nodejs simple webserver

simpleWebServer.js

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

var port = process.env.PORT || 3000;

http.createServer(function(req, res) {
    
    var pathname = __dirname + url.parse(req.url).pathname;
    
    if (path.extname(pathname) == "") {
        pathname += "/";
    }
    if (pathname.charAt(pathname.length-1) == "/"){
        pathname += "index.html";
    }
    
    fs.exists(pathname, function(exists) {
        if(exists){
            switch(path.extname(pathname)) {
                case ".html":
                    res.writeHead(200, {"Content-Type": "text/html"});
                    break;
                case ".js":
                    res.writeHead(200, {"Content-Type": "text/javascript"});
                    break;
                case ".css":
                    res.writeHead(200, {"Content-Type": "text/css"});
                    break;
                case ".gif":
                    res.writeHead(200, {"Content-Type": "image/gif"});
                    break;
                case ".jpg":
                    res.writeHead(200, {"Content-Type": "image/jpeg"});
                    break;
                case ".png":
                    res.writeHead(200, {"Content-Type": "image/png"});
                    break;
                case ".svg":
                    res.writeHead(200, {"Content-Type": "image/svg+xml"});
                    break;
                default:
                    res.writeHead(200, {"Content-Type": "application/octet-stream"});
            }

            fs.readFile(pathname, function(err, data) {
                res.end(data);
            });
        } 
        else {
            res.writeHead(404, {"Content-Type": "text/html"});
            res.end("404 Not Found");
        }
    });

}).listen(port, "0.0.0.0");

console.log("Server running at http://127.0.0.1:" + port);