根据内容 组装树结构 递归

getAreaTree(areaList, pCode) {
      var result = [],
        temp;
      for (var i in areaList) {
        let item = areaList[i];
        if (item.parentCode == pCode) {
          let tempObj = {};
          tempObj.value = item.areaCode;
          tempObj.label = item.areaName;
          result.push(tempObj);
          temp = this.getAreaTree(areaList, item.areaCode);
          if (temp.length > 0) {
            tempObj.children = temp;
          }
        }
      }
      return result;
    }