Node.js talk

talk.md

Introduction to Node.js

Who

• Developer for Kainos (Java, Scala, Rails, JavaScript, HTML, CSS)
• Student at University of Bath
• Write a lot about JavaScript at www.javascriptplayground.com
• @Jack_Franklin on Twitter

Origins of Node

• Server side JavaScript done right
• runs on Chrome's V8 Engine (it's quick)
• Evented I/O - runs single non-blocking thread with event loop
• this is great as JS was designed to be run in a single thread environment (browser)

Node right now

• V0.8 standardised the API (non breaking)
• currently V0.8.4, much more stable than < 0.8
• Install via installers, from source or via package manager like Brew.

NPM

• Package Manager for Node (think rubygems / bundler for Node)
• Full of really useful modules (and some less useful ones)
• 12,627 packages as of yesterday (browse at http://search.npmjs.org/)

Event Driven JavaScript

• Learn to think Asynchronously "Once node has completed a task, the callback for it is fired. But there can only be one callback firing at the same time. Until that callback has finished executing, all other callbacks have to wait in line. In addition to that, there is no guarantee on the order in which the callbacks will fire." From: http://debuggable.com/posts/understanding-node-js:4bd98440-45e4-4a9a-8ef7-0f7ecbdd56cb
• Related: Async.js https://github.com/caolan/async/

## Callbacks

• Lots and lots of callbacks

var net = require('net');

var server = net.createServer(function (socket) {
  socket.write('Echo server\r\n');
  socket.pipe(socket);
});

server.listen(1337, '127.0.0.1');

• How to avoid: http://callbackhell.com/

Naming your Callbacks

• Did you know you can name them?

var net = require('net');
var server = net.createServer(function writeResponse(socket) {
  socket.write('Echo server\r\n');
  socket.pipe(socket);
});
server.listen(1337, '127.0.0.1');

Avoiding Callbacks: Modules

• "Write small modules that each do one thing, and assemble them into other modules that do a bigger thing. You can't get into callback hell if you don't go there." Isaac Schlueter - Node.js core contributor @izs

• write your code in a file like normal:

//file socket-module.js
function writeResponse(socket) {
  socket.write('Echo server\r\n');
  socket.pipe(socket);
});
module.exports = {
  resp: writeResponse
}

(this follows the CommonJS module structure)

• require and use it

var net = require('net');
var socketModule = require('socket-module');
var server = net.createServer(socketModule.resp);
server.listen(1337, '127.0.0.1');

Databases with Node

• Redis & the Redis NPM Package is awesome
• Adapters for all common DB solutions

Web Frameworks

• Most popular is Express JS - www.expressjs.com
• Loads out there - Google "node js framework"
• Geddy, Flatiron, RailwayJS
• Tools like this are slowly but surely maturing

Express

var app = express.createServer();

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

app.listen(3000);

• routing, views (Jade), etc
• very extensible
• About to hit V3

Unit Testing

• NodeUnit https://github.com/caolan/nodeunit
• Mocha http://visionmedia.github.com/mocha/
• Lots more. Find one that suits (I love Mocha)

In the wild

• JSBin by @rem - www.jsbin.com - pure awesomeness
• TweetDig by @mheap - www.tweetdig.com - 2.5m tweets per day

To Sum Up

• Node is still very young, although standards and conventions are beginning to be defined.
• Lack of resources is slowly becoming less of an issue.
• V0.8 is huge improvement on prior versions.
• Node is seriously quick if used properly.

Further Resources

• @Peepcode screencasts www.peepcode.com
• CodeSchool Node course www.codeschool.com
• Async JavaScript book from Trevor Burnhan www.leanpub.com/asyncjs
• How to Node blog www.howtonode.org/

Any Questions?

• Slides on Github: gist.github.com/jackfranklin
• www.javascriptplayground.com for JavaScript tutorials (including Node)
• @Jack_Franklin if you can put up with even more of me rambling