router.js

var fs = require("fs");
var path = require("path");
var mime = require("./mime").types;

function route(handle, pathname, request, response) {
    console.log("About to route a request for " + pathname);
    if (typeof handle[pathname] === 'function') {
        handle[pathname](request, response);
    } else {
        var realPath = "public" + pathname;
        var ext = path.extname(realPath);

        ext = ext ? ext.slice(1) : 'unknown';
        var contentType = mime[ext] || "text/plain";
            
        fs.exists(realPath, function (exists) {
            if (!exists) {
                response.writeHead(404, {
                    'Content-Type': 'text/plain'
                });
                response.write("This request URL " + pathname + " was not found on this server.");
                response.end();
            } else {
                fs.readFile(realPath, "binary", function (err, file) {
                    if (err) {
                        response.writeHead(500, {
                            'Content-Type': 'text/plain'
                        });

                        response.end(err);
                    } else {
                        response.writeHead(200, {
                            'Content-Type': contentType
                        });

                        response.write(file, "binary");

                        response.end();
                    }
                });
            }
        });
    }
}

exports.route = route;