From e36f2bd697a6c33aaa480a332db15d884fdb6f83 Mon Sep 17 00:00:00 2001
From: Michael Dellanoce <mdellanoce@pendo.io>
Date: Wed, 30 Aug 2023 13:51:17 -0400
Subject: [PATCH 1/2] only call createHTMLDocument where it is needed

---
 packages/rrweb/src/record/mutation.ts | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/packages/rrweb/src/record/mutation.ts b/packages/rrweb/src/record/mutation.ts
index 097d1a8fd5..53eb072c86 100644
--- a/packages/rrweb/src/record/mutation.ts
+++ b/packages/rrweb/src/record/mutation.ts
@@ -497,14 +497,6 @@ export default class MutationBuffer {
     if (isIgnored(m.target, this.mirror)) {
       return;
     }
-    let unattachedDoc;
-    try {
-      // avoid upsetting original document from a Content Security point of view
-      unattachedDoc = document.implementation.createHTMLDocument();
-    } catch (e) {
-      // fallback to more direct method
-      unattachedDoc = this.doc;
-    }
     switch (m.type) {
       case 'characterData': {
         const value = m.target.textContent;
@@ -597,6 +589,14 @@ export default class MutationBuffer {
             value,
           );
           if (attributeName === 'style') {
+            let unattachedDoc;
+            try {
+              // avoid upsetting original document from a Content Security point of view
+              unattachedDoc = document.implementation.createHTMLDocument();
+            } catch (e) {
+              // fallback to more direct method
+              unattachedDoc = this.doc;
+            }
             const old = unattachedDoc.createElement('span');
             if (m.oldValue) {
               old.setAttribute('style', m.oldValue);

From 1ad42a7f331ab9409bdc21dc1b33ae77d46d10f6 Mon Sep 17 00:00:00 2001
From: Eoghan Murray <eoghan@getthere.ie>
Date: Mon, 9 Oct 2023 14:43:15 +0100
Subject: [PATCH 2/2] Perf: create the mutation document once as a 'singleton'
 as it can be reused

---
 packages/rrweb/src/record/mutation.ts | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/packages/rrweb/src/record/mutation.ts b/packages/rrweb/src/record/mutation.ts
index 53eb072c86..c947b7d304 100644
--- a/packages/rrweb/src/record/mutation.ts
+++ b/packages/rrweb/src/record/mutation.ts
@@ -188,6 +188,7 @@ export default class MutationBuffer {
   private shadowDomManager: observerParam['shadowDomManager'];
   private canvasManager: observerParam['canvasManager'];
   private processedNodeManager: observerParam['processedNodeManager'];
+  private unattachedDoc: HTMLDocument;
 
   public init(options: MutationBufferParam) {
     (
@@ -589,15 +590,17 @@ export default class MutationBuffer {
             value,
           );
           if (attributeName === 'style') {
-            let unattachedDoc;
-            try {
-              // avoid upsetting original document from a Content Security point of view
-              unattachedDoc = document.implementation.createHTMLDocument();
-            } catch (e) {
-              // fallback to more direct method
-              unattachedDoc = this.doc;
+            if (!this.unattachedDoc) {
+              try {
+                // avoid upsetting original document from a Content Security point of view
+                this.unattachedDoc =
+                  document.implementation.createHTMLDocument();
+              } catch (e) {
+                // fallback to more direct method
+                this.unattachedDoc = this.doc;
+              }
             }
-            const old = unattachedDoc.createElement('span');
+            const old = this.unattachedDoc.createElement('span');
             if (m.oldValue) {
               old.setAttribute('style', m.oldValue);
             }