📦 JavaScript Arrays

Last Updated: 12th October 2025

An array is a special variable that can hold multiple values in a single name.
Each value in an array has a position (index) starting from 0.

Hinglish Tip 🗣: Array ek aisi list hoti hai jisme hum ek hi variable me kai saari values rakh sakte hain — jaise ek dabba jisme alag-alag items hain.

✏ Creating an Array

We can create arrays in two ways:

// Using square brackets (most common)
let fruits = ["Apple", "Banana", "Mango"];

// Using new Array() constructor
let numbers = new Array(10, 20, 30, 40);

console.log(fruits);
console.log(numbers);

💡 Both ways are valid, but the square bracket [] method is preferred because it’s simple and clean.

Accessing Array Elements

We can access an array element by referring to the index number.

let colors = ["Red", "Green", "Blue"];

console.log(colors[0]); // Red
console.log(colors[1]); // Green
console.log(colors[2]); // Blue

Modifying Array Elements

We can update any value in an array using its index.

let fruits = ["Apple", "Banana", "Mango"];
fruits[1] = "Orange"; // Replace Banana with Orange
console.log(fruits); // ["Apple", "Orange", "Mango"]

🧩 Nested Arrays

Arrays can also contain other arrays inside them (multi-dimensional arrays).

let matrix = [
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9],
];

console.log(matrix[0]); // [1, 2, 3]
console.log(matrix[1][2]); // 6

Hinglish Tip 🗣: Nested array ko 2D array bhi kehte hain — jaise Excel sheet me rows aur columns hote hain.

Array Destructuring

It means unpacking an array into multiple variables.

let fruits = ["Apple", "Banana", "Mango"];
let [a, b, c] = fruits;

console.log(a); // Apple
console.log(b); // Banana
console.log(c); // Mango

Spread with Arrays

Example 1: Copy an Array

const fruits = ["apple", "banana"];
const moreFruits = [...fruits]; // makes a copy
console.log(moreFruits);

Example 2: Merge arrays

const a = [1, 2, 3];
const b = [4, 5];
const merged = [...a, ...b];
console.log(merged);

Example 3: Flatten an Array

const array = [
  [1, 2],
  [3, 4],
];
const flattened = [...array[0], ...array[1]];
console.log(flattened);

Example 4: Merge Arrays with Destructuring

const a = [1, 2, 3];
const b = [4, 5];
const [c, d, ...rest] = [...a, ...b];
console.log(c); // 1
console.log(d); // 2
console.log(rest); // [3, 4, 5]

Example 5: Add New Elements to an Array

const array = [1, 2, 3];
const newArray = [...array, 4, 5];
console.log(newArray); // [1, 2, 3, 4, 5]

💡 Quick Practice

  1. Create an array called subjects with values ["Math", "Science", "English"].
  2. Print the 2nd element of the array.
  3. Change “English” to “Computer”.
  4. Exercises Set 1
  5. Exercises Set 2
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