From 806078cabd7275994dbc4e8eb772ed4663159eb6 Mon Sep 17 00:00:00 2001
From: Sascha Schulz <sschulz@dh-software.de>
Date: Di, 04 Jul 2023 16:09:22 +0200
Subject: [PATCH] add dom events
---
index.html | 1710 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 1.710 insertions(+), 0 deletions(-)
diff --git a/index.html b/index.html
index 9bc8568..d31dd79 100644
--- a/index.html
+++ b/index.html
@@ -895,6 +895,1716 @@
</pre>
</section>
</section>
+ <section>
+ <section>
+ <h2>JavaScript</h2>
+ </section>
+ <section>
+ <style>
+ table.my-table td:not(:first-child) {
+ text-align: center;
+ }
+
+ table.my-table td:not(:last-child), table.my-table th:not(:last-child) {
+ border-right: 1px solid white;
+ }
+
+ table.my-table td {
+ vertical-align: middle;
+ }
+ </style>
+ <table class="my-table">
+ <tr>
+ <th></th>
+ <th>c / c++</th>
+ <th>Java</th>
+ <th>C#</th>
+ <th>JS</th>
+ </tr>
+ <tr>
+ <td>Formale Spezifikation</td>
+ <td colspan="4" class="fragment">ja</td>
+ </tr>
+ <tr>
+ <td>Ãœbersetzung</td>
+ <td class="fragment">Nativ kompiliert</td>
+ <td class="fragment" colspan="2">Bytecode</td>
+ <td class="fragment">Interpretiert / kompiliert (JIT)</td>
+ </tr>
+ <tr>
+ <td>Typisierung</td>
+ <td colspan="3" class="fragment">statisch</td>
+ <td class="fragment">dynamisch</td>
+ </tr>
+ <tr>
+ <td>Speicher-Management</td>
+ <td class="fragment">Manuell</td>
+ <td class="fragment" colspan="3">Garbage Collector</td>
+ </tr>
+ </table>
+ </section>
+ <section>
+ <h3>Begrifflichkeiten</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function add(x, y) {
+ return x + y;
+ }
+
+ const a = 5;
+ const b = add(a, 6);
+ const c = [];
+ </code>
+ </pre>
+ <div><span class="fragment">Operator, </span><span class="fragment">Aufruf (Call), </span><span class="fragment">Ausdruck (Expression), </span><span class="fragment">Parameter, </span><span class="fragment">Argument, </span><span class="fragment">Literal, </span></div><div><span class="fragment">Zuweisung (Assignment), </span><span class="fragment">Linke Hand (Left hand), Rechte Hand (Right hand)</span></div>
+ </section>
+ <section>
+ <h3>Vorbereiten der Beispiele (bei Bedarf)</h3>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ # im Ordner 'examples/'
+ . hooks/post-checkout
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Ausführung</h3>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ # node [Script-Datei], z.B.
+ node index.js
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Ausgaben</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ console.log("Hello World!");
+ </code>
+ </pre>
+ </section>
+
+ <section>
+ <h3>Variablen</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ // < es6
+ var x = 1;
+
+ // >= es6
+ let y = 2;
+ const z = 3;
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ var yes = false;
+
+ if (yes) {
+ var a = 1;
+ }
+
+ console.log(a);
+ </code>
+ </pre>
+ <pre class="fragment">
+ <code class="bash" data-trim data-line-numbers>
+ undefined
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ var yes = false;
+
+ if (yes) {
+ let a = 1;
+ }
+
+ console.log(a);
+ </code>
+ </pre>
+ <pre class="fragment">
+ <code class="bash" data-trim data-line-numbers>
+ ReferenceError: a is not defined
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function foo() {
+ var yes = false;
+
+ if (yes) {
+ var a = 1;
+ }
+ }
+
+ foo();
+
+ console.log(a);
+ </code>
+ </pre>
+ <pre class="fragment">
+ <code class="bash" data-trim data-line-numbers>
+ ReferenceError: a is not defined
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3><code>var</code></h3>
+ <ul>
+ <li>hat <code>function</code>-Scope</li>
+ <li>wird durch <span class="italic">hoisting</span> ("hochziehen") aus dem Block heraus an den Start der Funktion gezogen</li>
+ </ul>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ var yes = false;
+ var a;
+
+ if (yes) {
+ a = 1;
+ }
+
+ console.log(a);
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3><code>let</code>, <code>const</code></h3>
+ <ul>
+ <li>haben intuitiven Block-Scope (wie viele andere Programmiersprachen auch)</li>
+ <li>daher nur an Ort und Stelle gültig in der angegebenen Reihenfolge</li>
+ </ul>
+ </section>
+ <section>
+ <h3>Datentypen</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ let x = 5; // Number (Integer)
+ let f = 1.25; // Number (Float)
+ let b = true; // Boolean
+ let s = "hallo"; // String
+ let a = []; // Array
+ let o = {}; // Objekt
+ let nan = NaN; // Not a Number
+ let n = null; // Null
+ let u = undefined; // Undefiniert
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Alternation</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ if (x == 1) {
+ // Code
+ }
+ else if (x == 2) {
+ // alternativer Code
+ }
+ else {
+ // Fallback
+ }
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Schleifen</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ for (let i = 0; i < 5; i++) {
+ // Code
+ }
+ </code>
+ </pre>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const a = [1, 2, 3];
+
+ for (const element of a) {
+ // Code
+ }
+ </code>
+ </pre>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ while (i == 1) {
+ // Code
+ }
+ </code>
+ </pre>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ do {
+ // Code
+ } while (i == 1)
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Arrays</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ let a = [1, 2, 3];
+
+ a.push(4);
+ a.push(5);
+
+ a.pop();
+
+ console.log(a);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ [1, 2, 3, 4]
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Objekte</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ let o = {x: 1, y: 2};
+
+ console.log(o.z);
+
+ console.log(o);
+
+ o.z = 3;
+
+ console.log(o);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ undefined
+ { x: 1, y: 2 }
+ { x: 1, y: 2, z: 3 }
+ </code>
+ </pre>
+ </section>
+ <section>
+ <div>Objekte funktionieren intern wie Hash-Maps</div>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ let o = {};
+
+ o.a = 1;
+ o["a"] = 1; // alternativ
+
+ o["$ !"] = 2; // so sind auch komplexe Schlüssel möglich
+
+ // o."$ !" = 2; => Syntaxfehler
+ // o.$ ! = 2; => Syntaxfehler
+
+ o[true] = 3;
+
+ console.log(Object.keys(o));
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ [ 'a', '$ !', 'true' ]
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Funktionen</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function foo() {
+ console.log("foo");
+ }
+
+ function bar(a) {
+ return a;
+ }
+
+ foo();
+
+ const a = bar(1);
+
+ console.log(a);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ foo
+ 1
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ let sum = function(a, b) {
+ return a + b;
+ }
+
+ let subtract = function() {
+ console.log(arguments);
+
+ return arguments[0] - arguments[1];
+ }
+
+ console.log(sum(1, 2));
+ console.log(subtract(1, 2));
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 3
+ [Arguments] { '0': 1, '1': 2 }
+ -1
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Funktionen als Konstruktor</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function Rectangle(a, b) {
+ this.a = a;
+ this.b = b;
+ }
+
+ const r = new Rectangle(2, 3);
+
+ console.log(r.a);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 2
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Objektorientierung</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function Rectangle(a, b) {
+ this.a = a;
+ this.b = b;
+ }
+
+ // jede Funktion besitzt einen Prototypen
+ Rectangle.prototype.getArea = function() {
+ return this.a * this.b;
+ }
+
+ const r1 = new Rectangle(2, 3);
+ const r2 = new Rectangle(4, 5);
+
+ console.log(r1.getArea());
+ console.log(r2.getArea());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 6
+ 20
+ </code>
+ </pre>
+ </section>
+ <section>
+ <img data-src="/assets/images/constructor-and-its-prototype.svg">
+ </section>
+ <section>
+ <div>Dynamische Änderung des Prototypen</div>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function Rectangle(a, b) {
+ this.a = a;
+ this.b = b;
+ }
+
+ const r = new Rectangle(2, 3);
+
+ console.log(r.getArea);
+
+ Rectangle.prototype.getArea = function() {
+ return this.a * this.b;
+ }
+
+ console.log(r.getArea);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ undefined
+ [Function (anonymous)]
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Aufgabe</h3>
+ Bringe dem Array eine Methode bei, welche die Summe aller enthaltenen Zahlen zurückgibt
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const a = [1, 2, 3];
+
+ console.log(a.sum());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 6
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Lösung</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ Array.prototype.sum = function() {
+ let sum = 0;
+
+ for (let number of this) {
+ sum += number;
+ }
+
+ return sum;
+ }
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Vererbung</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers="1-13|15-18|20-29">
+ // Oberklasse
+ function Shape() {
+ }
+
+ Shape.prototype.getType = function() {
+ return "Shape";
+ }
+
+ // Unterklasse
+ function Rectangle(a, b) {
+ this.a = a;
+ this.b = b;
+ }
+
+ // Prototype der Oberklasse in die Unterklasse kopieren
+ Rectangle.prototype = Object.create(Shape.prototype);
+ // Konstruktor der Oberklasse am Prototypen durch den eigenen ersetzen
+ Rectangle.prototype.constructor = Rectangle;
+
+ const r = new Rectangle(2, 3);
+
+ console.log(r.getType());
+
+ // .getType() selber implementieren
+ Rectangle.prototype.getType = function() {
+ return "Rectangle";
+ }
+
+ console.log(r.getType());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Shape
+ Rectangle
+ </code>
+ </pre>
+ </section>
+ <section>
+ <img data-src="/assets/images/inheritance-es5.svg">
+ </section>
+ <section>
+ <div>
+ <img width="800" height="500" data-src="/assets/images/mdn-prototype.jpg">
+ </div>
+ <p>
+ <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push" style="font-size: 16px">https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push</a>
+ </p>
+ </section>
+ <section>
+ <h3>Objektorientierung in es6</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ class Rectangle {
+ constructor(a, b) {
+ this.a = a;
+ this.b = b;
+ }
+
+ getArea() {
+ return this.a * this.b;
+ }
+ }
+
+ const r = new Rectangle(2, 3);
+
+ console.log(r.getArea());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 6
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Vererbung in es6</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers="1-6|8-16|18-27">
+ // Oberklasse
+ class Shape {
+ getType() {
+ return "Shape";
+ }
+ }
+
+ // Unterklasse erbt von Oberklasse
+ class Rectangle extends Shape {
+ constructor(a, b) {
+ super();
+
+ this.a = a;
+ this.b = b;
+ }
+ }
+
+ const r = new Rectangle(2, 3);
+
+ console.log(r.getType());
+
+ // Implementierung per Prototype weiterhin möglich, falls man so will
+ Rectangle.prototype.getType = function() {
+ return "Rectangle";
+ }
+
+ console.log(r.getType());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Shape
+ Rectangle
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Asynchronität</h3>
+ <p>Asynchron: Es wird nicht auf die Beendigung des Befehls gewartet, sondern mit dem Programm fortgefahren. Die Vollendung des asynchronen Befehls tritt <i style="font-style: italic">irgendwann</i> in der Zukunft ein.</p>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ setTimeout(callback, time); // Ausführung nach [time] Millisekunden
+ setInterval(callback, interval); // Ausführung alle [interval] Millisekunden
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ setTimeout(function() {
+ // Code, der nach 2 Sekunden ausgeführt wird
+ console.log("zweiter");
+ }, 2000);
+
+ console.log("erster");
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ erster
+ zweiter
+ </code>
+ </pre>
+ </section>
+ <section>
+ <p>Aufgabe: Schreibe ein Programm, das zwei weitere beliebige Texte mit jeweils 2 Sekunden Verzögerung von einander ausgibt, d.h.</p>
+ <p>"erster" -> 2s -> "zweiter" -> 2s -> "Text A" -> 2s -> "Text B"</p>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ setTimeout(function() {
+ console.log("zweiter");
+
+ // weiterer Code
+ }, 2000);
+
+ console.log("erster");
+ </code>
+ </pre>
+ </section>
+ <section>
+ Lösung: Callback-Hell oder Pyramide des Todes
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ setTimeout(function() {
+ console.log("zweiter");
+
+ setTimeout(function() {
+ console.log("Text A");
+
+ setTimeout(function() {
+ console.log("Text B");
+
+
+ }, 2000);
+ }, 2000);
+ }, 2000);
+
+ console.log("erster");
+ </code>
+ </pre>
+ </section>
+ <section>
+ Hilfsmittel: Promises
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ new Promise(function (resolve, reject) {
+ // ich bin fertig
+ resolve();
+
+ // es ist ein Fehler aufgetreten
+ reject();
+ });
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const p = new Promise(function (resolve, reject) {...});
+ const p2 = new Promise(function (resolve, reject) {...});
+ const p3 = new Promise(function (resolve, reject) {...});
+ const p4 = new Promise(function (resolve, reject) {...});
+
+ p
+ .then(function() { return p2; })
+ .then(function() { return p3; })
+ .then(function() { return p4; });
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ console.log("erster");
+
+ delay(2000)
+ .then(function () {
+ console.log("zweiter");
+
+ return delay(2000);
+ })
+ .then(function() {
+ console.log("Text A");
+
+ return delay(2000);
+ })
+ .then(function() {
+ console.log("Text B");
+ })
+ </code>
+ </pre>
+ </section>
+ <section>
+ Aufgabe: Implementiere die Funktion "delay"
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const delay = function() {
+ // implementieren
+ }
+
+ console.log("erster");
+
+ delay(2000)
+ .then(function () {
+ console.log("zweiter");
+
+ return delay(2000);
+ })
+ .then(function() {
+ console.log("Text A");
+
+ return delay(2000);
+ })
+ .then(function() {
+ console.log("Text B");
+ })
+ </code>
+ </pre>
+ </section>
+ <section>
+ Lösung:
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const delay = function(ms) {
+ return new Promise(function(resolve, reject) {
+ setTimeout(function() {
+ resolve();
+ }, ms);
+ });
+ }
+
+ console.log("erster");
+
+ delay(2000)
+ .then(function () {
+ console.log("zweiter");
+
+ return delay(2000);
+ })
+ .then(function() {
+ console.log("Text A");
+
+ return delay(2000);
+ })
+ .then(function() {
+ console.log("Text B");
+ })
+ </code>
+ </pre>
+ </section>
+ <section>
+ Rückgabewerte mit Promises
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const p = new Promise(function(resolve, reject) {
+ resolve("ok");
+ });
+
+ p.then(function(value) {
+ console.log(value);
+ });
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ ok
+ </code>
+ </pre>
+ </section>
+ <section>
+ Fehlerbehandlung mit Promises
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const p = new Promise(function(resolve, reject) {
+ reject(new Error("Fehler"));
+ });
+
+ p
+ .then(function() {
+ console.log("Ich werde nicht aufgerufen")
+ })
+ .catch(function(e) {
+ console.log(e.message);
+ });
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Fehler
+ </code>
+ </pre>
+ </section>
+ <section>
+ Datei lesen mit NodeJS
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const fs = require("fs");
+
+ fs.readFile("./hello.txt", {encoding: "utf8"}, function(error, data) {
+ console.log(data);
+ });
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Hello World!
+ </code>
+ </pre>
+ </section>
+ <section>
+ Aufgabe: "Promisifiziere" analog zu "delay" in der letzten Aufgabe den Aufruf von fs.readFile()
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const fs = require("fs");
+
+ function readFile() {
+ // implementieren
+ }
+
+ readFile("./hello.txt").then(function(content) {
+ console.log(content);
+ });
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Hello World!
+ </code>
+ </pre>
+ </section>
+ <section>
+ Lösung:
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const fs = require("fs");
+
+ function readFile(path) {
+ return new Promise(function (resolve, reject) {
+ fs.readFile(path, {encoding: "utf8"}, function(error, data) {
+ resolve(data);
+ });
+ });
+ }
+
+ readFile("./hello.txt").then(function(content) {
+ console.log(content);
+ });
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Hello World!
+ </code>
+ </pre>
+ </section>
+ <section>
+ Aufgabe: Nutze die vorherige Lösung nun für eine Promise-Kette, sodass die Inhalte der zwei Dateien "hello.txt" und "hallo.txt" nacheinander ausgegeben werden:
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Hello World!
+
+ Hallo Welt!
+
+ </code>
+ </pre>
+ </section>
+ <section>
+ Lösung:
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const fs = require("fs");
+
+ function readFile(path) {
+ return new Promise(function (resolve, reject) {
+ fs.readFile(path, {encoding: "utf8"}, function(error, data) {
+ resolve(data);
+ });
+ });
+ }
+
+ readFile("./hello.txt")
+ .then(function(content) {
+ console.log(content);
+
+ return readFile("./hallo.txt");
+ })
+ .then(function(content) {
+ console.log(content);
+ });
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Hello World!
+
+ Hallo Welt!
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Async - Await</h3>
+ <ul>
+ <li>Syntaktischer Zucker für Promises</li>
+ <li>Nutzung von <code>await</code> nur im Kontext einer <code>async</code>-Funktion möglich</li>
+ </ul>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ async function wrapper() {
+ const p = new Promise(function(resolve, reject) {
+ resolve("Hello from Promise!");
+ });
+
+ const result = await p;
+
+ console.log(result);
+ }
+
+ wrapper();
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Hello from Promise!
+ </code>
+ </pre>
+ </section>
+ <section>
+ Aufgabe: Schreibe die Lösung der vorherigen Aufgabe nach Async - Await um
+ </section>
+ <section>
+ Lösung:
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const fs = require("fs");
+
+ function readFile(path) {
+ return new Promise(function (resolve, reject) {
+ fs.readFile(path, {encoding: "utf8"}, function(error, data) {
+ resolve(data);
+ });
+ });
+ }
+
+ async function wrapper() {
+ const content1 = await readFile("./hello.txt");
+ const content2 = await readFile("./hallo.txt");
+
+ console.log(content1);
+ console.log(content2);
+ }
+
+ wrapper();
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ Hello World!
+
+ Hallo Welt!
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Destructuring</h3>
+ <p>Auflösen von komplexen Strukturen</p>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ // Objekt destrukturieren (per Attribut-Namen)
+ const { a, b } = { a: 1, b: 2 };
+
+ console.log(a);
+ console.log(b);
+
+ // Array destrukturieren (per Position)
+ const [ c, d ] = [3, 4];
+
+ console.log(c);
+ console.log(d);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 1
+ 2
+ 3
+ 4
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ // Bei Objekten Elemente umbenennen oder auch auslassen
+ const { a: x, b: y } = { a: 1, b: 2, c: 3 };
+
+ console.log(x);
+ console.log(y);
+
+ // Bei Arrays Elemente auslassen
+ const [ , a, b, , c] = [3, 4, 5, 6, 7, 8];
+
+ console.log(a);
+ console.log(b);
+ console.log(c);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 1
+ 2
+ 4
+ 5
+ 7
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ // Verschachteltes Destructuring
+ const {a: [, x, ] } = { a: [0, 1, 2]};
+
+ console.log(x);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 1
+ </code>
+ </pre>
+ </section>
+ <section>
+ Aufgabe: x soll die 5 enthalten
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const o = { a: [0, {b: [0, 5]}, 2]};
+
+ const { /* Destructuring-Ausdruck */ } = o;
+
+ console.log(x);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 5
+ </code>
+ </pre>
+ </section>
+ <section>
+ Lösung:
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const o = { a: [0, { b: [0, 5] }, 2]};
+
+ const { a: [, { b: [, x] }]} = o;
+
+ console.log(x);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 5
+ </code>
+ </pre>
+ </section>
+ <section>
+ Aufgabe: x soll die 3 enthalten
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const o = { a: [0, {b: [0, { c: [{ x: 5 }, { d: 3}] }]}, 2]};
+
+ const { /* Destructuring-Ausdruck */ } = o;
+
+ console.log(x);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 3
+ </code>
+ </pre>
+ </section>
+ <section>
+ Lösung:
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const o = { a: [0, {b: [0, { c: [{ x: 5 }, { d: 3}] }]}, 2]};
+
+ const { a: [, {b: [, { c: [, { d: x}] }] }] } = o;
+
+ console.log(x);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 3
+ </code>
+ </pre>
+ </section>
+ <section>
+ <p>Destructuring zum parallelen Ausführen von mehreren Promises</p>
+ <pre>
+ <code class="js" data-trim data-line-numbers="1-10|11-21">
+ const fs = require("fs");
+
+ function readFile(path) {
+ return new Promise(function (resolve, reject) {
+ fs.readFile(path, {encoding: "utf8"}, function(error, data) {
+ resolve(data);
+ });
+ });
+ }
+
+ async function wrapper() {
+ const [ content1, content2 ] = await Promise.all([
+ readFile("./hello.txt"),
+ readFile("./hallo.txt")
+ ]);
+
+ console.log(content1);
+ console.log(content2);
+ }
+
+ wrapper();
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Try-Catch-Finally</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function throwError() {
+ try {
+ throw new Error("Fehler!");
+ return "Hello World!";
+ }
+ catch (e) {
+ return e.message;
+ }
+ finally {
+ console.log("Finally wird immer ausgeführt");
+ return "Finally!";
+ }
+ }
+
+ const result = throwError();
+ console.log(result);
+ </code>
+ </pre>
+ <pre class="fragment">
+ <code class="bash" data-trim data-line-numbers>
+ Finally wird immer ausgeführt
+ Finally!
+ </code>
+ </pre>
+ </section>
+ <section>
+ <p>Anwendungsbeispiel für Try-Catch-Finally</p>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function readFromDatabase() {
+ try {
+ db.connect();
+ return db.read();
+ }
+ catch (e) {
+ console.log(e.stack);
+ return "";
+ }
+ finally {
+ if (db.open) {
+ db.close();
+ }
+ }
+ }
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Scope</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function a() {
+ const x = 5;
+
+ return function() {
+ return x * x;
+ };
+ }
+
+ const squareX = a();
+ const result = squareX();
+
+ console.log(result);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 25
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>this</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ class MyClass {
+ constructor(a) {
+ this.a = a;
+ }
+
+ getA() {
+ return this.a;
+ }
+ }
+
+ const x = new MyClass(5);
+ const y = new MyClass(10);
+
+ console.log(x.getA());
+ console.log(y.getA());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 5
+ 10
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ global.a = 5;
+
+ function foo() {
+ this.a += 10;
+ }
+
+ foo();
+
+ console.log(a);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 15
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ class MyClass {
+ /* ... */
+ setA() {
+ function f() {
+ this.a += 100;
+ }
+ f();
+ }
+ }
+
+ const x = new MyClass(5);
+
+ x.setA();
+
+ console.log(x.getA());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ TypeError: Cannot read property 'a' of undefined
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ class MyClass {
+ /* ... */
+ setA() {
+ const me = this;
+ function f() {
+ me.a += 100;
+ }
+ f();
+ }
+ }
+
+ const x = new MyClass(5);
+
+ x.setA();
+
+ console.log(x.getA());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 105
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Arrow-Funktionen</h3>
+ <ul>
+ <li>Kompakte Schreibweise einer normalen Funktion</li>
+ <li>Bei Einzeilern ist das <code>return</code> nicht notwendig</li>
+ <li>this-Pointer des aktuellen Kontextes wird beibehalten</li>
+ </ul>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ // Einzeiler
+ const f1 = _ => 1;
+ const f2 = () => 1;
+ const f3 = (x) => x * x;
+ const f4 = (x, y) => x + y;
+
+ // Mehrzeiler
+ const f5 = (x, y) => {
+ return x * y;
+ };
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ class MyClass {
+ /* ... */
+ setA() {
+ const f = () => {
+ this.a += 100;
+ }
+ f();
+ }
+ }
+
+ const x = new MyClass(5);
+
+ x.setA();
+
+ console.log(x.getA());
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 105
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Generator-Funktionen</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function* generator() {
+ let i = 0;
+
+ while(true) {
+ yield i;
+ i++;
+ }
+ }
+
+ const g = generator();
+
+ console.log(g.next().value);
+ console.log(g.next().value);
+ console.log(g.next().value);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 1
+ 2
+ 3
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Generator-Funktionen</h3>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function* generator() {
+ yield 1;
+ yield 2;
+ yield 3;
+ }
+
+ const g = generator();
+
+ for (const i of g) {
+ console.log(i);
+ }
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 1
+ 2
+ 3
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Nützliche Array-Funktionen</h3>
+ </section>
+ <section>
+ Aufgabe: Schreibe ein Programm, das den Gesamtumsatz aus dem ersten Halbjahr berechnet
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const revenues = [
+ {month: 0, revenue: 1000},
+ {month: 1, revenue: 2000},
+ {month: 2, revenue: 3000},
+ {month: 3, revenue: 4000},
+ {month: 4, revenue: 5000},
+ {month: 5, revenue: 6000},
+ {month: 6, revenue: 6000},
+ {month: 7, revenue: 5000},
+ {month: 8, revenue: 4000},
+ {month: 9, revenue: 3000},
+ {month: 10, revenue: 2000},
+ {month: 11, revenue: 1000}
+ ];
+
+ let totalRevenue = 0;
+
+ /* ... */
+
+ console.log(totalRevenue);
+ </code>
+ </pre>
+ </section>
+ <section>
+ Lösung
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ totalRevenue = revenues
+ .filter((revenue) => revenue.month < 6)
+ .map((revenue) => revenue.amount)
+ .reduce((sum, amount) => sum + amount, 0);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ 21000
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+
+ a.filter((e) => e > 2); // Filterung
+ a.map((e) => e * 2); // Umformung
+ a.reduce((p, e) => p + e, 0); // Zusammenrechnung / Reduzierung
+ a.some((e) => e > 5); // true wenn min. ein Element die Bedingung erfüllt
+ a.every((e) => e > 5); // true wenn alle Elemente die Bedingung erfüllen
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Map</h3>
+ <ul>
+ <li>auch als "assoziatives Array" bezeichnet</li>
+ <li>iterierbare Liste</li>
+ <li>ideal zur Assoziation von z.B. Hashes zu Objekt-Instanzen o.ä.</li>
+ <li>nutzbar ab es6 / es2015</li>
+ <li>löst herkömmliche Objekte als Hash-Map ab</li>
+ </ul>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const m = new Map();
+
+ m.set("a", 0);
+ m.set("a", 1);
+ m.set("b", 2);
+
+ m.has("c"); // => false
+
+ m.delete("b");
+
+ console.log(m.get("a")); // => 1
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ m.forEach((k, v) => console.log(k, v)) // => "a" 1 ...
+
+ for (const entry of m.entries()) {
+ console.log(entry); // => ["a", 1] ...
+ }
+
+ for (const key of m.keys()) {
+ console.log(key); // => "a" ...
+ }
+
+ for (const value of m.values()) {
+ console.log(value); // => "1" ...
+ }
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>Set</h3>
+ <ul>
+ <li>enthält nur einzigartige Werte</li>
+ <li>iterierbare Liste</li>
+ <li>ideale Struktur, wenn einzelne Werte einzigartig sein sollen</li>
+ <li>nutzbar ab es6 / es2015</li>
+ <li>löst individuelle Lösungen mittels Arrays und Array.prototype.indexOf o.ä. ab</li>
+ </ul>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ const s = new Set();
+
+ s.add("a");
+ s.add("a");
+
+ s.has("c"); // => false
+
+ s.delete("a");
+
+ console.log(s.size); // => 0
+ </code>
+ </pre>
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ s.forEach((k, v) => console.log(k, v)) // => "a" "a" ...
+
+ for (const entry of m.entries()) {
+ console.log(entry); // => ["a", "a"] ...
+ }
+
+ for (const key of m.keys()) {
+ console.log(key); // => "a"...
+ }
+
+ for (const value of s.values()) {
+ console.log(value); // => "a" ...
+ }
+ </code>
+ </pre>
+ </section>
+ <section>
+ <h3>DOM-Events</h3>
+ <ul>
+ <li>funktionale Ausführung von Code</li>
+ <li>Trigger können Klicks, Scrollen, Tastendrücke, Änderungen der Fenstergröße usw. sein</li>
+ </ul>
+ </section>
+ <section>
+ <img data-src="/assets/images/dom-events.svg">
+ </section>
+ <section>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function doSomething(e) {
+ console.log("capture");
+ }
+
+ function click(e) {
+ console.log("bubble");
+ }
+
+ div.addEventListener("click", doSomething, true);
+
+ button.addEventListener("click", click, false /* default */);
+ </code>
+ </pre>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ capturing
+ bubble
+ </code>
+ </pre>
+ </section>
+ <section>
+ <p>Aufgabe: Erweitere das vorherige Beispiel so, dass das div-Element einen weiteren Click-Handler bekommt,
+ der den Text "bubble2" anzeigt, nachdem "bubble" in der Konsole geloggt wurde.</p>
+
+ <p>Erwartete Ausgabe:</p>
+ <pre>
+ <code class="bash" data-trim data-line-numbers>
+ capturing
+ bubble
+ bubble2
+ </code>
+ </pre>
+ </section>
+ <section>
+ <p>Lösung:</p>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function doSomething(e) {
+ console.log("capture");
+ }
+
+ // neu
+ function doSomething2(e) {
+ console.log("bubble2");
+ }
+
+ function click(e) {
+ console.log("bubble");
+ }
+
+ div.addEventListener("click", doSomething, true);
+ div.addEventListener("click", doSomething2, false); // neu
+
+ button.addEventListener("click", click, false /* default */);
+ </code>
+ </pre>
+ </section>
+ <section>
+ Die Bubble-Phase stoppen
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function click(e) {
+ e.stopPropagation()
+ }
+ </code>
+ </pre>
+ </section>
+ <section>
+ <p>Aufgabe: Ändere das Ergebnis des vorherigen Beispiels, sodass die Bubble-Phase auf Ebene des button-Elements gestoppt wird. Was ändert sich in der Ausgabe?</p>
+ </section>
+ <section>
+ <p>Lösung:</p>
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ function doSomething(e) {
+ console.log("capture");
+ }
+
+ function doSomething2(e) {
+ console.log("bubble2");
+ }
+
+ function click(e) {
+ e.stopPropagation();
+ console.log("bubble");
+ }
+
+ div.addEventListener("click", doSomething, true);
+ div.addEventListener("click", doSomething2, false);
+
+ button.addEventListener("click", click, false /* default */);
+ </code>
+ </pre>
+ </section>
+ <section>
+ Events programatisch triggern:
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ button.dispatchEvent(new Event("click"));
+ </code>
+ </pre>
+ </section>
+ <section>
+ Events sind synchron:
+ <pre>
+ <code class="js" data-trim data-line-numbers>
+ doSomethingElse();
+
+ button.dispatchEvent(new Event("click"));
+
+ doAnotherThing(); // wird erst ausgeführt, wenn zuvor alle Event-Handler fertig sind
+ </code>
+ </pre>
+ </section>
+ </section>
</div>
</div>
--
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