Skip to content

BackTop — spec

Synthesized from Ant Design BackTop. Floating "scroll to top" button that appears after the user scrolls past a threshold. Pairs with long-content pages.

When to use

  • Long content pages (articles, feeds, dashboards) where users scroll far.
  • Mobile particularly (more painful to scroll back).

When NOT to use: - Short pages (< 1.5 viewport heights). - Scroll-snap pages where each snap is a "section" (different nav pattern).

Anatomy

[content]
[content]
[content]
[content]
[content]
                       [↑]   ← appears after scroll past threshold
[content]

API

<BackTop
  visibilityHeight={400}
  duration={500}
  onClick={() => track("back-to-top")}
>
  <button className="back-top-button">↑</button>
</BackTop>
Prop Type Default Description
visibilityHeight number 400 Px scrolled before button appears
duration number 450 Ms for smooth-scroll-up animation
target () => HTMLElement window Scrollable container
onClick () => void — Custom callback

States

State Visual
Hidden (scroll < threshold) Not rendered / fade-out
Visible Floating button bottom-right; subtle shadow
Hover Subtle bg shift
Pressed Scrolling animation in progress

Position + tokens

Bottom-right anchor; safe-area-aware for iOS.

--back-top-bg
--back-top-fg
--back-top-shadow
--back-top-size                  (40-48px)
--space-md                       (offset from edges)
--motion-medium                  (fade + scroll)
--ease-out
--z-fab

Accessibility

  • <button aria-label="페이지 맨 위로 이동">.
  • Smooth scroll respects prefers-reduced-motion (instant scroll if reduced).
  • Focus visible.
  • Keyboard: Home key also scrolls to top in many browsers; BackTop is a visual affordance, not a replacement.

Code example

<BackTop visibilityHeight={600}>
  <button
    className="back-top-button"
    aria-label="맨 위로"
  >
    <ArrowUpIcon />
  </button>
</BackTop>

Reduced motion

@media (prefers-reduced-motion: reduce) {
  /* Replace smooth scroll with instant jump */
}

JS: 

const reduced = matchMedia("(prefers-reduced-motion: reduce)").matches;
window.scrollTo({ top: 0, behavior: reduced ? "auto" : "smooth" });

Korean conventions

  • 맨 위로 / 위로 / 처음으로 — typical labels (해요체 OK).
  • For Korean B2C: chevron arrow icon usual; some apps use full-text "맨 위로" in narrow strip.

Don't

  • Don't show BackTop on short pages — visual noise.
  • Don't omit aria-label.
  • Don't override scroll behavior without reduced-motion check.
  • Don't auto-fire scroll without user click.

References

  • Ant: BackTop
  • Native: window.scrollTo({ behavior: "smooth" })

Cross-reference