webserver.js

var port = 3000;

var http = require("http");
var path = require("path");
var url = require("url");
var fs = require("fs");

var request = require("request");

http.createServer( function(req, res) {

    var now = new Date();

    var filename = req.url || "index.html";
    var ext = path.extname(filename);
    var localPath = __dirname;
    var validExtensions = {
        ".html" : "text/html",
        ".js": "application/javascript",
        ".css": "text/css",
        ".txt": "text/plain",
        ".jpg": "image/jpeg",
        ".gif": "image/gif",
        ".png": "image/png",
        ".json": "application/json",
        ".map": "application/javascript",
        ".ico":"image/ico",
        "":"text/html"
    };
    var isValidExt = validExtensions[ext];

    if (isValidExt) {

        localPath += filename;
        path.exists(localPath, function(exists) {
            if(exists) {
                console.log("Serving file: " + localPath);
                getFile(localPath, res, isValidExt);
            } else {
                console.log("File not found: " + localPath);
                res.writeHead(404);
                res.end();
            }
        });

    } else {
        console.log("Invalid file extension detected: " + ext);
    }

}).listen(process.env.PORT || port);

function getFile(localPath, res, mimeType) {
    fs.readFile(localPath, function(err, contents) {
        if(!err) {
            res.setHeader("Content-Length", contents.length);
            res.setHeader("Content-Type", mimeType);
            res.statusCode = 200;
            res.end(contents);
        } else {
            res.writeHead(500);
            res.end();
        }
    });
}