Virtualizer

Data display component. This page is the API reference, generated from the source code. Usage guidance and live examples are on the Chinese page.

HeadlessStylesVueReactWeb Components

Anatomy

Parts in bold are required.

data-scope="virtualizer": root · viewport · content · item

API reference

Descriptions of individual props, events and slots are written in Chinese and appear on the Chinese page.

Artifacts

Layer	Value
Custom element	<xh-virtualizer>
Vue components	XhVirtualizerContent XhVirtualizerItem XhVirtualizerRoot XhVirtualizerViewport
Composable	useVirtualizer
State machine	virtualizerMachine
Skin	@xihan-ui/styles/virtualizer.css

Props

Prop	Type	Required
count	number
estimateSize	number | ((index: number) => number)
overscan	number
horizontal	boolean
gap	number
getItemKey	(index: number) => string | number
onRangeChange	(details: VirtualizerRangeChangeDetails) => void
scrollMargin	number
paddingStart	number
paddingEnd	number
lanes	number
viewportTabIndex	number
scrollContainer	VirtualizerScrollContainer
anchor	VirtualizerAnchor
stickyIndices	number[]
estimateFromMeasured	boolean

Events

Custom elements put the payload in detail; Vue emits an event of the same name.

Event	Payload
range-change	VirtualizerRangeChangeDetails

Slots

Only slots with a payload are listed.

Vue component	Slot	Payload
XhVirtualizerRoot	default	VirtualizerRootSlotProps

React adapter props

Only the props each component declares itself: DOM attributes inherited from ComponentPropsWithRef are left out, and root props already listed in the Props table are not repeated. The Vue counterpart is the slot table above.

React component	Prop	Type	Required
XhVirtualizerItem	value	number | string	Yes
XhVirtualizerItem	measure	boolean
XhVirtualizerRoot	children	SlotChildren<VirtualizerRootSlotProps>

State

The following names are internal to the state machine.

States: idle · scrolling

Events: SCROLL.START · SCROLL.END · MEASURE

connect API

getXxxProps() returns the host attributes of the matching part.

Member	Type
virtualItems	readonly VirtualizerItemState[]
totalSize	number
startIndex	number | null
endIndex	number | null
horizontal	boolean
lanes	number
scrolling	boolean
collectionVirtualizer	CollectionVirtualizer
scrollToIndex	(index: number, options?: VirtualizerScrollToOptions) => void
measureElement	(element: HTMLElement | null) => void
measure	() => void
registerItemElement	(index: number, element: HTMLElement | null) => void
getRootProps	() => T['element']
getViewportProps	() => T['element']
getContentProps	() => T['element']
getItemProps	(props: VirtualizerItemProps) => T['element']

Accessibility

Keyboard

Specification: W3C APG. Each row is a stable behavior id that the conformance tests cover; the conditions and effects are described on the Chinese page.

No keyboard interaction: the component takes no focus, or focus behavior comes entirely from native elements.

Style reference

Skin

@xihan-ui/styles/virtualizer.css is written against [data-scope="virtualizer"][data-part="root"] part selectors; the published build uses the mount class .xh-scope-virtualizer in place of data-scope (same specificity) and sits in the xihan.components layer. Put overrides in xihan.overrides; the part selectors work as usual.

Data attributes

Produced by connect; valueless attributes are omitted while their condition does not hold.

Part	Attribute	Value
root	data-orientation	'horizontal' | 'vertical'
root	data-scroll-container	undefined | props.scrollContainer
root	data-scrolling	'' (present only while the condition holds)
viewport	data-anchor	'end' | undefined
viewport	data-orientation	'horizontal' | 'vertical'
viewport	data-scroll-container	undefined | props.scrollContainer
content	data-orientation	'horizontal' | 'vertical'
item	data-fixed	'' (present only while the condition holds)
item	data-index	props.index
item	data-lane	item.lane | undefined
item	data-orientation	'horizontal' | 'vertical'

CSS variables

The public override slots, generated from what the standalone skin actually consumes.

Variable	Part	CSS property	State	Default from
--xh-virtualizer-sticky-bg	item	background	fixed	--xh-bg-surface
--xh-virtualizer-sticky-layer	item	z-index	fixed	--xh-layer-sticky