# BumpStrip (/docs/charts/bump-strip)

BumpStrip answers "where do we rank, and which way is it moving?" — position on an inverted ordinal scale, so #1 sits on
top and climbing draws upward. Ranks are not values: Sparkline would lie about the distance between #2 and #3.

```tsx
<BumpStrip data={[5, 5, 4, 4, 4, 3, 2, 2, 3, 2, 1, 1]} title="Category rank" width={220} height={26} />
```

## Install

```tsx
import { BumpStrip } from "@microcharts/react/bump-strip";

<BumpStrip data={weeklyRanks} title="Category rank" />
```

Setup (package + stylesheet): [Quickstart](/docs/quickstart#set-up-with-an-ai-agent) or paste [`/agent-setup.md`](/agent-setup.md) into your agent.


## When to use it

- **Good for** — leaderboard rows, category-rank trends in KPI cards.
- **Avoid for** — continuous values (Sparkline), or more than ~15 rank levels.


## Variants

```tsx
// null = unranked that period — the line breaks, honestly
<BumpStrip data={[2, null, null, 3, 1, 1]} />
```

```tsx
<BumpStrip data={ranks} maxRank={10} />
```

## Edge cases

```tsx
<BumpStrip data={[3]} maxRank={5} />
```

```tsx
// every period null — no line, no dots; the summary says so plainly
<BumpStrip data={[null, null, null]} />
```

```tsx
// rank never moves — no change dots, a level line
<BumpStrip data={[3, 3, 3, 3, 3]} />
```

A single ranked period draws its two end labels with no visible line — there is no trajectory to show yet. An all-`null`
series renders the frame with neither line nor labels; the accessible name reports it directly rather than describing a
blank chart. A flat run (rank never changes) draws a level line with zero change dots, since `dots="changes"` only marks
the periods where rank actually moved.


## Why this default

Change dots mark only the periods where rank actually moved — flat runs stay quiet, so the eye lands on the transitions.
End labels ("#5" → "#1") anchor the ordinal read without an axis.

## Accessibility

The accessible name is the full trajectory — **"From #8 to #1 over 12 weeks; best #1."** The interactive entry steps the
periods (**"Week 7 of 12: #2."**).

The interactive entry follows the shared [interaction contract](/docs/accessibility#one-interaction-contract):
arrow keys rove between units on both axes, `Home` and `End` jump to the ends, and a click, tap, `Enter` or
`Space` selects a unit — pinning its readout so it survives blur, until you select it again or press `Escape`.
On touch, a tap pins and a drag scrubs.

## Props

| Prop | Type | Description |
| --- | --- | --- |
| `data` (required) | `(number \| null)[]` | 1-based integer ranks; null = unranked period (gap). |
| `maxRank` | `number` | Fix the band so small multiples share a rank scale. |
| `dots` | `"changes" \| "none"` | Mark the moments rank actually moved. |
| `label` | `"ends" \| "last" \| "none"` | "#5" → "#1" endpoint labels. |
| `animate` | `boolean` | (interactive) Opt-in entrance motion when the chart mounts client-side — add `import "@microcharts/react/motion"` once. Inert on the server, on hydrated server HTML, and under `prefers-reduced-motion`. |

Plus the shared grammar — `data`, `domain`, `color`, `title`, `summary`, `format` — and the layout props (`width`, `height`, `className`, `style`) that every chart accepts. Interactive entries also share `animate` and `live`, and — wherever a chart has more than one navigable unit — `onActive`, `onSelect`, `selectedIndex` and `defaultSelectedIndex`; and — wherever the chart shows a hover value — `readout`. See [the shared grammar](/docs/quickstart#the-shared-grammar).