Bug 1995468 - Support URL pasting in markdown editor

js/text-editor.js

@@ -78,6 +78,10 @@ Bugzilla.TextEditor = class TextEditor {
       this.textareaOnInput(event);
     });
 
+    this.$textarea.addEventListener('paste', (/** @type {ClipboardEvent} */ event) => {
+      this.textareaOnPaste(event);
+    });
+
     this.togglePreviewTab();
 
     if (this.useMarkdown) {
@@ -284,6 +288,28 @@ Bugzilla.TextEditor = class TextEditor {
     this.togglePreviewTab();
   }
 
+  /**
+   * Called whenever content is pasted to the `<textarea>`. If the pasted content is a URL and there
+   * is a selection, insert a Markdown link with the URL and the selected text as the label.
+   * @param {ClipboardEvent} event `paste` event.
+   */
+  textareaOnPaste(event) {
+    const data = event.clipboardData?.getData('text');
+
+    if (data.match(/^https?:\/\//) && URL.canParse(data)) {
+      const { start, end, beforeText, selectedText, afterText } = this.getSelection();
+
+      if (selectedText) {
+        event.preventDefault();
+
+        this.updateText(`${beforeText}[${selectedText}](${data})${afterText}`, {
+          start: start + 1,
+          end: end + 1,
+        });
+      }
+    }
+  }
+
   /**
    * Get information related to the selected text in the `<textarea>`.
    * @returns {{ start: number, end: number, beforeText: string, selectedText: string, afterText: