帮我写一个js深拷贝的代码

好的，以下是一个简单的 JS 深拷贝的代码实现：

function deepCopy(obj) {
  if (typeof obj !== 'object' || obj === null) {
    return obj;
  }
  let copy = Array.isArray(obj) ? [] : {};
  for (let key in obj) {
    if (Object.prototype.hasOwnProperty.call(obj, key)) {
      copy[key] = deepCopy(obj[key]);
    }
  }
  return copy;
}

使用方法：

let original = {
  name: 'John',
  age: 30,
  hobbies: ['reading', 'traveling'],
  address: {
    city: 'New York',
    state: 'NY'
  }
};

let copy = deepCopy(original);
console.log(copy); // { name: 'John', age: 30, hobbies: [ 'reading', 'traveling' ], address: { city: 'New York', state: 'NY' } }

// 修改副本的值
copy.name = 'Mike';
copy.hobbies.push('swimming');
copy.address.city = 'Los Angeles';

// 验证原始对象是否被修改
console.log(original); // { name: 'John', age: 30, hobbies: [ 'reading', 'traveling' ], address: { city: 'New York', state: 'NY' } }