app.js

// vendor
var express = require('express');

var app = express();

// depending on the placement, we can either catch or override routes
app.use(app.router);

// every route in the routes/user.js file will be served under /user
app.use('/user', require('./routes/user').middleware);

// every route in the routes/post.js file will be served under /post
app.use('/post', require('./routes/post').middleware);

// last middleware will be 404 handler
app.use(function(req, res, next) {
    // 404 handler
});

/// regular routes

app.get('/', function(req, res, next) {
    res.send('Hello World!\n');
});

/// go go go!

var server = app.listen(3000);

package.json

{
    "name": "routes-example",
    "version": "0.0.0",
    "dependencies": {
        "express": "3.0.6"
    }
}

post.js

// vendor
var express = require('express');

var router = new express.Router();

// routes also have the .param method to allow for easier resource loading
// in this case we will make sure all our routes load the post
router.param('post_id', function(req, res, next, post_id) {
    // simulate loading a post
    setTimeout(function() {
        req.post = { name: 'foo' };
        next();
    }, 1000);
});

router.get('/:post_id', function(req, res, next) {
    res.send(req.post.name + '\n');
});

router.post('/:post_id/comment', function(req, res, next) {
    // we could add the comment to req.post here
    res.send('\\o/\n');
});

module.exports = router;

user.js

// vendor
var express = require('express');

var router = new express.Router();

router.get('/foo', function(req, res, next) {
    // for the full url
    res.send(req.originalUrl + '\n');

    // for just /foo
    //req.url
});

router.post('/bar', function(req, res, next) {
    res.send(req.originalUrl + '\n');
});

module.exports = router;