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fix(select): scroll button bumpiness #3692

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f21a467
fix: select component scroll button bumpiness
antlio Oct 2, 2025
0beb274
docs(changeset): fix: select component scroll button bumpiness
antlio Oct 2, 2025
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5 changes: 5 additions & 0 deletions .changeset/bumpy-jokes-judge.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'@radix-ui/react-select': patch
---

fix: scroll button display bumpiness
36 changes: 30 additions & 6 deletions packages/react/select/src/select.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -1449,24 +1449,33 @@ const SelectScrollUpButton = React.forwardRef<
const viewportContext = useSelectViewportContext(SCROLL_UP_BUTTON_NAME, props.__scopeSelect);
const [canScrollUp, setCanScrollUp] = React.useState(false);
const composedRefs = useComposedRefs(forwardedRef, viewportContext.onScrollButtonChange);
const getItems = useCollection(props.__scopeSelect);

useLayoutEffect(() => {
if (contentContext.viewport && contentContext.isPositioned) {
const viewport = contentContext.viewport;

function handleScroll() {
const canScrollUp = viewport.scrollTop > 0;
const items = getItems();
const firstItem = items[0]?.ref.current;
const firstItemHeight = firstItem?.offsetHeight ?? 0;

// we use Math.ceil here because if the UI is zoomed-in
// `scrollTop` is not always reported as an integer
const canScrollUp = Math.ceil(viewport.scrollTop) > firstItemHeight;
setCanScrollUp(canScrollUp);
}
handleScroll();
viewport.addEventListener('scroll', handleScroll);
return () => viewport.removeEventListener('scroll', handleScroll);
}
}, [contentContext.viewport, contentContext.isPositioned]);
}, [contentContext.viewport, contentContext.isPositioned, getItems]);

return canScrollUp ? (
<SelectScrollButtonImpl
{...props}
ref={composedRefs}
direction="up"
onAutoScroll={() => {
const { viewport, selectedItem } = contentContext;
if (viewport && selectedItem) {
Expand Down Expand Up @@ -1496,27 +1505,33 @@ const SelectScrollDownButton = React.forwardRef<
const viewportContext = useSelectViewportContext(SCROLL_DOWN_BUTTON_NAME, props.__scopeSelect);
const [canScrollDown, setCanScrollDown] = React.useState(false);
const composedRefs = useComposedRefs(forwardedRef, viewportContext.onScrollButtonChange);
const getItems = useCollection(props.__scopeSelect);

useLayoutEffect(() => {
if (contentContext.viewport && contentContext.isPositioned) {
const viewport = contentContext.viewport;
const items = getItems();
const lastItem = items[items.length - 1]?.ref.current;
const lastItemHeight = lastItem?.offsetHeight ?? 0;

function handleScroll() {
const maxScroll = viewport.scrollHeight - viewport.clientHeight;
// we use Math.ceil here because if the UI is zoomed-in
// `scrollTop` is not always reported as an integer
const canScrollDown = Math.ceil(viewport.scrollTop) < maxScroll;
const canScrollDown = Math.ceil(viewport.scrollTop) <= maxScroll - lastItemHeight;
setCanScrollDown(canScrollDown);
}
handleScroll();
viewport.addEventListener('scroll', handleScroll);
return () => viewport.removeEventListener('scroll', handleScroll);
}
}, [contentContext.viewport, contentContext.isPositioned]);
}, [contentContext.viewport, contentContext.isPositioned, getItems]);

return canScrollDown ? (
<SelectScrollButtonImpl
{...props}
ref={composedRefs}
direction="down"
onAutoScroll={() => {
const { viewport, selectedItem } = contentContext;
if (viewport && selectedItem) {
Expand All @@ -1532,13 +1547,14 @@ SelectScrollDownButton.displayName = SCROLL_DOWN_BUTTON_NAME;
type SelectScrollButtonImplElement = React.ComponentRef<typeof Primitive.div>;
interface SelectScrollButtonImplProps extends PrimitiveDivProps {
onAutoScroll(): void;
direction?: 'up' | 'down';
}

const SelectScrollButtonImpl = React.forwardRef<
SelectScrollButtonImplElement,
SelectScrollButtonImplProps
>((props: ScopedProps<SelectScrollButtonImplProps>, forwardedRef) => {
const { __scopeSelect, onAutoScroll, ...scrollIndicatorProps } = props;
const { __scopeSelect, onAutoScroll, direction = 'down', ...scrollIndicatorProps } = props;
const contentContext = useSelectContentContext('SelectScrollButton', __scopeSelect);
const autoScrollTimerRef = React.useRef<number | null>(null);
const getItems = useCollection(__scopeSelect);
Expand Down Expand Up @@ -1568,7 +1584,15 @@ const SelectScrollButtonImpl = React.forwardRef<
aria-hidden
{...scrollIndicatorProps}
ref={forwardedRef}
style={{ flexShrink: 0, ...scrollIndicatorProps.style }}
style={{
position: 'absolute',
left: 0,
right: 0,
zIndex: 1,
pointerEvents: 'auto',
...(direction === 'up' ? { top: 0 } : { bottom: 0 }),
...scrollIndicatorProps.style
}}
onPointerDown={composeEventHandlers(scrollIndicatorProps.onPointerDown, () => {
if (autoScrollTimerRef.current === null) {
autoScrollTimerRef.current = window.setInterval(onAutoScroll, 50);
Expand Down