オブジェクトの反復処理

const user = {
  id: 5,
  name: 'Chelsey Dietrich',
  username: 'Kamren',
  email: 'Lucio_Hettinger@annie.ca',
};

console.log(Object.keys(user)); // ['id', 'name', 'username', 'email']
console.log(Object.values(user)); // [5, 'Chelsey Dietrich', 'Kamren', 'Lucio_Hettinger@annie.ca']

console.log(Object.entries(user));
/*
[
  ['id', 5] 
  ['name', 'Chelsey Dietrich']
  ['username', 'Kamren']
  ['email', 'Lucio_Hettinger@annie.ca']
]
*/

// キーと値のペアを反復処理の中で扱う
Object.keys(user).map((k) => {
  console.log(k, user[k]);
});
Object.entries(user).map(([k, v]) => {
  console.log(k, v);
});