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                <paragraph-component data-title="Intro aux Web Components">Contenu de mon paragraphe!</paragraph-component>




                let tmpl = document.createElement('template');
// Nous ajoutons le title dans le template
tmpl.innerHTML = `
  :host div {
      border: 1px solid black;
  :host span {
        text-align: center;
        font-size: 3em;
    <span id="title"></span>

class ParagraphComponent extends HTMLElement {
    static get observedAttributes() {
        // On indique de recevoir une notification quand l'attribut data-title change de valeur
        return ['data-title'];
    constructor() {
        // Dans le constructeur, on ne fait qu'indiquer d'utiliser shadow DOM
        // On ne gère pas encore le rendu 
        this.root = this.attachShadow({
            mode: 'open'

    // Getter pour récupérer l'attribut data-title
    get title() {
        return this.getAttribute('data-title');

    // On génère le rendu dès que notre balise est ajoutée au DOM
    connectedCallback() {

    // On met à jour le rendu quand le title change
    attributeChangedCallback(attrName, oldVal, newVal) {

    // Méthode qui génère le rendu
    render() {
        // Clone le template
        const content = tmpl.content.cloneNode(true);
        // Ajoute le title
        const title = content.getElementById("title");
        title.textContent = this.title;
        // On re-initialise le contenu de notre balise (plusieurs appels à render)
        while (this.root.firstChild) this.root.removeChild(this.root.firstChild);


window.customElements.define('paragraph-component', ParagraphComponent);