5.js

/**
 *Simple Express app
 *with multiple middleware functions.
 */

// create an express app

var express = require('express'),
	morgan = require('morgan'),
	app = express(),
	port = process.env.PORT || 3000,
	testMode = false;

// add logging middleware to log each request
// see: https://www.npmjs.org/package/morgan

app.use(morgan('dev'));

// add middleware to always send a 'hello world' response

app.use(function(req, res, next) {
	if (req.url == '/test') {
		console.log('enabling test mode');
		testMode = true;
	}
	next();
});

// add middleware to always send a 'hello world' response

app.use(function(req, res) {
	var data = testMode ? JSON.stringify(req.headers) : '<h1>hello world</h1>';

	var contentType = testMode ? 'text/plain' : 'text/html';

	res.writeHead(200, {
		'Content-Type': contentType
	});
	res.end(data);
});

//listen on localhost:3000

app.listen(port);
console.log('server started on port %s', port);