Destructuring

const point = [3, 7];
const [x, y] = point;
console.log(x); // 3
console.log(y); // 7

const [first, , third] = [10, 20, 30];
console.log(first); // 10
console.log(third); // 30

const [head, ...tail] = [1, 2, 3, 4, 5];
console.log(head); // 1
console.log(tail); // [2, 3, 4, 5]

let a = 1, b = 2;
[a, b] = [b, a];
console.log(a, b); // 2 1

const [x = 0, y = 0, z = 0] = [10, 20];
console.log(z); // 0 — default applied

const person = { name: "Alice", age: 30, city: "NYC" };
const { name, age } = person;
console.log(name); // "Alice"
console.log(age);  // 30

const { name: fullName } = person;
console.log(fullName); // "Alice"

const user = { id: 1, address: { city: "London", zip: "EC1A" } };
const { address: { city } } = user;
console.log(city); // "London"