From 31297557cfaa11a8c7ccc9364249adfaff167a79 Mon Sep 17 00:00:00 2001
From: Michael Dellanoce <mdellanoce@pendo.io>
Date: Wed, 6 Dec 2023 11:28:15 -0500
Subject: [PATCH] optimize isParentRemoved for large remove lists

---
 .changeset/late-keys-whisper.md       |  5 +++++
 packages/rrweb/src/record/mutation.ts | 19 +++++++++++--------
 2 files changed, 16 insertions(+), 8 deletions(-)
 create mode 100644 .changeset/late-keys-whisper.md

diff --git a/.changeset/late-keys-whisper.md b/.changeset/late-keys-whisper.md
new file mode 100644
index 0000000000..daf97ae1dc
--- /dev/null
+++ b/.changeset/late-keys-whisper.md
@@ -0,0 +1,5 @@
+---
+'rrweb': patch
+---
+
+Optimize isParentRemoved for large remove lists
diff --git a/packages/rrweb/src/record/mutation.ts b/packages/rrweb/src/record/mutation.ts
index d08c2c7892..083b878d0d 100644
--- a/packages/rrweb/src/record/mutation.ts
+++ b/packages/rrweb/src/record/mutation.ts
@@ -144,6 +144,7 @@ export default class MutationBuffer {
   private attributes: attributeCursor[] = [];
   private attributeMap = new WeakMap<Node, attributeCursor>();
   private removes: removedNodeMutation[] = [];
+  private removesMap = new Map<number, number>();
   private mapRemoves: Node[] = [];
 
   private movedMap: Record<string, true> = {};
@@ -358,7 +359,7 @@ export default class MutationBuffer {
 
     for (const n of this.movedSet) {
       if (
-        isParentRemoved(this.removes, n, this.mirror) &&
+        isParentRemoved(this.removesMap, n, this.mirror) &&
         !this.movedSet.has(n.parentNode!)
       ) {
         continue;
@@ -369,7 +370,7 @@ export default class MutationBuffer {
     for (const n of this.addedSet) {
       if (
         !isAncestorInSet(this.droppedSet, n) &&
-        !isParentRemoved(this.removes, n, this.mirror)
+        !isParentRemoved(this.removesMap, n, this.mirror)
       ) {
         pushAdd(n);
       } else if (isAncestorInSet(this.movedSet, n)) {
@@ -498,6 +499,7 @@ export default class MutationBuffer {
     this.attributes = [];
     this.attributeMap = new WeakMap<Node, attributeCursor>();
     this.removes = [];
+    this.removesMap = new Map<number, number>();
     this.addedSet = new Set<Node>();
     this.movedSet = new Set<Node>();
     this.droppedSet = new Set<Node>();
@@ -709,6 +711,7 @@ export default class MutationBuffer {
                   ? true
                   : undefined,
             });
+            this.removesMap.set(nodeId, this.removes.length - 1);
           }
           this.mapRemoves.push(n);
         });
@@ -778,16 +781,16 @@ function deepDelete(addsSet: Set<Node>, n: Node) {
 }
 
 function isParentRemoved(
-  removes: removedNodeMutation[],
+  removesMap: Map<number, number>,
   n: Node,
   mirror: Mirror,
 ): boolean {
-  if (removes.length === 0) return false;
-  return _isParentRemoved(removes, n, mirror);
+  if (removesMap.size === 0) return false;
+  return _isParentRemoved(removesMap, n, mirror);
 }
 
 function _isParentRemoved(
-  removes: removedNodeMutation[],
+  removesMap: Map<number, number>,
   n: Node,
   mirror: Mirror,
 ): boolean {
@@ -796,10 +799,10 @@ function _isParentRemoved(
     return false;
   }
   const parentId = mirror.getId(parentNode);
-  if (removes.some((r) => r.id === parentId)) {
+  if (removesMap.has(parentId)) {
     return true;
   }
-  return _isParentRemoved(removes, parentNode, mirror);
+  return _isParentRemoved(removesMap, parentNode, mirror);
 }
 
 function isAncestorInSet(set: Set<Node>, n: Node): boolean {