fix(noUnknownAttribute): recognize React 19 transition events by ternaus · Pull Request #12089 · biomejs/biome

ternaus · 2026-10-02T18:30:02Z

Summary

Fixes #12088.

noUnknownAttribute reports valid React 19 transition event handlers as unknown. Accept onTransitionCancel, onTransitionRun, onTransitionStart, and their capture variants when the React dependency range permits React 19 or later. React 18, misspellings, and unsupported animation-cancel handlers retain diagnostics.

Implementation, fixtures, documentation, and this description were prepared with Codex.

Test Plan

Regression fails without the fix; all 20 no_unknown_attribute spec tests pass.
INSTA_UPDATE=no cargo test -p biome_js_analyze -- --skip specs::correctness::no_unused_variables::invalid_vue_slot_typed_props_vue: 3,552 tests passed, three ignored, one filtered out. The excluded Vue snapshot has a whitespace mismatch that also fails on the unmodified upstream base 8cfb219c02; its snapshot is unchanged in this PR.
just f and workspace just l pass.

Docs

Rule rustdoc describes the React 19 manifest requirement. A patch changeset links the issue.

changeset-bot · 2026-10-02T18:30:07Z

🦋 Changeset detected

Latest commit: 668b65c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/wasm-web	Patch
@biomejs/backend-jsonrpc	Patch

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agentscanapp · 2026-10-02T18:30:08Z

A maintainer will take a look as soon as they can. In the meantime, please make sure that:

the description follows our PR template
any related issues are linked
existing tests still pass

Copilot

Copilot review overview

🟢 Approval recommended

The version-gated implementation matches React 19 behavior and has focused positive and negative regression coverage.

Review effort: Balanced
Findings: None

What changed in this PR

Updates noUnknownAttribute to recognize React 19 transition event handlers while preserving diagnostics for earlier React versions and invalid names.

Changes:

Adds version-gated transition handler recognition.
Adds React 18/19 regression fixtures and snapshots.
Updates rule documentation and release notes.

File	Description
`.changeset/swift-phones-lead.md`	Documents the user-facing bug fix.
`crates/biome_js_analyze/src/lint/suspicious/no_unknown_attribute.rs`	Adds React 19 transition props and documentation.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_18_transition_events/invalid.package.json`	Configures the React 18 test.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_18_transition_events/invalid.jsx`	Tests rejection under React 18.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_18_transition_events/invalid.jsx.snap`	Records React 18 diagnostics.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/valid.package.json`	Configures the valid React 19 test.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/valid.jsx`	Tests accepted React 19 handlers.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/valid.jsx.snap`	Records diagnostic-free output.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/invalid.package.json`	Configures invalid React 19 cases.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/invalid.jsx`	Tests misspellings and unsupported handlers.
`crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/invalid.jsx.snap`	Records expected React 19 diagnostics.

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coderabbitai · 2026-10-02T18:35:37Z

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Configuration used: Repository: biomejs/biome/.coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between 4c1612b and 668b65c.

⛔ Files ignored due to path filters (3)

crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_18_transition_events/invalid.jsx.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/invalid.jsx.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/valid.jsx.snap is excluded by !**/*.snap and included by **

📒 Files selected for processing (8)

.changeset/swift-phones-lead.md
crates/biome_js_analyze/src/lint/suspicious/no_unknown_attribute.rs
crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_18_transition_events/invalid.jsx
crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_18_transition_events/invalid.package.json
crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/invalid.jsx
crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/invalid.package.json
crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/valid.jsx
crates/biome_js_analyze/tests/specs/suspicious/noUnknownAttribute/react_19_transition_events/valid.package.json

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Walkthrough

The rule’s React 19+ lookup now recognises six transition event handlers, including capture variants. New fixtures cover React 18 and React 19 dependency versions, with valid and invalid JSX attributes. A patch changeset describes the update.

Priority: ⬇️ Low

Change: Bug fix · Severity of issue fixed: Low

Merge Risk: ⚪ Minimal · up to 668b6

The change recognizes the React 19 transition handlers while retaining diagnostics for malformed spellings and React 18. No concrete merge-blocking issue remains.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: recognising React 19 transition events in `noUnknownAttribute`.
Description check	✅ Passed	The description directly explains the React 19 event-handler fix, retained diagnostics, implementation, tests, and documentation.
Linked Issues check	✅ Passed	The PR meets the coding requirements in issue `#12088`. `no_unknown_attribute.rs` adds the six transition event names and their capture variants to the React 19+ case-insensitive lookup. The React 19 va…
Out of Scope Changes check	✅ Passed	The changes stay within issue `#12088`. The rule update, React 18 and React 19 fixtures, test manifests, rustdoc, and patch changeset all support the requested recognition and regression coverage. No un…

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codspeed · 2026-10-02T18:56:41Z

Merging this PR will not alter performance

✅ 113 untouched benchmarks
⏩ 298 skipped benchmarks¹

_{Comparing ternaus:codex/react19-transition-events (668b65c) with main (8cfb219)}

298 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

dyc3

This is fine. There's some other refactors that should happen in this rule that I'll handle. Thank you.

ternaus added 2 commits October 2, 2026 19:03

fix(lint): recognize React 19 transition event handlers

d89ef8e

docs(changeset): link transition handler issue

668b65c

Copilot AI balanced review requested due to automatic review settings October 2, 2026 18:30

github-actions Bot added A-Linter Area: linter L-JavaScript Language: JavaScript and super languages labels Oct 2, 2026

Copilot started reviewing on behalf of ternaus October 2, 2026 18:30

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dyc3 approved these changes Oct 2, 2026

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dyc3 merged commit dba2a37 into biomejs:main Oct 2, 2026
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github-actions Bot mentioned this pull request Oct 2, 2026

ci: release #12065

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fix(noUnknownAttribute): recognize React 19 transition events - #12089

fix(noUnknownAttribute): recognize React 19 transition events#12089
dyc3 merged 2 commits into
biomejs:mainfrom
ternaus:codex/react19-transition-events

ternaus commented Oct 2, 2026

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ternaus commented Oct 2, 2026

Summary

Test Plan

Docs

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changeset-bot Bot commented Oct 2, 2026

🦋 Changeset detected

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🟢 Approval recommended

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coderabbitai Bot commented Oct 2, 2026

Walkthrough

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codspeed Bot commented Oct 2, 2026

Merging this PR will not alter performance

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