# Slope chart

A React component in [Beamline](https://beamline.io/)'s [Charts & data-vis](https://beamline.io/components/charts) category. Live demo: https://beamline.io/components/slope-chart

Change between two points in time per item, by value or by rank: labels on both sides that never collide, rising and falling told by the end marker (▲ ▼) and the signed change as well as colour, and hover or focus to pick one item out.

## Use it for

- Before/after for a handful of items: share by channel this quarter against last, a ranking that moved.

## Not for

- Many periods ([line-chart](https://beamline.io/components/line-chart)).
- Exact amounts for one period ([bar-chart](https://beamline.io/components/bar-chart)).

## Anatomy

- title, description, table button
- period headings (start, end; overline role)
- start axis and end axis
- one line per item, ending in ▲ (rose), ▼ (fell) or ● (flat)
- start labels (item buttons: name and value; columns measured in the faces the look sets, so names never truncate while there is room)
- end labels (value, signed change, name)
- hatched stub for a missing end

## Variants

- **0**: scale: value · rank (1 at the top)
- **1**: better: higher (rises are good, green) · lower (falls are good) · neither (accent and muted)
- **2**: labels by room: full (name and value on both sides) · medium (names on the start side) · narrow, on phones (values at the start; value, ▲▼ and name at the end)

## States

- loading (skeleton)
- empty
- missing start or end: the known point stays, a hatched stub and “Not measured” stand on the missing side, no line is invented
- active item (its line thickens and is drawn again on top; the others fade toward the card colour, and their labels step down to ink-3, never below 4.5:1)
- pinned item (aria-pressed)
- table view (start, end, change)
- right-to-left: categorical period columns mirror with the comparison table; figures and date ranges remain LTR-isolated
- names keep their own direction (dir=auto), so a truncated name shows its start in RTL too

## Keyboard

- Tab focuses the active (or first) item; ↑/↓ move through items in their start order, Home/End to the ends
- Focus or hover highlights the item; Escape releases it
- Each item's accessible name reads both values and the change
- Label buttons and pointer line targets are at least 24 px tall/wide. Stable item keys control pinning; hover/focus preview never changes the caller selection. Overlapping line targets resolve to the nearest drawn line, not SVG paint order.

## Motion

Lines draw from the start axis once; nothing moves under reduced motion. Highlight is immediate.

## Props

| Prop | Type | Default | Description |
| --- | --- | --- | --- |
| `data` | `SlopeItem[]` | — | { key, label, start: number \| null, end: number \| null }. |
| `startLabel / endLabel` (required) | `string` | — | Period headings: "Q2", "Q3". |
| `scale` | `"value" \| "rank"` | — | Plot values, or positions in each period's ranking. Default value. |
| `better` | `"higher" \| "lower" \| "neither"` | — | Which direction reads as good. Default higher. |
| `format / formatChange` | `(v: number) => string` | — | Values, and the signed change (default: the difference in format's terms). |
| `height` | `number` | — | Plot height; 30 px per item, at least 200, by default. |
| `active / defaultActive / onActiveChange` | `string \| null` | — | The highlighted item's key. |
| `title / hideTitle / description` | `string / boolean / ReactNode` | — | The figure's name (a heading unless hidden) is always its accessible name. |
| `table` | `boolean` | — | Offer “View as table”. Default true. |
| `loading` | `boolean` | — | Skeleton of the chart's shape; keeps the frame's size. |
| `actions` | `ReactNode` | — | Controls beside the legend (range, offset). |
| `className` | `string` | — | Lands on the figure. |
| `formatChangeSpoken` | `(change: number) => string` | — | Full spoken change amount/unit after rose or fell. Receives the signed delta; return an unsigned amount such as 18 percentage points. Visible formatChange is unchanged. |
| `classNames` | `ChartClassNames` | — | Frame, tooltip and slice-list parts as applicable to this chart. |
| `style / ref` | `CSSProperties / Ref<HTMLElement>` | — | The native chart figure; layout measurement refs stay internal. |

## Dependencies

`motion`

## Import

```tsx
import { SlopeChart } from "@/components/slope-chart/slope-chart";
```

## Get it

Slope chart is part of Beamline: 190 React components and screens your coding agent (Claude Code, Codex, Cursor or any MCP client) installs into your app through Beamline's MCP server, as a ready-built package or as plain React source you can change. $49 one payment (regular $200), no subscription, a year of updates, one licence for your whole team. [Get Beamline](https://beamline.io/checkout?pack=complete) · [Connect your agent](https://beamline.io/connect)

## More in Charts & data-vis

- [Activity heatmap](https://beamline.io/components/activity-heatmap): A calendar of daily counts, one cell per day on a sequential ramp: weeks across, weekdays down, month and weekday labels, a legend scale, hatched days…
- [Area chart](https://beamline.io/components/area-chart): Amounts over time as filled areas: overlapping, stacked or as shares of 100%, five fills, two strokes, five curves, a range handle; gaps for missing…
- [Bar chart](https://beamline.io/components/bar-chart): Amounts by category as bars: columns or rows, grouped, stacked or as shares, reference lines, five looks (rounded, cells, trace, isometric, monospace), a…
- [Composed chart](https://beamline.io/components/composed-chart): Different measures on one time axis: bars, lines and areas per series, a left and a right value axis with their own formats, and reference lines.
- [Gauge](https://beamline.io/components/gauge): One value against a known range: a semicircle, a 270° dial or a full ring, filled or with a needle, coloured bands with their names (healthy, busy…
- [Line chart](https://beamline.io/components/line-chart): Values over time as lines: curves, point markers, dashed series for forecasts, reference lines for limits and targets, an optional zero baseline and a…
- [Pie chart](https://beamline.io/components/pie-chart): A few shares of a whole as a pie or donut, with spaced slices, percent labels, a centre readout and a list of every slice with value and share; hovering…
- [Radar chart](https://beamline.io/components/radar-chart): A few series compared across the same five to eight dimensions as polygons on a polygon or circle grid; hover or arrow keys pick a dimension and read…
- [Radial chart](https://beamline.io/components/radial-chart): Progress of a few measures toward their targets as concentric rings, full or half circle, with a centre readout and a list of each ring's value, target…
- [Ridgeline](https://beamline.io/components/ridgeline): Distributions per group as overlapping density ridges (response time by region, order size by plan): an overlap control, median and p95 readouts per row…
- [Sankey chart](https://beamline.io/components/sankey-chart): Flows between stages as bands whose width is the amount: sources to pages to outcomes, budgets to teams; hovering or focusing a node lights its flows and…
- [Sparkline](https://beamline.io/components/sparkline): A compact trend beside its value: point along it or focus it and use ← → to read each point; nulls are gaps. TrendLine is the bare line.
- [Streamgraph](https://beamline.io/components/streamgraph): Stacked flows over time around a centre baseline, with silhouette, wiggle, expand (shares) and zero offsets: a legend that turns layers on and off, a…
- [Treemap](https://beamline.io/components/treemap): Nested rectangles sized by value (spend by team, then service), squarified so tiles stay close to square: labels that fit or hide, hover and focus…
- [Waffle chart](https://beamline.io/components/waffle-chart): Units of a whole as a grid of cells by category (seats used of a plan, tickets by channel): a 10×10 grid by default, hatched cells for units whose…