使用node.js向mongodb添加数据时出错

const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:27017/mydatabase';

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  console.log('Connected to MongoDB database');
  // 在这里执行添加数据的操作
  db.close();
});

db.createCollection('mycollection', function(err, res) {
  if (err) throw err;
  console.log('Collection created');
});

const data = { name: 'John', age: 30 };

db.collection('mycollection').insertOne(data, function(err, res) {
  if (err) throw err;
  console.log('Data inserted');
});