Simple HTTP Router Idea

app.js

var micro = require('./lib/micro');
  
micro.get('/json', function(req, res) {
  res.json({
      a: 1
    , b: '2'
  });
});

micro.get('/text', function(req, res) {
  res.text('foooo!');
});

micro.get('/html', function(req, res) {
  res.html('<h1>Hey!</h1>');
});

micro.listen(8000);

micro.js

/*! 
 * Micro ~ Conceptual light weight HTTP router.
 *
 * @author Garrett Johnson
 */

var http = require('http')
  , url = require('url')
  , server = new http.Server()
  , methods = ['GET', 'POST', 'PUT', 'DELETE']
  , mappings = {}
  , router = {}
  , cache = {};

/**
 * Expose `server`.
 */

exports = module.exports = server;

/**
 * Route requests.
 */

server.on('request', onRequest);

/**
 * Creates a routing function for a specific http verb.
 *
 * @param {String} http method
 * @return {Function}
 */

function makeMethodRouter (method) {
  return function (path, callback) {
    var map = mappings[method];
    map[path] = callback;
  };
};

/**
 * Iterate over supported verbs and create a bound routing function.
 */

methods.forEach(function(method){
  exports[method.toLowerCase()] = router[method] = makeMethodRouter(method);
  mappings[method] = {};
});

/**
 * Http request callback. Looks up the callback for the pathname.
 *
 * @param {HttpServerRequest} request instance
 * @param {HttpServerResponse} response instance
 */

function onRequest (req, res) {
  var key = req.method + req.url
    , cached = cache[key];
  return (
    cached ?
    cached.call(null, req, res) :
    (function(){
      var parts = url.parse(req.url)
        , route = cache[key] = mappings[req.method][parts.pathname] || function(req, res){
            res.text('page not found', 404);
          };
      return route.call(null, req, res);
    })()
  );
};

/**
 * Augments a simple `send` method for writing out the response.
 *
 * @param {String} body to write
 * @param {Number} optional http status code, defaults to 200
 * @param {String} optional content type, defaults to text/html
 */

http.ServerResponse.prototype.send = function(body, statusCode, contentType) {
  this.statusCode = statusCode || 200;
  this.setHeader('Content-Type', contentType);
  this.setHeader('Content-Length', body.length);
  this.end(body, 'utf8');
  return this;
};

/**
 * Augments a `json` method into the response
 *
 * @param {Object|Array} object to turn into json
 * @param {Number} optional http status code, defaults to 200
 */

http.ServerResponse.prototype.json = function(obj, statusCode) {
  this.send(JSON.stringify(obj), statusCode, 'application/json');
  return this;
};

/**
 * Augments a `html` method into the response
 *
 * @param {String} body to send
 * @param {Number} optional http status code, defaults to 200
 */

http.ServerResponse.prototype.html = function(body, statusCode) {
  this.send(body, statusCode, 'text/html');
  return this;
};

/**
 * Augments a `text` method into the response
 *
 * @param {String} body to send
 * @param {Number} optional http status code, defaults to 200
 */

http.ServerResponse.prototype.text = function(body, statusCode) {
  this.send(body, statusCode, 'text/plain');
  return this;
};