📚 JavaScript Arrays: The Essential Guide

Arrays are one of the most commonly used data structures in JavaScript. They help store and manage collections of data — whether it’s a list of numbers, strings, or even objects.

🚀 What Is an Array?

An array is a special variable that can hold more than one value at a time.

const fruits = ["apple", "banana", "cherry"];

JavaScript arrays are zero-indexed, meaning the first element has index 0.

console.log(fruits[0]); // 'apple'

✨ Common Array Methods

🔁 Looping Through Arrays

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

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

// or with for...of
for (const num of nums) {
  console.log(num);
}

🧪 Real-World Example: Remove Duplicates

function removeDuplicates(arr) {
  return [...new Set(arr)];
}

console.log(removeDuplicates([1, 2, 2, 3, 4, 4]));
// Output: [1, 2, 3, 4]

🧩 LeetCode Example: Two Sum

LeetCode Problem: 1. Two Sum

var twoSum = function(nums, target) {
  const map = new Map();

  for (let i = 0; i < nums.length; i++) {
    const complement = target - nums[i];
    if (map.has(complement)) {
      return [map.get(complement), i];
    }
    map.set(nums[i], i);
  }

  return [];
};

// Example:
console.log(twoSum([2, 7, 11, 15], 9)); // Output: [0, 1]

This example showcases how arrays can be combined with maps to solve algorithmic problems efficiently.

🔚 Final Thoughts

Arrays are fundamental in JavaScript and serve as the building blocks for handling ordered collections of data. Mastering their methods and usage is essential for any JavaScript developer.

📌 Pro Tip: Practice transforming, filtering, and reducing arrays to get comfortable with functional programming in JavaScript.