🧩 Day 7 — Arrays & Array Methods in JavaScript

Welcome to Day 7 🎉 — Today we’ll dive into one of the most essential data structures in JavaScript — the Array. Arrays allow you to store multiple values in a single variable, making it easy to handle collections of data like numbers, names, or products.

📦 1️⃣ What is an Array?

An array is a special variable that can hold multiple values at once. Instead of creating several variables, you can group values inside square brackets [].

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

🔍 2️⃣ Accessing Elements

Each element in an array has an index (position), starting from 0.

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

➕ 3️⃣ Modifying Arrays

You can change values using their index or add new ones dynamically.

fruits[1] = "Mango"; // Change Banana to Mango
fruits.push("Grapes"); // Add to end
fruits.unshift("Orange"); // Add to start
console.log(fruits);

🧹 4️⃣ Removing Elements

There are multiple ways to remove elements from arrays:

fruits.pop(); // Removes last
fruits.shift(); // Removes first
fruits.splice(1, 1); // Removes one element at index 1

⚙️ 5️⃣ Common Array Methods

Let’s explore the most used methods to process arrays:

• .length — Returns total elements
• .indexOf() — Finds index of a value
• .includes() — Checks if value exists
• .concat() — Merges two arrays

let colors = ["Red", "Blue", "Green"];
console.log(colors.length);     // 3
console.log(colors.indexOf("Blue")); // 1
console.log(colors.includes("Yellow")); // false

🧩 6️⃣ Array Iteration (map, filter, forEach)

forEach()

Executes a function for each array element.

colors.forEach((color) => console.log(color));

map()

Creates a new array with transformed values.

let upperColors = colors.map((c) => c.toUpperCase());
console.log(upperColors);

filter()

Returns a new array with only elements that match a condition.

let numbers = [10, 20, 30, 40];
let above20 = numbers.filter((num) => num > 20);
console.log(above20); // [30, 40]

🧠 7️⃣ Practice Task

1. Create an array of your top 5 favorite movies.
2. Add and remove a movie using push() and pop().
3. Use map() to make them all uppercase.
4. Filter movies with more than 5 letters.

🎯 Summary

Arrays are essential for grouping and processing data efficiently. Tomorrow, we’ll explore **Strings and String Methods**, another core part of JavaScript data handling.

← Prev Next →