Stony Brook Computing Society

Alexa's Node.js Workshop

Resources and tutorial code built for the SBCS Sept. 6th 2017 Node.js Workshop

Step 0: What is Node.js?

Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient. Node.js' package ecosystem, npm, is the largest ecosystem of open source libraries in the world.

Alrighty, lets get you set up.

Step 1: Installation

Install Node.js v4+ to run. Then either open powershell or the Node.js command prompt and navigate to your working directory.

To test if it works, run the following:

$ npm install -d
$ node
> console.log("Hello World");
Hello World

Now put your console.log() statement into a *.js file, and run it like so:

$ node step1.js
Hello World

Step 2: HTTP

So that isn't very exciting, so lets send hello world over http.

// Include http module.
var http = require('http');

//create http server and send a 200 OK header, as well as the body 'Hello Http'.
var server = http.createServer(function(req, res) {
  res.writeHead(200);
  res.end('Hello Http');
});
server.listen(8080);

Run:

$ node step2_http.js

You will notice that it doesn't exit right away. That's because a node program will always run until it's certain that no further events are possible. Navigate to http://localhost:8080/

Step 3: Modules

One of the staples of node.js is that you can use modules within your project. In this case we will initalize the function world() to be exported.

//hello.js
exports.world = function() {
  console.log('Hello World');
}

And here we will import world() into another file by calling it with require('./hello').

//step3_modules.js
var hello = require('./hello');
hello.world();

NPM

Now that we get the basic idea of how a module works, you can include any module you want from here: https://www.npmjs.com/

For example: https://www.npmjs.com/package/mysql How to install:

$ npm install mysql --save

Step 4: Eventemitter

The main idea: action -> reaction

var events = require('events');
var eventEmitter = new events.EventEmitter();

var reaction = function reaction()
{
  console.log('ow');
}
eventEmitter.on('poke', reaction);

eventEmitter.emit('poke');

Step 5: Sample Page

We can type everything back by hosting HTML pages with HTTP, so on and so forth.

var http = require('http');
var url = require('url');
var fs = require('fs');

http.createServer(function (req, res) {
  var q = url.parse(req.url, true);
  var filename = "." + q.pathname;
  fs.readFile(filename, function(err, data) {
    if (err) {
      res.writeHead(404, {'Content-Type': 'text/html'});
      return res.end("404 Not Found");
    }
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.write(data);
    return res.end();
  });
}).listen(8080);

But this sucks right? Luckily we have Express.js to help us with routing and serving a web client, that could potentially function as a REST API as well.

Step 6: Express.js

Routing!!

const express = require('express')
const app = express()
var path = require('path');

app.get('/home', function(req, res) {
    res.sendFile(path.join(__dirname + '/home.html'));
});

app.get('/', function(req, res) {
    res.sendFile(path.join(__dirname + '/index.html'));
});

app.listen(3000, function () {
  console.log('Example app listening on port 3000!')
})

MongoDB, ExpressJS, AngularJS and NodeJS

The MEAN Stack is not a hipster thing, as delusional people try to assertain with no real reasoning behind their empty statements. The MEAN stack is a very real thing. Here’s a slideshare for you to look at.

MongoDB as a database ExpressJS as your web framework AngularJS as your client-side framework NodeJS as the platform

The glaring benefit of using a stack such as this is the ease with which you can transfer objects through your application without having to resort to different interfaces, data presentation alternatives, and programming languages. You can really get away with just using JavaScript everywhere.