小程序云开发实现数据库异步操作同步化

// 云函数入口文件const cloud = require('wx-server-sdk') cloud.init()const db = cloud.database()const _ = db.commandconst result={ code:'', body:''}// 云函数入口函数exports.main = (event, context) => { return new Promise((resolve, reject) => {  db.collection('fan_user').where({   tel:_.eq(event.tel)  }).get().then((res)=>{    if(res.data.length){ //用户已注册     result.code=400;     result.body='该账户已注册';     resolve(result)    }else{ //用户未注册      db.collection('fan_user').add({       data:{        tel:event.tel,        password:event.password       }      }).then((res)=>{       result.code=200;       result.body=res;       resolve(result)      })    }  }) }) }