JavaScript Array Methods You Should Know: A Practical Guide

const products = [
  { id: 1, name: "Laptop", price: 75000, category: "electronics", stock: 8, tags: ["work", "premium"] },
  { id: 2, name: "Mouse", price: 1200, category: "electronics", stock: 25, tags: ["accessory"] },
  { id: 3, name: "Keyboard", price: 2500, category: "electronics", stock: 0, tags: ["accessory", "gaming"] },
  { id: 4, name: "Notebook", price: 300, category: "stationery", stock: 40, tags: ["study"] },
  { id: 5, name: "Headphones", price: 4500, category: "electronics", stock: 12, tags: ["audio", "premium"] }
];

console.log("=== 1. Original Products ===");
console.log(products);

// map() creates a new array by transforming every element.
console.log("\\n=== 2. map() - Product Names ===");
const productNames = products.map(product => product.name);
console.log(productNames);

// filter() keeps only elements that satisfy a condition.
console.log("\\n=== 3. filter() - Products In Stock ===");
const availableProducts = products.filter(product => product.stock > 0);
console.log(availableProducts);

// find() returns the first element matching the condition.
console.log("\\n=== 4. find() - Find Laptop ===");
const laptop = products.find(product => product.name === "Laptop");
console.log(laptop);

// findIndex() returns the index of the first matching element.
console.log("\\n=== 5. findIndex() - Find Keyboard ===");
const keyboardIndex = products.findIndex(product => product.name === "Keyboard");
console.log("Keyboard index:", keyboardIndex);

// some() returns true when at least one element matches.
console.log("\\n=== 6. some() - Any Out-of-Stock Product? ===");
const hasOutOfStock = products.some(product => product.stock === 0);
console.log("Has out-of-stock product:", hasOutOfStock);

// every() returns true only when every element matches.
console.log("\\n=== 7. every() - Are All Products Valid? ===");
const allProductsValid = products.every(product => product.price > 0);
console.log("All products have valid prices:", allProductsValid);

// reduce() combines all array elements into one accumulated value.
console.log("\\n=== 8. reduce() - Calculate Inventory Value ===");
const inventoryValue = products.reduce((total, product) => {
  return total + product.price * product.stock;
}, 0);
console.log("Total inventory value:", inventoryValue);

// sort() orders elements using a custom comparison function.
console.log("\\n=== 9. sort() - Products By Price ===");
const productsByPrice = [...products].sort((a, b) => a.price - b.price);
console.log(productsByPrice.map(product => `${product.name}: ₹${product.price}`));

// includes() checks whether an exact value exists in an array.
console.log("\\n=== 10. includes() - Check Product Name ===");
console.log("Contains Laptop:", productNames.includes("Laptop"));
console.log("Contains Tablet:", productNames.includes("Tablet"));

// flatMap() maps values and flattens the resulting arrays by one level.
console.log("\\n=== 11. flatMap() - Collect All Tags ===");
const allTags = products.flatMap(product => product.tags);
console.log(allTags);

// Set removes duplicate values from the flattened result.
console.log("\\n=== 12. Set + Array.from() - Unique Tags ===");
const uniqueTags = Array.from(new Set(allTags));
console.log(uniqueTags);

// Chaining methods allows multiple transformations in a readable pipeline.
console.log("\\n=== 13. Method Chaining - Premium Products ===");
const premiumProducts = products
  .filter(product => product.tags.includes("premium"))
  .map(product => ({
    name: product.name,
    price: product.price,
    available: product.stock > 0
  }));
console.log(premiumProducts);

// reduce() can also build grouped objects from an array.
console.log("\\n=== 14. reduce() - Group Products By Category ===");
const groupedProducts = products.reduce((groups, product) => {
  if (!groups[product.category]) {
    groups[product.category] = [];
  }
  groups[product.category].push(product.name);
  return groups;
}, {});
console.log(groupedProducts);

console.log("\\n=== 15. Final Summary ===");
console.log("Total products:", products.length);
console.log("Available products:", availableProducts.length);
console.log("Unique tags:", uniqueTags.length);
console.log("Inventory value: ₹" + inventoryValue);
console.log("Array processing completed successfully.");