Node.js primer

© 2015 PayPal Inc. All rights reserved. Confidential and proprietary.

Node.js

Quhan ArunasalamJune / 03 / 2015 Hackathon@SST

© 2015 PayPal Inc. All rights reserved. Confidential and proprietary

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.


Node.jsRun Javascript on the server


Understanding the Event LoopThe guts of Node


DoJSON based REST APIsWeb / Mobile-Web AppsNetwork Apps

Don’t CPU intensive work

When to use Node?


Test the waters via REPLThe Read-Eval-Print Loop

• 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 REPLRead-Eval-Print-Loop

$ node

> var a = [1, 2, 3];

> console.log(a);[ 1, 2, 3 ]

> a.forEach(function (z) { console.log(z); });123


Lab 2.2: Baby-stepsBuilding the classic Hello World

$ mkdir hello && cd hello

$ touch index.js

// index.jsconsole.log('Hello SST');

$ node indexHello SST

https://www.flickr.com/photos/munakz/9228501911/



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.



Lab 2.3: Requiring thingsModifying your previous Hello World example

$ touch greet.js

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

// index.jsvar greet =

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

$ node indexHello SST


Lab 2.4: Requiring things (again)Let’s get bilingual

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

// index.jsvar greet =

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

$ node indexHello SSTKonbanwa SST


Lab 2.5: Requiring things (one last time)Another way of handling exports

// greet.jsmodule.exports = {

hello: function () { return 'Hello SST'; },

konbanwa: function () { return 'Konbanwa SST'; }

};


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.



Lab 2.6: Create a better (Hello) WorldBy building a web server

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

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) WorldTa-daa!


Reuse and share code

NPM


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.



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


Lab 2.7: Initializing your Hello World projectWith metadata

$ npm init

...

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


Lab 2.8: Saving the momentInstalling and using a 3rd party module

$ npm install --save moment

// index.jsvar http = require('http');var greet = require('./greet.js');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 momentTa-daa!


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 world8814 packages available (at the time of screenshot)


Let’s not publish another hello worldHiding away your little secrets

{ "name": "hello", "version": "1.0.0",

"private": true, "description": "An app to say Hello

SST", ...}

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For more information, please contact:

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

Quhan Arunasalam

Technology

Node.js primer