Node JS For StartersDesign, implement and deploy a web service in mere minutes

Take that, JAVA!

What is Node?● Node is a server that runs JS -

imagine a headless chrome on a remote machine and that’s it (it does use chrome’s v8 engine to run JS)

● Script is run in an event-driven non-blocking loop

● It’s great for asynchronous tasks

● NodeJS is really just javascript running on the server, so you get all the goodies JS provides, and more

The Bad● CPU intensive● Not scalable by itself (however we

can scale by reverse proxying multiple node instances to nginx - just ask Duran how)

● It’s very low level - you do need to worry about things like memory leaks and error handling - otherwise these will break your app

The Good● A familiar language (it’s really just

JavaScript)● Non-blocking functional language● Ability to share codes between

frontend (browser) and backend (server)

● NPM package manager● Projects everywhere on git,

everywhere people!

Hello, world.The code

hello.js

console.log('hello world');

The command

node hello.js

… yes, you can use it to write little command line tools, just ask me how after this

Let’s talk structureA typical nodejs app consists of:

●An entry point (usually index.js)

●A package.json file for dependencies and project details

●A node_modules directory where the dependencies will be stored (vendors directory for php coders)

●A src or app directory for your own code source (I prefer app - I keep src for resources that need build)

●A .gitignore, of course, and don’t forget your readme.md too.

.ideanode_modules

Dependencies ManagementNodejs dependencies are managed via npm, through the package.json file. There are 2 sections:

●dependencies - required for the app

●devDependencies - optional for development only

E.g."devDependencies": { "chai": "^3.5.0", "mocha": "^2.4.5", "uglify-js": "^2.6.1", },"dependencies": { "async": "^2.0.0-rc.5"}

Our first NodeJS web service!Now let’s try to make a little web service that takes 2 numbers and return the result of first number multiplying the second one, and we’ll make:

●The web service itself that takes input and sends out json outputs

●A little module that does the calculation

We’ll also need to manage the different configurations for different environments, and A package for unit tests, but we’ll get on those later.

Embrace ExpressWe use express package for the server:

npm install --save --save-exact express

And with just a few lines it’s up and running:

Set up a service for multiplications!Math is hard, so we need a dedicated service for this thingy:

File: app/service/multiply.js

Content:

Pretty hardcore right?

And what is this `module.exports` thingy? It’s really a wrapper - your code will be exposed via module.exports, and by NOT putting functions in module.exports you can essentially create ‘private’ functions - we can chat more on this after the session.

Put it all togetherHere’s how we include our packages:

And here’s how we route a nice url /X/x/Y

Run itLet’s say we want to run it on port 1200:

PORT=1200 node index.js

Want fancy? Put it in package.json

"start": "PORT=1200 node index.js",

And we can run by

npm start

So far we’ve been on the synchronous side of the operation: output is sent immediately once input is processed, but sometimes it may take a while to process something, but you want to give the user instant feedback (that you are on it), here’s the little trick:

You can continue doing stuff after response is sent - node js is after all, javascript; by nature, it allows for operation to happen continuously (try it in browser if you don’t believe me). Note: for async operations, I have a nice bonus page after this, stay tuned.

Immediate Response & work in background

NodeJS best practicesI’ll list only a few here, for the full list go here: https://devcenter.heroku.com/articles/node-best-practices

●Always start project with npm init.

●Adapt to ECMAScript6 standards (https://nodejs.org/en/docs/es6/), you can thank me later when you start learning modern languages such as swift.

●Keep all lib file names in lowercase and use dash(-) instead of camel case, e.g. service-sapi.js

●Use 2 spaces indentation (BTW, for php, please use PSR2 - 4 spaces unless you are in drupal…)

● It’s better to fix the version of your dependencies (Duran/Lito will be super happy if you do this), e.g. npm install foobar --save --save-exact

Bonus content: Heroku the free playgroundSign up on Heroku.com and you can deploy in mere minutes.

Go to the project, and all you need to do:

See it in action:

Bonus content: universal JSYes we can make our node js modules compatible with both browser and server-side, all we need to do is to use window object reference and assign also to the module exports. See code below:

1. Always use IIFE (immediately invoked function expression) to enclose it for isolation on browser (not required for node)

2. Verify if module exists before assigning to module.exports

3. Use (this) to make `window` available from server-side to avoid syntax errorQuizz: what is ‘window’ object in server mode?

Bonus content: unit testsToolset:

Prerequisite:

npm install -g mocha

Bonus content: Async callsEnough talk, let’s code:

Useful resourcesDeploy nodejs app with herokuhttps://devcenter.heroku.com/articles/getting-started-with-nodejs#introduction

Free mongodb host (up to 500mb storage, perfect for personal projects)https://mlab.com/

NPMhttps://www.npmjs.com/

Best practice (actual practical advice)https://github.com/mattdesl/module-best-practices

Udemy Course: https://www.udemy.com/nodejs-for-beginning-programmers-100-practical/

Dora the explorer...Beginners:

●Find out how to serve static web pages

●Write a piece of code that connects to a mongodb instance

ABOVE & BEYOND:

●Rewrite the editorial review page with nodejs

●Rewrite the BAC search results page with nodejs