From 41f574155df89bb5122646a0978fa8821c35fc16 Mon Sep 17 00:00:00 2001
From: Shannon Booth <shannon@serenityos.org>
Date: Sun, 13 Oct 2024 14:30:45 +1300
Subject: [PATCH] LibWeb: Factor out AO for 'try to scroll to the fragment'

I had made a stab at implementing this to determine whether it could
assist in fixing an issue where scroll_to_the_fragment was not getting
called at the appropriate time. It did not fix that issue, and actually
ended up breaking one of our in tree tests. In the meantime, factor out
this method into a standalone function.
---
 Userland/Libraries/LibWeb/DOM/Document.cpp | 26 +++++++++++++++++-----
 Userland/Libraries/LibWeb/DOM/Document.h   |  1 +
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/Userland/Libraries/LibWeb/DOM/Document.cpp b/Userland/Libraries/LibWeb/DOM/Document.cpp
index 969316c62ff..f7aa3684b1b 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Document.cpp
@@ -2310,6 +2310,25 @@ void Document::scroll_to_the_fragment()
     }
 }
 
+// https://html.spec.whatwg.org/multipage/browsing-the-web.html#try-to-scroll-to-the-fragment
+void Document::try_to_scroll_to_the_fragment()
+{
+    // FIXME: According to the spec we should only scroll here if document has no parser or parsing has stopped.
+    //        It should be ok to remove this after we implement navigation events and scrolling will happen in
+    //        "process scroll behavior".
+    //  To try to scroll to the fragment for a Document document, perform the following steps in parallel:
+    //  1. Wait for an implementation-defined amount of time. (This is intended to allow the user agent to
+    //     optimize the user experience in the face of performance concerns.)
+    //  2. Queue a global task on the navigation and traversal task source given document's relevant global
+    //     object to run these steps:
+    //      1. If document has no parser, or its parser has stopped parsing, or the user agent has reason to
+    //         believe the user is no longer interested in scrolling to the fragment, then abort these steps.
+    //      2. Scroll to the fragment given document.
+    //      3. If document's indicated part is still null, then try to scroll to the fragment for document.
+
+    scroll_to_the_fragment();
+}
+
 // https://drafts.csswg.org/cssom-view-1/#scroll-to-the-beginning-of-the-document
 void Document::scroll_to_the_beginning_of_the_document()
 {
@@ -4378,11 +4397,8 @@ void Document::update_for_history_step_application(JS::NonnullGCPtr<HTML::Sessio
 
     // 8. If documentIsNew is true, then:
     if (document_is_new) {
-        // FIXME: 1. Try to scroll to the fragment for document.
-        // FIXME: According to the spec we should only scroll here if document has no parser or parsing has stopped.
-        //        It should be ok to remove this after we implement navigation events and scrolling will happen in
-        //        "process scroll behavior".
-        scroll_to_the_fragment();
+        // 1. Try to scroll to the fragment for document.
+        try_to_scroll_to_the_fragment();
 
         // 2. At this point scripts may run for the newly-created document document.
         m_ready_to_run_scripts = true;
diff --git a/Userland/Libraries/LibWeb/DOM/Document.h b/Userland/Libraries/LibWeb/DOM/Document.h
index 80d7693d52c..4fc1b5bc958 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.h
+++ b/Userland/Libraries/LibWeb/DOM/Document.h
@@ -347,6 +347,7 @@ public:
     Element const* target_element() const { return m_target_element.ptr(); }
     void set_target_element(Element*);
 
+    void try_to_scroll_to_the_fragment();
     void scroll_to_the_fragment();
     void scroll_to_the_beginning_of_the_document();