my first node.js server

server.js

var http      = require('http')
  , url       = require("url")
  , path      = require("path")
  , fs        = require('fs')
  , mime      = require('mime')
;

var server = http.createServer(function(request, response) {

  var uri = url.parse(request.url).pathname
    , filename = path.join(process.cwd(), uri)
    , baseUrl = (uri.substr(-1, 1) == '/') ? uri : uri + '/'
  ;

  console.log('URI requested: ', uri);

  var fileExists = false;

  fs.exists(filename, function(exists) {
    if(!exists) {
      response.writeHead(404, {"Content-Type": "text/plain"});
      response.write("404 Not Found\n");
      response.end();
      return;
    }

    // If thq request uri is a directory,
    // try and load index.html.  If one doesn't exist
    // create a directory listing
    if (fs.statSync(filename).isDirectory()) {
      filename += 'index.html';
      fs.exists(filename, function(exists) {
        if (!exists) {
          console.log('File not found: ', filename);
          console.log('Building directory listing...');
          filename = filename.replace('index.html', '');

          fs.readdir(filename, function (err, files) {
            if (err) {
              throw err;
            }

            response.writeHead(500, { 'content-type': 'text/html' });

            files.map(function (file) {
              return path.join(filename, file);
            }).filter(function (file) {
              return fs.statSync(file).isFile();
            }).forEach(function (file) {
              console.log("%s (%s)", file, path.extname(file));

              response.write('<a href="' + baseUrl + path.basename(file) + '">' + path.basename(file) + '</a><br>');
            });

            response.end();
            return;
          });
        }
        else {
          fileExists = true;
        }
      });
    }
    else {
      fileExists = true;
    }

    // if the request is for a file that exists, load it
    if (fileExists) {
      fs.readFile(filename, "binary", function(err, file) {
        if(err) {
          response.writeHead(500, { 'content-type': 'text/plain' });
          console.log('error')
          response.write(err + "\n");
          response.end();
          return;
        }

        response.writeHead(200, {"content-type": mime.lookup(path.basename(filename))});
        response.write(file, "binary");
        response.end();
      });
    }

  });

});
server.listen(8080);