let user = {name: 'Mike', age: 30}
let {name, age} = user; // == let {age, name} = user; (순서를 신경쓰지 않아도 됨)
// let name = user.name;
// let age = user.age;

console.log(name); // 'Mike'
console.log(age);  // 30
let user = {name: 'Mike', age: 30}
let {name: userName, age: userAge} = user; // 순서를 신경쓰지 않아도 됨
// let userName = user.name;
// let userAge = user.age;

console.log(userName); // 'Mike'
console.log(userAge);  // 30
let user = {name: 'Mike', age: 30};
let {name, age, gender} = user;
// -> gender = undefined

let {name, age, gender = 'male'} = user;
// -> gender가 undefined 이면 'male'