INTRO TO NODE.JS

@eschoff - @funkytek - @uhduh - @wearefractal

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The GOAL of NODE.JS IS TO provide an easy way to build scaleable network programs

NODE.JS IS NOT ANOTHER WEB FRAMEWORK

NODE.JS IS:

A Web Server

TCP Server

Awesome Robot Server

Drone Controller

Command Line Application

Proxy Server

Steaming Server

VoiceMail Server

Music Machine

(any thing that has to deal with I/0)

WHY NODE.JS?

Non-Blocking I/O

Based On Chrome's V8 Engine

49,000+ Modules

Very Active Community

Supported on Mac, Linux, and Windows

One Language to Rule them All

JavaScript is the Language of the Web

Basic Example

Create helloworld.js with:

console.log('Hello World');

On the command line run

node helloworld.js

You should see

Hello World

Basic HTTP SERVER


var http = require('http');
 
var server = http.createServer(function (req, res) {
  res.writeHead(200);
  res.end('Hello World');
});
 
server.listen(4000);

* Running this script on my development box I can achieve 10,000+ requests per second with 100 concurrent connections without

breaking a sweat.

What is

Non-Blocking IO?

AND WHY SHOULD I CARE?

BLOCKING I/0

// Get Users - 20ms
$query = 'SELECT * FROM users WHERE id = ?';
$users = query($query, array($_GET['id']));
print_r($users);

// Get Activities - 130ms
$query = 'SELECT * FROM activities WHERE user_id = ? ORDER BY TIMESTAMP LIMIT 50';
$activities = query($query, array($_GET['id']));
print_r($activities);

// Get Leader Board - 120ms
$query = 'SELECT count(points),user_id FROM activities GROUP BY user_id LIMIT 50';
$leader_board = query($query);
print_r($leader_board);

270ms = SUM($user, $activities, $leader_board)

NON-BLOCKING I/0

// Get Users - 20ms
var query = 'SELECT * FROM users WHERE id = ?';
db.query(query, [req.query.id], function (err, users) {
    console.log(users);
});

// Get Activities - 130ms
query = 'SELECT * FROM activities WHERE user_id = ? ORDER BY TIMESTAMP LIMIT 50';
db.query(query, [req.query.id], function (err, activities) {
    console.log(activities);
});

// Get Leader Board - 120ms
query = 'SELECT count(points),user_id FROM activities GROUP BY user_id LIMIT 50';
db.query(query, function (err, leader_board) {
    console.log(leader_board);
});

130ms = MAX(user, activities, leader_board)

THE MOST JARRING THING ABOUT SERVER SIDE JAVASCRIPT IS THINKING IN CALLBACKS

The NODE.JS CALLBACK PATTERN

awesomeFunction(args, function (err, data) {
    if (err) {
        // Handle Error
    }
    
    // Do something awesome with the data
});

Error First then success... ALWAYS!
Because this is the defacto standard, 99.99999% of the time you will be able to guess how a Node.js module works

The Node Package manager

otherwise known as NPM!

NPM is how you harness the awesomeness of the Node.js community

USING NPM

It's standard practice to install modules locally for your current project. Modules are installed in ./node-modules in the current directory

To install a new module:

npm install <module>

To find a module in the repo:

npm find <module>

To list the modules (and dependancies) for the current project:

npm list

Basic Module Example

var currentCount = 0;

module.exports.incr = function () {
    return ++currentCount;
};

Once you've created a module in counter.js you use it like this...

var counter = require('./counter');
counter.incr();
var count = counter.inrc();

Keep this in mind... modules are loaded once and cached. So when you load the module a second time in your app, require just returns the cached module object. This lets you do interesting things...

INSTALLING YOUR MODULES

Run npm link in the module directory. Then run

npm link module in the project directory.

Add the module's Gitub URL to your package.json dependancies and run npm install.

"dependencies": {
    "my-module": "https://github.com/my-name/my-module/tarball/master"
}

CREATING YOU OWN MODULES

require('./example') will load either example.js or example/index.js or the entry point defined in package.json

Run npm init to bootstrap your new module, this will create the package.json

Try to stick to creating "Pure JavaScript" module if possible. It will give you less headaches down the road