npm install express npm install express -g npm install express --save npm install nodemon --save-dev

 {
  "name": "application-name",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node app.js"
  },
  "dependencies": {
    "express": "3.4.8",
    "jade": "*"
  },  "devDependencies: {  }
 }

• HTTP, HTTPS & TCP interfaces
• File System I/O
• Streams
• Child Process
• Cluster
• . . .

 var fs = require('fs');
 fs.readFile(filename, [options], callback); fs.readFileSync(filename, [options]);
 fs.writeFile(filename, data, [options], callback); fs.writeFileSync(filename, data, [options]);
 fs.rmdir(path, callback); fs.unlink(path, callback); fs.readdir(path, callback);

• Readable (req, fs, stdout, stderr)
• Writable (res, fs, stdin)
• Duplex (TCP sockets, crypto)
• Transform (zlib, crypto)

 http.createServer(function (req, res) {   fs.readFile(__dirname + '/file.txt', function (err, data) {     res.end(data);   }); });

 http.createServer(function (req, res) {   var stream = fs.createReadStream(__dirname + '/file.txt');   stream.pipe(res); });

 var cp = require('child_process'); cp.spawn(command, [args], [options]); cp.exec(command, [options], callback); cp.execFile(file, [args], [options], [callback]);
 cp.fork(modulePath, [args], [options]);

 child.stdin  // Writable stream child.stdout // Readable stream child.stderr // Readable stream
 // Sync, used with 'forked' process only child.send(message); child.on('message', callback);

 var cluster = require('cluster'),     http = require('http'),
     numCPUs = require('os').cpus().length;

 if (cluster.isMaster) {
   for (var i = 0; i < numCPUs; i++) {
     cluster.fork();
   }
 } else {
   http.createServer(function (req, res) {
     res.writeHead(200, {'Content-Type': 'text/plain'});
     res.end('Hello World!');
   }).listen(3000);
 }

• Middleware system
• Router
• Templating (Jade, EJS)

 npm install -g express express appname

 var express = require('express'),     app = express();
 app.set('port', process.env.PORT || 3000); app.set('view engine', 'jade'); app.set('views', __dirname + '/views');
 app.use(express.bodyParser()); app.use(express.methodOverride()); app.use(app.router); app.use(express.static(path.join(__dirname, 'public')));
 app.listen(app.get('port'));

 app.use(function (req, res, next) {  // Do something...  next(); // Call next middleware });
var middleware = function (req, res, next) {  // Do something...  next(); // Call next middleware};

 app.get('/', function (req, res) {   res.render('index'); });
 app.get('/user', middleware, function (req, res) {   res.render('user'); // Render page for authorized users only });

 var AuthError = function (msg) {   Error.call(this);   Error.captureStackTrace(this, arguments.callee);   this.message = msg;   this.name = 'AuthError'; };
 AuthError.prototype.__proto__ = Error.prototype;

 app.use(function (err, req, res, next) {   if (err.name == 'AuthError') {     res.send(401, {error: err.message});   } });

 var middleware = function (req, res, next) {   if (req.body.password != 'password') {     return next(new AuthError('Unauthorized'));   }   next(); };

 var Schema = require('mongoose').Schema;
 var UserSchema = new Schema({   username: {     type: String,     unique: true,     required: true   },   comments: [{body: String, date: Date}],   modified: {     type: Date,     default: Date.now   },   role: String }); var User = mongoose.model('User', UserSchema);

 var user = new User(data); user.save(function (err, user) {}); User.find(function (err, users) {}); User.find({role: 'Moderator'}, function (err, users) {}); User.findOne({username: 'user'}, function (err, user) {}); User.findById(id, function (err, user) {   user.remove(function (err) {}); });