const prices = [10, 20, 30];
const doubled = prices.map(p => p * 2);
// [20, 40, 60]

const users = [{ name: "John" }, { name: "Jane" }];
const names = users.map(u => u.name);
// ["John", "Jane"]

const numbers = [1, 2, 3, 4, 5];
const evens = numbers.filter(n => n % 2 === 0);
// [2, 4]

const users = [
  { name: "John", active: true },
  { name: "Jane", active: false },
];
const activeUsers = users.filter(u => u.active);
// [{ name: "John", active: true }]

const users = [
  { id: 1, name: "John" },
  { id: 2, name: "Jane" },
];

const jane = users.find(u => u.name === "Jane");
// { id: 2, name: "Jane" }

const janeIndex = users.findIndex(u => u.name === "Jane");
// 1

const ages = [18, 21, 25, 16];

ages.some(age => age < 18);  // true (at least one)
ages.every(age => age >= 18); // false (not all)

const numbers = [1, 2, 3, 4];
const sum = numbers.reduce((acc, n) => acc + n, 0);
// 10

const items = [
  { name: "Apple", price: 1 },
  { name: "Banana", price: 2 },
];
const total = items.reduce((acc, item) => acc + item.price, 0);
// 3

// Group by category
const grouped = items.reduce((acc, item) => {
  const key = item.category;
  acc[key] = acc[key] || [];
  acc[key].push(item);
  return acc;
}, {});

const fruits = ["apple", "banana", "orange"];
fruits.includes("banana"); // true
fruits.includes("grape");  // false

const nested = [[1, 2], [3, 4]];
nested.flat(); // [1, 2, 3, 4]

const users = [{ tags: ["a", "b"] }, { tags: ["c"] }];
users.flatMap(u => u.tags); // ["a", "b", "c"]

const numbers = [3, 1, 4, 1, 5];
numbers.sort((a, b) => a - b); // [1, 1, 3, 4, 5]

const users = [{ name: "Zoe" }, { name: "Amy" }];
users.sort((a, b) => a.name.localeCompare(b.name));
// [{ name: "Amy" }, { name: "Zoe" }]