When writing programs, we often need to store multiple related values.
For example:

• A list of fruits

• Marks of students

• Daily tasks

• Favorite movies

If we store each value separately, our code quickly becomes messy.

let fruit1 = "Apple";
let fruit2 = "Banana";
let fruit3 = "Mango";
let fruit4 = "Orange";

Managing many variables like this is difficult.

JavaScript provides a better solution: Arrays.

Arrays allow us to store multiple values inside a single variable.

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What Are Arrays?

An array is a collection of values stored in ordered positions.

Each value in an array is called an element.

Example:

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

Here:

• fruits is the array

• "Apple", "Banana", "Mango", "Orange" are elements

• Elements are stored in a specific order

Arrays are useful when we need to group related data together.

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How to Create an Array

In JavaScript, arrays are created using square brackets [].

Example:

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

Another example:

let tasks = ["Study", "Exercise", "Read", "Code"];

An array can store different types of values:

let mixedArray = ["Hello", 25, true];

However, usually arrays store similar types of data for clarity.

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Accessing Elements Using Index

Each element in an array has a position called an index.

Important rule:

Array indexing starts from 0.

Example:

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

Index	Value
0	Apple
1	Banana
2	Mango
3	Orange

Access elements like this:

console.log(fruits[0]); // Apple
console.log(fruits[2]); // Mango

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Updating Elements

We can update a value in an array by assigning a new value to its index.

Example:

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

fruits[1] = "Orange";

console.log(fruits);

Output:

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

Here we replaced Banana with Orange.

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Array Length Property

JavaScript arrays have a built-in property called length.

It tells us how many elements are in the array.

Example:

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

console.log(fruits.length);

Output:

4

This means the array contains 4 elements.

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Looping Through Arrays

Often we want to perform an action on every element in an array.

We can use a for loop.

Example:

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

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

Output:

Apple
Banana
Mango
Orange

The loop runs from index 0 to length - 1.

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Why Arrays Are Useful

Arrays help us:

• Store multiple values in one variable

• Keep related data organized

• Process many values using loops

Instead of writing many variables, we can store everything in a single structured collection.

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Assignment Idea

Try this small exercise:

1️⃣ Create an array of 5 favorite movies

Example:

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

2️⃣ Print the first and last movie

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

3️⃣ Change one movie

movies[2] = "The Dark Knight";

console.log(movies);

4️⃣ Loop through the array

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