Learn JavaScript

What you will practise

Learn JavaScript to work with data and make pages interactive. Start with variables, then practise functions, arrays and asynchronous operations.

• Distinguish numbers, strings and booleans.
• Write conditions, loops and functions.
• Transform arrays and understand promises.

Before you start: No experience is required to start. Basic HTML helps with browser exercises.

A first example to understand

function total(price, quantity) {
  return price * quantity;
}
console.log(total(4, 3)); // 12

The function receives a price and a quantity and returns their product. It prints 12. return passes a value back; console.log lets you inspect it.

Try it: Call total with a price of 7 and a quantity of 3. Predict the result before running the code.

Build a to-do list: a JavaScript project in four steps

Understand a specific concept

• Beginner JavaScript project: a to-do list in 4 steps
• Why does JavaScript return 23 instead of 5?
• Understanding Promises and Async / Await in JavaScript (ES6+)
• Mastering map(), filter(), and reduce() in JavaScript (Clear Examples)