# SparkBar (/docs/charts/sparkbar)

SparkBar renders discrete values as compact bars from a zero baseline: one bar per period, always anchored at zero,
because a bar that starts anywhere else misstates its magnitude. Each period is its own count — a deploy total, a daily
total — rather than a sample on a continuous curve. In `bar` mode the endpoint bar takes the accent, since "where did it
land" is usually the first question a run of counts answers.

`winloss` mode discards magnitude on purpose and collapses each value to its sign: wins above the mid-line, losses
below, and a tie (`0`) as a thin neutral dash on it. There every bar keeps its own win/loss/tie color, endpoint
included, because the sign is what matters at each position. Sign is doubled by position and color wherever signed data
appears, so direction survives forced-colors.

```tsx
<SparkBar data={[4, 6, 2, 8, 5, 9]} width={120} height={32} title="Deploys per day" />
```

## Install

```tsx
import { SparkBar } from "@microcharts/react/sparkbar";

<SparkBar data={[4, 6, 2, 8, 5, 9]} title="Deploys per day" />
```

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

## Try it

```tsx
import { SparkBar } from "@microcharts/react/sparkbar/interactive";

<SparkBar
  data={[4, 6, 2, 8, 5, 9, 3, 7, 6, 10]}
  mode="bar"
/>
```

## When to use it

Use it for discrete magnitudes, win–loss streaks, and period-over-period counts. For a continuous trend shape use
[Sparkline](/docs/charts/sparkline), which is also the better choice at hundreds of points, where bars become noise.

## Sizing

`width` and `height` are viewBox units that also set the rendered pixel box. Omit them and drive the width from CSS for
a chart that fills its container — the viewBox keeps the aspect ratio.

**default**

```tsx
// data alone → an intrinsic 80×20 box
<SparkBar data={[4, 6, 2, 8, 5, 9]} />
```

**fixed size**

```tsx
// width & height are viewBox units — they also set the pixel box
<SparkBar data={[4, 6, 2, 8, 5, 9]} width={200} height={48} />
```

**responsive**

```tsx
// omit width/height, let CSS drive the width — the viewBox keeps the ratio
<div style={{ width: "100%", maxWidth: 320 }}>
  <SparkBar data={[4, 6, 2, 8, 5, 9]} style={{ width: "100%", height: "auto" }} />
</div>
```

### Where the plot floor sits

In `bar` mode the bars stand on the bottom edge of the viewBox. There is no bottom padding, so a bar's foot and the box
bottom are the same line. That is what seats the chart on the text baseline when it sits inline. Draw your own rule or
divider _below_ the box rather than flush with it, or it covers the bar feet by a pixel or two. `winloss` mode insets
its bottom edge instead, because a mid-line streak has no floor to stand on.

## Variants

```tsx
<SparkBar data={[4, 6, 2, 8, 5, 9]} />
```

```tsx
<SparkBar data={[1, -1, 1, 1, -1, 1, -1]} mode="winloss" />
```

```tsx
// a 0 is a tie — a neutral dash on the mid-line, never a win or a loss
<SparkBar data={[1, -1, 0, 1, 0, -1, 1]} mode="winloss" />
```

```tsx
<SparkBar data={[4, 6, 2, 8, 5, 9]} label="last" />
```

```tsx
<SparkBar data={[4200, 6100, 2800, 8600]} label="last" locale="de-DE" />
```

The endpoint label and accessible summary both follow `format`/`locale`: 8600 reads "8.600" under `de-DE` rather than
the English "8,600".

## Edge cases

```tsx
<SparkBar data={[]} title="No deploys yet" />
```

```tsx
<SparkBar data={[6]} title="One deploy" />
```

An empty series renders no bars and an accessible name that says so, rather than a flat or invented baseline. A single
value still renders as one zero-anchored bar, and `winloss` mode treats it the same way a longer streak would: a lone
win, loss, or tie.

```tsx
// 0 is data and paints nothing; null is absence
<SparkBar data={[4, 0, 6, null, 3, 0]} />
```

A zero paints no bar. Bar length encodes magnitude, and zero magnitude is zero length, so the slot keeps its place on
the pitch and stays empty. A period you have no reading for takes `null`, which occupies no slot at all. Pass the real
zero rather than substituting `null` for it: the generated summary counts a zero in the range and skips a gap, and the
interactive entry reads a zero as "0" where it reads a gap as "no data". In `winloss` mode a `0` is a tie instead — a
state rather than a magnitude — so it keeps its dash on the mid-line.

## Name the bars

The interactive entry takes `labels`, indexed like `data`. The hover readout then names the period it shows instead of
only its value, and the live region announces the name ahead of the position:

```tsx
import { SparkBar } from "@microcharts/react/sparkbar/interactive";

<SparkBar data={mrr} labels={["Jun 2026", "Jul 2026", "Aug 2026"]} />;
```

The chip reads `Aug 2026 · 1.1K`, and the announcement reads "Aug 2026. Point 3 of 12: 1.1K." The name also arrives on
`onActive` and `onSelect` as `datum.label`, so a host that renders its own readout gets it without a second lookup.

A hole in the array, or an empty string, leaves that one bar on the positional wording. Both joins are localizable
through the `named` and `namedChip` string templates. The static entry ignores `labels`: it has no readout to name, and
the generated summary stays value-based.

## Four homes

**In a sentence**

```tsx
<p>
  Deploys peaked at nine mid-week{" "}
  <span className="mc-inline">
    <SparkBar data={deploys} width={70} height={16} summary={false} />
  </span>{" "}
  — quieter since.
</p>
```

**In a table cell**

```tsx
<td>
  <SparkBar data={services[0].deploys} width={56} height={16} />
</td>
```

**In a KPI card**

```tsx
<div className="kpi">
  <span className="figure">5 / 7</span>
  <span className="unit">last 7 runs</span>
  <SparkBar data={ciRuns} mode="winloss" width={80} height={26} />
</div>
```

**In a tab header**

```tsx
<button className="tab">
  CI <SparkBar data={ciRuns} mode="winloss" width={44} height={14} />
</button>
<button className="tab">
  Release <SparkBar data={releaseRuns} mode="winloss" width={44} height={14} />
</button>
```

## Accessibility

The accessible name is generated from the data. The example above reads:

> Deploys per day. Trending up 125%. Range 2 to 9. Last value 9.

Sign is doubled by position (above or below the baseline), never by color alone, so the chart survives forced-colors and
color-blind viewing.

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, press `Escape`, or
press outside the chart. On touch, a tap pins and a drag scrubs.

## Props

| Prop | Type | Description |
| --- | --- | --- |
| `data` (required) | `number[]` | Values; negatives dip below the baseline. |
| `mode` | `"bar" \| "winloss"` | Magnitude bars, or a win/loss/tie streak (sign only). |
| `gap` | `number` | Empty fraction of each slot (0–0.9). |
| `label` | `"none" \| "last"` | Direct endpoint value label. |
| `positive` | `"up" \| "down"` | "up" (default); "down" flips which sign is good. |
| `labels` | `(string \| undefined)[]` | (interactive) Names for the bars, indexed like `data`; the readout shows them. |
| `title` | `string` | Accessible name; joins the auto summary. |
| `summary` | `string \| false` | Override or disable the auto summary. |
| `locale` | `string \| string[]` | BCP 47 locale(s) for the endpoint label and summary. |
| `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).