fix(auto-resize): stop re-dispatching input event on programmatic value writes#3206
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segunadebayo merged 3 commits intoJul 20, 2026
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Add basic/controlled autoresize examples for Nuxt, Solid, Svelte, and Preact, plus Playwright tests for typing and paste. Also set the Svelte app document title.
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Closes #3204
📝 Description
autoresizeTextareaoverrides the element'svaluesetter and re-dispatches a bubblinginputevent on every programmatic value change. React writes.valueprogrammatically when reconciling controlled inputs and relies on those writes being side-effect-free, so the synthesized event fires the framework'sonChangea second time with the value React just restored, reverting the controlled state.The synthetic event was added in 5bd226d (
fix: autoresize + input event) to work around a real bug: the override reads thevaluedescriptor from the prototype but defines the property on the element, which clobbers the own-property value tracker React installs at mount (inputValueTracking). With the tracker no longer seeing programmatic writes, its last-known value goes stale and React swallows the next genuineinputevent — the type → clear → retype case inexamples/next-ts/pages/autoresize-controlled.tsx.This PR fixes that root cause instead: the setter override now wraps the element's own
valuedescriptor (the framework tracker) when one is present, falling back to the prototype descriptor otherwise. Programmatic writes keep flowing through the tracker, so it stays in sync and noinputevent needs to be synthesized.resize()was already called synchronously inside the setter, so resizing behavior is unchanged.⛳️ Current behavior (updates)
For a controlled textarea with autoresize whose state isn't committed synchronously (input rejection, external stores/signals):
onChangetwice — once with the typed value, then again with the restored previous value, reverting the controlled state🚀 New behavior
onChangefires once per keystroke; programmatic.valuewrites no longer dispatchinputevents💣 Is this a breaking change (Yes/No):
No. Code that relied on receiving the synthesized
inputevent after programmatic writes would no longer get it, but that event only existed as a workaround and is exactly what corrupts controlled inputs.📝 Additional Information
Added unit tests in
packages/utilities/auto-resize/tests/autoresize-textarea.test.tsthat emulate React's value tracking and change deduplication. All four fail onmainand pass with this fix. I ran the vitest suite forpackages/utilitieslocally; I was not able to run the Playwright suite in this environment.