Node.js primer

© 2015 PayPal Inc. All rights reserved. Confidential and proprietary.
Node.js
Quhan Arunasalam
June / 03 / 2015 Hackathon@SST

© 2015 PayPal Inc. All rights reserved. Confidential and proprietary
What we’re going to explore today
2
Node.js
NPM
An open source, cross-platform
runtime environment for
server-side Javascript applications.
A package manager for Javascript.

Node.js
Run Javascript on the server
3

Understanding the Event Loop
The guts of Node
4

Do
JSON based REST APIs
Web / Mobile-Web Apps
Network Apps
Don’t CPU intensive work
When to use Node?
5

Test the waters via REPL
The Read-Eval-Print Loop
6
• Provides a way to
interactively run JavaScript
and see the results.
• Useful for debugging, testing,
or just trying things out.
https://www.flickr.com/photos/snype451/5752753663/

Lab 2.1: Test the waters via REPL
Read-Eval-Print-Loop
7
$ node
> var a = [1, 2, 3];
> console.log(a);
[ 1, 2, 3 ]
> a.forEach(function (z) { console.log(z); });
1
2
3

Lab 2.2: Baby-steps
Building the classic Hello World
8
$ mkdir hello && cd hello
$ touch index.js
// index.js
console.log('Hello SST');
$ node index
Hello SST
https://www.flickr.com/photos/munakz/9228501911/

The module system
The building blocks of a Node app
9
http://pixabay.com/en/lego-building-blocks-shapes-puzzle-297773/
• Makes it possible to include
other Javascript files into your
app.
• Helps organize your code into
separate parts with limited
responsibilities.
• Using modules is simple -
You just require() them.

Lab 2.3: Requiring things
Modifying your previous Hello World example
10
$ touch greet.js
// greet.js
exports.hello = function () {
return 'Hello SST';
}
// index.js
var greet = require('./greet.js');
console.log(greet.hello());
$ node index
Hello SST

Lab 2.4: Requiring things (again)
Let’s get bilingual
11
// greet.js
exports.hello = function () {
return 'Hello SST';
}
exports.konbanwa = function () {
return 'Konbanwa SST';
}
// index.js
console.log(greet.hello());
console.log(greet.konbanwa());
$ node index
Hello SST
Konbanwa SST

Lab 2.5: Requiring things (one last time)
Another way of handling exports
12
// greet.js
module.exports = {
hello: function () {
return 'Hello SST';
},
konbanwa: function () {
return 'Konbanwa SST';
}
};

In-built modules
Don’t worry, we’re getting to the fun parts
13
http://commons.wikimedia.org/wiki/File:AMC_V8_engine_360_CID_customized_um.JPG
Node ships with a number of
core modules. For example:
• console - Sends output to
stdout or stderr.
• http - Provides a server and
client for HTTP traffic.
• fs - Provides functions to
interact with the file system.

Lab 2.6: Create a better (Hello) World
By building a web server
14
// index.js
var http = require('http');
http.createServer(function (req, res) {
res.writeHead(200);
res.end(greet.hello());
}).listen(80);
console.log('Server running at port 80');

Lab 2.6: Create a better (Hello) World
Ta-daa!
15

Reuse and share code
NPM
16

What is npm?
It’s 3 things actually
17
https://www.flickr.com/photos/kamshots/3096111340/
• A module registry, containing
a collection of open-source
code.
• A standard, to define
dependencies on other
packages.
• A package manager, for
locally installed modules.

The npmjs.com registry
Note the 134,726 packages available (at the time of screenshot)
18

Lab 2.7: Initializing your Hello World project
With metadata
19
$ npm init
...
name: (hello)
version: (1.0.0)
description: An app to say Hello SST
entry point: (index.js)
test command:
git repository:
keywords: helloworld
author: Quhan Arunasalam
license: (ISC)

Lab 2.8: Saving the moment
Installing and using a 3rd party module
20
$ npm install --save moment
// index.js
var http = require('http');
var moment = require('moment');
http.createServer(function (req, res) {
res.writeHead(200);
res.end('Hi! It is now ' + moment().format('h:mm:ss a'));
}).listen(80);
console.log('Server running at port 80');

Lab 2.8: Saving the moment
Ta-daa!
21

© 2015 PayPal Inc. All rights reserved. Confidential and proprietary 22
Figuring out package.json
{
"name": "hello",
"version": "1.0.0",
"description": "An app to say Hello SST",
"main": "index.js",
"scripts": {
"test": "echo "Error: no test specified" && exit 1"
},
"keywords": [
"helloworld"
],
"author": "Quhan Arunasalam",
"license": "ISC",
"dependencies": {
"moment": "^2.9.0"
}
}

Let’s not publish another hello world
8814 packages available (at the time of screenshot)
23

Let’s not publish another hello world
Hiding away your little secrets
24
{
"name": "hello",
"version": "1.0.0",
"private": true,
"description": "An app to say Hello SST",
...
}

© 2015 PayPal Inc. All rights reserved. Confidential and proprietary.
For more information, please contact:
PayPal Singapore
5 Temasek Boulevard #09-01, Suntec Tower Five, Singapore 038985
Quhan Arunasalam

Node.js primer

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