SelectiveProxy

/*
Install Dependencies:
npm install http-proxy colors connect util --save
*/

var util = require('util'),
    colors = require('colors'),
    http = require('http'),
    connect = require('connect'),
    httpProxy = require('http-proxy');

//
// Basic Connect App
//
connect.createServer(
  function (req, res, next) {
    var _write = res.write;

    res.write = function (data) {
      _write.call(res, data.toString().replace("Ruby", "nodejitsu2"));
    }
    next();
  },
  function (req, res) {
    console.log('host: ' + req.headers['host'] + '; url ' + req.url);
    if (req.headers['host'] === "stackoverflow.com") {
        proxy.web(req, res, { target: 'http://localhost:9013' });
    } else {
        proxy.web(req, res, { target: req.url });
    }
    proxy.on('error', function (err, req, res) {
      if (!res.headerSent) {
        res.writeHead(500, {
          'Content-Type': 'text/plain'
        });
      }
      console.log(err);
      res.end('Something went wrong. And we are reporting a custom error message.');
    });
  }
).listen(8013);

//
// Basic Http Proxy Server
//
var proxy = httpProxy.createProxyServer({
  // target: 'http://localhost:9013'
});

//
// Target Http Server
//
http.createServer(function (req, res) {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('Hello, I know Ruby\n');
}).listen(9013);

util.puts('http proxy server'.blue + ' started '.green.bold + 'on port '.blue + '8013'.yellow);
util.puts('http server '.blue + 'started '.green.bold + 'on port '.blue + '9013 '.yellow);