Q16. What is destructuring in JavaScript? Explain with array and object examples.

// array — বাঁ পাশে ধন্ডার বন্ধনী
const [first, second, third] = [10, 20, 30];

console.log(first, second, third); // 10 20 30

// object — বাঁ পাশে লাল বন্ধনী
const { name, age } = { name: "Rahim", age: 25 };

console.log(name, age); // "Rahim" 25

// নাম বদলানো
const { name: userName } = { name: "Rahim" };
console.log(userName); // "Rahim"

// ডিফল্ট মান
const { role = "user" } = {};
console.log(role); // "user"

// বাকিগুলো বের করা (rest)
const [a, ...others] = [1, 2, 3, 4];
console.log(a, others); // 1 [2, 3, 4]

// skip করা — ফাঁকা জায়গা রাখতে হয়
const [, second] = ["x", "y", "z"];
console.log(second); // "y"

// nested
const {
  user: { name, address: { city } },
} = {
  user: { name: "Rahim", address: { city: "Dhaka" } },
};

console.log(name, city); // "Rahim" "Dhaka"

// swap — অতিরিক্ত ভেরিয়েবল ছাড়াই
let a = 1;
let b = 2;
[a, b] = [b, a];

console.log(a, b); // 2 1

function greet({ name, age = 0 }) {
  return name + " (" + age + ")";
}

console.log(greet({ name: "Rahim", age: 25 })); // "Rahim (25)"

// map-এর সাথে খুব প্রাকৃতিক
const users = [{ name: "Rahim" }, { name: "Karim" }];

console.log(
  users.map(({ name }) => name)
); // ["Rahim", "Karim"]