for in 循环

  this.$ajax.post(this.$httpConfig.config.rolelist, params)
          .then(res => {
            if (res.data.code === 2000) {
              this.searchRoleList = res.data.data.list;
              let result = [],//定义一个数组
                tmpData = this.searchRoleList;//要循环的对象
              for (let index in tmpData) {
                result.push({'id': tmpData[index].roleId, 'value': tmpData[index].roleName});//将你要的id和value以对象的形式追加到数组里
              }

              cb(result);
            }
          })
          .catch(res => {
            this.searchRoleList = [];
            cb(this.searchRoleList);
          });