Confuration related to configure and start server

app.js

const express = require("express");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
let routes = require("../routes/routes");
let server = express();

let create = (config, db) => {
  server.set("env", config.env);
  server.set("port", config.port);
  server.set("hostname", config.hostname);

  // add middleware to parse the json
  server.use(bodyParser.json());
  server.use(
    bodyParser.urlencoded({
      extended: false
    })
  );

  //connect the database
  mongoose.connect(db.database, {
    useNewUrlParser: true,
    useCreateIndex: true,
    useUnifiedTopology: true
  });

  routes.init(server);
};

let start = () => {
  let hostname = server.get("hostname"),
    port = server.get("port");
  server.listen(port, function() {
    console.log(
      "Express server listening on - http://" + hostname + ":" + port
    );
  });
};

module.exports = {
  create: create,
  start: start
};