$ mkdir hello-world

{
 
"name": "hello-world",
 
"description": "hello world test app",
 
"version": "0.0.1",
 
"private": true,
 
"dependencies": {
  "express": "3.x"
}
}

$ npm install

$ npm ls
hello-world@0.0.1 /private/tmp
└─┬ express@3.0.0beta7
 ├── commander@0.6.1
 ├─┬ connect@2.3.9
 │ ├── bytes@0.1.0
 │ ├── cookie@0.0.4
 │ ├── crc@0.2.0
 │ ├── formidable@1.0.11
 │ └── qs@0.4.2
 ├── cookie@0.0.3
 ├── debug@0.7.0
 ├── fresh@0.1.0
 ├── methods@0.0.1
 ├── mkdirp@0.3.3
 ├── range-parser@0.0.4
 ├─┬ response-send@0.0.1
 │ └── crc@0.2.0
 └─┬ send@0.0.3
  └── mime@1.2.6

var express = require('express');
var app = express();

app.get('/hello.txt', function(req, res){
 res.send('Hello World');
});

var server = app.listen(3000, function() {
  console.log('Listening on port %d', server.address().port);
});

$ npm install -g express-generator

Usage: express [options]
Options:
 -h, --help     output usage information
 -V, --version    output the version number
 -e, --ejs      add ejs engine support (defaults to jade)
 -H, --hogan     add hogan.js engine support
 -c, --css  add stylesheet support (less|stylus|compass) (defaults to plain css)
 -f, --force     force on non-empty directory

$ express --css stylus myapp
create : myapp
create : myapp/package.json
create : myapp/app.js
create : myapp/public
create : myapp/public/javascripts
create : myapp/public/images
create : myapp/public/stylesheets
create : myapp/public/stylesheets/style.styl
create : myapp/routes
create : myapp/routes/index.js
create : myapp/views
create : myapp/views/index.jade
create : myapp/views/layout.jade

install dependencies:
$ cd myapp && npm install

run the app:
$ DEBUG=myapp node app

$ npm start

app.use(function(err, req, res, next){
 console.error(err.stack);
 res.send(500, 'Something broke!');
});

var bodyParser = require('body-parser');
var methodOverride = require('method-override');
app.use(bodyParser());
app.use(methodOverride());
app.use(app.router);
app.use(function(err, req, res, next){
 // logic
});

var bodyParser = require('body-parser');
var methodOverride = require('method-override'); 

app.use(bodyParser());
app.use(methodOverride());
app.use(app.router);
app.use(logErrors);
app.use(clientErrorHandler);
app.use(errorHandler);

function logErrors(err, req, res, next) {
 console.error(err.stack);
 next(err);
}

function clientErrorHandler(err, req, res, next) {
 if (req.xhr) {
  res.send(500, { error: 'Something blew up!' });
 } else {
  next(err);
 }
}

function errorHandler(err, req, res, next) {
 res.status(500);
 res.render('error', { error: err });
}

{
 "name": "app",
 "version": "0.0.1",
 "dependencies": {
  "express": "3.x",
  "redis": "*"
 }
}

var express = require('express');
var redis = require('redis');
var db = redis.createClient();
var app = express();

app.use(function(req, res, next){
 var ua = req.headers['user-agent'];
 db.zadd('online', Date.now(), ua, next);
});

app.use(function(req, res, next){
 var min = 60 * 1000;
 var ago = Date.now() - min;
 db.zrevrangebyscore('online', '+inf', ago, function(err, users){
  if (err) return next(err);
  req.online = users;
  next();
 });
});

app.get('/', function(req, res){
 res.send(req.online.length + ' users online');
});

app.listen(3000);

$ DEBUG=express:* node ./bin/www

express:application booting in development mode +0ms
express:router defined get /hello.txt +0ms
express:router defined get /hello.txt +1ms

$ DEBUG=my-application node ./bin/www