests with Promise.all.
5 min read
25

JavaScript Project: To-Do List App

Build a complete to-do list app step by step with state, rendering, events, delegation, filters and localStorage, using everything from the JavaScript course.
7 min read