server.js

var http = require("http");
var fs = require("fs");
var url = require("url");
var port = 8080;

/* Global variables */
var listingData;
var server;

var requestHandler = function (request, response) {
  var parsedUrl = url.parse(request.url);
  /*
    Your request handler should send listingData in the JSON format if a GET request 
    is sent to the '/listings' path. Otherwise, it should send a 404 error. 

    HINT: explore the request object and its properties 
    http://stackoverflow.com/questions/17251553/nodejs-request-object-documentation
   */
  if (request.method === "GET" && parsedUrl.path === "/listings") {
      response.statusCode = 200;
      response.write(listingData);
  } else {
      response.statusCode = 404;
      response.write("Bad gateway error");
  }
    response.end();
};

fs.readFile("listings.json", "utf8", function (err, data) {

  //  This callback function should save the data in the listingData variable, then start the server.
  listingData = data;
    startServer();
});

function startServer(){
    server = http.createServer(requestHandler);
    server.listen(port, function() {
        console.log("Server listening on: http://127.0.0.1:" + port);
    });
}