diff --git a/Libraries/LibWeb/DOM/Document.cpp b/Libraries/LibWeb/DOM/Document.cpp
index 42a9749be97..40287ac8d9a 100644
--- a/Libraries/LibWeb/DOM/Document.cpp
+++ b/Libraries/LibWeb/DOM/Document.cpp
@@ -1004,13 +1004,13 @@ String Document::title() const
     //    element that is a child of the document element.
     if (auto const* document_element = this->document_element(); is<SVG::SVGElement>(document_element)) {
         if (auto const* title_element = document_element->first_child_of_type<SVG::SVGTitleElement>())
-            value = title_element->child_text_content();
+            value = title_element->child_text_content().to_utf8_but_should_be_ported_to_utf16();
     }
 
     // 2. Otherwise, let value be the child text content of the title element, or the empty string if the title element
     //    is null.
     else if (auto title_element = this->title_element()) {
-        value = title_element->text_content().value_or(String {});
+        value = title_element->text_content().value_or({}).to_utf8_but_should_be_ported_to_utf16();
     }
 
     // 3. Strip and collapse ASCII whitespace in value.
@@ -1045,7 +1045,7 @@ WebIDL::ExceptionOr<void> Document::set_title(String const& title)
         }
 
         // 3. String replace all with the given value within element.
-        element->string_replace_all(title);
+        element->string_replace_all(Utf16String::from_utf8(title));
     }
 
     // -> If the document element is in the HTML namespace
@@ -1074,7 +1074,7 @@ WebIDL::ExceptionOr<void> Document::set_title(String const& title)
         }
 
         // 4. String replace all with the given value within element.
-        element->string_replace_all(title);
+        element->string_replace_all(Utf16String::from_utf8(title));
     }
 
     // -> Otherwise
diff --git a/Libraries/LibWeb/DOM/DocumentLoading.cpp b/Libraries/LibWeb/DOM/DocumentLoading.cpp
index 0ca2acfd854..a82e7efb3da 100644
--- a/Libraries/LibWeb/DOM/DocumentLoading.cpp
+++ b/Libraries/LibWeb/DOM/DocumentLoading.cpp
@@ -309,7 +309,7 @@ static WebIDL::ExceptionOr<GC::Ref<DOM::Document>> load_media_document(HTML::Nav
         img {
             background-color: #fff;
         }
-    )~~~"_string);
+    )~~~"_utf16);
     TRY(document->head()->append_child(style_element));
 
     auto url_string = document->url_string();
diff --git a/Libraries/LibWeb/DOM/Node.cpp b/Libraries/LibWeb/DOM/Node.cpp
index d83d277d14a..bdeead59784 100644
--- a/Libraries/LibWeb/DOM/Node.cpp
+++ b/Libraries/LibWeb/DOM/Node.cpp
@@ -165,18 +165,20 @@ Optional<String> Node::alternative_text() const
 }
 
 // https://dom.spec.whatwg.org/#concept-descendant-text-content
-String Node::descendant_text_content() const
+Utf16String Node::descendant_text_content() const
 {
-    StringBuilder builder;
+    StringBuilder builder(StringBuilder::Mode::UTF16);
+
     for_each_in_subtree_of_type<Text>([&](auto& text_node) {
         builder.append(text_node.data());
         return TraversalDecision::Continue;
     });
-    return builder.to_string_without_validation();
+
+    return builder.to_utf16_string_without_validation();
 }
 
 // https://dom.spec.whatwg.org/#dom-node-textcontent
-Optional<String> Node::text_content() const
+Optional<Utf16String> Node::text_content() const
 {
     // The textContent getter steps are to return the following, switching on the interface this implements:
 
@@ -185,23 +187,23 @@ Optional<String> Node::text_content() const
         return descendant_text_content();
 
     // If CharacterData, return this’s data.
-    if (is<CharacterData>(this))
-        return static_cast<CharacterData const&>(*this).data().to_utf8_but_should_be_ported_to_utf16();
+    if (auto const* character_data = as_if<CharacterData>(*this))
+        return character_data->data();
 
     // If Attr node, return this's value.
-    if (is<Attr>(*this))
-        return static_cast<Attr const&>(*this).value();
+    if (auto const* attribute = as_if<Attr>(*this))
+        return Utf16String::from_utf8(attribute->value());
 
     // Otherwise, return null
     return {};
 }
 
 // https://dom.spec.whatwg.org/#ref-for-dom-node-textcontent%E2%91%A0
-void Node::set_text_content(Optional<String> const& maybe_content)
+void Node::set_text_content(Optional<Utf16String> const& maybe_content)
 {
     // The textContent setter steps are to, if the given value is null, act as if it was the empty string instead,
     // and then do as described below, switching on the interface this implements:
-    auto content = maybe_content.value_or(String {});
+    auto content = maybe_content.value_or({});
 
     // If DocumentFragment or Element, string replace all with the given value within this.
     if (is<DocumentFragment>(this) || is<Element>(this)) {
@@ -213,17 +215,13 @@ void Node::set_text_content(Optional<String> const& maybe_content)
     }
 
     // If CharacterData, replace data with node this, offset 0, count this’s length, and data the given value.
-    else if (is<CharacterData>(this)) {
-        auto* character_data_node = as<CharacterData>(this);
-        character_data_node->set_data(Utf16String::from_utf8(content));
-
-        // FIXME: CharacterData::set_data is not spec compliant. Make this match the spec when set_data becomes spec compliant.
-        //        Do note that this will make this function able to throw an exception.
+    else if (auto* character_data = as_if<CharacterData>(*this)) {
+        MUST(character_data->replace_data(0, character_data->length_in_utf16_code_units(), content));
     }
 
     // If Attr, set an existing attribute value with this and the given value.
-    if (is<Attr>(*this)) {
-        static_cast<Attr&>(*this).set_value(content);
+    else if (auto* attribute = as_if<Attr>(*this)) {
+        attribute->set_value(content.to_utf8_but_should_be_ported_to_utf16());
     }
 
     // Otherwise, do nothing.
@@ -524,21 +522,21 @@ void Node::invalidate_style(StyleInvalidationReason reason, Vector<CSS::Invalida
     document().style_invalidator().add_pending_invalidation(*this, move(invalidation_set), options.invalidate_elements_that_use_css_custom_properties);
 }
 
-String Node::child_text_content() const
+Utf16String Node::child_text_content() const
 {
-    if (!is<ParentNode>(*this))
-        return String {};
+    auto const* parent_node = as_if<ParentNode>(*this);
+    if (!parent_node)
+        return {};
 
-    StringBuilder builder;
-    as<ParentNode>(*this).for_each_child([&](auto& child) {
-        if (is<Text>(child)) {
-            auto maybe_content = as<Text>(child).text_content();
-            if (maybe_content.has_value())
-                builder.append(maybe_content.value());
-        }
+    StringBuilder builder(StringBuilder::Mode::UTF16);
+
+    parent_node->for_each_child_of_type<Text>([&](auto const& child) {
+        if (auto content = child.text_content(); content.has_value())
+            builder.append(*content);
         return IterationDecision::Continue;
     });
-    return MUST(builder.to_string());
+
+    return builder.to_utf16_string();
 }
 
 // https://dom.spec.whatwg.org/#concept-shadow-including-root
@@ -2045,14 +2043,14 @@ void Node::replace_all(GC::Ptr<Node> node)
 }
 
 // https://dom.spec.whatwg.org/#string-replace-all
-void Node::string_replace_all(String const& string)
+void Node::string_replace_all(Utf16String string)
 {
     // 1. Let node be null.
     GC::Ptr<Node> node;
 
     // 2. If string is not the empty string, then set node to a new Text node whose data is string and node document is parent’s node document.
     if (!string.is_empty())
-        node = realm().create<Text>(document(), Utf16String::from_utf8(string));
+        node = realm().create<Text>(document(), move(string));
 
     // 3. Replace all with node within parent.
     replace_all(node);
@@ -2862,7 +2860,7 @@ ErrorOr<String> Node::name_or_description(NameOrDescription target, Document con
             // If the current node has at least one direct child title element, select the appropriate title based on
             // the language rules for the SVG specification, and return the title text alternative as a flat string.
             element->for_each_child_of_type<SVG::SVGTitleElement>([&](SVG::SVGTitleElement const& title) mutable {
-                title_element_text = title.text_content();
+                title_element_text = title.text_content().map([](auto const& title) { return title.to_utf8_but_should_be_ported_to_utf16(); });
                 return IterationDecision::Break;
             });
             if (title_element_text.has_value())
@@ -2879,7 +2877,7 @@ ErrorOr<String> Node::name_or_description(NameOrDescription target, Document con
         //    then use the subtree of the first such element.
         if (is<HTML::HTMLTableElement>(*element))
             if (auto& table = (const_cast<HTML::HTMLTableElement&>(static_cast<HTML::HTMLTableElement const&>(*element))); table.caption())
-                return table.caption()->text_content().release_value();
+                return table.caption()->text_content()->to_utf8_but_should_be_ported_to_utf16();
 
         // https://w3c.github.io/html-aam/#fieldset-element-accessible-name-computation
         // 2. If the accessible name is still empty, then: if the fieldset element has a child that is a legend element,
@@ -2888,7 +2886,7 @@ ErrorOr<String> Node::name_or_description(NameOrDescription target, Document con
             Optional<String> legend;
             auto& fieldset = (const_cast<HTML::HTMLFieldSetElement&>(static_cast<HTML::HTMLFieldSetElement const&>(*element)));
             fieldset.for_each_child_of_type<HTML::HTMLLegendElement>([&](HTML::HTMLLegendElement const& element) mutable {
-                legend = element.text_content().release_value();
+                legend = element.text_content()->to_utf8_but_should_be_ported_to_utf16();
                 return IterationDecision::Break;
             });
             if (legend.has_value())
@@ -3010,7 +3008,7 @@ ErrorOr<String> Node::name_or_description(NameOrDescription target, Document con
     if (is_text() && (!parent_element() || (parent_element()->is_referenced() || !parent_element()->is_hidden() || !parent_element()->has_hidden_ancestor() || parent_element()->has_referenced_and_hidden_ancestor()))) {
         if (layout_node() && layout_node()->is_text_node())
             return as<Layout::TextNode>(layout_node())->text_for_rendering().to_utf8_but_should_be_ported_to_utf16();
-        return text_content().release_value();
+        return text_content()->to_utf8_but_should_be_ported_to_utf16();
     }
 
     // H. Otherwise, if the current node is a descendant of an element whose Accessible Name or Accessible Description
diff --git a/Libraries/LibWeb/DOM/Node.h b/Libraries/LibWeb/DOM/Node.h
index 2edeeec2dd2..8f6d81f199e 100644
--- a/Libraries/LibWeb/DOM/Node.h
+++ b/Libraries/LibWeb/DOM/Node.h
@@ -268,9 +268,9 @@ public:
 
     virtual Optional<String> alternative_text() const;
 
-    String descendant_text_content() const;
-    Optional<String> text_content() const;
-    void set_text_content(Optional<String> const&);
+    Utf16String descendant_text_content() const;
+    Optional<Utf16String> text_content() const;
+    void set_text_content(Optional<Utf16String> const&);
 
     WebIDL::ExceptionOr<void> normalize();
 
@@ -288,7 +288,7 @@ public:
     const HTML::HTMLElement* enclosing_html_element() const;
     const HTML::HTMLElement* enclosing_html_element_with_attribute(FlyString const&) const;
 
-    String child_text_content() const;
+    Utf16String child_text_content() const;
 
     Node& shadow_including_root();
     Node const& shadow_including_root() const
@@ -399,7 +399,7 @@ public:
     WebIDL::ExceptionOr<void> unsafely_set_html(Element&, StringView);
 
     void replace_all(GC::Ptr<Node>);
-    void string_replace_all(String const&);
+    void string_replace_all(Utf16String);
 
     bool is_same_node(Node const*) const;
     bool is_equal_node(Node const*) const;
diff --git a/Libraries/LibWeb/DOM/Node.idl b/Libraries/LibWeb/DOM/Node.idl
index fc7a2365f57..9e86e8fe89b 100644
--- a/Libraries/LibWeb/DOM/Node.idl
+++ b/Libraries/LibWeb/DOM/Node.idl
@@ -38,7 +38,7 @@ interface Node : EventTarget {
     // FIXME: [LegacyNullToEmptyString] is not allowed on nullable types as per the Web IDL spec.
     //        However, we only apply it to setters, so this works as a stop gap.
     //        Replace this with something like a special cased [LegacyNullToEmptyString].
-    [LegacyNullToEmptyString, CEReactions] attribute DOMString? textContent;
+    [LegacyNullToEmptyString, CEReactions] attribute Utf16DOMString? textContent;
     [CEReactions] undefined normalize();
 
     [ImplementedAs=clone_node_binding, CEReactions] Node cloneNode(optional boolean deep = false);
diff --git a/Libraries/LibWeb/DOM/StyleElementUtils.cpp b/Libraries/LibWeb/DOM/StyleElementUtils.cpp
index 38b8f4818fe..0cc9899a299 100644
--- a/Libraries/LibWeb/DOM/StyleElementUtils.cpp
+++ b/Libraries/LibWeb/DOM/StyleElementUtils.cpp
@@ -52,7 +52,7 @@ void StyleElementUtils::update_a_style_block(DOM::Element& style_element)
         return;
 
     // 5. If the Should element's inline behavior be blocked by Content Security Policy? algorithm returns "Blocked" when executed upon the style element, "style", and the style element's child text content, then return. [CSP]
-    if (ContentSecurityPolicy::should_elements_inline_type_behavior_be_blocked_by_content_security_policy(style_element.realm(), style_element, ContentSecurityPolicy::Directives::Directive::InlineType::Style, style_element.child_text_content()) == ContentSecurityPolicy::Directives::Directive::Result::Blocked)
+    if (ContentSecurityPolicy::should_elements_inline_type_behavior_be_blocked_by_content_security_policy(style_element.realm(), style_element, ContentSecurityPolicy::Directives::Directive::InlineType::Style, style_element.child_text_content().to_utf8_but_should_be_ported_to_utf16()) == ContentSecurityPolicy::Directives::Directive::Result::Blocked)
         return;
 
     // 6. Create a CSS style sheet with the following properties:
@@ -78,7 +78,7 @@ void StyleElementUtils::update_a_style_block(DOM::Element& style_element)
     //          Left uninitialized.
     m_style_sheet_list = style_element.document_or_shadow_root_style_sheets();
     m_associated_css_style_sheet = m_style_sheet_list->create_a_css_style_sheet(
-        style_element.text_content().value_or(String {}),
+        style_element.text_content().value_or({}).to_utf8_but_should_be_ported_to_utf16(),
         "text/css"_string,
         &style_element,
         style_element.attribute(HTML::AttributeNames::media).value_or({}),
diff --git a/Libraries/LibWeb/Editing/Internal/Algorithms.cpp b/Libraries/LibWeb/Editing/Internal/Algorithms.cpp
index acd859bd92e..ef77b584702 100644
--- a/Libraries/LibWeb/Editing/Internal/Algorithms.cpp
+++ b/Libraries/LibWeb/Editing/Internal/Algorithms.cpp
@@ -383,11 +383,10 @@ void canonicalize_whitespace(DOM::BoundaryPoint boundary, bool fix_collapsed_spa
         if (is<DOM::Text>(*start_node) && start_offset != 0) {
             auto parent_white_space_collapse = resolved_keyword(*start_node->parent(), CSS::PropertyID::WhiteSpaceCollapse);
 
-            // FIXME: Find a way to get code points directly from the UTF-8 string
-            auto start_node_data = Utf16String::from_utf8(*start_node->text_content());
-            auto offset_minus_one_code_point = start_node_data.code_point_at(start_offset - 1);
+            auto start_node_data = start_node->text_content().release_value();
+            auto offset_minus_one_code_unit = start_node_data.code_unit_at(start_offset - 1);
 
-            if (parent_white_space_collapse != CSS::Keyword::Preserve && (offset_minus_one_code_point == 0x20 || offset_minus_one_code_point == 0xA0)) {
+            if (parent_white_space_collapse != CSS::Keyword::Preserve && (offset_minus_one_code_unit == 0x20 || offset_minus_one_code_unit == 0xA0)) {
                 --start_offset;
                 continue;
             }
@@ -436,22 +435,21 @@ void canonicalize_whitespace(DOM::BoundaryPoint boundary, bool fix_collapsed_spa
         if (is<DOM::Text>(*end_node) && end_offset != end_node->length()) {
             auto parent_white_space_collapse = resolved_keyword(*end_node->parent(), CSS::PropertyID::WhiteSpaceCollapse);
 
-            // FIXME: Find a way to get code points directly from the UTF-8 string
-            auto end_node_data = Utf16String::from_utf8(*end_node->text_content());
-            auto offset_code_point = end_node_data.code_point_at(end_offset);
+            auto end_node_data = end_node->text_content().release_value();
+            auto offset_code_unit = end_node_data.code_unit_at(end_offset);
 
-            if (parent_white_space_collapse != CSS::Keyword::Preserve && (offset_code_point == 0x20 || offset_code_point == 0xA0)) {
+            if (parent_white_space_collapse != CSS::Keyword::Preserve && (offset_code_unit == 0x20 || offset_code_unit == 0xA0)) {
                 // 1. If fix collapsed space is true, and collapse spaces is true, and the end offsetth
                 //    code unit of end node's data is a space (0x0020): call deleteData(end offset, 1)
                 //    on end node, then continue this loop from the beginning.
-                if (fix_collapsed_space && collapse_spaces && offset_code_point == 0x20) {
+                if (fix_collapsed_space && collapse_spaces && offset_code_unit == 0x20) {
                     MUST(static_cast<DOM::CharacterData&>(*end_node).delete_data(end_offset, 1));
                     continue;
                 }
 
                 // 2. Set collapse spaces to true if the end offsetth code unit of end node's data is a
                 //    space (0x0020), false otherwise.
-                collapse_spaces = offset_code_point == 0x20;
+                collapse_spaces = offset_code_unit == 0x20;
 
                 // 3. Add one to end offset.
                 ++end_offset;
@@ -500,7 +498,7 @@ void canonicalize_whitespace(DOM::BoundaryPoint boundary, bool fix_collapsed_spa
             // AD-HOC: Use the white-space-collapse longhand instead of "white-space" shorthand: https://github.com/w3c/editing/issues/486.
             if (is<DOM::Text>(*end_node) && end_offset == end_node->length() && precedes_a_line_break(end_node)) {
                 auto parent_white_space_collapse = resolved_keyword(*end_node->parent(), CSS::PropertyID::WhiteSpaceCollapse);
-                if (parent_white_space_collapse != CSS::Keyword::Preserve && end_node->text_content().value().ends_with_bytes(" "sv)) {
+                if (parent_white_space_collapse != CSS::Keyword::Preserve && end_node->text_content()->ends_with(" "sv)) {
                     // 1. Subtract one from end offset.
                     --end_offset;
 
@@ -560,10 +558,10 @@ void canonicalize_whitespace(DOM::BoundaryPoint boundary, bool fix_collapsed_spa
             replacement_whitespace_view = replacement_whitespace_view.substring_view(1);
 
             // 2. If element is not the same as the start offsetth code unit of start node's data:
-            auto start_node_data = Utf16String::from_utf8(*start_node->text_content());
-            auto start_node_code_point = start_node_data.code_point_at(start_offset);
+            auto start_node_data = start_node->text_content().release_value();
+            auto start_node_code_unit = start_node_data.code_unit_at(start_offset);
 
-            if (element != start_node_code_point) {
+            if (element != start_node_code_unit) {
                 // 1. Call insertData(start offset, element) on start node.
                 auto& start_node_character_data = static_cast<DOM::CharacterData&>(*start_node);
                 MUST(start_node_character_data.insert_data(start_offset, Utf16String::from_code_point(element)));
@@ -1695,7 +1693,7 @@ bool is_allowed_child_of_node(Variant<GC::Ref<DOM::Node>, FlyString> child, Vari
             HTML::TagNames::tbody, HTML::TagNames::tfoot, HTML::TagNames::thead, HTML::TagNames::tr);
         if (parent_is_table_like && is<DOM::Text>(child_node.ptr())) {
             auto child_text_content = child_node->text_content().release_value();
-            if (!all_of(child_text_content.bytes_as_string_view(), Infra::is_ascii_whitespace))
+            if (!all_of(child_text_content, Infra::is_ascii_whitespace))
                 return false;
         }
 
@@ -2907,7 +2905,8 @@ void normalize_sublists_in_node(GC::Ref<DOM::Node> item)
         // 2. If child is an ol or ul, or new item is null and child is a Text node whose data
         //    consists of zero of more space characters:
         auto child_text = child->text_content();
-        auto text_is_all_whitespace = child_text.has_value() && all_of(child_text.value().bytes_as_string_view(), Infra::is_ascii_whitespace);
+        auto text_is_all_whitespace = child_text.has_value() && all_of(*child_text, Infra::is_ascii_whitespace);
+
         if ((is<HTML::HTMLOListElement>(*child) || is<HTML::HTMLUListElement>(*child))
             || (!new_item && is<DOM::Text>(*child) && text_is_all_whitespace)) {
             // 1. Set new item to null.
diff --git a/Libraries/LibWeb/HTML/HTMLAnchorElement.cpp b/Libraries/LibWeb/HTML/HTMLAnchorElement.cpp
index ee1f926cfda..5afc6514b2f 100644
--- a/Libraries/LibWeb/HTML/HTMLAnchorElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLAnchorElement.cpp
@@ -164,14 +164,14 @@ GC::Ref<DOM::DOMTokenList> HTMLAnchorElement::rel_list()
 }
 
 // https://html.spec.whatwg.org/multipage/text-level-semantics.html#dom-a-text
-String HTMLAnchorElement::text() const
+Utf16String HTMLAnchorElement::text() const
 {
     // The text attribute's getter must return this element's descendant text content.
     return descendant_text_content();
 }
 
 // https://html.spec.whatwg.org/multipage/text-level-semantics.html#dom-a-text
-void HTMLAnchorElement::set_text(String const& text)
+void HTMLAnchorElement::set_text(Utf16String const& text)
 {
     // The text attribute's setter must string replace all with the given value within this element.
     string_replace_all(text);
diff --git a/Libraries/LibWeb/HTML/HTMLAnchorElement.h b/Libraries/LibWeb/HTML/HTMLAnchorElement.h
index 1fa0c2fba26..8ffd4095063 100644
--- a/Libraries/LibWeb/HTML/HTMLAnchorElement.h
+++ b/Libraries/LibWeb/HTML/HTMLAnchorElement.h
@@ -26,8 +26,8 @@ public:
 
     GC::Ref<DOM::DOMTokenList> rel_list();
 
-    String text() const;
-    void set_text(String const&);
+    Utf16String text() const;
+    void set_text(Utf16String const&);
 
     // ^EventTarget
     // https://html.spec.whatwg.org/multipage/interaction.html#the-tabindex-attribute:the-a-element
diff --git a/Libraries/LibWeb/HTML/HTMLAnchorElement.idl b/Libraries/LibWeb/HTML/HTMLAnchorElement.idl
index bac32dd50b4..a967bbc562e 100644
--- a/Libraries/LibWeb/HTML/HTMLAnchorElement.idl
+++ b/Libraries/LibWeb/HTML/HTMLAnchorElement.idl
@@ -16,7 +16,7 @@ interface HTMLAnchorElement : HTMLElement {
     [CEReactions, Reflect] attribute DOMString hreflang;
     [CEReactions, Reflect] attribute DOMString type;
 
-    [CEReactions] attribute DOMString text;
+    [CEReactions] attribute Utf16DOMString text;
 
     [CEReactions, Reflect=referrerpolicy, Enumerated=ReferrerPolicy] attribute DOMString referrerPolicy;
 
diff --git a/Libraries/LibWeb/HTML/HTMLDetailsElement.cpp b/Libraries/LibWeb/HTML/HTMLDetailsElement.cpp
index 7da433ef830..81e80b7d2ac 100644
--- a/Libraries/LibWeb/HTML/HTMLDetailsElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLDetailsElement.cpp
@@ -252,7 +252,7 @@ WebIDL::ExceptionOr<void> HTMLDetailsElement::create_shadow_tree_if_needed()
         :host([open]) summary {
             list-style-type: disclosure-open;
         }
-    )~~~"_string);
+    )~~~"_utf16);
     MUST(shadow_root->append_child(style));
 
     m_summary_slot = static_cast<HTML::HTMLSlotElement&>(*summary_slot);
diff --git a/Libraries/LibWeb/HTML/HTMLElement.cpp b/Libraries/LibWeb/HTML/HTMLElement.cpp
index ebdb67e86b7..495dade5706 100644
--- a/Libraries/LibWeb/HTML/HTMLElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLElement.cpp
@@ -389,7 +389,7 @@ String HTMLElement::get_the_text_steps()
     // 1. If element is not being rendered or if the user agent is a non-CSS user agent, then return element's descendant text content.
     document().update_layout(DOM::UpdateLayoutReason::HTMLElementGetTheTextSteps);
     if (!layout_node())
-        return descendant_text_content();
+        return descendant_text_content().to_utf8_but_should_be_ported_to_utf16();
 
     // 2. Let results be a new empty list.
     Vector<Variant<String, RequiredLineBreakCount>> results;
diff --git a/Libraries/LibWeb/HTML/HTMLInputElement.cpp b/Libraries/LibWeb/HTML/HTMLInputElement.cpp
index 3000c0c17df..9020ba2f01c 100644
--- a/Libraries/LibWeb/HTML/HTMLInputElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLInputElement.cpp
@@ -1203,15 +1203,15 @@ void HTMLInputElement::update_file_input_shadow_tree()
         return;
 
     auto files_label = has_attribute(HTML::AttributeNames::multiple) ? "files"sv : "file"sv;
-    m_file_button->set_text_content(MUST(String::formatted("Select {}...", files_label)));
+    m_file_button->set_text_content(Utf16String::formatted("Select {}...", files_label));
 
     if (m_selected_files && m_selected_files->length() > 0) {
         if (m_selected_files->length() == 1)
-            m_file_label->set_text_content(m_selected_files->item(0)->name());
+            m_file_label->set_text_content(Utf16String::from_utf8(m_selected_files->item(0)->name()));
         else
-            m_file_label->set_text_content(MUST(String::formatted("{} files selected.", m_selected_files->length())));
+            m_file_label->set_text_content(Utf16String::formatted("{} files selected.", m_selected_files->length()));
     } else {
-        m_file_label->set_text_content(MUST(String::formatted("No {} selected.", files_label)));
+        m_file_label->set_text_content(Utf16String::formatted("No {} selected.", files_label));
     }
 }
 
diff --git a/Libraries/LibWeb/HTML/HTMLOptionElement.cpp b/Libraries/LibWeb/HTML/HTMLOptionElement.cpp
index b0613401c65..ccf061991fe 100644
--- a/Libraries/LibWeb/HTML/HTMLOptionElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLOptionElement.cpp
@@ -93,7 +93,9 @@ Utf16String HTMLOptionElement::value() const
 {
     // The value of an option element is the value of the value content attribute, if there is one.
     // ...or, if there is not, the value of the element's text IDL attribute.
-    return Utf16String::from_utf8(attribute(HTML::AttributeNames::value).value_or(text()));
+    if (auto value = attribute(HTML::AttributeNames::value); value.has_value())
+        return Utf16String::from_utf8(*value);
+    return text();
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-option-value
@@ -121,8 +123,7 @@ String HTMLOptionElement::label() const
     // must return that attribute's value; otherwise, it must return the element's label.
     if (auto label = attribute(HTML::AttributeNames::label); label.has_value())
         return label.release_value();
-
-    return text();
+    return text().to_utf8_but_should_be_ported_to_utf16();
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-option-label
@@ -133,9 +134,9 @@ void HTMLOptionElement::set_label(String const& label)
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-option-text
-String HTMLOptionElement::text() const
+Utf16String HTMLOptionElement::text() const
 {
-    StringBuilder builder;
+    StringBuilder builder(StringBuilder::Mode::UTF16);
 
     // Concatenation of data of all the Text node descendants of the option element, in tree order,
     // excluding any that are descendants of descendants of the option element that are themselves
@@ -146,11 +147,11 @@ String HTMLOptionElement::text() const
     });
 
     // Return the result of stripping and collapsing ASCII whitespace from the above concatenation.
-    return MUST(Infra::strip_and_collapse_whitespace(builder.string_view()));
+    return Infra::strip_and_collapse_whitespace(builder.to_utf16_string());
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-option-text
-void HTMLOptionElement::set_text(String const& text)
+void HTMLOptionElement::set_text(Utf16String const& text)
 {
     string_replace_all(text);
     // Note: this causes children_changed() to be called, which will update the <select>'s label
diff --git a/Libraries/LibWeb/HTML/HTMLOptionElement.h b/Libraries/LibWeb/HTML/HTMLOptionElement.h
index 5465999d3ae..f793c44e76e 100644
--- a/Libraries/LibWeb/HTML/HTMLOptionElement.h
+++ b/Libraries/LibWeb/HTML/HTMLOptionElement.h
@@ -26,8 +26,8 @@ public:
     Utf16String value() const;
     WebIDL::ExceptionOr<void> set_value(Utf16String const&);
 
-    String text() const;
-    void set_text(String const&);
+    Utf16String text() const;
+    void set_text(Utf16String const&);
 
     [[nodiscard]] String label() const;
     void set_label(String const&);
diff --git a/Libraries/LibWeb/HTML/HTMLOptionElement.idl b/Libraries/LibWeb/HTML/HTMLOptionElement.idl
index 39e09b4b60d..0ccf269d5de 100644
--- a/Libraries/LibWeb/HTML/HTMLOptionElement.idl
+++ b/Libraries/LibWeb/HTML/HTMLOptionElement.idl
@@ -12,6 +12,6 @@ interface HTMLOptionElement : HTMLElement {
     attribute boolean selected;
     [CEReactions] attribute Utf16DOMString value;
 
-    [CEReactions] attribute DOMString text;
+    [CEReactions] attribute Utf16DOMString text;
     readonly attribute long index;
 };
diff --git a/Libraries/LibWeb/HTML/HTMLOutputElement.cpp b/Libraries/LibWeb/HTML/HTMLOutputElement.cpp
index 3e73a00038d..bc5e2e7b963 100644
--- a/Libraries/LibWeb/HTML/HTMLOutputElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLOutputElement.cpp
@@ -50,7 +50,7 @@ GC::Ref<DOM::DOMTokenList> HTMLOutputElement::html_for()
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-output-defaultvalue
-String HTMLOutputElement::default_value() const
+Utf16String HTMLOutputElement::default_value() const
 {
     // 1. If this element's default value override is non-null, then return it.
     if (m_default_value_override.has_value())
@@ -61,7 +61,7 @@ String HTMLOutputElement::default_value() const
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-output-defaultvalue
-void HTMLOutputElement::set_default_value(String const& default_value)
+void HTMLOutputElement::set_default_value(Utf16String const& default_value)
 {
     // 1. If this's default value override is null, then string replace all with the given value within this and return.
     if (!m_default_value_override.has_value()) {
@@ -77,7 +77,7 @@ void HTMLOutputElement::set_default_value(String const& default_value)
 Utf16String HTMLOutputElement::value() const
 {
     // The value getter steps are to return this's descendant text content.
-    return Utf16String::from_utf8(descendant_text_content());
+    return descendant_text_content();
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-output-value
@@ -87,7 +87,7 @@ void HTMLOutputElement::set_value(Utf16String const& value)
     m_default_value_override = default_value();
 
     // 2. String replace all with the given value within this.
-    string_replace_all(value.to_utf8_but_should_be_ported_to_utf16());
+    string_replace_all(value);
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#the-output-element:concept-form-reset-control
diff --git a/Libraries/LibWeb/HTML/HTMLOutputElement.h b/Libraries/LibWeb/HTML/HTMLOutputElement.h
index aef1b22e1b0..f4d328b6f89 100644
--- a/Libraries/LibWeb/HTML/HTMLOutputElement.h
+++ b/Libraries/LibWeb/HTML/HTMLOutputElement.h
@@ -31,8 +31,8 @@ public:
         return output;
     }
 
-    String default_value() const;
-    void set_default_value(String const&);
+    Utf16String default_value() const;
+    void set_default_value(Utf16String const&);
 
     Utf16String value() const override;
     void set_value(Utf16String const&);
@@ -69,7 +69,7 @@ private:
 
     GC::Ptr<DOM::DOMTokenList> m_html_for;
 
-    Optional<String> m_default_value_override {};
+    Optional<Utf16String> m_default_value_override;
 };
 
 }
diff --git a/Libraries/LibWeb/HTML/HTMLOutputElement.idl b/Libraries/LibWeb/HTML/HTMLOutputElement.idl
index a91566e2220..1b884fe336f 100644
--- a/Libraries/LibWeb/HTML/HTMLOutputElement.idl
+++ b/Libraries/LibWeb/HTML/HTMLOutputElement.idl
@@ -12,7 +12,7 @@ interface HTMLOutputElement : HTMLElement {
     [CEReactions, Reflect] attribute DOMString name;
 
     readonly attribute DOMString type;
-    [CEReactions] attribute DOMString defaultValue;
+    [CEReactions] attribute Utf16DOMString defaultValue;
     [CEReactions] attribute Utf16DOMString value;
 
     readonly attribute boolean willValidate;
diff --git a/Libraries/LibWeb/HTML/HTMLScriptElement.cpp b/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
index c9c37aadac3..e0d084d650f 100644
--- a/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
@@ -188,6 +188,7 @@ void HTMLScriptElement::prepare_script()
 
     // 5. Let source text be el's child text content.
     auto source_text = child_text_content();
+    auto source_text_utf8 = source_text.to_utf8_but_should_be_ported_to_utf16();
 
     // 6. If el has no src attribute, and source text is the empty string, then return.
     if (!has_attribute(HTML::AttributeNames::src) && source_text.is_empty()) {
@@ -278,7 +279,7 @@ void HTMLScriptElement::prepare_script()
     // 19. If el does not have a src content attribute, and the Should element's inline behavior be blocked by Content Security Policy?
     //     algorithm returns "Blocked" when given el, "script", and source text, then return. [CSP]
     if (!has_attribute(AttributeNames::src)
-        && ContentSecurityPolicy::should_elements_inline_type_behavior_be_blocked_by_content_security_policy(realm(), *this, ContentSecurityPolicy::Directives::Directive::InlineType::Script, source_text) == ContentSecurityPolicy::Directives::Directive::Result::Blocked) {
+        && ContentSecurityPolicy::should_elements_inline_type_behavior_be_blocked_by_content_security_policy(realm(), *this, ContentSecurityPolicy::Directives::Directive::InlineType::Script, source_text_utf8) == ContentSecurityPolicy::Directives::Directive::Result::Blocked) {
         dbgln("HTMLScriptElement: Refusing to run inline script because it violates the Content Security Policy.");
         return;
     }
@@ -452,7 +453,7 @@ void HTMLScriptElement::prepare_script()
         if (m_script_type == ScriptType::Classic) {
             // 1. Let script be the result of creating a classic script using source text, settings object's realm, base URL, and options.
             // FIXME: Pass options.
-            auto script = ClassicScript::create(m_document->url().to_byte_string(), source_text, settings_object.realm(), base_url, m_source_line_number);
+            auto script = ClassicScript::create(m_document->url().to_byte_string(), source_text_utf8, settings_object.realm(), base_url, m_source_line_number);
 
             // 2. Mark as ready el given script.
             mark_as_ready(Result(move(script)));
diff --git a/Libraries/LibWeb/HTML/HTMLScriptElement.h b/Libraries/LibWeb/HTML/HTMLScriptElement.h
index d989eb55c98..d01f9f56487 100644
--- a/Libraries/LibWeb/HTML/HTMLScriptElement.h
+++ b/Libraries/LibWeb/HTML/HTMLScriptElement.h
@@ -57,8 +57,8 @@ public:
     void unmark_as_already_started(Badge<DOM::Range>);
     void unmark_as_parser_inserted(Badge<DOM::Range>);
 
-    String text() { return child_text_content(); }
-    void set_text(String const& text) { string_replace_all(text); }
+    Utf16String text() { return child_text_content(); }
+    void set_text(Utf16String const& text) { string_replace_all(text); }
 
     [[nodiscard]] bool async() const;
     void set_async(bool);
diff --git a/Libraries/LibWeb/HTML/HTMLScriptElement.idl b/Libraries/LibWeb/HTML/HTMLScriptElement.idl
index 47933ac566f..52ff587830d 100644
--- a/Libraries/LibWeb/HTML/HTMLScriptElement.idl
+++ b/Libraries/LibWeb/HTML/HTMLScriptElement.idl
@@ -17,8 +17,8 @@ interface HTMLScriptElement : HTMLElement {
     [CEReactions, Reflect=referrerpolicy, Enumerated=ReferrerPolicy] attribute DOMString referrerPolicy;
     [CEReactions, Reflect] attribute DOMString integrity;
     [CEReactions, Enumerated=FetchPriorityAttribute, Reflect=fetchpriority] attribute DOMString fetchPriority;
-    
-    [CEReactions] attribute DOMString text;
+
+    [CEReactions] attribute Utf16DOMString text;
 
     static boolean supports(DOMString type);
 
diff --git a/Libraries/LibWeb/HTML/HTMLSelectElement.cpp b/Libraries/LibWeb/HTML/HTMLSelectElement.cpp
index 042b2125a3a..c900281cd1d 100644
--- a/Libraries/LibWeb/HTML/HTMLSelectElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLSelectElement.cpp
@@ -632,7 +632,7 @@ void HTMLSelectElement::update_inner_text_element()
     // Update inner text element to the label of the selected option
     for (auto const& option_element : m_cached_list_of_options) {
         if (option_element->selected()) {
-            m_inner_text_element->set_text_content(MUST(Infra::strip_and_collapse_whitespace(option_element->label())));
+            m_inner_text_element->set_text_content(Infra::strip_and_collapse_whitespace(Utf16String::from_utf8(option_element->label())));
             return;
         }
     }
diff --git a/Libraries/LibWeb/HTML/HTMLTextAreaElement.cpp b/Libraries/LibWeb/HTML/HTMLTextAreaElement.cpp
index c0b4be74b4d..73d0c1d6795 100644
--- a/Libraries/LibWeb/HTML/HTMLTextAreaElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLTextAreaElement.cpp
@@ -114,10 +114,10 @@ void HTMLTextAreaElement::reset_algorithm()
     m_user_validity = false;
     m_dirty_value = false;
     // and the raw value to its child text content.
-    set_raw_value(Utf16String::from_utf8(child_text_content()));
+    set_raw_value(child_text_content());
 
     if (m_text_node) {
-        m_text_node->set_text_content(m_raw_value.to_utf8_but_should_be_ported_to_utf16());
+        m_text_node->set_text_content(m_raw_value);
         update_placeholder_visibility();
     }
 }
@@ -129,7 +129,7 @@ void HTMLTextAreaElement::clear_algorithm()
     m_dirty_value = false;
 
     // and set the raw value of element to an empty string.
-    set_raw_value(Utf16String::from_utf8(child_text_content()));
+    set_raw_value(child_text_content());
 
     // Unlike their associated reset algorithms, changes made to form controls as part of these algorithms do count as
     // changes caused by the user (and thus, e.g. do cause input events to fire).
@@ -155,14 +155,14 @@ void HTMLTextAreaElement::form_associated_element_was_inserted()
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-textarea-defaultvalue
-String HTMLTextAreaElement::default_value() const
+Utf16String HTMLTextAreaElement::default_value() const
 {
     // The defaultValue attribute's getter must return the element's child text content.
     return child_text_content();
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#dom-textarea-defaultvalue
-void HTMLTextAreaElement::set_default_value(String const& default_value)
+void HTMLTextAreaElement::set_default_value(Utf16String const& default_value)
 {
     // The defaultValue attribute's setter must string replace all with the given value within this element.
     string_replace_all(default_value);
@@ -379,7 +379,7 @@ void HTMLTextAreaElement::create_shadow_tree_if_needed()
     handle_readonly_attribute(attribute(HTML::AttributeNames::readonly));
     // NOTE: If `children_changed()` was called before now, `m_raw_value` will hold the text content.
     //       Otherwise, it will get filled in whenever that does get called.
-    m_text_node->set_text_content(m_raw_value.to_utf8_but_should_be_ported_to_utf16());
+    m_text_node->set_text_content(m_raw_value);
     handle_maxlength_attribute();
     MUST(m_inner_text_element->append_child(*m_text_node));
 
@@ -430,9 +430,9 @@ void HTMLTextAreaElement::children_changed(ChildrenChangedMetadata const* metada
     // The children changed steps for textarea elements must, if the element's dirty value flag is false,
     // set the element's raw value to its child text content.
     if (!m_dirty_value) {
-        set_raw_value(Utf16String::from_utf8(child_text_content()));
+        set_raw_value(child_text_content());
         if (m_text_node)
-            m_text_node->set_text_content(m_raw_value.to_utf8_but_should_be_ported_to_utf16());
+            m_text_node->set_text_content(m_raw_value);
         update_placeholder_visibility();
     }
 }
diff --git a/Libraries/LibWeb/HTML/HTMLTextAreaElement.h b/Libraries/LibWeb/HTML/HTMLTextAreaElement.h
index 6b43d5ce293..49d62342844 100644
--- a/Libraries/LibWeb/HTML/HTMLTextAreaElement.h
+++ b/Libraries/LibWeb/HTML/HTMLTextAreaElement.h
@@ -77,8 +77,8 @@ public:
     // https://www.w3.org/TR/html-aria/#el-textarea
     virtual Optional<ARIA::Role> default_role() const override { return ARIA::Role::textbox; }
 
-    String default_value() const;
-    void set_default_value(String const&);
+    Utf16String default_value() const;
+    void set_default_value(Utf16String const&);
 
     Utf16String value() const override;
     void set_value(Utf16String const&);
diff --git a/Libraries/LibWeb/HTML/HTMLTextAreaElement.idl b/Libraries/LibWeb/HTML/HTMLTextAreaElement.idl
index a38e1eefd63..d5056fc406a 100644
--- a/Libraries/LibWeb/HTML/HTMLTextAreaElement.idl
+++ b/Libraries/LibWeb/HTML/HTMLTextAreaElement.idl
@@ -22,7 +22,7 @@ interface HTMLTextAreaElement : HTMLElement {
     [CEReactions, Reflect] attribute DOMString wrap;
 
     readonly attribute DOMString type;
-    [CEReactions] attribute DOMString defaultValue;
+    [CEReactions] attribute Utf16DOMString defaultValue;
     [LegacyNullToEmptyString] attribute Utf16DOMString value;
     readonly attribute unsigned long textLength;
 
diff --git a/Libraries/LibWeb/HTML/HTMLTitleElement.cpp b/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
index cb0a313f53b..7cf3fa57c61 100644
--- a/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
@@ -37,14 +37,14 @@ void HTMLTitleElement::children_changed(ChildrenChangedMetadata const* metadata)
 }
 
 // https://html.spec.whatwg.org/multipage/semantics.html#dom-title-text
-String HTMLTitleElement::text() const
+Utf16String HTMLTitleElement::text() const
 {
     // The text attribute's getter must return this title element's child text content.
     return child_text_content();
 }
 
 // https://html.spec.whatwg.org/multipage/semantics.html#dom-title-text
-void HTMLTitleElement::set_text(String const& value)
+void HTMLTitleElement::set_text(Utf16String const& value)
 {
     // The text attribute's setter must string replace all with the given value within this title element.
     string_replace_all(value);
diff --git a/Libraries/LibWeb/HTML/HTMLTitleElement.h b/Libraries/LibWeb/HTML/HTMLTitleElement.h
index ddaba971cca..67cd341bf3e 100644
--- a/Libraries/LibWeb/HTML/HTMLTitleElement.h
+++ b/Libraries/LibWeb/HTML/HTMLTitleElement.h
@@ -17,8 +17,8 @@ class HTMLTitleElement final : public HTMLElement {
 public:
     virtual ~HTMLTitleElement() override;
 
-    String text() const;
-    void set_text(String const& value);
+    Utf16String text() const;
+    void set_text(Utf16String const& value);
 
 private:
     HTMLTitleElement(DOM::Document&, DOM::QualifiedName);
diff --git a/Libraries/LibWeb/HTML/HTMLTitleElement.idl b/Libraries/LibWeb/HTML/HTMLTitleElement.idl
index d7b296491f1..08a7b4d8092 100644
--- a/Libraries/LibWeb/HTML/HTMLTitleElement.idl
+++ b/Libraries/LibWeb/HTML/HTMLTitleElement.idl
@@ -6,6 +6,6 @@ interface HTMLTitleElement : HTMLElement {
 
     [HTMLConstructor] constructor();
 
-    [CEReactions] attribute DOMString text;
+    [CEReactions] attribute Utf16DOMString text;
 
 };
diff --git a/Libraries/LibWeb/Infra/CharacterTypes.h b/Libraries/LibWeb/Infra/CharacterTypes.h
index bab63ade765..03040a202d0 100644
--- a/Libraries/LibWeb/Infra/CharacterTypes.h
+++ b/Libraries/LibWeb/Infra/CharacterTypes.h
@@ -11,7 +11,8 @@
 
 namespace Web::Infra {
 
-constexpr auto ASCII_WHITESPACE = "\t\n\f\r "sv;
+constexpr inline auto ASCII_WHITESPACE = "\t\n\f\r "sv;
+constexpr inline auto ASCII_WHITESPACE_CODE_POINTS = to_array<u32>({ '\t', '\n', '\f', '\r', ' ' });
 
 // https://infra.spec.whatwg.org/#ascii-whitespace
 constexpr bool is_ascii_whitespace(u32 code_point)
diff --git a/Libraries/LibWeb/Infra/Strings.cpp b/Libraries/LibWeb/Infra/Strings.cpp
index eb5cb41337a..bd601359573 100644
--- a/Libraries/LibWeb/Infra/Strings.cpp
+++ b/Libraries/LibWeb/Infra/Strings.cpp
@@ -85,6 +85,29 @@ ErrorOr<String> strip_and_collapse_whitespace(StringView string)
     return String::from_utf8(builder.string_view().trim(Infra::ASCII_WHITESPACE));
 }
 
+// https://infra.spec.whatwg.org/#strip-and-collapse-ascii-whitespace
+Utf16String strip_and_collapse_whitespace(Utf16String const& string)
+{
+    // Replace any sequence of one or more consecutive code points that are ASCII whitespace in the string with a single U+0020 SPACE code point.
+    if (!string.contains_any_of(Infra::ASCII_WHITESPACE_CODE_POINTS))
+        return string;
+
+    StringBuilder builder(StringBuilder::Mode::UTF16);
+
+    for (auto code_point : string) {
+        if (Infra::is_ascii_whitespace(code_point)) {
+            if (!builder.utf16_string_view().ends_with(" "sv))
+                builder.append(' ');
+            continue;
+        }
+
+        builder.append_code_point(code_point);
+    }
+
+    // ...and then remove any leading and trailing ASCII whitespace from that string.
+    return Utf16String::from_utf16(builder.utf16_string_view().trim(Infra::ASCII_WHITESPACE));
+}
+
 // https://infra.spec.whatwg.org/#code-unit-prefix
 bool is_code_unit_prefix(StringView potential_prefix_utf8, StringView input_utf8)
 {
diff --git a/Libraries/LibWeb/Infra/Strings.h b/Libraries/LibWeb/Infra/Strings.h
index d61e2b19bde..f0caacdb95d 100644
--- a/Libraries/LibWeb/Infra/Strings.h
+++ b/Libraries/LibWeb/Infra/Strings.h
@@ -16,6 +16,7 @@ namespace Web::Infra {
 String normalize_newlines(String const&);
 Utf16String normalize_newlines(Utf16String const&);
 ErrorOr<String> strip_and_collapse_whitespace(StringView string);
+Utf16String strip_and_collapse_whitespace(Utf16String const& string);
 bool is_code_unit_prefix(StringView potential_prefix, StringView input);
 ErrorOr<String> convert_to_scalar_value_string(StringView string);
 ByteBuffer isomorphic_encode(StringView input);
diff --git a/Libraries/LibWeb/SVG/SVGElement.cpp b/Libraries/LibWeb/SVG/SVGElement.cpp
index ccc0744d02e..5336d4821bd 100644
--- a/Libraries/LibWeb/SVG/SVGElement.cpp
+++ b/Libraries/LibWeb/SVG/SVGElement.cpp
@@ -143,7 +143,7 @@ bool SVGElement::should_include_in_accessibility_tree() const
     bool has_title_or_desc = false;
     auto role = role_from_role_attribute_value();
     for_each_child_of_type<SVGElement>([&has_title_or_desc](auto& child) {
-        if ((is<SVGTitleElement>(child) || is<SVGDescElement>(child)) && !child.text_content()->trim_ascii_whitespace().value().is_empty()) {
+        if ((is<SVGTitleElement>(child) || is<SVGDescElement>(child)) && !child.text_content()->utf16_view().trim_ascii_whitespace().is_empty()) {
             has_title_or_desc = true;
             return IterationDecision::Break;
         }
@@ -152,9 +152,9 @@ bool SVGElement::should_include_in_accessibility_tree() const
     // https://w3c.github.io/svg-aam/#include_elements
     // TODO: Add support for the SVG tabindex attribute, and include a check for it here.
     return has_title_or_desc
-        || (aria_label().has_value() && !aria_label().value().trim_ascii_whitespace().value().is_empty())
-        || (aria_labelled_by().has_value() && !aria_labelled_by().value().trim_ascii_whitespace().value().is_empty())
-        || (aria_described_by().has_value() && !aria_described_by().value().trim_ascii_whitespace().value().is_empty())
+        || (aria_label().has_value() && !aria_label()->bytes_as_string_view().trim_whitespace().is_empty())
+        || (aria_labelled_by().has_value() && !aria_labelled_by()->bytes_as_string_view().trim_whitespace().is_empty())
+        || (aria_described_by().has_value() && !aria_described_by()->bytes_as_string_view().trim_whitespace().is_empty())
         || (role.has_value() && ARIA::is_abstract_role(role.value()) && role != ARIA::Role::none && role != ARIA::Role::presentation);
 }
 
diff --git a/Libraries/LibWeb/SVG/SVGScriptElement.cpp b/Libraries/LibWeb/SVG/SVGScriptElement.cpp
index 188129d1509..a03cd95df17 100644
--- a/Libraries/LibWeb/SVG/SVGScriptElement.cpp
+++ b/Libraries/LibWeb/SVG/SVGScriptElement.cpp
@@ -152,7 +152,7 @@ void SVGScriptElement::process_the_script_element()
 
     } else {
         // Inline script content
-        script_content = child_text_content();
+        script_content = child_text_content().to_utf8_but_should_be_ported_to_utf16();
         if (script_content.is_empty())
             return;
     }
diff --git a/Libraries/LibWeb/WebDriver/ElementReference.cpp b/Libraries/LibWeb/WebDriver/ElementReference.cpp
index 6c6cf30df70..19003defc6e 100644
--- a/Libraries/LibWeb/WebDriver/ElementReference.cpp
+++ b/Libraries/LibWeb/WebDriver/ElementReference.cpp
@@ -520,7 +520,7 @@ String element_rendered_text(DOM::Node& node)
     // FIXME: The spec does not define how to get the element's rendered text, other than to do exactly as Selenium does.
     //        This implementation is not sufficient, as we must also at least consider the shadow DOM.
     if (!is<HTML::HTMLElement>(node))
-        return node.text_content().value_or(String {});
+        return node.text_content().value_or({}).to_utf8_but_should_be_ported_to_utf16();
 
     auto& element = static_cast<HTML::HTMLElement&>(node);
     return element.inner_text();