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Node.js

Quhan ArunasalamJune / 11 / 2015 ITE@PayPal

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What we’re going to explore today

Node.js

NPM

An open source, cross-platform runtime environment for server-side Javascript applications.

A package manager for Javascript.

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Node.jsRun Javascript on the server

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DoJSON based REST APIsWeb / Mobile-Web AppsNetwork Apps

Don’t CPU intensive work

When to use Node?

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The module systemThe building blocks of a Node app

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.

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Lab 2.1: Requiring thingsBuilding the classic Hello World example

Create a folder called hello.

In it, create 2 new files called greet.js and index.js

greet.jsexports.hello = function () {return 'Hello ITE';};

index.jsvar greet = require('./greet.js');console.log(greet.hello());

Run the app using node indexHello ITE

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Lab 2.2: Requiring things (again)Let’s get bilingual

Modify greet.jsexports.hello = function () {return 'Hello ITE';};exports.konbanwa = function () {return 'Konbanwa ITE';};

Modify index.jsvar greet =

require('./greet.js');console.log(greet.hello());console.log(greet.konbanwa());

Run the app using node indexHello ITEKonbanwa ITE

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In-built modulesDon’t worry, we’re getting to the fun parts

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.

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Lab 2.3: Create a better (Hello) WorldBy building a web server

Modify index.jsvar http = require('http');var greet = require('./greet.js');

function server(req, res) {res.end(greet.hello());

}

http.createServer(server).listen(8000);console.log('Server running at port 8000');

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Lab 2.3: Create a better (Hello) WorldTa-daa!

* Press Ctrl+C on your Terminal to stop the app

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Reuse and share code

NPM

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What is npm?It’s 3 things actually

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.

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

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Lab 2.4: Initializing your Hello World projectWith metadata

Initialize your app with:npm init

...

name: (hello) version: (1.0.0) description: An app to say Hello ITEentry point: (index.js) test command: git repository: keywords: helloworldauthor: Quhan Arunasalamlicense: (ISC)

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Lab 2.5: Saving the momentInstalling and using a 3rd party module

Install the moment module using:npm install --save moment

Modify index.jsvar 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');

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Lab 2.5: Saving the momentTa-daa!

* Press Ctrl+C on your Terminal to stop the app

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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" }}

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For more information, please contact:

PayPal Singapore5 Temasek Boulevard #09-01, Suntec Tower Five, Singapore 038985

Quhan Arunasalam