nodemon //用于安装后，不用重启服务 前端通过："proxy": "http://localhost:8080" 拦截 yarn add moongoose
在运行时，保证已经安装mongoDB,且mongo,and mongod的关联运行
yarn add jsonwebtoken //用于返回信息
yarn add dotenv //keep it run on different Service or environment variables
yarn add mongoose-unique-validator //验证 email is unique
yarn add lodash //解析错误的结果(check email err)
mailtrap data //regist and send the email
yarn add nodemailer