Achieving Greatness with Node.js

Practical hacking with JavaScript

Reid Burke — @reid

JavaScript

Prototype-based, object-oriented scripting language.

  • Web sites
  • Widgets
  • Browser extensions

JavaScript Everywhere

Most popular language on GitHub: https://github.com/languages

Server-Side JavaScript

Started in 1996: Netscape LiveWire.

Refined since then: AppJet, EtherPad, CommonJS.

Used in Yahoo!'s YQL.

Node.js

Event-driven I/O framework for server-side JavaScript.

Easily create scalable network apps, like web servers.

Created in 2009. Uses the V8 JavaScript engine from Google.

http://nodejs.org/

Hello, world!

var http = require('http');

http.createServer(
    function (request, response) {
        response.writeHead(200,
            {'Content-Type': 'text/plain'});
        response.end('Hello World\n');
}).listen(8000);

console.log('Started at
    http://127.0.0.1:8000/');

Installing

http://bit.ly/howtonode

  • Easy build on Linux, Mac, Solaris.
  • Windows binaries available.
  • Node.js Package Manager

Node.js Package Manager

http://bit.ly/howtonode — Step 4

The package manager for Node.js modules.

npm install modulename
var foo = require('modulename');

Registry: http://search.npmjs.org/

Play

Type node to start a REPL.

$ node
> console.log('Hello, Bucharest!');
Hello, Bucharest!

Control-D to quit.

Start a script file with node script.js.

What can I build with this?

Socket.io

npm install socket.io

Easy realtime browser apps! http://socket.io/

<script src="//socket.io/socket.io.js">
</script><script> 
 var socket = new io.Socket({url}); 
 socket.connect();
 socket.on('connect', function(){ … }) 
 socket.on('message', function(){ … }) 
 socket.on('disconnect', function(){ … }) 
</script>

Smarmation

Using socket.io to create a realtime game.

http://swarmation.com/

NowJS

npm install now — http://nowjs.com/

var nowjs = require("now");
var everyone = nowjs.initialize(httpServer);

everyone.now.getServerInfo = function(callback){
  db.doQuery(callback);
}

<script>now.getServerInfo(function(data){
  // data contains the query results
});</script>

DNode

npm install dnode

Freestyle RPC between Node.js, the browser, Perl, Ruby and Java.

https://github.com/substack/dnode

Realtime apps

  • Games: massively-multiplayer is easy!
  • Chatroom
  • Shared whiteboard
  • Live stock quotes
  • Streaming charts with http://smoothiecharts.org/
  • Your hack

Web Site Frameworks

Node.js is not a web server, it's a framework to make one.

Many projects exist to help build a web site.

Connect

npm install connect

Low-level middleware stack for creating HTTP servers.

http://github.com/senchalabs/connect

Express

npm install express

var app = express.createServer();

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

app.listen(3000);

Router, view rendering, configuration, etc.

http://expressjs.com/

Debugger

npm install node-inspector

Works for any Node.js program. Handy!

node --debug-brk app.js
node-inspector

You can now debug your app in WebKit browser.

node --debug # Enable debug mode
node --debug-brk # Break on startup

http://nodejs.org/docs/latest/api/debugger.html

Node.js API

http://nodejs.org/docs/latest/api/

  • HTTP, UDP, DNS, TLS/SSL, Crypto, File System
  • Child process spawning
  • Events
    • .on vs. .once
    • .removeListener
  • Buffers: fast way to handle large data
  • Much more

Callbacks

var file = "/etc/redhat-release";
fs.stat(file, function(err, stat) {
    if (stat.isFile()) {
        fs.readFile(file, function(err, file) {
            postRequest("http://example.com", file, function (err, response) {
                if (response.status === 200) {
                    db.save(file, function (err) {
                        next();
                    });
                }
            });
        });
    }
});

Better Callbacks

var file = "/etc/redhat-release";

function onPost(err, response) {
    if (response.status !== 200) throw err;
    db.save(file, next);
}

function onRead(err, file) {
    postRequest("http://example.com", file, onPost);
}

function onStat(err, stat) {
    if (stat.isFile()) fs.readFile(file, onRead);
}

fs.stat(file, onStat);

jsdom

npm install jsdom

Implementation of the W3C DOM. Headless browser!

var jsdom = require("jsdom");
jsdom.env("http://nodejs.org/dist/", [
  'http://yui.yahooapis.com/3.3.0/build/simpleyui/simpleyui-min.js'
], function(errors, window) {
  console.log("there have been",
    window.Y.all("a").size(),
    "nodejs releases!");
});

https://github.com/tmpvar/jsdom

YUI on Node.js

npm install yui3

Run YUI on Node.js!

https://github.com/davglass/nodejs-yui3

Demo

http://express.davglass.com

Serialport

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  8eeee 8eee 8eee8e 8e 8eee8 8e    8eee8 8   8 8eee8e  8e  
     88 88   88   8 88 88  8 88    88    8   8 88   8  88  
  8ee88 88ee 88   8 88 88  8 88eee 88    8eee8 88   8  88

npm install serialport

Talk to physical devices, like an Arduino.

  • Interact with sensors
  • Write to LED displays
  • Physical controls: dials, switches, etc.

Arduno and Node.js

Using a physical dial to seek a YouTube video synced to many devices.

Control a R/C boat from a web browser.

Taking JSON from YQL and writing it to a LED matrix.

This is just the beginning!

Thanks

Steal this deck

http://bit.ly/hacknode

About this slideshow

Open Hack Europe 2011