From cbdd8b949aa481d91db03be4be05201a06cac74a Mon Sep 17 00:00:00 2001
From: ccschmitz <ccschmitz@gmail.com>
Date: Thu, 15 May 2025 06:23:50 -0500
Subject: [PATCH] Fix infinite loop in replaceActions

We were seeing issues getting into an infinite loop calling `splice` to reset actions (I believe only with large action sets). Replacing the array completely seems to get around this issue.
---
 packages/rrweb/src/replay/index.ts   |  7 +++--
 packages/rrweb/src/replay/machine.ts | 40 +++++++++++++++-------------
 packages/rrweb/src/replay/timer.ts   |  8 +++++-
 3 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/packages/rrweb/src/replay/index.ts b/packages/rrweb/src/replay/index.ts
index c84b9a70..248e6d8f 100644
--- a/packages/rrweb/src/replay/index.ts
+++ b/packages/rrweb/src/replay/index.ts
@@ -54,7 +54,6 @@ import type {
   incrementalData,
   Handler,
   Emitter,
-  metaEvent,
   mutationData,
   scrollData,
   inputData,
@@ -403,7 +402,7 @@ export class Replayer {
       (e) => e.type === EventType.FullSnapshot,
     );
     if (firstMeta) {
-      const { width, height } = firstMeta.data as metaEvent['data'];
+      const { width, height } = firstMeta.data ;
       setTimeout(() => {
         this.emitter.emit(ReplayerEvents.Resize, {
           width,
@@ -2019,7 +2018,7 @@ export class Replayer {
                 const svp = styleValues[s] as styleValueWithPriority;
                 targetEl.style.setProperty(s, svp[0], svp[1]);
               } else {
-                const svs = styleValues[s] as string;
+                const svs = styleValues[s] ;
                 targetEl.style.setProperty(s, svs);
               }
             }
@@ -2252,7 +2251,7 @@ export class Replayer {
     const adoptStyleSheets = (targetHost: Node, styleIds: number[]) => {
       const stylesToAdopt = styleIds
         .map((styleId) => this.styleMirror.getStyle(styleId))
-        .filter((style) => style !== null) as CSSStyleSheet[];
+        .filter((style) => style !== null);
       if (hasShadowRoot(targetHost))
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
         (targetHost as HTMLElement).shadowRoot!.adoptedStyleSheets =
diff --git a/packages/rrweb/src/replay/machine.ts b/packages/rrweb/src/replay/machine.ts
index 6f994c52..e8d7ebed 100644
--- a/packages/rrweb/src/replay/machine.ts
+++ b/packages/rrweb/src/replay/machine.ts
@@ -250,29 +250,31 @@ export function createPlayerService(
         }),
         /* Highlight Code Start */
         replaceEvents: assign((ctx, machineEvent) => {
+          if (machineEvent.type !== 'REPLACE_EVENTS') return ctx;
+
           const { events: curEvents, timer, baselineTime } = ctx;
-          if (machineEvent.type === 'REPLACE_EVENTS') {
-            const { events: newEvents } = machineEvent.payload;
-            curEvents.length = 0;
-            const actions: actionWithDelay[] = [];
-            for (const event of newEvents) {
-              addDelay(event, baselineTime);
-              curEvents.push(event);
-              if (event.timestamp >= timer.timeOffset + baselineTime) {
-                const castFn = getCastFn(event, false);
-                actions.push({
-                  doAction: () => {
-                    castFn();
-                  },
-                  delay: event.delay!,
-                });
-              }
-            }
+          const { events: newEvents } = machineEvent.payload;
+
+          if (newEvents.length === 0) return ctx;
+
+          curEvents.length = 0;
+          const actions: actionWithDelay[] = [];
+          const timeThreshold = timer.timeOffset + baselineTime;
 
-            if (timer.isActive()) {
-              timer.replaceActions(actions);
+          for (const event of newEvents) {
+            addDelay(event, baselineTime);
+            curEvents.push(event);
+            if (event.timestamp >= timeThreshold) {
+              actions.push({
+                doAction: getCastFn(event, false),
+                delay: event.delay!,
+              });
             }
           }
+
+          if (timer.isActive()) {
+            timer.replaceActions(actions);
+          }
           return { ...ctx, events: curEvents };
         }),
         /* Highlight Code End */
diff --git a/packages/rrweb/src/replay/timer.ts b/packages/rrweb/src/replay/timer.ts
index 2233e355..fa90c4a4 100644
--- a/packages/rrweb/src/replay/timer.ts
+++ b/packages/rrweb/src/replay/timer.ts
@@ -52,8 +52,14 @@ export class Timer {
   }
 
   public replaceActions(actions: actionWithDelay[]) {
+    const rafWasActive = this.raf === true;
+
     this.actions.length = 0;
-    this.actions.splice(0, 0, ...actions);
+    this.actions = [...actions];
+
+    if (rafWasActive) {
+      this.raf = requestAnimationFrame(this.rafCheck.bind(this));
+    }
   }
   /* End Highlight Code */