# Rolling number (Notchset): prompt.md (v2.1.0)

- id: `rolling-number` · version 2.1.0 · component · free
- category: Text & motion
- build: one set of files for every shadcn style
- install: `npx shadcn@latest add https://notchset.dev/r/rolling-number.json`
- npm dependencies: none
- registry dependencies: utils, https://notchset.dev/r/notchset-foundation.json
- docs: https://notchset.dev/components/rolling-number
- The install command carries everything this item needs (files, CSS, tokens, npm and registry dependencies). Prefer it to copying source by hand.

A figure that changes because of what you did rolls only the digits that changed, right to left, so you see where the change landed. It never counts up on arrival; screen readers hear the final value once..

## Build it
- Stack: React 18.3 or 19, TypeScript, Tailwind CSS v4 utility classes on the foundation's roles, a components.json (imports use its aliases).
- Packages: none beyond React.
- Files: `components/ui/notchset/rolling-number.tsx`.
- Registry dependencies, installed with it automatically: shadcn `utils` (cn), `notchset-foundation`.
- Builds: one set of files, the same for every shadcn style.
- Exports to keep: `RollingNumber`, and every exported type.
- CSS: the install adds the notchset foundation (its roles, keyframes and motion switch, reading your shadcn tokens for colour) to your global stylesheet once. Nothing to import by hand.
- Re-running `add` (or `--overwrite`) re-applies those rules: put overrides in your own CSS, never in the installed rules.
- Colours: every part reads the foundation's roles (`--ns-canvas`, `--ns-ink`, `--ns-line`, `--ns-signal` …), which read your shadcn tokens (`--background`, `--foreground`, `--border`, `--destructive` …), plus the optional `--success` and `--warning`. Retheme on `:root` or any container; never add Tailwind colour classes inside the component.
- This item reads `--ns-ease`, `--ns-time-dialog`.
- Retune it (on any ancestor) with the foundation's roles and hooks: `--ns-bad`, `--ns-bad-ink`, `--ns-band`, `--ns-band-edge`, `--ns-band-grade`, `--ns-band-optimal`, `--ns-beat`, `--ns-bezel`, `--ns-canvas`, `--ns-cat-1`, `--ns-cat-2`, `--ns-cat-3`, `--ns-cat-4`, `--ns-cat-5`, `--ns-cat-6`, `--ns-check`, `--ns-chip`, `--ns-control`, `--ns-control-pad`, `--ns-control-sm`, `--ns-deep`, `--ns-deep-ink`, `--ns-deep-ink-2`, `--ns-deep-line`, `--ns-dialog`, `--ns-dialog-lg`, `--ns-dialog-sm`, `--ns-ease`, `--ns-ease-in`, `--ns-ease-panel`, `--ns-ease-pop`, `--ns-field`, `--ns-flood-arc`, `--ns-flood-aurora`, `--ns-flood-behind-1`, `--ns-flood-behind-2`, `--ns-flood-bloom`, `--ns-flood-deep`, `--ns-flood-dial-bloom`, `--ns-flood-glass`, `--ns-flood-grain`, `--ns-flood-image`, `--ns-flood-ink`, `--ns-flood-ink-low`, `--ns-flood-light`, `--ns-flood-mid`, `--ns-flood-pale`, `--ns-flood-pane`, `--ns-flood-pane-edge`, `--ns-flood-pill-ink`, `--ns-flood-ribbon`, `--ns-flood-ribbon-core`, `--ns-flood-shadow`, `--ns-flood-sheen`, `--ns-flood-wash`, `--ns-font-body`, `--ns-font-display`, `--ns-font-mono`, `--ns-font-script`, `--ns-glass`, `--ns-glass-blur`, `--ns-glass-shadow`, `--ns-glow`, `--ns-grain`, `--ns-gutter`, `--ns-header`, `--ns-heat`, `--ns-hover`, `--ns-ink`, `--ns-ink-2`, `--ns-ink-3`, `--ns-ink-4`, `--ns-leading`, `--ns-lift`, `--ns-light-1`, `--ns-light-2`, `--ns-light-3`, `--ns-light-spread`, `--ns-light-strength`, `--ns-line`, `--ns-line-soft`, `--ns-lit-edge`, `--ns-menu-dy`, `--ns-menu-row`, `--ns-mesh`, `--ns-mesh-frost`, `--ns-ok`, `--ns-ok-ink`, `--ns-orb-body`, `--ns-orb-cool`, `--ns-orb-core`, `--ns-orb-dawn`, `--ns-orb-deep`, `--ns-orb-edge`, `--ns-orb-grain`, `--ns-orb-ground`, `--ns-orb-halo`, `--ns-orb-inner`, `--ns-orb-key`, `--ns-orb-lift`, `--ns-orb-limb`, `--ns-orb-limb-from`, `--ns-orb-rim`, `--ns-orb-skin-hi`, `--ns-orb-skin-lo`, `--ns-orb-skin-mid`, `--ns-orb-warm`, `--ns-panel`, `--ns-panel-w`, `--ns-prism-edge`, `--ns-prism-glint`, `--ns-prism-sheen`, `--ns-prism-tint`, `--ns-pulse`, `--ns-radius`, `--ns-radius-card`, `--ns-radius-full`, `--ns-radius-lg`, `--ns-radius-sm`, `--ns-radius-xl`, `--ns-raised`, `--ns-range`, `--ns-row`, `--ns-row-compact`, `--ns-segment`, `--ns-selected`, `--ns-series`, `--ns-series-core`, `--ns-series-lilac`, `--ns-series-tint`, `--ns-shadow-dialog`, `--ns-shadow-float`, `--ns-shadow-panel`, `--ns-sheet`, `--ns-sheet-bottom`, `--ns-side`, `--ns-signal`, `--ns-sleep-awake`, `--ns-sleep-deep`, `--ns-sleep-light`, `--ns-sleep-rem`, `--ns-space-1`, `--ns-space-2`, `--ns-space-3`, `--ns-space-4`, `--ns-space-5`, `--ns-space-6`, `--ns-space-8`, `--ns-space-section`, `--ns-stack-on`, `--ns-standing-critical`, `--ns-standing-in`, `--ns-standing-out`, `--ns-state-doing`, `--ns-state-done`, `--ns-state-review`, `--ns-state-todo`, `--ns-switch-h`, `--ns-switch-w`, `--ns-text-body`, `--ns-text-control`, `--ns-text-display`, `--ns-text-figure`, `--ns-text-headline`, `--ns-text-hero`, `--ns-text-lede`, `--ns-text-meta`, `--ns-text-page`, `--ns-text-record`, `--ns-text-small`, `--ns-text-strong`, `--ns-text-sub`, `--ns-text-title`, `--ns-tile-shadow`, `--ns-time-born`, `--ns-time-color`, `--ns-time-dialog`, `--ns-time-menu`, `--ns-time-page`, `--ns-time-panel`, `--ns-time-toast`, `--ns-tint`, `--ns-tint-ink`, `--ns-toast-bottom`, `--ns-toast-left`, `--ns-touch`, `--ns-tracking-display`, `--ns-tracking-headline`, `--ns-warn`, `--ns-warn-ink`, `--ns-wash-clay`, `--ns-wash-dusk`, `--ns-wash-graphite`, `--ns-wash-ink`, `--ns-wash-sage`, `--ns-wash-sand`, `--ns-weight-light`, `--ns-weight-medium`, `--ns-weight-regular`, `--ns-weight-strong`, `--ns-well`.
- Never add Tailwind colour classes inside the component.

```tsx
import { Button } from "@/components/ui/notchset/button";
```

## Parts
- A single export that takes props.

## Match the original
- Read `components/ui/notchset/rolling-number.tsx` as the reference implementation before changing or recreating anything, and match it: sizes, colours per theme, motion timings, copy and behaviour.
- If you deviate (a prop you can't honour, a style you changed, a dependency you swapped), say so in your reply, part by part.
- Keep the accessibility contract, the keyboard map and the motion levels listed below.

## Use it when

### Not when

## Mistakes
- Recreating the component instead of installing it

## Usage

```tsx
"use client";
import * as React from "react";
import { Button } from "@/components/ui/notchset/button";
import { RollingNumber } from "@/components/ui/notchset/rolling-number";

export default function RollingNumberDemo() {
  const [seats, setSeats] = React.useState(8);
  return (
    <div className="flex items-center gap-3">
      <Button size="sm" aria-label="One seat fewer" onClick={() => setSeats(Math.max(1, seats - 1))}>
        −
      </Button>
      <span className="min-w-36 text-[length:var(--ns-text-strong)] font-[number:var(--ns-weight-strong)] tabular-nums">
        <RollingNumber value={`$${(seats * 48).toLocaleString("en-US")}.00`} />
      </span>
      <Button size="sm" aria-label="One more seat" onClick={() => setSeats(seats + 1)}>
        +
      </Button>
      <span className="text-[length:var(--ns-text-small)] text-[var(--ns-ink-3)]">{seats} seats × $48 a month</span>
    </div>
  );
}
```

This example also uses `button` (https://notchset.dev/components/button). Installing this item doesn't bring them; to paste the example as it is: `npx shadcn@latest add https://notchset.dev/r/rolling-number.json https://notchset.dev/r/button.json`.

## Props

| Prop | Type | Default | What it does |
|---|---|---|---|
| `value` | `string` |  | Required. |
| `instant` | `boolean` |  | Swap without rolling: a figure that follows a reader along a chart reads, it doesn't roll (no change was made). |

Full docs: https://notchset.dev/components/rolling-number

## Customising
- Colours: every part reads the foundation's roles (`--ns-canvas`, `--ns-ink`, `--ns-line`, `--ns-signal` …), which read your shadcn tokens (`--background`, `--foreground`, `--border`, `--destructive` …), plus the optional `--success` and `--warning`. Retheme on `:root` or any container; never add Tailwind colour classes inside the component.
- Dark mode follows the `.dark` class or `data-theme="dark"` on an ancestor (the shadcn and next-themes conventions).
- Update later: Commit or stash local changes first (or copy the files), so the update can be undone. Read https://notchset.dev/r/changelog.json for the new versions: a major version, an entry marked breaking or a merge says what to change. Then re-run the install with `--overwrite`, on a branch. It replaces the component's files, the shared helper files they import, and the item's CSS rules in the global stylesheet, so review the whole diff (components, shared files, CSS), re-apply your own edits, and run the app's typecheck, tests and build.

## Accessibility contract (preserve when editing)

## Install

```bash
npx shadcn@latest add https://notchset.dev/r/rolling-number.json
```

Or add the `@notchset` registry to components.json and run `npx shadcn@latest add @notchset/rolling-number`. Every components.json style gets the same files.

## Continue the workflow

- [Price summary](https://notchset.dev/blocks/price-summary)
- [Plan picker](https://notchset.dev/blocks/plan-picker)
- [Express pay](https://notchset.dev/blocks/express-pay)

## Source

### components/ui/notchset/rolling-number.tsx

```tsx
// Notchset rolling-number 2.1.0 · https://notchset.dev/changelog
"use client";
import { cn } from "@/lib/utils";

/*
 * Rolling number: a figure that changes because of what you just did (seats, a plan, a forecast category, a
 * deal moved) rolls only the digits that changed, right to left with a slight stagger, so you see where the
 * change landed and how big it was. It never counts up on arrival: a figure you open a page to is simply there.
 * Digits are tabular so nothing beside them shifts; screen readers get the final value once, not every digit.
 * Reduced motion swaps instantly.
 */
type RollingNumberProps = {
  value: string;
  /** Swap without rolling: a figure that follows a reader along a chart reads, it doesn't roll (no change was made). */
  instant?: boolean | undefined;
  className?: string | undefined;
};

const DIGITS = "0123456789";

function Digit({ d, delay, instant }: { d: number; delay: number; instant?: boolean | undefined }) {
  return (
    <span aria-hidden data-ns-mask="" className="relative inline-block h-[1lh] overflow-hidden align-bottom select-none">
      <span
        data-ns-roll=""
        data-ns-glide=""
        className={cn("flex flex-col", !instant && "[transition:transform_var(--ns-time-dialog)_var(--ns-ease)]")}
        style={{ transform: `translateY(${-d * 10}%)`, transitionDelay: instant ? undefined : `${delay}ms` }}
      >
        {DIGITS.split("").map((c) => (
          <span key={c} className="block h-[1lh]">
            {c}
          </span>
        ))}
      </span>
      {/* the digit's own width, so a 1 isn't as wide as an 8 in fonts that aren't fully tabular */}
      <span className="invisible block h-0">{DIGITS[d]}</span>
    </span>
  );
}

function RollingNumber({ value, instant, className }: RollingNumberProps) {
  const chars = value.split("");
  return (
    <span data-slot="rolling-number" role="text" aria-label={value} className={cn("relative inline-flex tabular-nums", className)}>
      {/* what a selection copies: the figure itself, laid invisibly over the strips (which can't be selected) */}
      <span aria-hidden className="absolute inset-0 whitespace-nowrap text-transparent select-text">
        {value}
      </span>
      {chars.map((c, i) => {
        /* keyed from the right, so a figure gaining a digit doesn't roll every digit after it */
        const fromRight = chars.length - i;
        return DIGITS.includes(c) ? (
          <Digit key={`d${fromRight}`} d={+c} delay={Math.min(fromRight, 6) * 18} instant={instant} />
        ) : (
          <span key={`c${fromRight}${c}`} aria-hidden className="select-none">
            {/* a plain space would collapse between flex items ("46days") */}
            {c === " " ? "\u00a0" : c}
          </span>
        );
      })}
    </span>
  );
}

export { RollingNumber, type RollingNumberProps };
```

The foundation (the tokens listed above, keyframes and motion levels) installs once with the first component; its CSS is public at https://notchset.dev/r/notchset-foundation.json.