server.js~

var http = require('http');

var fs = require('fs');

var path = require('path');

var mime = require('mime');

var cache = {};

function sendFile(res, filePath, fileContents) {
    res.writeHead(
        200,
        {"content-type": mime.lookup(path.basename(filePath))}
    );
    res.end(fileContents);
}

function serveStatic(res, cache, absPath) {
    if (cache[absPath]) {
        sendFile(res, absPath, cache[absPath])
    } else {
        fs.exists(absPath, function (exists) {
            if (exists) {
                fs.readFile(absPath, function(err, data) {
                    if (err) {
                        send404(res);
                    } else {
                        cache[absPath] = data;
                        sendFile(res, absPath, data)
                    }
                })
            } else {
                send404(res);
            }
        }) 
    }
}

var server = http.createServer(function(req, res) {
    var filePath = false;

    if (req.url == '/') {
        filePath = 'public/index.html'
    } else {
        filePath = 'public' + req.url;
    }

    var absPath = './' + filePath;
    serveStatic(res, cache, absPath);
})

server.listen(3000, function() {
    console.log("Serverlistening on port 3000.");
});