Custom Axis Keys

Configuration Used

The data objects use month and count, not x and y. Without the keys below, the fitter would read every point as missing.

trendlineLinear: {
    xAxisKey: 'month',   // default: 'x'
    yAxisKey: 'count',   // default: 'y'
    colorMin: '#e74c3c',
    width: 2,
    lineStyle: 'dashed',
    label: { text: 'Signups', display: true, displayValue: false },
}

• Data shape: { month: '2025-01-01', count: 120 }, one object per point
• Time axis: the x values are dates, so the chart loads the date-fns adapter
• displayValue: false: on a time axis the slope is per millisecond, which is not a number anyone wants to read. Convert the x values to days first if you need it
• parsing: Chart.js needs its own parsing to plot the points — the trendline keys do not affect the line itself. If you set options.parsing instead, the plugin falls back to those keys and the two options above can be left out