Arrays in JavaScript

• Arrays are one of the most commonly used data structures in JavaScript.
• They allow us to store multiple values in a single variable, making code cleaner and easier to manage.
• Instead of creating many variables, arrays help group related values together.

For example, rather than writing:

let mark1 = 85;
let mark2 = 90;
let mark3 = 78;

we can write:

let marks = [85, 90, 78];

This makes the code more organized and scalable.

What is an Array?

An array is a special type of object in JavaScript used to store an ordered collection of values.

let fruits = ["apple", "banana", "orange"];

Here:

• "apple" is at index 0
• "banana" is at index 1
• "orange" is at index 2

JavaScript arrays always start indexing from 0.

Accessing Array Elements

You can access elements using their index.

let fruits = ["apple", "banana", "orange"];

console.log(fruits[0]);
console.log(fruits[1]);

Output:

apple
banana

Updating Values

You can modify any value in the array.

let numbers = [10, 20, 30];

numbers[1] = 50;

console.log(numbers);

Output:

[10, 50, 30]

Array Length

To find the number of elements in an array, use .length.

let colors = ["red", "blue", "green"];

console.log(colors.length);

Output:

3

Looping Through Arrays

Arrays are commonly used with loops.

let nums = [1, 2, 3, 4, 5];

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

• This prints each element one by one.

Important Built-in Array Methods(To be discussed)

push() – Add element at the end

let arr = [1, 2, 3];
arr.push(4);

console.log(arr);

Output:

[1, 2, 3, 4]

pop() – Remove last element

arr.pop();

shift() – Remove first element

arr.shift();

unshift() – Add element at the beginning

arr.unshift(0);

Arrays Can Store Multiple Data Types

JavaScript arrays can hold different types of values.

let mixed = [10, "hello", true, 25.5];

• This flexibility is one of JavaScript’s strengths.

Is Array a Data Type?

Arrays are technically objects in JavaScript.

typeof [1, 2, 3]

Output:

"object"

To specifically check for arrays:

Array.isArray([1, 2, 3]);

Output:

true

Conclusion

• Arrays are essential in JavaScript programming.
• They help manage collections of data efficiently and are widely used in web development, data handling, and algorithms.