Chart Spec

Every static definition and dynamic chart builder resolves to a ChartSpec. The spec owns chart composition, scale factories or fixed scale instances, and presentation.

type ChartSpec<TMarks extends readonly ChartMark[]> = {
  marks: TMarks
  guides?: boolean
  color?: ChartColorOptions
  gradients?: readonly ChartLinearGradient[]
  clip?: boolean
  margin?: number | Partial<ChartMargin>
  theme?: Partial<ChartTheme>
} & ([ChartMarkScaleX<TMarks[number]>] extends [never]
  ? { x?: null }
  : { x: ChartAxisOptions }) &
  ([ChartMarkScaleY<TMarks[number]>] extends [never]
    ? { y?: null }
    : { y: ChartAxisOptions })

Properties#

The detailed option contracts live in Scales, guides, and color. Mark-specific channels and defaults live in the mark reference.

Marks and layer order#

marks is the grammar's composition unit:

import { areaY, defineChart, lineY, ruleY } from '@tanstack/charts'
import { scaleUtc } from 'd3-scale'
import { scaleLinear } from '@tanstack/charts-scales/linear'

const definition = defineChart({
  marks: [
    areaY(rows, { x: 'date', y: 'value', fillOpacity: 0.12 }),
    ruleY([target], {
      stroke: '#dc2626',
      strokeWidth: 1.5,
      strokeDasharray: '4 2',
    }),
    lineY(rows, { x: 'date', y: 'value', points: true }),
  ],
  x: { scale: scaleUtc },
  y: { scale: scaleLinear, grid: true },
})

Each mark materializes channels for scale resolution, then emits renderer- neutral scene nodes and optional interaction points. Marks may use different datum types in the same spec. Their inferred datum types become a union in interaction callbacks.

A data-less crosshair emits only transient focus-guide presentation. Place it before the first ordinary mark for an underlay or after ordinary marks for an overlay; it contributes no scale domain values or interaction points.

Built-in marks infer stable keys from a unique primitive top-level id, nested data.id, or mark-owned positional candidate. Supply key when none is unique. Mark IDs default from layer order; set id explicitly when a mark must retain identity while its order changes.

Conditional positional axes#

Each axis used by the marks is required. Supply a compatible factory for an inferred domain or a configured instance for a fixed domain:

const axes = {
  x: { scale: scaleUtc },
  y: { scale: scaleLinear },
}

Omit an unused dimension:

const horizontalThresholds = defineChart({
  marks: [ruleY([25, 50, 75])],
  y: { scale: scaleLinear().domain([0, 100]) },
})

axis: false hides an axis but does not remove its scale. Scene compilation still guards untyped consumers that omit or null an axis used by a mark.

Guides and margins#

Guide visibility and geometry are separate:

• x.axis: false or y.axis: false hides one axis.
• guides: false hides all guides and removes their implicit margin.
• Omitted margin sides are measured from ticks, rotation, titles, edge overhang, color legends, and Cartesian text marks.
• margin: 0 locks every side to zero.
• margin: { left: 80 } locks only the left side.

Automatic margins contain guide and text-mark labels unless the side is locked or the plot is clipped; they do not choose a collision policy. Control dense guide labels with the scale's tick behavior, ticks, format, or tickRotate.

Clip and gradient resources#

clip and gradients are scene data consumed by the default SVG and Canvas renderers:

const definition = defineChart({
  marks,
  x,
  y,
  clip: true,
  gradients: [
    {
      id: 'revenue',
      y1: 1,
      y2: 0,
      stops: [
        { offset: 0, color: '#2563eb', opacity: 0.08 },
        { offset: 1, color: '#2563eb', opacity: 0.72 },
      ],
    },
  ],
})

Reference a declared gradient from a mark paint as url(#revenue). idPrefix scopes generated resource IDs when multiple charts share a document. See Rendering and export.

Theme#

The complete default theme is exported as defaultChartTheme:

interface ChartTheme {
  foreground: string
  muted: string
  grid: string
  background: string
  palette: readonly string[]
}

theme is partial. The palette is replaced as one value rather than merged by index. The default palette uses CSS custom-property fallbacks:

.dashboard {
  --ts-chart-1: #38bdf8;
  --ts-chart-2: #fb7185;
  --ts-chart-3: #4ade80;
}

Because the default foreground and guide colors use currentColor, charts inherit light and dark mode without a JavaScript theme switch. Override theme tokens when the application needs an explicit visual system.