fix #3493 (thanks, @Westbrook)

Gray Norton · Gray Norton · commit aebf233749b0 · 2022-12-14T16:33:27.000-08:00
diff --git a/.changeset/slimy-bees-appear.md b/.changeset/slimy-bees-appear.md
@@ -0,0 +1,5 @@
+---
+'@lit-labs/virtualizer': patch
+---
+
+Fix [#3493: Doesn't update on scroll when a clipping ancestor is in Shadow DOM](https://github.com/lit/lit/issues/3493)
diff --git a/packages/labs/virtualizer/src/Virtualizer.ts b/packages/labs/virtualizer/src/Virtualizer.ts
@@ -20,7 +20,11 @@ import {
   ScrollToCoordinates,
   BaseLayoutConfig,
 } from './layouts/shared/Layout.js';
-import {RangeChangedEvent, VisibilityChangedEvent, UnpinnedEvent} from './events.js';
+import {
+  RangeChangedEvent,
+  VisibilityChangedEvent,
+  UnpinnedEvent,
+} from './events.js';
 import {ScrollerController} from './ScrollerController.js';
 
 export const virtualizerRef = Symbol('virtualizerRef');
@@ -863,6 +867,9 @@ function getMarginValue(value: string): number {
 
 // TODO (graynorton): Deal with iframes?
 function getParentElement(el: Element) {
+  if (el.assignedSlot !== null) {
+    return el.assignedSlot;
+  }
   if (el.parentElement !== null) {
     return el.parentElement;
   }

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +'@lit-labs/virtualizer': patch
 +---
++
 +Fix [#3493: Doesn't update on scroll when a clipping ancestor is in Shadow DOM](https://github.com/lit/lit/issues/3493)