diff --git a/Userland/Libraries/LibWeb/DOM/Document.cpp b/Userland/Libraries/LibWeb/DOM/Document.cpp
index 3ae99605a0..35b6444e34 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Document.cpp
@@ -216,16 +216,19 @@ JS::NonnullGCPtr<Document> Document::create_and_initialize(Type type, String con
     //    whose type is type,
     //    content type is contentType,
     //    origin is navigationParams's origin,
-    //    FIXME: policy container is navigationParams's policy container,
+    //    policy container is navigationParams's policy container,
     //    FIXME: permissions policy is permissionsPolicy,
-    //    FIXME: active sandboxing flag set is navigationParams's final sandboxing flag set,
+    //    active sandboxing flag set is navigationParams's final sandboxing flag set,
     //    FIXME: and cross-origin opener policy is navigationParams's cross-origin opener policy,
     //    FIXME: load timing info is loadTimingInfo,
-    //    FIXME: and navigation id is navigationParams's id.
+    //    and navigation id is navigationParams's id.
     auto document = Document::create(*window);
     document->m_type = type;
     document->m_content_type = content_type;
     document->set_origin(navigation_params.origin);
+    document->m_policy_container = navigation_params.policy_container;
+    document->m_active_sandboxing_flag_set = navigation_params.final_sandboxing_flag_set;
+    document->m_navigation_id = navigation_params.id;
 
     document->m_window = window;
     window->set_associated_document(*document);
@@ -1962,4 +1965,24 @@ void Document::set_domain(String const& domain)
     dbgln("(STUBBED) Document::set_domain(domain='{}')", domain);
 }
 
+void Document::set_navigation_id(Optional<AK::String> navigation_id)
+{
+    m_navigation_id = move(navigation_id);
+}
+
+Optional<String> Document::navigation_id() const
+{
+    return m_navigation_id;
+}
+
+HTML::SandboxingFlagSet Document::active_sandboxing_flag_set() const
+{
+    return m_active_sandboxing_flag_set;
+}
+
+HTML::PolicyContainer Document::policy_container() const
+{
+    return m_policy_container;
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/DOM/Document.h b/Userland/Libraries/LibWeb/DOM/Document.h
index 7b280fb2e2..8be46b9dc1 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.h
+++ b/Userland/Libraries/LibWeb/DOM/Document.h
@@ -29,6 +29,7 @@
 #include <LibWeb/HTML/HTMLScriptElement.h>
 #include <LibWeb/HTML/History.h>
 #include <LibWeb/HTML/Origin.h>
+#include <LibWeb/HTML/SandboxingFlagSet.h>
 #include <LibWeb/HTML/Scripting/Environments.h>
 #include <LibWeb/HTML/Window.h>
 
@@ -371,6 +372,16 @@ public:
     // https://html.spec.whatwg.org/#completely-loaded
     bool is_completely_loaded() const;
 
+    // https://html.spec.whatwg.org/multipage/dom.html#concept-document-navigation-id
+    Optional<String> navigation_id() const;
+    void set_navigation_id(Optional<String>);
+
+    // https://html.spec.whatwg.org/multipage/origin.html#active-sandboxing-flag-set
+    HTML::SandboxingFlagSet active_sandboxing_flag_set() const;
+
+    // https://html.spec.whatwg.org/multipage/dom.html#concept-document-policy-container
+    HTML::PolicyContainer policy_container() const;
+
 protected:
     virtual void visit_edges(Cell::Visitor&) override;
 
@@ -506,6 +517,15 @@ private:
     // https://html.spec.whatwg.org/#completely-loaded-time
     Optional<AK::Time> m_completely_loaded_time;
 
+    // https://html.spec.whatwg.org/multipage/dom.html#concept-document-navigation-id
+    Optional<String> m_navigation_id;
+
+    // https://html.spec.whatwg.org/multipage/origin.html#active-sandboxing-flag-set
+    HTML::SandboxingFlagSet m_active_sandboxing_flag_set;
+
+    // https://html.spec.whatwg.org/multipage/dom.html#concept-document-policy-container
+    HTML::PolicyContainer m_policy_container;
+
     // https://html.spec.whatwg.org/multipage/interaction.html#visibility-state
     String m_visibility_state { "hidden" };
 };