🏝️ Sand.js

Sunburst Advanced Node Data

---

✨ What is Sand.js?

Sand.js is a lightweight, framework-agnostic JavaScript library for building sunburst charts using SVG.
It is fully data-driven: you describe your chart in JSON, and Sand.js takes care of both layout computation and rendering.

Sand.js is designed to be:

• Lightweight: no heavy dependencies.
• Agnostic: works with plain HTML, or in any framework.
• JSON-driven: describe your sunburst once, render anywhere.
• Accessible: interactive charts with sensible defaults.

---

📖 Key Concepts

Term	Description
Sunburst	The entire chart, composed of one or more layers.
Layer	A logical group of rings, defined by a dataset and a mode (free or align).
Ring	A radial band, automatically computed from nodes and their expandLevels.
Node	A declared unit of data in JSON. May have children (tree mode) or not (flat mode).
Leaf	A node without children.
Key-group	A logical grouping of nodes sharing the same key, used for alignment and interactions.
Arc	A computed geometric entity ready to be rendered (x0, x1, y0, y1).

---

🧩 Entities

Sunburst

Property	Type	Description
size.radius	number	Final radius in pixels.
size.angle?	number	Total angle (default 2π = full circle).
layers	Layer[]	List of layers from inside out.

---

Layer

Property	Type	Description
id	string	Unique identifier.
radialUnits	[n,n]	Radial interval in unit rings.
angleMode	"free" | "align"	Angular partition mode.
alignWith?	string	Reference layer ID (if align).
padAngle?	number	Angular spacing between arcs.
baseOffset?	number	Global rotation (radians).
arcOffsetMode?	"relative" | "absolute"	How offsets are applied.
tree	Node | Node[]	Data for the layer. Supports tree or flat structure.

---

Node

Property	Type	Description
name	string	Display name.
value	number	Size of the arc (summed if children exist).
key?	string	Stable identifier for alignment, animation, and coloring.
expandLevels?	number	Radial thickness in rings (default = 1).
offset?	number	Local offset.
color?	string	Custom arc color (overrides palette).
children?	Node[]	Child nodes (tree mode only).
tooltip?	string	Custom tooltip text.
collapsed?	boolean	Keep descendants hidden from layout while their values contribute to the parent arc.
hidden?	boolean	Hides the node completely.

---

Arc (computed by layout)

Property	Type	Description
layerId	string	Origin layer ID.
data	Node	Reference to original node.
x0, x1	number	Angular start and end (radians).
y0, y1	number	Inner/outer radius (pixels).
depth	number	Logical depth in its layer.
key?	string	Copy of node key.
percentage	number	Relative percentage in its parent.

---

🚀 Getting Started

npm install @akitain/sandjs

Render a sunburst in the browser:

<svg id="chart"></svg>
<script type="module">
  import { renderSVG } from 'sandjs';

  const config = {
    size: { radius: 160 },
    layers: [
      {
        id: 'root',
        radialUnits: [0, 2],
        angleMode: 'free',
        tree: [
          { name: 'Data', value: 6, key: 'data' },
          {
            name: 'Design',
            key: 'design',
            value: 4,
            children: [
              { name: 'UI', value: 2 },
              { name: 'Brand', value: 2 }
            ]
          }
        ]
      }
    ]
  };

  const chart = renderSVG({
    el: '#chart',
    config,
    tooltip: true,
    onArcClick: ({ arc }) => console.log('Pinned', arc.data.name)
  });

  // Update the chart later without re-attaching listeners
  chart.update({
    config: {
      ...config,
      size: { radius: 180 },
    }
  });
</script>

The demo under demo/ shows relative/absolute offsets, tooltips, and selection callbacks. Run npm run build and serve the folder (for example npx http-server .) to experiment.

Configuration essentials

• Layers (free or align): free splits siblings by value; align reuses the angular span of a keyed arc in another layer.
• Offsets: defaultArcOffset and per-node offset shift arcs. In relative mode the offset is a fraction of the available span; in absolute mode it is applied in radians.
• Padding: Use padAngle on a layer or node to reserve gap space between siblings.
• Callbacks: renderSVG exposes onArcEnter, onArcMove, onArcLeave, and onArcClick with the arc metadata and the rendered path.
• Tooltips: enable with tooltip: true or pass { formatter, container } for custom markup.
• Breadcrumbs: pass breadcrumbs: true to auto-render a trail or supply { container, formatter, separator }; formatArcBreadcrumb(arc) helps generate custom labels.
• Highlights: enable highlightByKey: true (or supply options) to add a shared class for arcs with the same key, and optionally toggle pinned highlights via pinOnClick.
• Collapsing: set collapsed: true on a node to keep its descendants hidden from the rendered layout while preserving its aggregated value.
• Updates: keep the returned handle from renderSVG and call chart.update({ config: nextConfig }) (or pass a full config) to redraw without re-binding listeners.

See src/types/index.ts for the full TypeScript contracts.

🧪 Build & Test

npm run test    # type check + node test runner
npm run build   # rollup (ESM + minified IIFE bundles)
npm run verify  # convenience: runs tests and build

dist/ contains the publishable artifacts. The IIFE bundle exposes window.SandJS for CDN usage (https://unpkg.com/@akitain/[email protected]/dist/sandjs.iife.min.js).

✅ Release Checklist

1. npm run verify
2. Manually review the demo/ example in a browser.
3. Update CHANGELOG.md and bump the package version.
4. npm publish --access public

---

🛣️ Roadmap

Phase 0.1 – MVP (npm + CDN)

• Core layout (layout(config) → arcs {x0,x1,y0,y1})
• SVG renderer (renderSVG({ el, config }))
• JSON-driven charts (radius, layers, nodes)
• Modes free / align with key
• Basic expandLevels (within a layer)
• Offsets: baseOffset, arcOffsetMode, defaultArcOffset
• Auto color palette (category10)
• Simple interactions: hover, click callbacks
• Builds: ESM + IIFE (CDN/global)
• Publish to npm + GitHub Pages demo

Phase 0.2 – Interactions & Stability

• Tooltips (name, value, %)
• Breadcrumbs (full path of arc)
• Highlight by key
• Collapse/expand (collapsed: true)
• API update(newConfig) (no animation yet)
• Unit tests for invariants (angles, radial order)

Phase 0.3 – Animation & Polish

• Animated transitions (update with interpolation by key)
• Zoom/drill-down
• Basic radial labels
• Export: exportSVG(), exportPNG()
• Color themes (qualitative, sequential, diverging)
• Accessibility (aria-labels, keyboard nav)

Phase 0.4 – Extensions & Performance

• Canvas renderer (performance for >5k arcs)
• Plugin system (legends, labels, effects)
• Layout-only mode (server / custom renderers)
• Partial angle support (gauge 180°/270°)
• Advanced animation (easing, delays)
• Large dataset tests (50k arcs in Canvas)
• Publish also on JSR (Deno/Bun)

Long term (1.0+)

• Online editor/playground
• Smart labels (collision detection)
• Skins/themes (flat, material, dark)
• Framework wrappers (React/Vue/Svelte)
• Full documentation site + gallery

📝 License

MIT © Aqu1tain