无法迭代mongodb集合

const MongoClient = require('mongodb').MongoClient;
const uri = "mongodb+srv://<username>:<password>@<cluster-url>/<database>?retryWrites=true&w=majority";
const client = new MongoClient(uri, { useNewUrlParser: true, useUnifiedTopology: true });

client.connect(err => {
  const collection = client.db("<database>").collection("<collection>");
  
  collection.find().toArray((err, documents) => {
    if (err) {
      console.error(err);
      return;
    }
    
    documents.forEach(document => {
      // 遍历文档数据
      console.log(document);
    });
    
    client.close();
  });
});