import chartExamplesUrl from "../site/chart-examples.js?url"

# Chart

<Callout type="warning" title="Alpha API" icon="triangle-alert">
  Chart support is alpha. The JavaScript API, generated markup, and option names may change before the stable 1.0 release.
</Callout>

Use Chart.js with Basecoat defaults for themed colors, external tooltips, and optional generated legends.

<Preview class="w-full">
  <canvas id="chart-example-overview" aria-label="Visitors by device"></canvas>
</Preview>

Chart is an optional JavaScript helper. Load Chart.js first, then `basecoat.js`, then `chart.js`.

```html
<script src="https://cdn.jsdelivr.net/npm/chart.js/dist/chart.umd.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/basecoat-css@1.0.0-beta.4/dist/js/basecoat.min.js" defer></script>
<script src="https://cdn.jsdelivr.net/npm/basecoat-css@1.0.0-beta.4/dist/js/chart.min.js" defer></script>
```

## Usage

```html
<canvas id="visitors-chart" aria-label="Monthly visitors"></canvas>

<script>
  document.addEventListener("DOMContentLoaded", () => {
    window.basecoat.chart("#visitors-chart", {
      type: "bar",
      labelKey: "month",
      data: [
        { month: "Jan", desktop: 186, mobile: 80 },
        { month: "Feb", desktop: 305, mobile: 200 },
        { month: "Mar", desktop: 237, mobile: 120 },
        { month: "Apr", desktop: 73, mobile: 190 },
        { month: "May", desktop: 209, mobile: 130 },
        { month: "Jun", desktop: 214, mobile: 140 },
      ],
      series: {
        desktop: { label: "Desktop", color: "var(--chart-1)" },
        mobile: { label: "Mobile", color: "var(--chart-2)" },
      },
    })
  })
</script>
```

`basecoat.chart()` targets the `<canvas>` directly and creates Basecoat's internal `.chart` container for Chart.js sizing. You do not need to add a wrapper or class in your HTML.

Charts default to `aspect-video`. Use a height, `min-h-*`, or `aspect-*` utility on a parent element when you need a different measuring box.

## Legend

Set `legend: true` to generate a Basecoat-styled legend after the canvas.

The generated legend is display-only by default, matching shadcn/ui. Use a Chart.js plugin or custom legend markup if you need click-to-toggle behavior.

```js
window.basecoat.chart("#visitors-chart", {
  type: "bar",
  labelKey: "month",
  data,
  series,
  legend: true,
})
```

## Series

`series` maps object keys from each data row to labels, colors, and optional Chart.js dataset settings.

```js
window.basecoat.chart("#revenue-chart", {
  type: "line",
  labelKey: "month",
  data,
  series: {
    recurring: {
      label: "Recurring",
      color: "var(--chart-1)",
      surface: "gradient",
      dataset: {
        fill: true,
        tension: 0.35,
      },
    },
    new: {
      label: "New",
      color: "var(--chart-2)",
      dataset: {
        borderDash: [4, 4],
      },
    },
  },
})
```

## Escape Hatches

Pass raw Chart.js options and plugins through `options` and `plugins`.

```js
const chart = window.basecoat.chart("#visitors-chart", {
  type: "bar",
  labelKey: "month",
  data,
  series,
  options: {
    indexAxis: "x",
    scales: {
      y: {
        beginAtZero: true,
      },
    },
    plugins: {
      tooltip: {
        mode: "index",
      },
    },
  },
  plugins: [myChartJsPlugin],
})
```

Pass complete Chart.js data through `chartData` when the simplified `data` plus `series` mapper is not enough.

```js
window.basecoat.chart("#custom-chart", {
  type: "scatter",
  chartData: {
    datasets: [
      {
        label: "Samples",
        data: [{ x: 1, y: 2 }, { x: 2, y: 5 }],
      },
    ],
  },
  options: {
    scales: {
      x: { type: "linear" },
    },
  },
})
```

`basecoat.chart()` returns the Chart.js instance for single targets and an array of instances for multi-target selectors.

## Examples

### Bar Chart - Multiple

<Preview class="w-full">
  <canvas id="chart-example-visitors" aria-label="Monthly visitors by device"></canvas>
</Preview>

### Line Chart - Linear

<Preview class="w-full">
  <canvas id="chart-example-line" aria-label="Revenue line chart"></canvas>
</Preview>

### Line Chart - Step

<Preview class="w-full">
  <canvas id="chart-example-step" aria-label="Support queue step chart"></canvas>
</Preview>

### Bar Chart - Stacked

<Preview class="w-full">
  <canvas id="chart-example-stacked" aria-label="Stacked pipeline bar chart"></canvas>
</Preview>

### Pie Chart - Donut

<Preview class="w-full">
  <canvas id="chart-example-donut" aria-label="Traffic source donut chart"></canvas>
</Preview>

### Radar Chart

<Preview class="w-full">
  <canvas id="chart-example-radar" aria-label="Channel performance radar chart"></canvas>
</Preview>

<script is:inline src="https://cdn.jsdelivr.net/npm/chart.js/dist/chart.umd.min.js"></script>
<script type="module" src={chartExamplesUrl}></script>

## API

| Option | Default | Description |
| --- | --- | --- |
| `type` | `"bar"` | Chart.js chart type. |
| `labelKey` | `"label"` | Row key used for labels. |
| `data` | `[]` | Array of row objects, or raw Chart.js data with `datasets`. |
| `series` | `{}` | Series config mapped from row keys. |
| `legend` | `false` | Generates a Basecoat legend after the canvas. |
| `tooltip` | `true` | Uses the Basecoat external tooltip. |
| `options` | `{}` | Raw Chart.js options. |
| `plugins` | `[]` | Raw Chart.js plugins. |
| `chartData` | `undefined` | Complete Chart.js data object. Overrides the data mapper. |

### Series options

| Option | Description |
| --- | --- |
| `label` | Display label for legends and tooltips. |
| `color` | Base color for the series stroke, fill, legend marker, and tooltip marker. |
| `surface` | Derives a fill from `color`. Use `true` for a translucent fill, `"gradient"` for an upstream-style vertical fade, or `{ from, to }` for custom opacity stops. |
| `dataset` | Raw Chart.js dataset options. |