From 1c6b3cc59a56eb28441bf4317e4728c0da5ed64b Mon Sep 17 00:00:00 2001
From: Sascha Schulz <sschulz@dh-software.de>
Date: Di, 20 Jun 2023 16:16:41 +0200
Subject: [PATCH] add this, arrow functions, generators and array helpers
---
index.html | 261 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 261 insertions(+), 0 deletions(-)
diff --git a/index.html b/index.html
index 92d3368..4bc8327 100644
--- a/index.html
+++ b/index.html
@@ -2125,6 +2125,267 @@
</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>
</div>
</div>
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