LibWeb: Implement ParentNode.append

Userland/Libraries/LibWeb/DOM/Document.idl

@@ -66,6 +66,7 @@ interface Document : Node {
     readonly attribute unsigned long childElementCount;
 
     [CEReactions, Unscopable] undefined prepend((Node or DOMString)... nodes);
+    [CEReactions, Unscopable] undefined append((Node or DOMString)... nodes);
 
     Element? querySelector(DOMString selectors);
     [NewObject] NodeList querySelectorAll(DOMString selectors);

Userland/Libraries/LibWeb/DOM/DocumentFragment.idl

@@ -10,6 +10,7 @@ interface DocumentFragment : Node {
     readonly attribute unsigned long childElementCount;
 
     [CEReactions, Unscopable] undefined prepend((Node or DOMString)... nodes);
+    [CEReactions, Unscopable] undefined append((Node or DOMString)... nodes);
 
     Element? querySelector(DOMString selectors);
     [NewObject] NodeList querySelectorAll(DOMString selectors);

Userland/Libraries/LibWeb/DOM/Element.idl

@@ -39,6 +39,7 @@ interface Element : Node {
     readonly attribute unsigned long childElementCount;
 
     [CEReactions, Unscopable] undefined prepend((Node or DOMString)... nodes);
+    [CEReactions, Unscopable] undefined append((Node or DOMString)... nodes);
 
     Element? querySelector(DOMString selectors);
     [NewObject] NodeList querySelectorAll(DOMString selectors);

Userland/Libraries/LibWeb/DOM/ParentNode.cpp

@@ -174,4 +174,21 @@ ExceptionOr<void> ParentNode::prepend(Vector<Variant<NonnullRefPtr<Node>, String
     return {};
 }
 
+ExceptionOr<void> ParentNode::append(Vector<Variant<NonnullRefPtr<Node>, String>> const& nodes)
+{
+    // 1. Let node be the result of converting nodes into a node given nodes and this’s node document.
+    auto node_or_exception = convert_nodes_to_single_node(nodes, document());
+    if (node_or_exception.is_exception())
+        return node_or_exception.exception();
+
+    auto node = node_or_exception.release_value();
+
+    // 2. Append node to this.
+    auto result = append_child(node);
+    if (result.is_exception())
+        return result.exception();
+
+    return {};
+}
+
 }

Userland/Libraries/LibWeb/DOM/ParentNode.h

@@ -31,6 +31,7 @@ public:
     NonnullRefPtr<HTMLCollection> get_elements_by_tag_name_ns(FlyString const&, FlyString const&);
 
     ExceptionOr<void> prepend(Vector<Variant<NonnullRefPtr<Node>, String>> const& nodes);
+    ExceptionOr<void> append(Vector<Variant<NonnullRefPtr<Node>, String>> const& nodes);
 
 protected:
     ParentNode(Document& document, NodeType type)