オブジェクトのディープコピー

メモとして。

const obj = [
  {
    name: 'taro',
    age: 24
  },
  
  {
    name: 'sato',
    age: 22
  },
]
const copyObj = obj.map(person => ({name : person.name ,age : person.age}))

for(let i = 0; i < copyObj.length; i++){
  copyObj[i].name = "keiko";
  copyObj[i].age = i + 20;
}

console.log(obj);
console.log(copyObj);

結果

[[object Object] {
  age: 24,
  name: "taro"
}, [object Object] {
  age: 22,
  name: "sato"
}]
[[object Object] {
  age: 20,
  name: "keiko"
}, [object Object] {
  age: 21,
  name: "keiko"
}]

配列も同様

const obj = [
  {
    answer: [
      [1,1,1],
      [1,1,1]
    ],
    remain: [2,2,2]
  }
]

const copyObj = obj.map(list => (
    {
      answer : [...list.answer],
      remain : list.remain
    }
  )
);

copyObj[0].answer[0] = [1,2,3];
copyObj[0].answer[1] = [4,5,6];

console.log(obj);
console.log(copyObj);

結果

[[object Object] {
  answer: [[1, 1, 1], [1, 1, 1]],
  remain: [2, 2, 2]
}]
[[object Object] {
  answer: [[1, 2, 3], [4, 5, 6]],
  remain: [2, 2, 2]
}]