Arrays

An array is an ordered, changeable list of values.

Syntax

const fruits = ["apple", "banana", "cherry"];

Example

fruits.push("date");
console.log(fruits[0]);
console.log(fruits.length);
console.log(fruits.includes("banana"));

Expected output

apple
4
true

Indexing starts at 0. .push() adds to the end. Common array methods .map(), .filter(), and .reduce() each take a callback function and return a new array (or value) without changing the original:

const doubled = [1, 2, 3].map((n) => n * 2); // [2, 4, 6]

Common mistakes

• Accessing an index that doesn't exist returns undefined rather than raising an error — check array.length first if you're not sure the index is valid.

Practice

Create an array of three favorite movies and log the second one.

const movies = ["Inception", "Arrival", "Interstellar"];
console.log(movies[1]);