Sample file that uses mongoose to connect to a MongoDB instance and performs simple CRUD operations.

mongoose_sample.js

const mongoose = require( 'mongoose' );
const util = require('util');

const Schema   = mongoose.Schema;
const CommentSchema = new Schema({
    username : String,
    content  : String,
    created  : Date
});

const Comment = mongoose.model( 'Comment', CommentSchema );

(async function (){
    const conn = await mongoose.connect( 'mongodb://localhost:27017', { useNewUrlParser: true, useUnifiedTopology: true } );

    await Comment.create({ username: 'user1', content: 'myContent', created: new Date });
    
    await Comment.updateOne({ username: 'user1' }, { content: 'updated content' });

    const comment = await Comment.findOne({ username: 'user1' });
    console.log(`user1: ${util.inspect(comment.toJSON())}`);

    await Comment.deleteOne({ username: 'user1' });

    await conn.disconnect();
})()