text: var MongoClient = require("mongodb").MongoClient;
  var express = require("express");
  var app = express();
  app.get("/", function(req, res) {
      MongoClient.connect("mongodb://127.0.0.1/mydb", function(err, db) {
          if (!err) {
              res.send("連接成功");
              console.log(db);
          } else {
              res.send("連接失敗");
              console.log(err);
          }
      });
  });
  app.listen(process.env.PORT || 3000);