server.js

var http = require("http");

var port = process.env.PORT

function start() {
function onRequest(request, response) {
  console.log("Request received.");
  response.writeHead(200, {"Content-Type": "text/plain"});
  response.write("Hello World");
  response.end();
}

http.createServer(onRequest).listen(port);

}

exports.start = start;
console.log("Server has started.");