手写深拷贝

function deepClone(obj = {}) {
  //递归结束的条件 只要递归递到值类型就返回
  if (typeof obj !== 'object' || obj == null) return obj
  //初始化返回结果
  let result
  
  if(obj instanceof Array) result = []
  else result = {}
  //遍历递归调用 复制树根
  for (let i in obj) {
    if (obj.hasOwnProperty(i)) {
      result[i] = deepClone(obj[i]) //键值对递归
    }
  }
  return result
}