index.js

var express = require('express');
var mongoose = require('mongoose');
var bodyParser = require('body-parser');
var app = express();

// DB setting
mongoose.set('useNewUrlParser', true);
mongoose.set('useFindAndModify', false);
mongoose.set('useCreateIndex', true);
mongoose.set('useUnifiedTopology', true);
mongoose.connect(process.env.MONGO_DB);
var db = mongoose.connection;
db.once('open', function(){
  console.log('DB connected');
});
db.on('error', function(err){
  console.log('DB ERROR : ', err);
});

// Other settings
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: true}));
app.use(function (req, res, next) {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE');
  res.header('Access-Control-Allow-Headers', 'content-type');
  next();
});

// API
app.use('/api/heroes', require('./api/heroes'));

// Port setting
var port = 3000;
app.listen(port, function(){
  console.log('server on! http://localhost:'+port);
});