JavaScript Arrays

🔹 What is an Array?

An array in JavaScript is a special type of object that stores multiple values in a single variable. Arrays are ordered collections that allow storing multiple data types such as numbers, strings, and objects.

🔹 Creating an Array

Arrays can be created using square brackets [] or the new Array() constructor.

✅ Using Square Brackets (Preferred)

let fruits = ["Apple", "Banana", "Cherry"];
console.log(fruits); // ["Apple", "Banana", "Cherry"]

✅ Using `new Array()` (Less Common)

let fruits = ["Apple", "Banana", "Cherry"];
console.log(fruits); // ["Apple", "Banana", "Cherry"]

📌 The first method ([]) is more commonly used because it's simpler and more readable.

🔹 Accessing Array Elements

Each item in an array has an index, starting from 0.

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

📌 If you try to access an index that doesn’t exist, it will return undefined.

🔹 Modifying Array Elements

You can change an element’s value by assigning a new value to a specific index.

let cars = ["Toyota", "Honda", "Ford"];
cars[1] = "BMW"; 
console.log(cars); // ["Toyota", "BMW", "Ford"]

📌 Arrays are mutable, meaning their elements can be updated.

🔹 Finding the Length of an Array

The .length property returns the number of elements in an array.

let animals = ["Dog", "Cat", "Elephant"];
console.log(animals.length); // 3

📌 Useful when looping through an array.

🔹 Adding and Removing Elements

✅ `push()` – Adds to the End

let fruits = ["Apple", "Banana"];
fruits.push("Mango");
console.log(fruits); // ["Apple", "Banana", "Mango"]

✅ `pop()` – Removes from the End

fruits.pop();
console.log(fruits); // ["Apple", "Banana"]

✅ `unshift()` – Adds to the Beginning

fruits.unshift("Grapes");
console.log(fruits); // ["Grapes", "Apple", "Banana"]

✅ `shift()` – Removes from the Beginning

fruits.shift();
console.log(fruits); // ["Apple", "Banana"]

📌 These methods allow dynamic modifications of arrays.

🔹 Looping Through an Array

Arrays can be iterated using loops like for and forEach().

✅ Using a `for` Loop

let numbers = [10, 20, 30, 40];
for (let i = 0; i < numbers.length; i++) {
  console.log(numbers[i]);
}

✅ Using `forEach()`

numbers.forEach(function(num) {
  console.log(num);
});

📌 forEach() is more modern and readable.

🔹 Checking if an Element Exists

✅ `includes()` – Checks if an Element is Present

let colors = ["Red", "Green", "Blue"];
console.log(colors.includes("Green")); // true
console.log(colors.includes("Yellow")); // false

📌 Useful for searching within arrays.

🔹 Merging Arrays

Arrays can be combined using concat().

let a = [1, 2];
let b = [3, 4];
let result = a.concat(b);
console.log(result); // [1, 2, 3, 4]

📌 concat() creates a new array, leaving the original unchanged.

🔹 Converting an Array to a String

✅ `join()` – Converts an Array into a String

let fruits = ["Apple", "Banana", "Cherry"];
console.log(fruits.join(", ")); // "Apple, Banana, Cherry"

📌 Helps when displaying array data in UI.

🔹 Conclusion

JavaScript arrays store multiple values, provide built-in methods for manipulation, and allow efficient iteration. Arrays are versatile and commonly used in data handling, user input storage, and looping through datasets.

JAVASCRIPT