fix(virtual-core): ignore stale connected measurements by LeoLB-Wang · Pull Request #1246 · TanStack/virtual

LeoLB-Wang · 2026-07-30T18:04:47Z

Changes

Ignore connected measured nodes whose data-index falls outside the current count before any key lookup or measurement callback.
Add a 22-to-1 count-shrink regression that independently exercises the ref and delayed ResizeObserver ingress paths.
Add a patch changeset for @tanstack/virtual-core.

Why

#1148 safely handles disconnected stale nodes. A node can also remain connected while React applies a count shrink; its old data-index can then reach getItemKey, which commonly indexes application data and may throw.

Testing

pnpm run test:pr
pnpm --filter @tanstack/virtual-core test:lib -- index.test.ts

Checklist

Followed the contributing guide.
Tested locally with pnpm run test:pr.
Added a changeset for the published package.

Summary by CodeRabbit

Bug Fixes
- Virtualized lists now safely ignore measurements from stale items after the item count decreases.
- Prevents invalid measurement updates and related errors from outdated connected elements.
- Improves stability when items are removed while their previous elements remain connected or trigger resize events.
- Ensures only currently valid items are measured and updated.
Tests
- Added regression coverage for stale measurements and resize events after list size changes.

coderabbitai · 2026-07-30T18:05:38Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: 585f50e2-d585-4f4e-b292-dfd867aa76e6

📥 Commits

Reviewing files that changed from the base of the PR and between c8c6fd2 and 3160b99.

📒 Files selected for processing (1)

packages/virtual-core/src/index.ts

🚧 Files skipped from review as they are similar to previous changes (1)

packages/virtual-core/src/index.ts

📝 Walkthrough

Walkthrough

Virtualizer measurement paths now ignore indexes outside the current item count. A regression test covers stale refs and delayed ResizeObserver callbacks after reducing count. A patch changeset documents the behavior.

Changes

Stale measurement handling

Layer / File(s)	Summary
Guard measurement indexes `packages/virtual-core/src/index.ts`, `.changeset/soft-tigers-sleep.md`	A shared range check makes ResizeObserver, direct measurement, and item resizing return early for invalid indexes. The changeset records a patch release.
Validate stale node handling `packages/virtual-core/tests/index.test.ts`	Regression coverage verifies that stale refs and late ResizeObserver callbacks do not access out-of-range item keys or throw after `count` shrinks.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the fix to ignore stale connected measurements in virtual-core.
Description check	✅ Passed	The description explains the change, motivation, tests, related issues, checklist, and changeset impact, but omits the explicit Release Impact section.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

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Create PR with unit tests

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Co-authored-by: Damian Pieczynski <piecyk@gmail.com>

coderabbitai

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@packages/virtual-core/src/index.ts`:
- Around line 492-495: Update the conditional in the surrounding index-handling
method to wrap the isIndexInRange(index) expression in parentheses, making the
if statement valid TypeScript while preserving its existing early-return
behavior.

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ℹ️ Review info

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Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 81b0b608-79f1-4e25-a759-8d899a35c5e8

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📒 Files selected for processing (1)

packages/virtual-core/src/index.ts

nx-cloud · 2026-07-31T03:34:38Z

View your CI Pipeline Execution ↗ for commit 3160b99

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`nx affected --targets=test:sherif,test:knip,tes...`	✅ Succeeded	4m 2s	View ↗
`nx run-many --target=build --exclude=examples/**`	✅ Succeeded	20s	View ↗

☁️ Nx Cloud last updated this comment at 2026-07-31 03:38:26 UTC

pkg-pr-new · 2026-07-31T03:35:02Z

More templates

@tanstack/angular-virtual

npm i https://pkg.pr.new/@tanstack/angular-virtual@1246

@tanstack/lit-virtual

npm i https://pkg.pr.new/@tanstack/lit-virtual@1246

@tanstack/marko-virtual

npm i https://pkg.pr.new/@tanstack/marko-virtual@1246

@tanstack/react-virtual

npm i https://pkg.pr.new/@tanstack/react-virtual@1246

@tanstack/solid-virtual

npm i https://pkg.pr.new/@tanstack/solid-virtual@1246

@tanstack/svelte-virtual

npm i https://pkg.pr.new/@tanstack/svelte-virtual@1246

@tanstack/virtual-core

npm i https://pkg.pr.new/@tanstack/virtual-core@1246

@tanstack/vue-virtual

npm i https://pkg.pr.new/@tanstack/vue-virtual@1246

commit: 3160b99

piecyk · 2026-07-31T03:46:09Z

Thanks @LeoLB-Wang

fix(virtual-core): ignore stale connected measurements

79f2ab7

piecyk reviewed Jul 30, 2026

View reviewed changes

Comment thread packages/virtual-core/src/index.ts Outdated

Apply suggestion from @piecyk

84175bb

Co-authored-by: Damian Pieczynski <piecyk@gmail.com>

coderabbitai Bot reviewed Jul 31, 2026

View reviewed changes

Comment thread packages/virtual-core/src/index.ts Outdated

LeoLB-Wang and others added 2 commits July 31, 2026 10:07

fix(virtual-core): restore stale index range helper

c8c6fd2

Simplify index range checks in index.ts

3160b99

piecyk merged commit d2cf98b into TanStack:main Jul 31, 2026
10 checks passed

github-actions Bot mentioned this pull request Jul 31, 2026

ci: Version Packages #1247

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fix(virtual-core): ignore stale connected measurements - #1246

fix(virtual-core): ignore stale connected measurements#1246
piecyk merged 4 commits into
TanStack:mainfrom
LeoLB-Wang:codex/fix-stale-index-measurement

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