Marketplace

layerchart

Expert guide for LayerChart, a Svelte component library for building diverse data visualizations (Cartesian, radial, hierarchical, geo, graph) with unopinionated building blocks, motion primitives, and advanced interactions.

$ インストール

git clone https://github.com/linehaul-ai/linehaulai-claude-marketplace /tmp/linehaulai-claude-marketplace && cp -r /tmp/linehaulai-claude-marketplace/plugins/layerchart/skills/layerchart ~/.claude/skills/linehaulai-claude-marketplace

// tip: Run this command in your terminal to install the skill

SKILL.md

View on GitHub →

name: layerchart description: Expert guide for LayerChart, a Svelte component library for building diverse data visualizations (Cartesian, radial, hierarchical, geo, graph) with unopinionated building blocks, motion primitives, and advanced interactions. license: MIT

LayerChart Skill

LayerChart is a comprehensive Svelte visualization framework built on Layer Cake, providing composable components for creating responsive, interactive charts across multiple visualization types.

Core Architecture

LayerChart operates on a component-based, data-driven philosophy. The library provides three primary categories of components:

Data-Driven Components render visual marks directly from data (Area, Bars, Spline, Pie, Sunburst, Treemap, Sankey, etc.). These components automatically handle scale transformations through LayerCake's context.

Motion-Enabled SVG Primitives (Rect, Circle, Arc, Group, Line, Path) provide low-level drawing utilities with built-in Svelte transition support for animated data updates.

Utility Components handle legends, tooltips, pan/zoom interactions, annotations, and layout operations (hierarchy, geo projections).

Visualization Types

Cartesian: Bar, Area, Stack, Scatter, Histogram, ClevelandDotPlot, BarStack, BarGroup
Radial: Pie, Arc, Sunburst, Threshold
Hierarchical: Pack, Tree, Treemap, Partition
Graph: Sankey, Link, Graph utilities
Geographic: Choropleth, Spike Map, Bubble Map, GeoTile, GeoPath, StateMap, AnimatedGlobe, Globe projections (Mercator, Azimuthal, Equal Earth, etc.)

Key Patterns

Data Preparation

Use LayerChart's data transformation utilities before passing to visualizations:

stack() - converts wide-format data into stacked series with baseline/top values
bin() - groups data into histogram bins with x0/x1 bounds
groupLonger() - pivots wide-format to long-format (one row per value)
flatten() - flattens nested arrays one level, with optional accessor
calcExtents() - calculates min/max across multiple fields, skipping nulls

Component Composition

All LayerChart visualizations sit within a LayerCake wrapper that establishes scales and context. Child components access scales via Svelte's context API.

<LayerCake x="date" y="value" data={data} padding={{...}}>
  <Svg>
    <Area />
    <Line />
    <AxisX />
  </Svg>
  <Canvas>
    <Points />  <!-- High-performance canvas rendering -->
  </Canvas>
  <Html>
    <Tooltip />
  </Html>
</LayerCake>

Interaction Patterns

Tooltips: Position over data with snap-to-data options
Pan/Zoom: Built-in context utilities for interactive navigation
Highlighting: Hover states trigger visual emphasis (opacity, stroke changes)
Selection: Use reactive variables and event handlers for interactive filtering

Responsive Design

LayerChart automatically handles responsive layouts via padding configuration and container dimensions. Components reactively update when data or scales change.

Common Implementation Tasks

Bar Charts: Use Bars component with x as categorical field. Stack with BarStack or group with BarGroup for multi-series.

Time Series: Configure xScale={scaleTime()} with temporal data. Use AxisX with tickFormat for readable date labels.

Geographic Visualizations: Select appropriate projection (Mercator for web maps, Azimuthal for polar), use GeoPath for boundaries, Choropleth for value mapping.

High-Volume Data: Render marks via Canvas instead of SVG for 5000+ points. Layer SVG axes/legends with Canvas for hybrid rendering.

Stacked/Grouped Series: Use stack() utility to transform data, then render via AreaStack/BarStack components.

Performance Considerations

Canvas rendering for 5000+ points (~60fps on modern hardware)
SVG for interactive elements and animations (<500 points recommended)
Hybrid approach: Canvas for marks + SVG for axes/legends
Scale calculations are reactive—only update scales when data/domain changes
Memoize expensive data transforms outside component lifecycle

Styling and Customization

All primitive components support standard SVG/Canvas attributes (stroke, fill, opacity, strokeWidth). Use Svelte's reactive statements for conditional styling based on interaction state or data values.

Gradient fills, patterns, and clipping available via ClipPath, RectClipPath, CircleClipPath components with SVG <defs>.

Integration Notes

Works seamlessly with D3 scales (linear, time, ordinal, log, threshold)
Supports multiple render contexts in same chart (SVG + Canvas + HTML)
Fully accessible with ARIA attributes on SVG elements
SSR-compatible for server-side rendering in SvelteKit
Zero external dependencies beyond Svelte and d3-array utilities