From a7fa757dd1422eff0870e06a3f337c8d31ad52be Mon Sep 17 00:00:00 2001
From: Luke <luke.wilde@live.co.uk>
Date: Mon, 5 Jul 2021 05:40:07 +0100
Subject: [PATCH] LibWeb: Implement the cloning steps for <template> elements

---
 .../LibWeb/HTML/HTMLTemplateElement.cpp          | 16 ++++++++++++++++
 .../Libraries/LibWeb/HTML/HTMLTemplateElement.h  |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/Userland/Libraries/LibWeb/HTML/HTMLTemplateElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLTemplateElement.cpp
index 3f9cff0184..bfa714f7ed 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLTemplateElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLTemplateElement.cpp
@@ -38,4 +38,20 @@ DOM::Document& HTMLTemplateElement::appropriate_template_contents_owner_document
     return document;
 }
 
+// https://html.spec.whatwg.org/multipage/scripting.html#the-template-element:concept-node-clone-ext
+void HTMLTemplateElement::cloned(Node& copy, bool clone_children)
+{
+    if (!clone_children)
+        return;
+
+    auto& template_clone = verify_cast<HTMLTemplateElement>(copy);
+
+    content()->for_each_child([&](auto& child) {
+        auto cloned_child = child.clone_node(&template_clone.content()->document(), true);
+
+        // FIXME: Should this use TreeNode::append_child instead?
+        template_clone.content()->append_child(cloned_child);
+    });
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLTemplateElement.h b/Userland/Libraries/LibWeb/HTML/HTMLTemplateElement.h
index b6d53874c1..6c5c3bd759 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLTemplateElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLTemplateElement.h
@@ -21,6 +21,8 @@ public:
     NonnullRefPtr<DOM::DocumentFragment> content() { return *m_content; }
     const NonnullRefPtr<DOM::DocumentFragment> content() const { return *m_content; }
 
+    virtual void cloned(Node& copy, bool clone_children) override;
+
 private:
     DOM::Document& appropriate_template_contents_owner_document(DOM::Document&);