title: node.js intro author: name: Andi Neck twitter: andineck url: http://intesso.com controls: true progress: true style: style.css output: index.html

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node.js intro

http://intesso.github.io/nodejs-introduction

feedback and pull requests welcome on GitHub

navigate with left, right keys

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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."

Source: https://nodejs.org/en/

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who uses node.js

and many more ...

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trend ( jan-2014 - nov-2016 )

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use cases

• build chain gulp, grunt: compile, lint, bundle, etc...
• website / webapp express, hapijs
• backend for mobile apps
• RESTful services restify
• microservices seneca
• desktop applications electron, e.g. atom, brave, visual studio code
• commandline tools npm package.json bin, commander, minimist
• messaging (TCP, UDP, http, https, ...) node.js api
• IoT Node-RED, cyclon.js
• native c, c++ modules addons
• basically any I/O, Network or Web Stuff that needs asynchronous/parallel processing

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runs on

basically anything:

windows, linux, mac, arm, docker ...

download: https://nodejs.org/en/download/

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what makes node.js stand out?

• same language on the server and the browser
• excellent module system npm
• more than
  • 230'000 npm modules (Jan 2016)
  • 350'000 npm modules (Nov 2016)
• quite good open source communities
• sharing spirit
• part of the linux foundation
• and there is more ...

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what is (was) io.js?

• a fork of node.js
• because developers were not happy with the development of the stewardship of joyent
• that was merged in September 2015 into node.js 4.0
• it lead to a well governed OSS projects
• that includes everyone: developers, organizations, ...
• under the umbrella of the linux foundation

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node.js releases

• LTS: long term support (even numbers)
  • current release (Nov 2016): V6 "Boron"
  • actively maintained for 18 month, maintenance mode afterwards
  • no more than two LTS versions at the same time
• Stable: shorter lifespan, more updates (odd numbers)
  • current release (Nov 2016): V7
  • when Stable release becomes the next LTS, no new features or breaking changes are added

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how was node.js started?

Ryan Dahls thesis

io needs to be done differently

original node.js presentation by Ryan Dahl

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the cost of i/o

  L1-cache           3 cycles

  L2-cache          14 cycles

  RAM              250 cycles

  Disk      41'000'000 cycles

  Network  240'000'000 cycles

don't block on I/O access

but how?

Threads in combination with Object oriented programming can be really painful and error prone.

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event-loop

source: https://strongloop.com/strongblog/node-js-performance-event-loop-monitoring/

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event-loop

• your code is single threaded, basically everything else runs in parallel
• event-loop event-loop explanation, ryan dahl's original presentation, is based on libuv
• EventEmitter to interact with the event-loop
• EventEmitter itself is synchronous

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more node.js building blocks

• module system
• events
• streams

what's underneath

• node.js is built on top of google chrome V8
• Microsoft submitted a pull request for support with it's ChakraCore in January 2016

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editors

• visual studio code
• atom
• brackets
• sublimetext
• vim
• WebMatrix
• WebStorm
• nodeclipse

pick whatever you like!

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debugging

debugging node.js within IDE or with node-inspector or with node >= 6

# install once
npm install -g node-inspector
# use
node-debug myapp.js
# chrome inspector included with node >= 6.0
node --inspect myapp.js

restarting node.js server on code changes use nodemon or forever

# install once
npm install -g nodemon
# use
nodemon myapp.js

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coding

file server

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

var server = http.createServer();

server.on('request', function (req, res) {
  if (req.url == '/favicon.ico') return res.end();
  var stream = fs.createReadStream(process.cwd() + req.url);
  stream.pipe(res);
});

server.listen(8000);
console.log('fileserver running at: http://localhost:8000');

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coding

using EventEmitter

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

var server = http.createServer();
server.on('request', function (req, res) {
  if (req.url == '/favicon.ico') return res.end();
  var stream = fs.createReadStream(process.cwd() + req.url, 'utf-8');
  stream.on('data', function(data){
    res.write('\n\ngot data: ' + data);
  });
  stream.on('error', function(err){
    res.write('\n\nshit happens' + err);
  });
  stream.on('end', function(){
    res.end('\n\ndone, no more data');
  });
});

server.listen(8000);
console.log('fileserver running at: http://localhost:8000');

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learning, learning, learning...

• node.js api
• web apis devdocs
• testing node.js server + npm online tonicdev
• testing node.js browserified bundles requirebin

get some great interacitve node.js lessons:

npm install learnyounode -g
npm install workshopper -g
npm install adventure -g
npm install functional-javascript-workshop -g

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built with node.js at intesso

• Traffic Control System
  • Realtime UI with WebSockets (socket.io)
  • TCP/XML Interfaces
• Intelligent Charging Station
  • Communication with OSGI bundle via 0mq
  • binding with python code with zerorpc
  • SOAP WebService Interfaces
  • Proprietary Binary Interface with Charging Station
  • Admin Web UI
• On demand Remote Access
• Modular Content Management System: GlintCMS, based on GlintApp
• and many Open Source npm Modules: andineck

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personal experiences with node.js @andineck

• started with v0.6
• v0.8, v0.12, v4.3 in production
• so far, I hardly ever experienced unexpected behaviour from node.js
• when something was not working the way I thought it should be, it was most of the time, because I didn't understand JavaScript well enough

see also: http://intesso.github.io/javascript-obstacles