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