Scroll Area
A scrollable region with a styled overlay scrollbar in place of the platform one. Wraps @base-ui/react/scroll-area: Base UI owns overflow detection and thumb geometry; we own the track, the thumb colour and the focus ring.
Preview
Rendered from the story the storybook (a11y) CI gate runs axe against — the preview can't show something that hasn't been verified.
Install
Two equivalent paths — the URL works in any shadcn-CLI setup; the alias works once you've registered @interlace in your components.json.
npx shadcn@latest add https://ds.interlace.tools/r/scroll-area.jsonnpx shadcn@latest add @interlace/scroll-areaBehavior
What this component does — the keyboard path, the measured colour, the text equivalent and the states it can be in. Every figure below is read out of the test or the source that enforces it by scripts/build-behavior-map.mjs, so nothing here can outlive the gate that keeps it true.
2 steps, 1 key press — replayed on every PR by the play function of KeyboardFlow. Axe cannot press a key, so this — not the a11y scan — is what proves the component is operable without a mouse.
- 1The overflowing viewport is in the tab sequence
- 2Tab reaches the region, and it actually scrollsTab
Measured contrast
packages/ui/__tests__/theme-contract-lock.test.ts ↗Every semantic colour pair this component's own source uses, measured against the shipped hexes in all 4 theme × scheme combinations. The tightest is ring on background at 8.39:1 (harbor · light), against a floor of 3:1.
| Pair | interlacelight | interlacedark | harborlight | harbordark | Floor |
|---|---|---|---|---|---|
| ring on backgroundfocus ring (SC 2.4.13) | 8.80:1 | 11.79:1 | 8.39:1 | 10.03:1 | 3.0:1SC 1.4.11 |
| ring on cardfocus ring inside a card | 8.80:1 | 10.92:1 | 8.86:1 | 9.10:1 | 3.0:1SC 1.4.11 |
Text pairs are held to 4.5:1 (WCAG 2.2 SC 1.4.3); borders, rings and chart axes to 3:1 (SC 1.4.11 non-text). Bold is the worst cell in the row — the one a brand fork has to keep an eye on.
Runtime contract
packages/ui/vitest.config.ts ↗Where it renders, how narrow it survives, and whether its lines are inside the coverage gate — three answers a consumer needs before the paste, not after the bug.
- Render boundary
'use client'Hydrates. It brings JavaScript to any route that imports it — put the boundary here, not at the page.
- Minimum viewport
MIN_VIEWPORT = 320Declared, not assumed. Below 320 CSS px the preflight contract draws a dev-mode outline — how to switch it on.
- Coverage gate
not in the gateThe 100% gate currently covers
src/charts/**/*.{ts,tsx}andsrc/lib/**/*.{ts,tsx}andsrc/primitives/{button-variants,data-state-model,meter-scale,skeleton-variants}.tsandsrc/primitives/{alert,aspect-ratio,avatar,badge,box,breadcrumb,button,callout,card,checkbox,code-editor,container,data-state,focus-ring,grade-badge,grid,input,label,meter,pagination,published-date,reading-time,section,section-boundary,separator,skip-link,stack,stat-strip,tag,textarea,typography,visually-hidden}.tsxandsrc/patterns/lint-playground.tsx. This file is outside it — the glob widens in phase 7.2.
History
This component is at v1.2.0, first shipped in @interlace/ui 1.0.0. The version is stamped as a banner into the file the install writes, so the copy in your tree says which one you have — compare it with the number above before deciding whether to re-run the install.
No release note names this component yet. It shipped with the release above and has not changed since — see the full changelog for what moved elsewhere in the DS.
Import
3 named exports — pull the parts you need.
import { MIN_VIEWPORT, ScrollArea, ScrollBar } from '@/components/ui/scroll-area';Anatomy
Extracted from the primitive's JSDoc header. The source is the only documentation that can't drift.
ScrollArea (ScrollArea.Root — relative, data-min-viewport=320)
├─ ScrollArea.Viewport (focus ring lives here — the scrollable box)
│ └─ ScrollArea.Content (children)
├─ ScrollBar (Scrollbar → Thumb — vertical by default)
└─ ScrollArea.CornerAPI reference
Parsed from the type declarations in the source — the same file the install writes into your tree, so this table can't drift from the component you get.
ScrollArea
Also accepts every prop of Base UI's <ScrollArea.Root> — behaviour we compose rather than reimplement.
ScrollBar
Also accepts every prop of Base UI's <ScrollArea.Scrollbar> — behaviour we compose rather than reimplement.
| Prop | Type | Default | Description |
|---|---|---|---|
| orientation | 'horizontal' | 'vertical' | 'vertical' | — |
Accessibility
Every story for this component is rendered headlessly and checked with axe-core (wcag2aa, wcag22aa, best-practice, ACT) on every PR. That gate has no continue-on-error, so what ships has zero known violations.
What follows is what static analysis can see. Axe cannot press a key and never sees an overlay open, so the operable-without-a-mouse claim lives in Behavior instead, where the keyboard path is replayed step by step.
- Focus + keyboard behaviour
- Owned by @base-ui/react/scroll-area — focus trapping, dismissal and typeahead come from the headless primitive, not from us.
- Focus ring (WCAG 2.2 SC 2.4.13)
- Inherited from the preflight focus contract shipped in @interlace/theme.
- Reduced motion
- No animation to gate.
- ARIA in the source
- None — semantics come from the element or the Base UI primitive rather than hand-written ARIA.
Examples
2 more states from the same story file.
R-rule compliance
Every primitive in @interlace/ui models to the portable 26-rule floor enforced by the componentApi ESLint preset. The cells below pin exactly where each rule applies in this file.
| Rule | Concept | Where |
|---|---|---|
| R4 | Extends Base UI part props | `React.ComponentProps<typeof BaseScrollArea.Root/Scrollbar>` |
| R6 | data-slot per part | scroll-area / -viewport / -scrollbar / -thumb |
| R7 | cn + ...rest | `cn('relative', className)` + `{...props}` |
| R8 | Enum for axis | `orientation = horizontal |
| R12 | Reuse over wrap | Base UI owns overflow detection and thumb geometry |
| R14 | Declares min viewport | `data-min-viewport={String(MIN_VIEWPORT)}` + exported const |
| R19 | Tokens only | `bg-border` thumb, `ring-ring/50` viewport ring |
| R25 | Client component | Required — Base UI ScrollArea ships client hooks |
| R26 | A11y | the VIEWPORT takes focus and shows a ring, so a scrollable region is keyboard-reachable (axe `scrollable-region-focusable`); arrow-key scrolling is asserted by `ScrollArea.stories.tsx` |
Minimum viewport
This primitive declares MIN_VIEWPORT = 320 CSS px (DESIGN_PRINCIPLES #14). When mounted in a container narrower than this, the preflight contract draws a dev-mode outline so the regression is visible during local development.
<body data-interlace-dev>...</body>
Add the data-interlace-dev attribute to the body in development builds only — preflight then outlines any primitive whose container is below its declared data-min-viewport.
Dependencies
- Base UI primitive
- @base-ui/react/scroll-area
- Lucide icons
- none
- NPM dependencies
@base-ui/react
- Registry dependencies
Source
The full implementation — components/ui/scroll-area.tsx once installed.
'use client';
import * as React from 'react';
// @interlace/scroll-area v1.2.0 — Interlace design system.
// Docs, props and live preview: https://ds.interlace.tools/c/scroll-area
// What changed since: https://ds.interlace.tools/c/scroll-area#history
// Generated banner — keep it, the upgrade diff reads this version.
// Mirrors the shadcn ScrollArea canon, built on Base UI.
// Upstream: https://base-ui.com/react/components/scroll-area
/**
* @interlace/ui — ScrollArea
*
* A scrollable region with a styled overlay scrollbar in place of the platform
* one. Wraps @base-ui/react/scroll-area: Base UI owns overflow detection and
* thumb geometry; we own the track, the thumb colour and the focus ring.
*
* The root renders a VERTICAL scrollbar only. `ScrollBar` is exported and
…99 more lines…Registry JSON
The raw registry record — what the shadcn CLI fetches.