clarify attribute change example

Sascha Schulz

2024-02-05 904d9655997b1cb46bb8044843465c8045092af8

 index.html

@@ -3451,6 +3451,235 @@
                  <p>Implementiere einen drehenden Würfel (Vorlage "templates/008-css/css-3d-cube.html")</p>
               </section>
            </section>
            <section>
               <section>
                  <h2>Web Components</h2>
               </section>
               <section>
                  <p>Was sind Web Components?</p>
                  <img data-src="/assets/images/web-components.svg">
               </section>
               <section>
                  <p>Vorteile</p>
                  <ul>
                     <li>Entwicklung eigener HTML-Elemente, welche sich nahtlos neben nativen Elementen nutzen lassen</li>
                     <li>Hohe Wiederverwendbarkeit in mehreren Projekten</li>
                     <li>Keine Libraries oder Frameworks notwendig, um eigene Elemente zu entwickeln</li>
                     <li>Kapselung des Scopes sowohl von JS (Variablen...) als auch CSS (id, class...)</li>
                  </ul>
               </section>
               <section>
                  <h3>Ansätze in der Vergangenheit und Alternativen heute</h3>
               </section>
               <section>
                  <h4>jQuery</h4>
                  <a href="https://api.jqueryui.com/accordion/#entry-examples" target="_blank">https://api.jqueryui.com/accordion/#entry-examples</a>
               </section>
               <section>
                  <pre>
                     <code class="html" data-trim data-line-numbers>
                        <script type="text/template">
                           <div id="accordion" class="ui-accordion ui-widget ui-helper-reset" role="tablist">
                              <h3 class="ui-accordion-header ui-corner-top ui-state-default ui-accordion-icons ui-accordion-header-active ui-state-active" role="tab" id="ui-id-1" aria-controls="ui-id-2" aria-selected="true" aria-expanded="true" tabindex="0">
                                 <span class="ui-accordion-header-icon ui-icon ui-icon-triangle-1-s"></span>Section 1</h3>
                              <div class="ui-accordion-content ui-corner-bottom ui-helper-reset ui-widget-content ui-accordion-content-active" id="ui-id-2" aria-labelledby="ui-id-1" role="tabpanel" aria-hidden="false" style="display: block; height: 166.8px;">
                                 <p>Mauris mauris ante, blandit et, ultrices a, suscipit eget.
                                    Integer ut neque. Vivamus nisi metus, molestie vel, gravida in,
                                    condimentum sit amet, nunc. Nam a nibh. Donec suscipit eros.
                                    Nam mi. Proin viverra leo ut odio.</p>
                              </div>
                              <h3 class="ui-accordion-header ui-corner-top ui-state-default ui-accordion-icons ui-accordion-header-collapsed ui-corner-all" role="tab" id="ui-id-3" aria-controls="ui-id-4" aria-selected="false" aria-expanded="false" tabindex="-1"><span class="ui-accordion-header-icon ui-icon ui-icon-triangle-1-e"></span>Section 2</h3>
                              <div class="ui-accordion-content ui-corner-bottom ui-helper-reset ui-widget-content" id="ui-id-4" aria-labelledby="ui-id-3" role="tabpanel" aria-hidden="true" style="display: none; height: 166.8px;">
                                 <p>Sed non urna. Phasellus eu ligula. Vestibulum sit amet purus.
                                    Vivamus hendrerit, dolor aliquet laoreet, mauris turpis velit,
                                    faucibus interdum tellus libero ac justo.</p>
                              </div>
                              <h3 class="ui-accordion-header ui-corner-top ui-state-default ui-accordion-icons ui-accordion-header-collapsed ui-corner-all" role="tab" id="ui-id-5" aria-controls="ui-id-6" aria-selected="false" aria-expanded="false" tabindex="-1"><span class="ui-accordion-header-icon ui-icon ui-icon-triangle-1-e"></span>Section 3</h3>
                              <div class="ui-accordion-content ui-corner-bottom ui-helper-reset ui-widget-content" id="ui-id-6" aria-labelledby="ui-id-5" role="tabpanel" aria-hidden="true" style="display: none; height: 166.8px;">
                                 <p>Nam enim risus, molestie et, porta ac, aliquam ac, risus.
                                    Quisque lobortis.Phasellus pellentesque purus in massa.</p>
                                 <ul>
                                    <li>List item one</li>
                                    <li>List item two</li>
                                    <li>List item three</li>
                                 </ul>
                              </div>
                           </div>
                        </script>
                     </code>
                  </pre>
               </section>
               <section>
                  <h4>angular</h4>
                  <img data-src="/assets/images/web-components-angular.png">
               </section>
               <section>
                  <pre>
                     <code class="html" data-trim data-line-numbers>
                        <script type="text/template">
                           <app-root _nghost-ng-c3715250071="" ng-version="17.0.0"><app-top-bar _ngcontent-ng-c3715250071="" _nghost-ng-c3918259376=""><a _ngcontent-ng-c3918259376="" routerlink="/" ng-reflect-router-link="/" href="/"><h1 _ngcontent-ng-c3918259376="">My Store</h1></a><a _ngcontent-ng-c3918259376="" routerlink="/cart" class="button fancy-button" ng-reflect-router-link="/cart" href="/cart"><em _ngcontent-ng-c3918259376="" class="material-icons">shopping_cart</em>Checkout
                              </a></app-top-bar><div _ngcontent-ng-c3715250071="" class="container"><router-outlet _ngcontent-ng-c3715250071=""></router-outlet><app-product-list _nghost-ng-c2837874410=""><h2 _ngcontent-ng-c2837874410="">Products</h2><div _ngcontent-ng-c2837874410=""><h3 _ngcontent-ng-c2837874410=""><a _ngcontent-ng-c2837874410="" title="Phone XL details" ng-reflect-router-link="/products,1" href="/products/1"> Phone XL </a></h3><p _ngcontent-ng-c2837874410=""> Description: A large phone with one of the best screens </p><!--bindings={
                                "ng-reflect-ng-if": "A large phone with one of the "
                              }--><button _ngcontent-ng-c2837874410="" type="button"> Share </button><app-product-alerts _ngcontent-ng-c2837874410="" _nghost-ng-c869072018="" ng-reflect-product="[object Object]"><p _ngcontent-ng-c869072018=""><button _ngcontent-ng-c869072018="" type="button">Notify Me</button></p><!--bindings={
                                "ng-reflect-ng-if": "true"
                              }--></app-product-alerts></div><div _ngcontent-ng-c2837874410=""><h3 _ngcontent-ng-c2837874410=""><a _ngcontent-ng-c2837874410="" title="Phone Mini details" ng-reflect-router-link="/products,2" href="/products/2"> Phone Mini </a></h3><p _ngcontent-ng-c2837874410=""> Description: A great phone with one of the best cameras </p><!--bindings={
                                "ng-reflect-ng-if": "A great phone with one of the "
                              }--><button _ngcontent-ng-c2837874410="" type="button"> Share </button><app-product-alerts _ngcontent-ng-c2837874410="" _nghost-ng-c869072018="" ng-reflect-product="[object Object]"><!--bindings={
                                "ng-reflect-ng-if": "false"
                              }--></app-product-alerts></div><div _ngcontent-ng-c2837874410=""><h3 _ngcontent-ng-c2837874410=""><a _ngcontent-ng-c2837874410="" title="Phone Standard details" ng-reflect-router-link="/products,3" href="/products/3"> Phone Standard </a></h3><!--bindings={
                                "ng-reflect-ng-if": ""
                              }--><button _ngcontent-ng-c2837874410="" type="button"> Share </button><app-product-alerts _ngcontent-ng-c2837874410="" _nghost-ng-c869072018="" ng-reflect-product="[object Object]"><!--bindings={
                                "ng-reflect-ng-if": "false"
                              }--></app-product-alerts></div><!--bindings={
                                "ng-reflect-ng-for-of": "[object Object],[object Object"
                              }--></app-product-list><!--container--></div>
                           </app-root>
                        </script>
                     </code>
                  </pre>
               </section>
               <section>
                  <h3>Aufbau einer Web Component</h3>
                  <pre>
                     <code class="html" data-trim data-line-numbers>
                        <script type="text/template">
                           <!--
                              Hinweis: Der Name bzw. der Selektor muss immer einen Bindestrich enthalten,
                              damit keine Namens-Kollisionen mit nativen HTML-Tags entstehen können
                           -->
                           <hello-world></hello-world>
                        </script>
                     </code>
                  </pre>
               </section>
               <section>
                  <pre>
                     <code class="js" data-trim data-line-numbers="1-16|19">
                        <script type="text/template">
                           class HelloWorldComponent extends HTMLElement {
                              constructor() {
                                 super();
									
                                 const shadowRoot = this.attachShadow({mode: "open"});
										
                                 shadowRoot.innerHTML = `
                                    <style>
                                       div {
                                          background-color: coral;
                                          color: white;
                                       }
                                    </style>
                                    <div>Hello World!</div>
                                 `;
                              }
                           }
									
                           window.customElements.define("hello-world", HelloWorldComponent);
                        </script>
                     </code>
                  </pre>
               </section>
               <section>
                  <iframe data-src="/assets/html/hello-world.html"></iframe>
               </section>
               <section>
                  <h4>Light DOM vs Shadow DOM</h4>
                  <img data-src="/assets/images/web-components-shadow-root.png" width="500px">
               </section>
               <section>
                  <h4>Suche von Elementen im Light- und Shadow DOM</h4>
                  <pre>
                     <code class="js" data-trim data-line-numbers>
                        <script type="text/template">
                           // Light DOM
                           const span = document.querySelector("span"); // Hi!
                           const divs = document.querySelectorAll("div");
									
                           console.log(divs.length); // => 1
									
                           // Shadow DOM
                           const helloWorld = document.querySelector("hello-world");
									
                           helloWorld.shadowRoot.querySelector("div"); // Hello World!
                        </script>
                     </code>
                  </pre>
               </section>
               <section>
                  <h3>Auf Attribute reagieren</h3>
                  <pre>
                     <code class=html data-trim data-line-numbers>
                        <script type="text/template">
                           <hello-world my-attribute="a"></hello-world>
                        </script>
                     </code>
                  </pre>
                  <pre>
                     <code class="js" data-trim data-line-numbers="2|8-10">
                        <script type="text/template">
                           class HelloWorldComponent extends HTMLElement {
                              static observedAttributes = ["my-attribute"];
									
                              constructor() {
                                 // ...
                              }
									
                              attributeChangedCallback(name, oldValue, newValue) {
                                 console.log(`${name}: changed from ${oldValue} to ${newValue}`);
                              }
                           }
                        </script>
                     </code>
                  </pre>
               </section>
               <section>
                  <h3>Aufgabe</h3>
                  <p>Lasse die eigene Komponente "hello-sayer" auf eine Änderung des "name"-Attributs reagieren, indem der dort eingetragene Name in der Komponente angezeigt wird (Beispiel: name="Joe" => Hello Joe!)</p>
                  <p>(/examples/templates/web-components/hello-sayer.html)</p>
               </section>
               <section>
                  <h3>Musterlösung</h3>
                  <pre>
                     <code class="js" data-trim data-line-numbers>
                        <script type="text/template">
                           class HelloSayerComponent extends HTMLElement {
                              static observedAttributes = ["name"];
									
                              constructor() {
                                 super();
									
                                 this.root = this.attachShadow({mode: "open"});
									
                                 this.root.innerHTML = `
                                    <style>
                                       div {
                                          background-color: coral;
                                          color: white;
                                       }
                                    </style>
                                    <div>Hello!</div>
                                 `;
                              }
									
                              attributeChangedCallback(name, oldValue, newValue) {
                                 this.root.querySelector("div").innerHTML = `Hello ${newValue}!`;
                              }
                           }
									
                           window.customElements.define("hello-sayer", HelloSayerComponent);
									
                           const names = ["Joe", "Allie"];
                           let counter = 0;
									
                           setInterval(() => document.querySelector("hello-sayer").setAttribute("name", names[counter++ % 2]), 2000);
                        </script>
                     </code>
                  </pre>
               </section>
               <section>
                  <iframe data-src="/assets/html/hello-sayer.html"></iframe>
               </section>
            </section>
         </div>
      </div>