fix: blur active element before component update during navigation#15452
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fix: blur active element before component update during navigation#15452MathiasWP wants to merge 2 commits intosveltejs:mainfrom
MathiasWP wants to merge 2 commits intosveltejs:mainfrom
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🦋 Changeset detectedLatest commit: 3894e26 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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…veltejs#14575) Blur the active element before `root.$set()` so that blur/focusout handlers fire while the old component's data is still valid. Previously, data was nulled out before blur fired, causing TypeErrors in blur handlers that accessed component data. Guarded by `!keepfocus` and only applies when the active element is not the body. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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The svelte-check type checker flags `window.__blur_test_result` as an error since the property doesn't exist on the Window type. Use the same `/** @type {any} */ (window)` cast pattern used in the test file. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Closes #14575
Summary
root.$set()so that blur/focusout handlers fire while the old component's data is still validroot.$set()would null out component data before the browser firedbluron the old active element, causingTypeError: Cannot set properties of undefinedin blur handlers that accesseddatagoto()and popstate (back button) navigation pathsEdge case analysis
Safe — no breakage expected
<body>after navigation (reset_focus()). The blur just fires slightly earlier now.keepFocus: true: Guarded by!keepfocus— no change in behavior.activeElement !== document.body— no spurious blur fires.reset_focus()still runs after component update.Edge cases (low risk)
goto(): The existingnav_tokensystem will abort the original navigation. This is already possible today — the fix just means blur fires slightly earlier, so such navigations could cancel more often. Very uncommon pattern and already fragile.alert()/confirm(): These block the JS thread, delaying navigation. Same behavior as before, just fires at a slightly different time.root.$set(), mutations could theoretically conflict — but Svelte's component update replaces the DOM anyway, so this is safe in practice.Test plan
pnpm buildpassesblur handler can access data during navigation(goto path)blur handler can access data during popstate navigation(back button path)pnpm -F @sveltejs/kit test:unit— no regressions (447 passed)🤖 Generated with Claude Code