Node.js primer for ITE students

© 2015 PayPal Inc. All rights reserved. Confidential and proprietary.
Node.js
Quhan Arunasalam
June / 11 / 2015 ITE@PayPal

© 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

Do
JSON based REST APIs
Web / Mobile-Web Apps
Network Apps
Don’t CPU intensive work
When to use Node?
4

The module system
The building blocks of a Node app
5
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 2.1: Requiring things
Building the classic Hello World example
6
Create a folder called hello.
In it, create 2 new files called greet.js and index.js
greet.js
exports.hello = function () {
return 'Hello ITE';
};
index.js
var greet = require('./greet.js');
console.log(greet.hello());
Run the app using node index
Hello ITE

Lab 2.2: Requiring things (again)
Let’s get bilingual
7
Modify greet.js
exports.hello = function () {
return 'Hello ITE';
};
exports.konbanwa = function () {
return 'Konbanwa ITE';
};
Modify index.js
console.log(greet.hello());
console.log(greet.konbanwa());
Run the app using node index
Hello ITE
Konbanwa ITE

In-built modules
Don’t worry, we’re getting to the fun parts
8
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 2.3: Create a better (Hello) World
By building a web server
9
Modify index.js
var http = require('http');
function server(req, res) {
res.end(greet.hello());
}
http.createServer(server).listen(8000);
console.log('Server running at port 8000');

Lab 2.3: Create a better (Hello) World
Ta-daa!
10
* Press Ctrl+C on your Terminal to stop the app

Reuse and share code
NPM
11

What is npm?
It’s 3 things actually
12
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)
13

Lab 2.4: Initializing your Hello World project
With metadata
14
Initialize your app with:
npm init
...
name: (hello)
version: (1.0.0)
description: An app to say Hello ITE
entry point: (index.js)
test command:
git repository:
keywords: helloworld
author: Quhan Arunasalam
license: (ISC)

Lab 2.5: Saving the moment
Installing and using a 3rd party module
15
Install the moment module using:
npm install --save moment
Modify index.js
var http = require('http');
var moment = require('moment');
function server(req, res) {
res.end('It is now ' + moment().format('h:mm:ss a'));
})
http.createServer(server).listen(8000);
console.log('Server running at port 8000');

Lab 2.5: Saving the moment
Ta-daa!
16
* Press Ctrl+C on your Terminal to stop the app

© 2015 PayPal Inc. All rights reserved. Confidential and proprietary 17
Figuring out package.json
{
"name": "hello",
"version": "1.0.0",
"description": "An app to say Hello ITE",
"main": "index.js",
"scripts": {
"test": "echo "Error: no test specified" && exit 1"
},
"keywords": [
"helloworld"
],
"author": "Quhan Arunasalam",
"license": "ISC",
"dependencies": {
"moment": "^2.10.3"
}
}

© 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 for ITE students

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