Agenda

1. Motivation
2. JavaScript usage
3. ECMAScript 6
4. Node.js

Motivation

Facts

• Since 1995
• Mocha → LiveScript → JavaScript
• On client- & server-side from the beginning
  • Netscape Navigator
  • Netscape Enterprise Server
• Since 1997 part of Ecma International → ECMAScript
  • ECMAScript 1 (1997)
  • ECMAScript 2 (1998)
  • ECMAScript 3 (1999)
  • ECMAScript 4 (the incomplete)
  • ECMAScript 5 (2009)
  • ECMAScript 6 (2015)
  • ECMAScript 7 (work in progress)

ECMAScript

• As JavaScript one of the most important web technologies
  • Beside HTML and CSS
• Interpreted at run-time
• Prototype-based
• Supports different programming paradigms
  • object-orientated (prototyps)
  • imperativ / procedural
  • functional
• Not typed at development time, but at run-time
  • But: TypeScript (Microsoft, 2012)

The Dawn Of Enterprise JavaScript

JavaScript Finds Its Place In Enterprise Software Development

ECMAScript!!!

Usage of JavaScript

Maybe not for Mission Control

• Hardware, device drivers, etc.

For the web & desktop

Frontend

• Web browser
  • Generally known
• At the beginning in use for "dynamic" content with out server connection
• AJAX brought the possibility to access data from server (2005)
• Easy to use because of JQuery (2006)

Single-Page-Apps

• Business-Logic inside the web browser
  • First request loads the whole logic into the client
  • Content reloading possible
• AngularJS by Google (2009)
  • Often in use as MEAN-Stack
  • MongoDB
  • ExpressJS
  • AgularJS
  • NodeJS

Backend

• Already forgotten? Netscape Enterprise Server
• Netscape → Mozilla, Mozilla Rhino (Java) & Mozilla SpiderMonkey (C)
• NodeJS as interpreter (2012)
  • Frist Mozilla SpiderMonkey, then Google V8
• Mongo DB
  • Based upon V8 by Google
• Back to the Server: Server-Side JavaScript On The Rise

What's new in ECMAScript 6

• Can I use it?

Variable scope

• Currently (var) global object (e.g. window), or function
• Now: let

		function doSomethingECMA5()  {
			var a = ['apple', 'banana'];
			for (var i = 0; i < a.length; i++) {
				console.log(i, a[i]);
			}
			console.log(i, a[i]);  // undefined, weil [0, 1]
		}
	

		function doSomethingECMA6()  {
			var a = ['apple', 'banana'];
			for (let i = 0; i < a.length; i++) {
				console.log(i, a[i]);
			}
			console.log(i, a[i]); // Nicht möglich
		}
	

Constants

• Currenly only by convention → UPPER CASE
• Or with object properties

		const MAX_COUNT = 5;

		console.log(MAX_COUNT); // 5

		MAX_COUNT = 6; // use strict = Error

		console.log(MAX_COUNT);
	

String

• New functions
• startsWith, endsWith, includes

		console.log('hello'.startsWith('hell')); // true

		console.log('hello'.endsWith('hell')); // false

		console.log('hello'.includes('ell')); // true
	

Arrow functions

		var quadrat = x => x*x;

		var result = quadrat(5);

		console.log(result); // 25
	

		var addition = (x,y) => x+y;

		var result = addition(5, 6);

		console.log(result); // 11
	

		() => { };
		x => { };
		(x, y) => { };
	

Spread operator

• Not well supported at the moment

		function apple(a, b) {
		    for (var i = 0; i < arguments.length; i++) {
		        console.log(arguments[i]);
		    }
		}


		apple('eins', 'zwei', 'drei');


		function banana(a, b, ...c) {
		    c.forEach(function(element) {
		        console.log(element);
		    });
		}

		banana('eins', 'zwei', 'drei');
	

Default parameter values

• Not well supported at the moment

		function tomato(a, b, c = 'three') {
		    console.log(a, b, c);
		}

		tomato('one', 'two'); // one, two, three
	

Iterators

• Not well spoorted at the moment

		var bands = ['Metallica', 'Queen', 'The Police', 'The Beatles'];

		var iterator = bands.values();
		iterator.next();
	

Generators

		function* counter() {
		    yield 1;
		    yield 2;
		}

		var someCounter = counter();
		var result = someCounter.next();

		console.log(result); // { value: 1, done: false }

		result = someCounter.next();

		console.log(result); // { value: 2, done: false }

		result = someCounter.next();

		console.log(result); // { value: undefined, done: true }
	

Modules

		export function say() {
			   return 'hello world';
		}
	

		import {say} from 'export';

		console.log(say());
	

Classes

		class Person {
		    constructor(firstname, lastname) {
		        this.firstname = firstname;
		        this.lastname = lastname;
		    }

		    toString() {
		        return this.firstname + ' ' + this.lastname;
		    }
		}

		var max = new Person('Max', 'Schmidt');

		console.log(max.toString()); // Max Schmidt
	

Classes

		class Employee extends Person {
		    constructor(firstname, lastname, id) {
		        super(fristname, lastname);
		        this.id = id;
		    }

		    toString() {
		        return this.id + ': ' + this.firstname + ' ' + this.lastname;
		    }
		}

		var anton = new Employee('Anton', 'Mayer', 1);

		console.log(anton.toString()); // 1: Anton Mayer
	

NodeJS

Facts

• JavaScript for the server
• V8 by Google, written in C
• Non blocking I/O
  • JavaScript Event-Loop
• Event-driven
• Single-Thread (actually)
• nodejs.org
• Linux, MacOS, Windows, SunOS, ARM
  • 32bit & 64bit
  • ARM6, ARM7, ARM8
• As of late 4.0.0, before 0.x.y
• Long Term Support (LTS)

NPM

• Node Package Manager
• ~183.000 Module at npmjs.com
• package.json describes the project
• Able to load libraries on demand
• Private NPM!

Documentation and API

• API
• NodeJS and ECMAScript 6

ExpressJS

"Fast, unopinionated, minimalist web framework for Node.js"

Questions?