From 482a095e1eb9ffd81d6c34d376ce1562ccb73575 Mon Sep 17 00:00:00 2001
From: Sascha Schulz <sschulz@dh-software.de>
Date: Mo, 17 Jul 2023 10:36:37 +0200
Subject: [PATCH] Merge branch 'draft'
---
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1 files changed, 479 insertions(+), 0 deletions(-)
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@@ -2125,6 +2125,485 @@
</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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