When writing programs in JavaScript, we often need to store multiple values together.

For example:

• A list of favorite movies

• A list of student marks

• A list of tasks

Instead of creating many variables, JavaScript provides arrays to store collections of values efficiently.

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What Are Arrays?

An array is a collection of values stored in a specific order.

Example:

let fruits = ["Apple", "Banana", "Orange"];

Here the array contains three elements:

Index	Value
0	Apple
1	Banana
2	Orange

Important point:

⚠️ Array indexing starts from 0.

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Why We Need Arrays

Imagine storing fruit names using separate variables.

let fruit1 = "Apple";
let fruit2 = "Banana";
let fruit3 = "Orange";

This works, but managing many variables becomes difficult.

Using an array is much easier:

let fruits = ["Apple", "Banana", "Orange"];

Now all values are stored in one structure.

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How to Create an Array

Arrays are created using square brackets [ ].

Example:

let numbers = [10, 20, 30, 40];

You can store different types of values:

let data = ["Viral", 22, true];

But usually arrays store similar types of data.

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Accessing Elements Using Index

Each array element has an index position.

Example:

let fruits = ["Apple", "Banana", "Orange"];

console.log(fruits[0]);

Output:

Apple

Access second element:

console.log(fruits[1]);

Output:

Banana

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Updating Array Elements

Array values can be changed using their index.

Example:

let fruits = ["Apple", "Banana", "Orange"];

fruits[1] = "Mango";

console.log(fruits);

Output:

["Apple", "Mango", "Orange"]

Here Banana was replaced by Mango.

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Array Length Property

The .length property tells us how many elements are in the array.

Example:

let fruits = ["Apple", "Banana", "Orange"];

console.log(fruits.length);

Output:

3

This is very useful when working with loops.

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Looping Over Arrays

To access all elements, we usually use a loop.

Example using a for loop:

let fruits = ["Apple", "Banana", "Orange"];

for (let i = 0; i < fruits.length; i++) {
  console.log(fruits[i]);
}

Output:

Apple
Banana
Orange

The loop runs once for each element in the array.

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Visual Representation of an Array

Example array:

let fruits = ["Apple", "Banana", "Orange"];

Visual structure:

Index →   0        1        2
        -------------------------
Value →  Apple   Banana   Orange

Each value is stored at a specific index position.

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Assignment Practice

1️⃣ Create an Array of Favorite Movies

let movies = [
  "Inception",
  "Interstellar",
  "Avengers",
  "Batman",
  "Joker"
];

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2️⃣ Print First and Last Element

console.log(movies[0]);
console.log(movies[movies.length - 1]);

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3️⃣ Change One Value

movies[2] = "Spider-Man";

console.log(movies);

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4️⃣ Loop Through the Array

for (let i = 0; i < movies.length; i++) {
  console.log(movies[i]);
}