Line

Trends over an ordered domain – one polyline per series.

Identity

chartType	line
Option bag	line
seriesData layout	seriesRows – row 0 = category header; later rows = series
Min grid	2 rows × 2 columns (header included)
Orientation	Yes – vertical (default) or horizontal
Sample	Line · Dual-axis line

---

Minimal chartData

{
  chartType: 'line',
  isDataTransposed: true,
  seriesData: [
    ['', 'Jan', 'Feb', 'Mar', 'Apr'],
    ['Visits', 120, 132, 128, 150],
  ],
  title: { visible: true, text: 'Weekly visits' },
  subtitle: { visible: false, text: '' },
  legend: { visible: false },
}

---

seriesData

Same seriesRows layout as clustered bar (with isDataTransposed: true):

[
  ['', 'Jan', 'Feb', 'Mar', 'Apr'],
  ['Visits', 120, 132, 128, 150],
  ['Signups', 40, 44, 41, 55],
]

Rule	Detail
Row 0	Ordered domain labels (categories / periods)
Later rows	One series each
Empty / null cells	Breaks in the line for that point (intentional gaps)

Shared layout rules: chartData schema · seriesData.

---

Option bag: line

Only chartType: 'line' reads cd.line. Stacked areas use the separate area bag.

Field	Default (new charts)	Role
width	2	Stroke width (px)
strokeDashArray	''	Dash pattern (SVG-style string)
drawPoints	false	Show point markers on the line
curveParameter	0.85	Curve tension (editor Smoothness control)
shadowIntensity	0	Soft shadow under the stroke
pointMarker	see below	Marker style when drawPoints is on
overrides	{}	Indexed style patches

Leave curveType at its default ('cardinal'). Prefer adjusting curveParameter (editor Smoothness) rather than swapping interpolation names.

Point markers

Rendered only when drawPoints: true. Resolution order: per-point override → per-series → global pointMarker.

{
  chartType: 'line',
  seriesData: [/* … */],
  line: {
    width: 2.5,
    drawPoints: true,
    curveParameter: 0.85,
    pointMarker: {
      shape: 'circle', // circle | square | diamond | triangle
      radius: 3,
      fill: null,      // null = series color
      stroke: '#ffffff',
      strokeWidth: 1,
    },
  },
}

Full marker surface: Point markers.

---

Axes & scales

Role	Vertical (default)	Horizontal
Domain	bottom	left
Primary range	left	bottom
Secondary range	right	top

• Dual-axis is fully supported on line charts: enable the secondary range axis and set boundSeries to the series indices that use it.
• Setting the range axis with customMin / customMax is normal (unlike bars, which bias toward including zero).
• Pair tick formats and preferredTickInterval with the side that holds the range role after orientation.

Details: Axes · Secondary · Axes · by chart type · Dual-axis line sample.

{
  chartType: 'line',
  isDataTransposed: true,
  seriesData: [
    ['', 'Q1', 'Q2', 'Q3', 'Q4'],
    ['Revenue', 120, 140, 155, 170],
    ['Margin %', 18, 19, 21, 20],
  ],
  axes: {
    right: {
      id: 'secondaryRange',
      enabled: true,
      visible: true,
      boundSeries: [1],
      labels: {
        preferredTickInterval: 5,
        numberFormat: {
          mode: 'custom',
          customFormat: {
            prefix: '',
            postfix: '%',
            thousandSeparator: ',',
            decimalSeparator: '.',
            decimalPlaces: 0,
            forceDecimals: false,
            signDisplay: 'auto',
            scaleDown: 0,
          },
        },
      },
    },
  },
}

---

Type-specific behaviour

• Series color still comes from legend.colors.
• Markers stay off until line.drawPoints: true (or you turn them on in the editor).
• For bar + line on one chart, use combo with combo.seriesTypes – do not put bar options in cd.line.
• Area fills belong on stackedArea / cd.area, not on line.

---

Pitfalls

• Expecting markers without drawPoints: true
• Putting area/bar fields on line (foreign-option-bag)
• Binding secondary with the wrong series index after reordering rows
• Forcing bar-style “must include zero” when a tighter range-axis span is what you want – set customMin / customMax deliberately (Value axis)
• Using stackedArea defaults/area bag when you only wanted a stroke

---

Related

• Stacked area · Combo · Point markers
• chartData schema · Axes
• Samples: Line · Dual-axis line · Percent axis