code: function clone(source) {
              if (!source || typeof source !== 'object') {
                  return source;
              }
  
              var cloned = source;
  
              if (isArray(source)) {
                  cloned = source.slice().map(clone);
              }
              else if (isObject(source) && 'isPrototypeOf' in source) {
                  cloned = {};
                  for (var key in source) {
                      if (hasOwnProperty.call(source, key)) {
                          cloned[key] = clone(source[key]);
                      }
                  }
              }
  
              return cloned;
          }
docs: 深复制对象，仅复制数据
  
  @param {Object} source 源数据
  @return {Object} 复制的数据