# Plugins (Sankey example)

> WestCoast Charts 1.1.5, release, public Core release, on npm. HTML: https://westcoast-charts.com/gallery/sankey/plugins/ · Index for agents: https://westcoast-charts.com/llms.txt

plotOptions.sankey.plugins: a registered plugin reserves a row and draws column totals, an inline plugin adds a tooltip row, another one listens to events. Hooks: reserve, afterRender, event, tooltip, describe, destroy (the same API for every premium type).

- Chart type: `sankey` (Sankey)
- Collection: Sankey · Sankey
- Raw configuration: https://westcoast-charts.com/gallery-src/sankey/plugins.js
- Standalone example: https://westcoast-charts.com/embed/samples/wcc/gallery/premium/sankey/plugins.html

## Setup

```js
import WestCoastCharts from 'west-coast-charts'
import types from 'west-coast-charts/types'
import premium from 'west-coast-charts/premium'

WestCoastCharts.use(types).use(premium)
const WestCoastChartsPremium = premium
WestCoastCharts.setLicenseKey(LICENCE_KEY) // paid production licence; localhost evaluation needs no key
```

## Options

```js
const options = {
  "chart": {
    "height": 360,
    "toolbar": {
      "show": false
    },
    "type": "sankey"
  },
  "series": [
    {
      "data": [
        [
          "Leads",
          "Qualified",
          300
        ],
        [
          "Leads",
          "Lost",
          500
        ],
        [
          "Qualified",
          "Won",
          120
        ],
        [
          "Qualified",
          "Lost",
          180
        ]
      ]
    }
  ],
  "plotOptions": {
    "sankey": {
      "plugins": [
        [
          {
            "name": "column-totals",
            "defaults": {
              "label": "Total",
              "color": null
            },
            "reserve": () => ({ bottom: 26 }),
            "afterRender": (p) => {
                const g = p.layer()
                const cols = {}
                p.api.nodes().forEach((n) => {
                  const b = p.api.nodeBox(n.id)
                  const c = (cols[n.column] = cols[n.column] || { l: b.x, r: b.x + b.width, v: 0 })
                  c.v += n.value
                })
                const y = p.area.y + p.area.height + 16
                const keys = Object.keys(cols)
                keys.forEach((k, i) => {
                  const c = cols[k]
                  // edge columns align to the outer side so the label stays inside the chart
                  const anchor = i === 0 ? 'start' : i === keys.length - 1 ? 'end' : 'middle'
                  const x = anchor === 'start' ? c.l : anchor === 'end' ? c.r : (c.l + c.r) / 2
                  p.text(g, x, y, p.options.label + ' ' + c.v.toLocaleString('en-US'), p.font(11, 600, p.options.color || p.theme.muted, { 'text-anchor': anchor }))
                })
              },
            "describe": () => 'Column totals are shown below the diagram.'
          },
          {
            "label": "Σ"
          }
        ],
        {
          "name": "share-of-column",
          "tooltip": (content, p) => {
                const pl = content.payload
                if (!pl || pl.kind !== 'node') return content
                const col = p.api.nodes().filter((n) => n.column === pl.node.column)
                const sum = col.reduce((s, n) => s + n.value, 0)
                content.rows.push({ label: 'Share of column (plugin)', value: Math.round((pl.node.value / sum) * 100) + '%' })
                return content
              }
        },
        {
          "name": "event-log",
          "event": (name, e, o) => { if (name === 'dataPointSelection' && o && o.node) console.log('plugin saw ' + name + ': ' + o.node.name) }
        }
      ]
    }
  },
  "theme": {
    "mode": "light",
    "preset": "coastal"
  }
}

const chart = new WestCoastCharts(document.querySelector('#chart'), options)
await chart.render()
```

## Verify

- Text check (Library 1.1.5): load `west-coast-charts/agent/describe` and call `chart.describe({ format: "json" })` for the actual drawn state. The live reader is on this example’s HTML page.
- Command line (Public agent tools 0.2.3, tested with Library 1.1.5; available from the versioned GitHub release and npm, https://westcoast-charts.com/docs/cli/index.md): `wcc chart export sankey-plugins.json --out sankey-plugins.svg --with-table` (save the options above as JSON first)