我想更新endtime,  //res已经获取到

    var index=res.data[0].ringtime.length-1

                     console.log('index',index)

                     db.collection("usersRing").doc(res.data[0]._id).update({

                      data: {

                        'ringtime'.+[index].endtime:new Date(),

                      },

                      success: resk =>{

                       wx.showToast({

                         title: '打卡成功',

                         icon: 'success',

                       })

                     console.log("创建数据成功", resk)

                      },

                      fail: err => {

                        wx.showToast({

                          title: '程序出错',

                          icon: '',

                        })

                      }

                    }) 

打印程序出错