Fix: shadow dom bugs

packages/rrweb-snapshot/test/rebuild.test.ts

@@ -47,6 +47,37 @@ describe('rebuild', function () {
     });
   });
 
+  describe('shadowDom', function () {
+    it('rebuild shadowRoot without siblings', function () {
+      const node = buildNodeWithSN(
+        {
+          id: 1,
+          tagName: 'div',
+          type: NodeType.Element,
+          attributes: {},
+          childNodes: [
+            {
+              id: 2,
+              tagName: 'div',
+              type: NodeType.Element,
+              attributes: {},
+              childNodes: [],
+              isShadow: true,
+            },
+          ],
+          isShadowHost: true,
+        },
+        {
+          doc: document,
+          mirror,
+          hackCss: false,
+          cache,
+        },
+      ) as HTMLDivElement;
+      expect(node.shadowRoot?.childNodes.length).toBe(1);
+    });
+  });
+
   describe('add hover class to hover selector related rules', function () {
     it('will do nothing to css text without :hover', () => {
       const cssText = 'body { color: white }';

packages/rrweb/src/record/index.ts

@@ -4,7 +4,11 @@ import {
   SlimDOMOptions,
   createMirror,
 } from 'rrweb-snapshot';
-import { initObservers, mutationBuffers } from './observer';
+import {
+  initObservers,
+  mutationBuffers,
+  processedNodeManager,
+} from './observer';
 import {
   on,
   getWindowWidth,
@@ -316,6 +320,7 @@ function record<T = eventWithTime>(
       stylesheetManager,
       canvasManager,
       keepIframeSrcFn,
+      processedNodeManager,
     },
     mirror,
   });
@@ -526,6 +531,7 @@ function record<T = eventWithTime>(
           iframeManager,
           stylesheetManager,
           shadowDomManager,
+          processedNodeManager,
           canvasManager,
           ignoreCSSAttributes,
           plugins:

packages/rrweb/src/record/mutation.ts

@@ -26,6 +26,7 @@ import {
   hasShadowRoot,
   isSerializedIframe,
   isSerializedStylesheet,
+  inDom,
 } from '../utils';
 
 type DoubleLinkedListNode = {
@@ -175,6 +176,7 @@ export default class MutationBuffer {
   private stylesheetManager: observerParam['stylesheetManager'];
   private shadowDomManager: observerParam['shadowDomManager'];
   private canvasManager: observerParam['canvasManager'];
+  private processedNodeManager: observerParam['processedNodeManager'];
 
   public init(options: MutationBufferParam) {
     ([
@@ -198,6 +200,7 @@ export default class MutationBuffer {
       'stylesheetManager',
       'shadowDomManager',
       'canvasManager',
+      'processedNodeManager',
     ] as const).forEach((key) => {
       // just a type trick, the runtime result is correct
       this[key] = options[key] as never;
@@ -271,19 +274,8 @@ export default class MutationBuffer {
         (n.getRootNode() as ShadowRoot).host
       )
         shadowHost = (n.getRootNode() as ShadowRoot).host;
-      // If n is in a nested shadow dom.
-      let rootShadowHost = shadowHost;
-      while (
-        rootShadowHost?.getRootNode?.()?.nodeType ===
-          Node.DOCUMENT_FRAGMENT_NODE &&
-        (rootShadowHost.getRootNode() as ShadowRoot).host
-      )
-        rootShadowHost = (rootShadowHost.getRootNode() as ShadowRoot).host;
-      // ensure contains is passed a Node, or it will throw an error
-      const notInDoc =
-        !this.doc.contains(n) &&
-        (!rootShadowHost || !this.doc.contains(rootShadowHost));
-      if (!n.parentNode || notInDoc) {
+
+      if (!n.parentNode || !inDom(n)) {
         return;
       }
       const parentId = isShadowRoot(n.parentNode)
@@ -647,6 +639,9 @@ export default class MutationBuffer {
    * Make sure you check if `n`'s parent is blocked before calling this function
    * */
   private genAdds = (n: Node, target?: Node) => {
+    // this node was already recorded in other buffer, ignore it
+    if (this.processedNodeManager.inOtherBuffer(n, this)) return;
+
     if (this.mirror.hasNode(n)) {
       if (isIgnored(n, this.mirror)) {
         return;
@@ -666,8 +661,15 @@ export default class MutationBuffer {
 
     // if this node is blocked `serializeNode` will turn it into a placeholder element
     // but we have to remove it's children otherwise they will be added as placeholders too
-    if (!isBlocked(n, this.blockClass, this.blockSelector, false))
+    if (!isBlocked(n, this.blockClass, this.blockSelector, false)) {
       n.childNodes.forEach((childN) => this.genAdds(childN));
+      if (hasShadowRoot(n)) {
+        n.shadowRoot.childNodes.forEach((childN) => {
+          this.processedNodeManager.add(childN, this);
+          this.genAdds(childN, n);
+        });
+      }
+    }
   };
 }
 

packages/rrweb/src/record/observer.ts

@@ -40,6 +40,7 @@ import {
   selectionCallback,
 } from '@rrweb/types';
 import MutationBuffer from './mutation';
+import ProcessedNodeManager from './processed-node-manager';
 
 type WindowWithStoredMutationObserver = IWindow & {
   __rrMutationObserver?: MutationObserver;
@@ -51,6 +52,7 @@ type WindowWithAngularZone = IWindow & {
 };
 
 export const mutationBuffers: MutationBuffer[] = [];
+export const processedNodeManager = new ProcessedNodeManager();
 
 const isCSSGroupingRuleSupported = typeof CSSGroupingRule !== 'undefined';
 const isCSSMediaRuleSupported = typeof CSSMediaRule !== 'undefined';

packages/rrweb/src/record/processed-node-manager.ts

@@ -0,0 +1,34 @@
+import type MutationBuffer from './mutation';
+
+/**
+ * Keeps a log of nodes that could show up in multiple mutation buffer but shouldn't be handled twice.
+ */
+export default class ProcessedNodeManager {
+  private nodeMap: WeakMap<Node, Set<MutationBuffer>> = new WeakMap();
+
+  constructor() {
+    this.periodicallyClear();
+  }
+
+  private periodicallyClear() {
+    requestAnimationFrame(() => {
+      this.clear();
+      this.periodicallyClear();
+    });
+  }
+
+  public inOtherBuffer(node: Node, thisBuffer: MutationBuffer) {
+    const buffers = this.nodeMap.get(node);
+    return (
+      buffers && Array.from(buffers).some((buffer) => buffer !== thisBuffer)
+    );
+  }
+
+  public add(node: Node, buffer: MutationBuffer) {
+    this.nodeMap.set(node, (this.nodeMap.get(node) || new Set()).add(buffer));
+  }
+
+  private clear() {
+    this.nodeMap = new WeakMap();
+  }
+}

packages/rrweb/src/record/shadow-dom-manager.ts

@@ -9,7 +9,7 @@ import {
   initScrollObserver,
   initAdoptedStyleSheetObserver,
 } from './observer';
-import { patch } from '../utils';
+import { patch, inDom } from '../utils';
 import type { Mirror } from 'rrweb-snapshot';
 import { isNativeShadowDom } from 'rrweb-snapshot';
 
@@ -49,7 +49,11 @@ export class ShadowDomManager {
         function (original: (init: ShadowRootInit) => ShadowRoot) {
           return function (this: HTMLElement, option: ShadowRootInit) {
             const shadowRoot = original.call(this, option);
-            if (this.shadowRoot)
+
+            // For the shadow dom elements in the document, monitor their dom mutations.
+            // For shadow dom elements that aren't in the document yet,
+            // we start monitoring them once their shadow dom host is appended to the document.
+            if (this.shadowRoot && inDom(this))
               manager.addShadowRoot(this.shadowRoot, this.ownerDocument);
             return shadowRoot;
           };

packages/rrweb/src/types.ts

@@ -37,6 +37,7 @@ import type {
   styleSheetRuleCallback,
   viewportResizeCallback,
 } from '@rrweb/types';
+import type ProcessedNodeManager from './record/processed-node-manager';
 
 export type recordOptions<T> = {
   emit?: (e: T, isCheckout?: boolean) => void;
@@ -105,6 +106,7 @@ export type observerParam = {
   stylesheetManager: StylesheetManager;
   shadowDomManager: ShadowDomManager;
   canvasManager: CanvasManager;
+  processedNodeManager: ProcessedNodeManager;
   ignoreCSSAttributes: Set<string>;
   plugins: Array<{
     observer: (
@@ -139,6 +141,7 @@ export type MutationBufferParam = Pick<
   | 'stylesheetManager'
   | 'shadowDomManager'
   | 'canvasManager'
+  | 'processedNodeManager'
 >;
 
 export type ReplayPlugin = {

packages/rrweb/src/utils.ts

@@ -518,3 +518,30 @@ export class StyleSheetMirror {
     return this.id++;
   }
 }
+
+export function getRootShadowHost(n: Node): Node | null {
+  const shadowHost = (n.getRootNode() as ShadowRoot).host;
+  // If n is in a nested shadow dom.
+  let rootShadowHost = shadowHost;
+
+  while (
+    rootShadowHost?.getRootNode?.()?.nodeType === Node.DOCUMENT_FRAGMENT_NODE &&
+    (rootShadowHost.getRootNode() as ShadowRoot).host
+  )
+    rootShadowHost = (rootShadowHost.getRootNode() as ShadowRoot).host;
+
+  return rootShadowHost;
+}
+
+export function shadowHostInDom(n: Node): boolean {
+  const doc = n.ownerDocument;
+  if (!doc) return false;
+  const shadowHost = getRootShadowHost(n);
+  return Boolean(shadowHost && doc.contains(shadowHost));
+}
+
+export function inDom(n: Node): boolean {
+  const doc = n.ownerDocument;
+  if (!doc) return false;
+  return doc.contains(n) || shadowHostInDom(n);
+}