In code-along/express-app/

Initialize a new project and install express
```
 npm init -y
 npm install --save express
```

Create an index.js containing the following code:

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

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

 app.listen(3000);

node .
Point browser to http://localhost:3000

Express.js Overview

Router

app.get(path, handlerFunction);

function handlerFunction(request, response){ //...

Express Hello World

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

server.get('/', function (req, res) {
  res.send('Hello World!');
});

server.listen(3000);

Node/http Hello World

var server = require('http').createServer();

server.on('request', function(req, res){
  res.write('Hello World!');
  res.end();
});

server.listen(3000);

Style note

This:

var app = require('express')();
var obj = require('returns-a-function')();

Is the same as this:

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

var aFunction = require('returns-a-function');
var obj = aFunction();

Node/HTTP Two Routes

//http-greet-route.js
var http = require('http');
var url = require('url');
var querystring = require('querystring');

var server = http.createServer(function(request, response){
  var reqUrl = url.parse(request.url);
  if(reqUrl.pathname == '/'){
    rootHandler(request, response);
  }
  else if (reqUrl.pathname ==  '/greet'){
    greetHandler(request, response);
  }
});

function rootHandler(req, res){
  res.end('Hello World!');
}

function greetHandler(req, res){
  var query = querystring.parse(url.parse(req.url).query);
  res.end('Hello ' + query.name);
}

server.listen(3000);

Express Two Routes

//my-express-project/misc/greeter.js

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

server.get('/', handleRoot);
server.get('/greet', handleGreet);

function handleRoot(req, res) {
  res.send('Hello World!');
}

function handleGreet(req, res) {
  res.send('Hello ' + req.query.name);
}

server.listen(3000);

Middleware

Map functions to a (set of) routes

app.use(path, middleware);

function middleware(req, res, next){
  //do some stuff
  next();
}

Middleware Example

var auth = require('auth-middleware');
var static = require('static-middleware');
var logger = require('log-middleware');

app.use(logger);
app.use('/assets', static('site/assets'));
app.use('/admin', auth)

/* handler functions omitted */
app.get('/', handleRoot);
app.get('/users', listUsersHandler);

app.get('/admin/home', adminHomeHandler);
app.get('/admin/users/create', userForm);
app.post('/admin/users/create', createUser);
// ...

One weird trick...

function handler(req, res){
  res.end('Hello World!');
}

function middleware(req, res, next){
  //do some stuff
  next();
}

app.use(path, middleware);
app.get(path, handler);

"Routes" are middleware that don't call next!

- also they typically use a shorthand use method

In code-along/express-app/ Initialize a new project and install express npm init -y npm install --save express Create an index.js containing the following code: var express = require('express'); var app = express(); app.get('/', function (req, res) { res.send('Hello World!'); }); app.listen(3000); node . Point browser to http://localhost:3000 - make sure this bit gets finished! - after this, talk a bit about yesterday - node core - async management - javascript review - ecosystem & NPM - with that groundwork laid, today: build some stuff