JavaScript

Prototype-based, object-oriented scripting language.

• Web sites
• Widgets
• Browser extensions

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

JavaScript Everywhere

JavaScript isn’t found on just websites.

• Television sets via Yahoo! Connected TV
• Universal remote controls
• Realtime stock trading apps

Finally, there's Server-Side JavaScript.

Server-Side JavaScript

Started in 1996: Netscape LiveWire.

Refined since then: AppJet, EtherPad, CommonJS.

Used in Yahoo!’s YQL.

Node.js

Evented I/O for V8 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

Easy installers for Windows and OS X.

http://nodejs.org/#download

Easily compiled from source on Linux and Solaris.

Node.js Package Manager

Bundled with Node.js.

http://npmjs.org

The package manager for Node.js modules.

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

Play

Type node to start a REPL.

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

Control-D to quit.

Start a script file with node script.js.

SockJS

npm install sockjs

Cross-browser WebSockets. http://sockjs.org

<script src="http://cdn.sockjs.org/sockjs-0.3.min.js">
</script><script> 
 var sock = new SockJS("http://hackday.org/tower");
 sock.onopen = function(){ … }); 
 sock.onmessage = function(ev){ … });
 sock.onclose = function(){ … });
</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 express = require('express');
var app = express();

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

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
• Streams: powerful concept used everywhere
• 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/3.5.0/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

High-performance, device-independent HTML5 applications with Yahoo! Mojito.

http://developer.yahoo.com/cocktails/mojito/

Serialport

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npm install serialport

Talk to physical devices, like an Arduino.

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

Node.js and Hardware

• Hardware MIDI controller: <http://tmpvar.com/project/tmpad/>
• Using a physical dial to seek a YouTube video synced to many devices: <http://popcornjs.com/>
• Control a R/C boat from a web browser: <http://bit.ly/nodeboat>
• Make your robot detect and avoid obstacles: <http://youtu.be/GVGMjsKy3WQ>
• Taking JSON from YQL and writing it to a LED matrix.

Node KO

Get inspired.

• http://2011.nodeknockout.com/
• http://2010.nodeknockout.com/

About this slideshow

• Slideshow source: https://github.com/reid/decks
• Slideshow system based on YUI 3: https://github.com/reid/upstage