Overlay Scroll

Installation

Examples

Props

Schema

Type aliases from this item's source — use them to shape the data you pass in.

interface OverlayScrollHandle {
  /** Underlying scroller DOM element; call .scrollTo() on it from a parent. */
  scrollerEl: HTMLElement | null
  /** Force thumb recalc after a non-DOM size change. */
  recompute: () => void
}

Files installed (2)

• components/ui/overlay-scroll/overlay-scroll.tsx10.6 kB

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  'use client'
  
  import * as React from 'react'
  import { cn } from '@/lib/utils'
  
  // Slack-style overlay scrollbar. Hides the native scrollbar entirely so the
  // scrolled content uses the full container width (no reservation), then draws
  // a thin auto-fading thumb absolutely positioned on top. Drag-to-scroll on the
  // thumb is supported via Pointer Events (mouse + touch + pen). Vertical only.
  //
  // Give the component a bounded height via the parent (e.g. `flex-1 min-h-0`
  // inside a flex column, or a fixed `h-*` / `max-h-*`). Without a bound it
  // expands to its content and the thumb is hidden.
  
  // Ported from OverlayScroll.vue's <style scoped> block. Injected once so the
  // component ships self-contained (Tailwind has no equivalent overlay-scrollbar
  // utility). Class names match the Vue source 1:1.
  const overlayScrollCss = `
  .overlay-scroll__inner {
    scrollbar-width: none;
    -ms-overflow-style: none;
    /* Stop wheel events from chaining to the page once the inner scroller
       hits its top/bottom. Without this, scrolling a long activity feed
       past its last item keeps scrolling the surrounding page — confusing
       when the inner region is a clearly bounded card. */
    overscroll-behavior: contain;
  }
  .overlay-scroll__inner::-webkit-scrollbar {
    display: none;
    width: 0;
    height: 0;
  }
  .overlay-scroll__thumb {
    position: absolute;
    top: 0;
    border-radius: 2px;
    background: var(--muted-foreground);
    opacity: 0;
    pointer-events: none;
    touch-action: none;
    user-select: none;
    -webkit-user-select: none;
    transition:
      opacity 0.2s ease,
      background-color 0.15s,
      width 0.12s ease;
    will-change: transform, opacity;
  }
  .overlay-scroll__thumb--draggable {
    cursor: pointer;
  }
  .overlay-scroll__thumb--visible {
    opacity: 0.4;
    pointer-events: auto;
  }
  .overlay-scroll:hover .overlay-scroll__thumb--visible {
    opacity: 0.6;
  }
  .overlay-scroll:hover .overlay-scroll__thumb--draggable:hover {
    opacity: 0.8;
    width: 8px !important;
    background: var(--foreground);
  }
  .overlay-scroll__thumb--dragging {
    opacity: 1 !important;
    background: var(--foreground) !important;
    width: 8px !important;
  }
  `
  
  function OverlayScrollStyle() {
    return <style dangerouslySetInnerHTML={{ __html: overlayScrollCss }} />
  }
  
  export interface OverlayScrollHandle {
    /** Underlying scroller DOM element; call .scrollTo() on it from a parent. */
    scrollerEl: HTMLElement | null
    /** Force thumb recalc after a non-DOM size change. */
    recompute: () => void
  }
  
  export interface OverlayScrollProps {
    /** Thumb width in px when idle. Expands to ~2x on hover / drag. */
    thumbWidth?: number
    /** Right offset of the thumb from the inner edge, in px. */
    thumbOffset?: number
    /** ms of scroll inactivity before the thumb fades. */
    idleHideMs?: number
    /** Allow dragging the thumb to scroll. */
    draggable?: boolean
    /** Tailwind classes forwarded to the outer wrapper. */
    className?: string
    children?: React.ReactNode
  }
  
  const OverlayScroll = React.forwardRef<OverlayScrollHandle, OverlayScrollProps>(
    ({ thumbWidth = 4, thumbOffset = 2, idleHideMs = 800, draggable = true, className, children }, ref) => {
      const scrollerRef = React.useRef<HTMLDivElement | null>(null)
      const thumbRef = React.useRef<HTMLDivElement | null>(null)
  
      const [thumbHeight, setThumbHeight] = React.useState(0)
      const [thumbTop, setThumbTop] = React.useState(0)
      const [showThumb, setShowThumb] = React.useState(false)
      const [isDragging, setIsDragging] = React.useState(false)
  
      // Refs that hold the latest value for callbacks bound once (no re-bind on
      // every render). Mirrors the Vue refs that the closures read directly.
      const isHoveredRef = React.useRef(false)
      const isDraggingRef = React.useRef(false)
      const thumbHeightRef = React.useRef(0)
      const hideTimerRef = React.useRef<ReturnType<typeof setTimeout> | null>(null)
      const idleHideMsRef = React.useRef(idleHideMs)
      const draggableRef = React.useRef(draggable)
  
      React.useEffect(() => {
        idleHideMsRef.current = idleHideMs
      }, [idleHideMs])
      React.useEffect(() => {
        draggableRef.current = draggable
      }, [draggable])
  
      const recompute = React.useCallback(() => {
        const el = scrollerRef.current
        if (!el) return
        const ratio = el.clientHeight / el.scrollHeight
        if (!Number.isFinite(ratio) || ratio >= 1) {
          thumbHeightRef.current = 0
          setThumbHeight(0)
          return
        }
        const h = Math.max(24, el.clientHeight * ratio)
        thumbHeightRef.current = h
        setThumbHeight(h)
        const maxScroll = el.scrollHeight - el.clientHeight
        const maxThumb = el.clientHeight - h
        setThumbTop(maxScroll > 0 ? (el.scrollTop / maxScroll) * maxThumb : 0)
      }, [])
  
      const flashThumb = React.useCallback(() => {
        if (thumbHeightRef.current === 0) return
        setShowThumb(true)
        if (hideTimerRef.current) clearTimeout(hideTimerRef.current)
        hideTimerRef.current = setTimeout(() => {
          if (!isHoveredRef.current && !isDraggingRef.current) setShowThumb(false)
        }, idleHideMsRef.current)
      }, [])
  
      const onScroll = React.useCallback(() => {
        recompute()
        flashThumb()
      }, [recompute, flashThumb])
  
      const onEnter = React.useCallback(() => {
        isHoveredRef.current = true
        recompute()
        if (thumbHeightRef.current > 0) setShowThumb(true)
      }, [recompute])
  
      const onLeave = React.useCallback(() => {
        isHoveredRef.current = false
        if (isDraggingRef.current) return
        if (hideTimerRef.current) clearTimeout(hideTimerRef.current)
        setShowThumb(false)
      }, [])
  
      // Pointer Events cover mouse + touch + pen on every modern browser
      // (Chrome 55+, Firefox 59+, Safari 13+, Edge). setPointerCapture keeps the
      // drag alive even if the pointer leaves the thumb, matching native feel.
      const activePointerIdRef = React.useRef<number | null>(null)
      const dragStartYRef = React.useRef(0)
      const dragStartScrollTopRef = React.useRef(0)
  
      const onPointerMove = React.useCallback((e: PointerEvent) => {
        if (activePointerIdRef.current !== e.pointerId) return
        const el = scrollerRef.current
        if (!el) return
        const maxScroll = el.scrollHeight - el.clientHeight
        const maxThumb = el.clientHeight - thumbHeightRef.current
        if (maxThumb <= 0) return
        const scrollRatio = maxScroll / maxThumb
        el.scrollTop = dragStartScrollTopRef.current + (e.clientY - dragStartYRef.current) * scrollRatio
      }, [])
  
      const endDragRef = React.useRef<(e?: PointerEvent) => void>(() => {})
  
      const endDrag = React.useCallback(
        (e?: PointerEvent) => {
          if (e && activePointerIdRef.current !== e.pointerId) return
          isDraggingRef.current = false
          setIsDragging(false)
          if (thumbRef.current && activePointerIdRef.current !== null) {
            try {
              thumbRef.current.releasePointerCapture(activePointerIdRef.current)
            } catch {
              // pointer may already be released; ignore
            }
          }
          activePointerIdRef.current = null
          const handler = endDragRef.current
          thumbRef.current?.removeEventListener('pointermove', onPointerMove)
          thumbRef.current?.removeEventListener('pointerup', handler)
          thumbRef.current?.removeEventListener('pointercancel', handler)
          if (!isHoveredRef.current) setShowThumb(false)
        },
        [onPointerMove],
      )
  
      React.useLayoutEffect(() => {
        endDragRef.current = endDrag
      }, [endDrag])
  
      const onThumbPointerDown = React.useCallback(
        (e: React.PointerEvent) => {
          if (!draggableRef.current || !scrollerRef.current || !thumbRef.current) return
          if (e.pointerType === 'mouse' && e.button !== 0) return
          e.preventDefault()
          isDraggingRef.current = true
          setIsDragging(true)
          activePointerIdRef.current = e.pointerId
          dragStartYRef.current = e.clientY
          dragStartScrollTopRef.current = scrollerRef.current.scrollTop
          thumbRef.current.setPointerCapture(e.pointerId)
          thumbRef.current.addEventListener('pointermove', onPointerMove)
          thumbRef.current.addEventListener('pointerup', endDrag)
          thumbRef.current.addEventListener('pointercancel', endDrag)
        },
        [onPointerMove, endDrag],
      )
  
      React.useEffect(() => {
        recompute()
        const scroller = scrollerRef.current
        if (!scroller) return
  
        const resizeObserver = new ResizeObserver(recompute)
        resizeObserver.observe(scroller)
  
        const inner = scroller.firstElementChild as HTMLElement | null
        let mutationObserver: MutationObserver | null = null
        if (inner) {
          resizeObserver.observe(inner)
          mutationObserver = new MutationObserver(recompute)
          mutationObserver.observe(inner, { childList: true, subtree: true })
        }
  
        return () => {
          resizeObserver.disconnect()
          mutationObserver?.disconnect()
          if (hideTimerRef.current) clearTimeout(hideTimerRef.current)
          endDrag()
        }
      }, [recompute, endDrag])
  
      React.useImperativeHandle(
        ref,
        () => ({
          get scrollerEl() {
            return scrollerRef.current
          },
          recompute,
        }),
        [recompute],
      )
  
      return (
        <div
          data-uipkge=""
          data-slot="overlay-scroll"
          className={cn('overlay-scroll relative', className)}
          onMouseEnter={onEnter}
          onMouseLeave={onLeave}
        >
          <OverlayScrollStyle />
          <div
            ref={scrollerRef}
            data-slot="overlay-scroll-viewport"
            className="overlay-scroll__inner h-full overflow-x-hidden overflow-y-auto"
            onScroll={onScroll}
          >
            {children}
          </div>
          <div
            ref={thumbRef}
            data-slot="overlay-scroll-thumb"
            aria-hidden="true"
            className={cn(
              'overlay-scroll__thumb',
              showThumb && 'overlay-scroll__thumb--visible',
              isDragging && 'overlay-scroll__thumb--dragging',
              draggable && 'overlay-scroll__thumb--draggable',
            )}
            style={{
              width: `${thumbWidth}px`,
              /* Read the right offset from --ovs-thumb-right when an ancestor
                 sets it (e.g. Sidebar pushes the thumb away from SidebarRail),
                 otherwise fall back to the prop. Lets the same primitive sit
                 flush in a card AND clear a rail without per-call config. */
              right: `var(--ovs-thumb-right, ${thumbOffset}px)`,
              height: `${thumbHeight}px`,
              transform: `translateY(${thumbTop}px)`,
            }}
            onPointerDown={onThumbPointerDown}
          />
        </div>
      )
    },
  )
  OverlayScroll.displayName = 'OverlayScroll'
  
  export { OverlayScroll }
  

• components/ui/overlay-scroll/index.ts0.1 kB

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Raw manifest:https://uipkge.dev/r/react/overlay-scroll.json

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