node js + mongoose

// getting-started.js
const mongoose = require('mongoose');
mongoose.connect("mongodb://localhost:27017/name", { useUnifiedTopology: true, useNewUrlParser: true });// getting-started.js
var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test', {useNewUrlParser: true});await mongoose.connect('mongodb://localhost/my_database', {  useNewUrlParser: true,  useUnifiedTopology: true});const db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function() {
  // we're connected!
});var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function() {
  // we're connected!
});