Performance refactor to avoid 2 function calls (bridging between rrweb-io#1543 and rrweb-io#1652)

Author: eoghanmurray

.changeset/removes-and-descendants.md

@@ -0,0 +1,5 @@
+---
+"rrweb": patch
+---
+
+Performance refactor to avoid 2 function calls (bridging between #1543 and #1652)

packages/rrweb/src/record/mutation.ts

@@ -6,7 +6,6 @@ import {
   isShadowRoot,
   needMaskingText,
   maskInputValue,
-  Mirror,
   isNativeShadowDom,
   getInputType,
   toLowerCase,
@@ -169,7 +168,7 @@ export default class MutationBuffer {
   private addedSet = new Set<Node>();
   private movedSet = new Set<Node>();
   private droppedSet = new Set<Node>();
-  private removesSubTreeCache = new Set<Node>();
+  private removesAndDescendants = new Set<Node>();
 
   private mutationCb: observerParam['mutationCb'];
   private blockClass: observerParam['blockClass'];
@@ -367,9 +366,11 @@ export default class MutationBuffer {
     }
 
     for (const n of this.movedSet) {
+      const movedParent = dom.parentNode(n);
       if (
-        isParentRemoved(this.removesSubTreeCache, n, this.mirror) &&
-        !this.movedSet.has(dom.parentNode(n)!)
+        movedParent && // can't be removed if it doesn't exist
+        this.removesAndDescendants.has(movedParent) &&
+        !this.movedSet.has(movedParent)
       ) {
         continue;
       }
@@ -379,7 +380,7 @@ export default class MutationBuffer {
     for (const n of this.addedSet) {
       if (
         !isAncestorInSet(this.droppedSet, n) &&
-        !isParentRemoved(this.removesSubTreeCache, n, this.mirror)
+        !this.removesAndDescendants.has(dom.parentNode(n)!)
       ) {
         pushAdd(n);
       } else if (isAncestorInSet(this.movedSet, n)) {
@@ -515,7 +516,7 @@ export default class MutationBuffer {
     this.addedSet = new Set<Node>();
     this.movedSet = new Set<Node>();
     this.droppedSet = new Set<Node>();
-    this.removesSubTreeCache = new Set<Node>();
+    this.removesAndDescendants = new Set<Node>();
     this.movedMap = {};
 
     this.mutationCb(payload);
@@ -750,7 +751,7 @@ export default class MutationBuffer {
                   ? true
                   : undefined,
             });
-            processRemoves(n, this.removesSubTreeCache);
+            populateWithDescendants(n, this.removesAndDescendants);
           }
           this.mapRemoves.push(n);
         });
@@ -814,35 +815,20 @@ function deepDelete(addsSet: Set<Node>, n: Node) {
   dom.childNodes(n).forEach((childN) => deepDelete(addsSet, childN));
 }
 
-function processRemoves(n: Node, cache: Set<Node>) {
+function populateWithDescendants(n: Node, s: Set<Node>) {
   const queue = [n];
 
   while (queue.length) {
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     const next = queue.pop()!;
-    if (cache.has(next)) continue;
-    cache.add(next);
+    if (s.has(next)) continue;
+    s.add(next);
     dom.childNodes(next).forEach((n) => queue.push(n));
   }
 
   return;
 }
 
-function isParentRemoved(removes: Set<Node>, n: Node, mirror: Mirror): boolean {
-  if (removes.size === 0) return false;
-  return _isParentRemoved(removes, n, mirror);
-}
-
-function _isParentRemoved(
-  removes: Set<Node>,
-  n: Node,
-  _mirror: Mirror,
-): boolean {
-  const node: ParentNode | null = dom.parentNode(n);
-  if (!node) return false;
-  return removes.has(node);
-}
-
 function isAncestorInSet(set: Set<Node>, n: Node): boolean {
   if (set.size === 0) return false;
   return _isAncestorInSet(set, n);