New features in 4.x

See Express 4.x docs for more examples and complete API documentation. You may also be interested in [Migrating from 3.x to 4.x](Migrating from 3.x to 4.x).

removed bundled middleware

None of the middleware from connect is bundled with express (or exposed on the express module). Any middleware you want to use should be installed and listed in your apps package.json. This allows for feature fixes and faster updates to middleware without affecting express core.

See middleware modules for a list of modules for old connect middleware.

Router improvements

express now exposes a better Router and route API to curb many instances of duplicating route naming and make it easier to split Routers into files for project organization.

no more app.use(app.router)

All routing methods will be added in the order in which they appear. You should not do app.use(app.router). This eliminates the most common issue with Express.

In other words, mixing app.use() and app[VERB]() will work exactly in the order in which they are called.

app.get('/', home);
app.use('/public', require('st')(process.cwd()));
app.get('/users', users.list);
app.post('/users', users.create);

app.route(path)

Instead of using the app.get(), app.post(), etc... verbs directly (which are still supported), a new route() method, which returns an instance of a Route, can be used. You can then call all of the HTTP verbs on this instance and even add middleware specific to this route.

app.route('/users')
.get(function(req, res, next) {})
.post(function(req, res, next) {})

route() takes a path argument which is the same argument you pass to .get() or .post() when creating a route.

Additionally, the returned route has an .all() method which is helpful if you want to add middleware to the route or handle all VERBS.

Router

Another addition is the public API for express Routers. A Router is like a mini express app. It contains no views or settings but does provide the typical routing APIs (.use, .get, .param, .route).

Apps and Routers can also .use() other routers allowing you to create files that export a router to organize your apps better.

Imagine an example routes/people.js in your project.

var people = express.Router();

people.use(function(req, res, next) {
});

people.get('/', function(req, res, next) {
});

module.exports.people = people;

You can mount it under the /people path so that any request to /people/* will route to the people router.

app.use('/people', require('./routes/people').people);

See the Router docs for more examples.