code: function recurs(parent, map) {
          const id = parent[idKey];
          const children = childrenMap[id];
          if (!children || children.length === 0) return parent;
          parent[childrenKey] = parent[childrenKey] || [];
          for (let i = 0; i < children.length; i++) {
              children[i] = recurs(children[i], map);
              if (typeof childRender === 'function') {
                  children[i] = childRender(children[i]);
              }
              parent[childrenKey].push(children[i]);
          }
          return parent;
      }
docs: 递归函数