server.js

var http=require('http');
var url=require('url');
function start(route){
    function onRequest(request,response){
        var pathName=url.parse(request.url).pathname;
        console.log("request for"+pathname+"received");
        route(pathname);
        response.writeHead(200,{"Content-type":"text/plain"});
        response.write("hello world");
        response.end();
    }
    http.createServer(onRequest).listen(3000);
    console.log("Server has started");
}
exports.start=start;

router.js

function route(pathName){
    console.log("About to route a request for"+pathName);
}
exports.route=route;

index.js

var server=require("./server");
var router=require("./router");
server.start(router.route);