From 67554c33cce46ec712ba6b7d077036971eee0b4e Mon Sep 17 00:00:00 2001
From: Justin Halsall <Juice10@users.noreply.github.com>
Date: Wed, 1 Apr 2026 12:00:00 +0800
Subject: [PATCH] Apply textContent on flush (#865)

* Apply textContent on flush

* fix typo

* Style sheet rules applied after <style>'s textContent override should work
---
 packages/rrweb/src/replay/index.ts            | 32 ++++++++++++++-
 .../test/__snapshots__/replayer.test.ts.snap  | 12 +++---
 .../test/events/style-sheet-rule-events.ts    | 40 +++++++++++++++++--
 packages/rrweb/test/replayer.test.ts          | 30 ++++++++++++++
 4 files changed, 102 insertions(+), 12 deletions(-)

diff --git a/packages/rrweb/src/replay/index.ts b/packages/rrweb/src/replay/index.ts
index 794a61b3..df567b3a 100644
--- a/packages/rrweb/src/replay/index.ts
+++ b/packages/rrweb/src/replay/index.ts
@@ -40,6 +40,7 @@ import {
   mouseMovePos,
   IWindow,
   canvasMutationCommand,
+  textMutation,
 } from '../types';
 import {
   createMirror,
@@ -171,11 +172,17 @@ export class Replayer {
     this.virtualStyleRulesMap = new Map();
 
     this.emitter.on(ReplayerEvents.Flush, () => {
-      const { scrollMap, inputMap } = this.treeIndex.flush();
+      const { scrollMap, inputMap, mutationData } = this.treeIndex.flush();
 
       this.fragmentParentMap.forEach((parent, frag) =>
         this.restoreRealParent(frag, parent),
       );
+      // apply text needs to happen before virtual style rules gets applied
+      // as it can overwrite the contents of a stylesheet
+      for (const d of mutationData.texts) {
+        this.applyText(d, mutationData);
+      }
+
       for (const node of this.virtualStyleRulesMap.keys()) {
         // restore css rules of style elements after they are mounted
         this.restoreNodeSheet(node);
@@ -896,7 +903,16 @@ export class Replayer {
       case IncrementalSource.Mutation: {
         if (isSync) {
           d.adds.forEach((m) => this.treeIndex.add(m));
-          d.texts.forEach((m) => this.treeIndex.text(m));
+          d.texts.forEach((m) => {
+            const target = this.mirror.getNode(m.id);
+            const parent = (target?.parentNode as unknown) as INode | null;
+            // remove any style rules that pending
+            // for stylesheets where the contents get replaced
+            if (parent && this.virtualStyleRulesMap.has(parent))
+              this.virtualStyleRulesMap.delete(parent);
+
+            this.treeIndex.text(m);
+          });
           d.attributes.forEach((m) => this.treeIndex.attribute(m));
           d.removes.forEach((m) => this.treeIndex.remove(m, this.mirror));
         }
@@ -1677,6 +1693,18 @@ export class Replayer {
     }
   }
 
+  private applyText(d: textMutation, mutation: mutationData) {
+    const target = this.mirror.getNode(d.id);
+    if (!target) {
+      return this.debugNodeNotFound(mutation, d.id);
+    }
+    try {
+      ((target as Node) as HTMLElement).textContent = d.value;
+    } catch (error) {
+      // for safe
+    }
+  }
+
   private legacy_resolveMissingNode(
     map: missingNodeMap,
     parent: Node,
diff --git a/packages/rrweb/test/__snapshots__/replayer.test.ts.snap b/packages/rrweb/test/__snapshots__/replayer.test.ts.snap
index 677562cf..c471f9d9 100644
--- a/packages/rrweb/test/__snapshots__/replayer.test.ts.snap
+++ b/packages/rrweb/test/__snapshots__/replayer.test.ts.snap
@@ -56,27 +56,27 @@ html.rrweb-paused *, html.rrweb-paused ::before, html.rrweb-paused ::after { ani
 file-cid-1
 @charset \\"utf-8\\";
 
-.c011xx { padding: 1.3125rem; flex: 0 0 auto; width: 100%; }
+.css-added-at-500 { padding: 1.3125rem; flex: 0 0 auto; width: 100%; }
 
 
 file-cid-2
 @charset \\"utf-8\\";
 
-.c01x { opacity: 1; transform: translateX(0px); }
+.css-added-at-200-overwritten-at-3000 { opacity: 1; transform: translateX(0px); }
 
-.css-added-at-400 { border: 1px solid blue; }
+.css-added-at-400-overwritten-at-3000 { border: 1px solid blue; }
 
 
 file-cid-3
 @charset \\"utf-8\\";
 
-.css-1uxxxx3 { position: fixed; top: 0px; right: 0px; left: 4rem; z-index: 15; flex-shrink: 0; height: 0.25rem; overflow: hidden; background-color: rgb(17, 171, 209); }
+.css-added-at-200 { position: fixed; top: 0px; right: 0px; left: 4rem; z-index: 15; flex-shrink: 0; height: 0.25rem; overflow: hidden; background-color: rgb(17, 171, 209); }
 
-.css-1c9xxxx { height: 0.25rem; background-color: rgb(190, 232, 242); opacity: 0; transition: opacity 0.5s ease 0s; }
+.css-added-at-200.alt { height: 0.25rem; background-color: rgb(190, 232, 242); opacity: 0; transition: opacity 0.5s ease 0s; }
 
 .css-added-at-1000-deleted-at-2500 { display: flex; flex-direction: column; min-width: 60rem; min-height: 100vh; color: blue; }
 
-.css-lsxxx { padding-left: 4rem; }
+.css-added-at-200.alt2 { padding-left: 4rem; }
 "
 `;
 
diff --git a/packages/rrweb/test/events/style-sheet-rule-events.ts b/packages/rrweb/test/events/style-sheet-rule-events.ts
index 0e266739..0536ea56 100644
--- a/packages/rrweb/test/events/style-sheet-rule-events.ts
+++ b/packages/rrweb/test/events/style-sheet-rule-events.ts
@@ -54,7 +54,7 @@ const events: eventWithTime[] = [
                         type: 3,
                         isStyle: true,
                         textContent:
-                          '\n.c01x {\n  opacity: 1;\n  transform: translateX(0);\n}\n',
+                          '\n.css-added-at-200-overwritten-at-3000 {\n  opacity: 1;\n  transform: translateX(0);\n}\n',
                       },
                     ],
                   },
@@ -64,7 +64,7 @@ const events: eventWithTime[] = [
                     tagName: 'style',
                     attributes: {
                       _cssText:
-                        '.css-1uxxxx3 { position: fixed; top: 0px; right: 0px; left: 4rem; z-index: 15; flex-shrink: 0; height: 0.25rem; overflow: hidden; background-color: rgb(17, 171, 209); }.css-1c9xxxx { height: 0.25rem; background-color: rgb(190, 232, 242); opacity: 0; transition: opacity 0.5s ease 0s; }.css-lsxxx { padding-left: 4rem; }',
+                        '.css-added-at-200 { position: fixed; top: 0px; right: 0px; left: 4rem; z-index: 15; flex-shrink: 0; height: 0.25rem; overflow: hidden; background-color: rgb(17, 171, 209); }.css-added-at-200.alt { height: 0.25rem; background-color: rgb(190, 232, 242); opacity: 0; transition: opacity 0.5s ease 0s; }.css-added-at-200.alt2 { padding-left: 4rem; }',
                       'data-emotion': 'css',
                     },
                     childNodes: [
@@ -111,7 +111,8 @@ const events: eventWithTime[] = [
       id: 101,
       adds: [
         {
-          rule: '.css-added-at-400{border: 1px solid blue;}',
+          rule:
+            '.css-added-at-400-overwritten-at-3000 {border: 1px solid blue;}',
           index: 1,
         },
       ],
@@ -141,7 +142,7 @@ const events: eventWithTime[] = [
             type: 3,
             isStyle: true,
             textContent:
-              '\n.c011xx {\n  padding: 1.3125rem;\n  flex: none;\n  width: 100%;\n}\n',
+              '\n.css-added-at-500 {\n  padding: 1.3125rem;\n  flex: none;\n  width: 100%;\n}\n',
           },
           nextId: null,
           parentId: 255,
@@ -184,6 +185,37 @@ const events: eventWithTime[] = [
     type: EventType.IncrementalSnapshot,
     timestamp: now + 2500,
   },
+  // overwrite all contents of stylesheet
+  {
+    data: {
+      texts: [
+        {
+          id: 102,
+          value: '.all-css-overwritten-at-3000 { color: indigo; }',
+        },
+      ],
+      attributes: [],
+      removes: [],
+      adds: [],
+      source: IncrementalSource.Mutation,
+    },
+    type: EventType.IncrementalSnapshot,
+    timestamp: now + 3000,
+  },
+  {
+    data: {
+      id: 101,
+      adds: [
+        {
+          rule: '.css-added-at-3100{color:blue;}',
+          index: 1,
+        },
+      ],
+      source: IncrementalSource.StyleSheetRule,
+    },
+    type: EventType.IncrementalSnapshot,
+    timestamp: now + 3100,
+  },
 ];
 
 export default events;
diff --git a/packages/rrweb/test/replayer.test.ts b/packages/rrweb/test/replayer.test.ts
index cd35fb2a..b563732f 100644
--- a/packages/rrweb/test/replayer.test.ts
+++ b/packages/rrweb/test/replayer.test.ts
@@ -223,6 +223,36 @@ describe('replayer', function () {
     expect(result).toEqual(false);
   });
 
+  it("should overwrite all StyleSheetRules by replacing style element's textContent while fast-forwarding", async () => {
+    await page.evaluate(`events = ${JSON.stringify(styleSheetRuleEvents)}`);
+    const result = await page.evaluate(`
+      const { Replayer } = rrweb;
+      const replayer = new Replayer(events);
+      replayer.pause(3500);
+      const rules = [...replayer.iframe.contentDocument.styleSheets].map(
+        (sheet) => [...sheet.rules],
+      ).flat();
+      rules.some((x) => x.selectorText === '.css-added-at-200-overwritten-at-3000');
+    `);
+
+    expect(result).toEqual(false);
+  });
+
+  it('should apply fast-forwarded StyleSheetRules that came after stylesheet textContent overwrite', async () => {
+    await page.evaluate(`events = ${JSON.stringify(styleSheetRuleEvents)}`);
+    const result = await page.evaluate(`
+      const { Replayer } = rrweb;
+      const replayer = new Replayer(events);
+      replayer.pause(3500);
+      const rules = [...replayer.iframe.contentDocument.styleSheets].map(
+        (sheet) => [...sheet.rules],
+      ).flat();
+      rules.some((x) => x.selectorText === '.css-added-at-3100');
+    `);
+
+    expect(result).toEqual(true);
+  });
+
   it('can fast-forward mutation events containing nested iframe elements', async () => {
     await page.evaluate(`
       events = ${JSON.stringify(iframeEvents)};