mongoose-and-koa-2.js

const Koa = require('koa');
const mongoose = require('mongoose');

// Excerpted from https://mongoosejs.com/docs/index.html
mongoose.connect('mongodb://localhost/test');
var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function() {
  // we're connected!
  app.listen(3000); // Start listening here
});

// Excerpted from https://koajs.com/#application
const app = new Koa();

app.use(async (ctx) => {
  ctx.body = 'Hello World';
});