From 4427386d5f7b376d923a791eb4197ce6c26501bb Mon Sep 17 00:00:00 2001
From: Luke Wilde <lukew@serenityos.org>
Date: Wed, 29 Dec 2021 13:02:21 +0000
Subject: [PATCH] LibWeb: Implement Element.getAttributeNames

---
 Userland/Libraries/LibWeb/DOM/Element.cpp | 12 ++++++++++++
 Userland/Libraries/LibWeb/DOM/Element.h   |  1 +
 Userland/Libraries/LibWeb/DOM/Element.idl |  1 +
 3 files changed, 14 insertions(+)

diff --git a/Userland/Libraries/LibWeb/DOM/Element.cpp b/Userland/Libraries/LibWeb/DOM/Element.cpp
index f421cde0f0..7e85c9263b 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Element.cpp
@@ -109,6 +109,18 @@ bool Element::has_attribute(const FlyString& name) const
     return m_attributes->get_attribute(name) != nullptr;
 }
 
+// https://dom.spec.whatwg.org/#dom-element-getattributenames
+Vector<String> Element::get_attribute_names() const
+{
+    // The getAttributeNames() method steps are to return the qualified names of the attributes in this’s attribute list, in order; otherwise a new list.
+    Vector<String> names;
+    for (size_t i = 0; i < m_attributes->length(); ++i) {
+        auto const* attribute = m_attributes->item(i);
+        names.append(attribute->name());
+    }
+    return names;
+}
+
 bool Element::has_class(const FlyString& class_name, CaseSensitivity case_sensitivity) const
 {
     return any_of(m_classes, [&](auto& it) {
diff --git a/Userland/Libraries/LibWeb/DOM/Element.h b/Userland/Libraries/LibWeb/DOM/Element.h
index 7e6f09b24d..b037e18438 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.h
+++ b/Userland/Libraries/LibWeb/DOM/Element.h
@@ -57,6 +57,7 @@ public:
     void remove_attribute(const FlyString& name);
     size_t attribute_list_size() const { return m_attributes->length(); }
     NonnullRefPtr<NamedNodeMap> const& attributes() const { return m_attributes; }
+    Vector<String> get_attribute_names() const;
 
     RefPtr<DOMTokenList> const& class_list();
 
diff --git a/Userland/Libraries/LibWeb/DOM/Element.idl b/Userland/Libraries/LibWeb/DOM/Element.idl
index fc7629c723..bb4aa457c9 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.idl
+++ b/Userland/Libraries/LibWeb/DOM/Element.idl
@@ -10,6 +10,7 @@ interface Element : Node {
     boolean hasAttribute(DOMString qualifiedName);
     boolean hasAttributes();
     [SameObject] readonly attribute NamedNodeMap attributes;
+    sequence<DOMString> getAttributeNames();
 
     HTMLCollection getElementsByTagName(DOMString tagName);
     HTMLCollection getElementsByTagNameNS(DOMString? namespace, DOMString localName);