Fix callback ref cleanup compatibility across React 17–19#760
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thebuilder
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July 14, 2026 10:41
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Summary
ref(null)cleanup pathWhy
React 19 supports cleanup functions returned from callback refs, but React 17 and 18 treat that return value as invalid and emit diagnostics.
useOnInViewreturned its cleanup unconditionally even though all three React majors are supported peers.The private version gate is deliberately limited to
19.because that is the newest declared and tested peer major. This keeps React 19 merged-ref cleanup composition while falling back conservatively for older, future, and malformed version strings.The packed fixture only verifies the consumer packaging and bundler boundary. Runtime cleanup and diagnostics are exercised in real Chromium by the existing Vitest Browser suite, avoiding a separate JSDOM runtime harness.
Fixes #755.
Verification
corepack pnpm buildcorepack pnpm exec vitest run— 77 tests passedcorepack pnpm run compat:packed -- 17corepack pnpm run compat:packed -- 18corepack pnpm run compat:packed -- 19corepack pnpm exec tsc --noEmitcorepack pnpm exec biome check src/useOnInView.tsx src/refCleanupSupport.ts src/__tests__/useOnInView.test.tsx scripts/compat fixtures/react-compat package.jsoncorepack pnpm dlx github-actionlint .github/workflows/test.ymluseOnInView: 1.06 kB / 1.1 kB size limit