mongoose.connect（）方法在powershell中报错

报错内容：

网站服务器连接成功，请访问localhost
(node:14116) Warning: Accessing non-existent property ‘MongoError’ of module exports inside circular dependency
(Use node --trace-warnings ... to show where the warning was created)
(node:14116) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
(node:14116) DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
(node:14116) DeprecationWarning: Listening to events on the Db class has been deprecated and will be removed in the next major version.
(node:14116) DeprecationWarning: collection.ensureIndex is deprecated. Use createIndexes instead.
数据库连接成功

原因：

第一个报错：(node:14116) Warning: Accessing non-existent property ‘MongoError’ of module exports inside circular dependency 是因为MongoDB的底层报错可忽略等待版本更新解决。
其余报错是因为字符串解析器报错需要在mongoose.connect（）方法中传入报错中提示的对象参数。

解决方案：

// 引入mongoose第三方模块
const mongoose = require('mongoose');
//连接数据库
mongoose.connect('mongodb://localhost/blog', {
        useNewUrlParser: true,
        useUnifiedTopology: true,
        useCreateIndex: true
    })
    .then(() => console.log('数据库连接成功'))
    .catch(() => console.log('数据库连接失败'))