var express = require('express')
var bodyParser = require('body-parser')
var path = require('path')
var mongoose = require('mongoose')
var _ = require('underscore')
var Movie = require('./models/movie')
var port = process.env.PORT || 3000
var app = express()
mongoose.connect('mongodb://localhost/imooc')
请问这里的mongoose.connect('mongodb://localhost/imooc')是什么意思,有什么作用?