深拷贝

function deepCopy(obj) {
        let result = Array.isArray(obj) ? [] : {};
        for (let key in obj) {
          if (obj.hasOwnProperty(key)) {
            if (typeof obj[key] === 'object' && obj[key] !== null) {
              result[key] = deepCopy(obj[key]);
            } else {
              result[key] = obj[key];
            }
          }
        }
        return result;
      }