正在學mongodb和node.js,現在想做個練習，后端獲取數據庫中的數據，通過res.send發送給前端頁面var express = require('express');var MongoClient = require('mongodb').MongoClient;var router = express.Router();var url = "mongodb://127.0.0.1:27017";router.get('/', function(req, res, next) {  res.render('goods',{title:'goods'});});router.get('/list', function(req, res, next) {        MongoClient.connect(url, function(err, db) {        if(err) throw err;        let immocmall = db.db('immocmall');        let mall_goods = immocmall.collection('mall-goods');        查詢productId為201710003的數據        var search = {"productId":201710003};        mall_goods.find(search ,function(err, cursor) {            //如何將數據發送給頁面            res.send(cursor.toString())        })    })})