Create web component util

core/static/webpack/easymde-index.ts

@@ -1,6 +1,7 @@
 // biome-ignore lint/correctness/noUndeclaredDependencies: shipped by easymde
 import "codemirror/lib/codemirror.css";
 import "easymde/src/css/easymde.css";
+import { InheritedComponent } from "#core:utils/web-components";
 // biome-ignore lint/correctness/noUndeclaredDependencies: Imported by EasyMDE
 import type CodeMirror from "codemirror";
 // biome-ignore lint/style/useNamingConvention: This is how they called their namespace
@@ -182,23 +183,10 @@ const loadEasyMde = (textarea: HTMLTextAreaElement) => {
   }
 };
 
-class MarkdownInput extends HTMLElement {
-  widget: HTMLTextAreaElement;
-
+class MarkdownInput extends InheritedComponent<"textarea"> {
   constructor() {
-    super();
-    this.widget = document.createElement("textarea");
+    super("textarea");
 
-    const attributes: Attr[] = []; // We need to make a copy to delete while iterating
-    for (const attr of this.attributes) {
-      attributes.push(attr);
-    }
-
-    for (const attr of attributes) {
-      this.removeAttributeNode(attr);
-      this.widget.setAttributeNode(attr);
-    }
-    this.appendChild(this.widget);
     window.addEventListener("DOMContentLoaded", () => loadEasyMde(this.widget));
   }
 }

core/static/webpack/utils/web-components.ts

@@ -0,0 +1,31 @@
+/**
+ * Safari doesn't support inheriting from HTML tags on web components
+ * The technique is to:
+ *  create a new web component
+ *  create the desired type inside
+ *  pass all attributes to the child component
+ *  store is at as a widget inside the parent
+ *
+ * To use this, you must use the tag name twice, once for creating the class
+ * and the second time while calling super to pass it to the constructor
+ **/
+export class InheritedComponent<
+  K extends keyof HTMLElementTagNameMap,
+> extends HTMLElement {
+  widget: HTMLElementTagNameMap[K];
+
+  constructor(tagName: K) {
+    super();
+    this.widget = document.createElement(tagName);
+    const attributes: Attr[] = []; // We need to make a copy to delete while iterating
+    for (const attr of this.attributes) {
+      attributes.push(attr);
+    }
+
+    for (const attr of attributes) {
+      this.removeAttributeNode(attr);
+      this.widget.setAttributeNode(attr);
+    }
+    this.appendChild(this.widget);
+  }
+}