الدوال التحويلية (map, filter, reduce)

function greet(name) {
  return `مرحبًا ${name}`;
}

const sayHi = greet; // الدالة قيمة، تقدر تخزّنها باسم آخر
console.log(sayHi("سارة"));

function repeat(action, times) { // دالة عليا — تأخذ دالة كمعامل
  for (let i = 0; i < times; i++) action(i);
}
repeat(i => console.log("تكرار رقم", i), 3);

const prices = [10, 20, 30];
const withTax = prices.map(p => p * 1.15);
console.log(withTax); // [11.5, 23, 34.5]
console.log(prices);  // [10, 20, 30] — الأصل لم يتغيّر

const numbers = [1, 2, 3, 4, 5, 6];
const evens = numbers.filter(n => n % 2 === 0);
console.log(evens); // [2, 4, 6]

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

const sum = numbers.reduce((acc, n) => acc + n, 0);
console.log(sum); // 15

const max = numbers.reduce((acc, n) => (n > acc ? n : acc), numbers[0]);
console.log(max); // 5

// بناء كائن من مصفوفة
const grouped = ["a", "bb", "ccc"].reduce((acc, word) => {
  acc[word.length] = word;
  return acc;
}, {});
console.log(grouped); // { '1': 'a', '2': 'bb', '3': 'ccc' }

const orders = [
  { item: "قهوة", price: 15, paid: true },
  { item: "شاي", price: 10, paid: false },
  { item: "عصير", price: 12, paid: true },
];

const totalPaid = orders
  .filter(o => o.paid)
  .map(o => o.price)
  .reduce((sum, price) => sum + price, 0);

console.log(totalPaid); // 27