From 5db51d85a3d8503766f84a092252439510986357 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Tue, 2 Nov 2021 19:20:57 +0100
Subject: [PATCH] LibWeb: Hide uninteresting whitespace text nodes from DOM
 inspector

Use a simple heuristic to exclude uninteresting whitespace and
de-clutter the inspector's DOM tree.

Uninteresting whitespace is currently one of these:
- Non-rendered whitespace-only text nodes
- Rendered whitespace-only text nodes between block-level elements
---
 Userland/Libraries/LibWeb/DOM/Node.cpp | 19 +++++++++++++++++++
 Userland/Libraries/LibWeb/DOM/Node.h   |  2 ++
 2 files changed, 21 insertions(+)

diff --git a/Userland/Libraries/LibWeb/DOM/Node.cpp b/Userland/Libraries/LibWeb/DOM/Node.cpp
index 29f3cfc7aa..08196e5352 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Node.cpp
@@ -676,6 +676,23 @@ RefPtr<Document> Node::owner_document() const
     return m_document;
 }
 
+// This function tells us whether a node is interesting enough to show up
+// in the DOM inspector. This hides two things:
+// - Non-rendered whitespace
+// - Rendered whitespace between block-level elements
+bool Node::is_uninteresting_whitespace_node() const
+{
+    if (!is<Text>(*this))
+        return false;
+    if (!static_cast<Text const&>(*this).data().is_whitespace())
+        return false;
+    if (!layout_node())
+        return true;
+    if (layout_node()->parent()->is_anonymous())
+        return true;
+    return false;
+}
+
 void Node::serialize_tree_as_json(JsonObjectSerializer<StringBuilder>& object) const
 {
     object.add("name", node_name().view());
@@ -702,6 +719,8 @@ void Node::serialize_tree_as_json(JsonObjectSerializer<StringBuilder>& object) c
     if (has_child_nodes()) {
         auto children = object.add_array("children");
         for_each_child([&children](DOM::Node& child) {
+            if (child.is_uninteresting_whitespace_node())
+                return;
             JsonObjectSerializer<StringBuilder> child_object = children.add_object();
             child.serialize_tree_as_json(child_object);
         });
diff --git a/Userland/Libraries/LibWeb/DOM/Node.h b/Userland/Libraries/LibWeb/DOM/Node.h
index cc4fa09e84..c8a85b88a6 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.h
+++ b/Userland/Libraries/LibWeb/DOM/Node.h
@@ -202,6 +202,8 @@ public:
 
     NonnullRefPtr<Node> get_root_node(GetRootNodeOptions const& options = {});
 
+    bool is_uninteresting_whitespace_node() const;
+
 protected:
     Node(Document&, NodeType);