server.js

const http = require('http');
const app = require('./backend/app');
const debug = require('debug')("node-angular");

const normailizePort = val => {

  var port = parseInt(val, 10);
  if (isNaN(port)) {
    return val;
  }

  if (port >= 0) {
    return port;
  }
  return false;
};

const onError = error => {
  if (error.syscall !== "listen") {
    throw error;
  }
  const bind = typeof addr === "string" ? "pipe" + addr : "port" + port;
  switch (error.code) {
    case "EACCES":
      console.error(bind + "requires elevated privalges");
      break;
    case "EADDRINUSE":
      console.error(bind + "is already in use");
      process.exit(1);
      break;
    default:
      throw error;
  }
}

const onListening = () => {
  const addr = server.address();
  const bind = typeof  addr == "string" ? "pipe" + addr : "port" + port;
  debug("Listeting on " + bind);
};

const port = process.env.PORT || 3000;
app.set('port', port);
const server = http.createServer(app);
server.on("error", onError);
server.on("listening", onListening);
server.listen(port);