Treemap API

Hierarchical tiles sized by value, each optionally split into two named parts (e.g. realized vs untapped), with a mobile-friendly stack fallback - see the Treemap demo.

Import

Web Component

import "@michi-vz/wc/treemap-chart";
// <michi-vz-treemap-chart> is now defined

Vanilla JS

import { mountTreemapChart } from "@michi-vz/core";

const chart = mountTreemapChart(el, props);

Props

Prop	Type	Default	Description
dataSet*	TreemapNode[]	—	Forest of nodes (each a leaf or a parent with children) sized by value and tiled to fill the area
title	string	—	Optional chart title rendered above the plot
paddingInner	number	1	Gap between sibling tiles in px (default 1).
paddingTop	number	18	Header strip height (px) reserved on parent tiles for their label in nested mode (default 18).
layout	"squarify" | "stack" | "auto"	"squarify"	Layout algorithm: "squarify" (treemap, default), "stack" (single-column, mobile-friendly), or "auto" (stack below `stackBreakpoint` width).
stackBreakpoint	number	—	Width (px) below which `layout: "auto"` switches to the stack layout (default 480).
splitLabels	[string, string]	["Filled", "Remaining"]	Names of the two split parts (default ["Filled","Remaining"]).
splitOpacity	number	0.35	Apparent colour strength of the remainder/untapped segment in [0,1] (default 0.35). Rendered as the solid colour under a white veil, so it reads as a lighter tint of the same hue on any background (light or dark) rather than depending on the backdrop.
showSplit	boolean	—	Render the primary/remainder split. Defaults to auto-on when any leaf carries `partial`.
showLegend	boolean	false	Render a 2-swatch split legend (uses splitLabels).
minTileShare	number	—	Floor each leaf's tiling area to this percent of the largest leaf, so tiny tiles stay visible.
filter	{ limit: number; sortingDir: "asc" | "desc" }	—	Keep only the top-N leaves by value.
valueFormatter	(n: number) => string	—	Formats numeric values shown in the default tooltip (defaults to a locale number formatter)
tooltipFormatter	(leaf: TreemapLeafContext) => string	—	Returns custom tooltip HTML for a hovered datum (sanitized before it is inserted)
onHighlightItem	(labels: string[]) => void	—	Called when the hovered/highlighted label(s) change

Common props — shared by every chart (14)

Prop	Type	Default	Description
width	number	900	Chart width in pixels
height	number	520	Chart height in pixels
margin	Margin	{ top: 36, right: 6, bottom: 6, left: 6 }	Inner margins (top/right/bottom/left, in px) reserved for axes, titles, and labels
colors	string[]	—	Categorical palette for series/labels without an explicit colour or colorsMapping entry
colorsMapping	Record<string, string>	—	Explicit label -> colour map; takes precedence over the palette and per-item colours
highlightItems	string[]	—	Labels to emphasise; all other marks dim
disabledItems	string[]	—	Labels to hide and exclude from scales/stacks
renderer	"svg" | "canvas"	"svg"	Render as inline SVG (default) or to a canvas (faster for large datasets); getContext() is identical either way
locale	string	—	BCP-47 locale used for number and date formatting
skipColorMappingDispatch	boolean	false	External-CSS mode: unmapped labels resolve to transparent and onColorMappingGenerated is not emitted, so mark colours come from your CSS via the data-label-safe contract
enableTransitions	boolean	true	Animate updates with CSS transitions (default true)
onColorMappingGenerated	(mapping: Record<string, string>) => void	—	Called with the resolved label -> colour map after the chart assigns colours
onChartDataProcessed	(context: ChartContext) => void	—	Called with the renderer-agnostic ChartContext whenever the data is (re)processed
onDataWarning	(warnings: DataWarning[]) => void	—	Called with any non-fatal data warnings (duplicate labels, non-finite values, gaps, ...)

Events

The web component dispatches these bubbling CustomEvents (the engine exposes the same via the on* callbacks in the table above):

Event	Detail	Fires when
michi-vz:highlight	string[]	hover highlight changes
michi-vz:colormapping	Record<string, string>	a color mapping is generated
michi-vz:dataprocessed	ChartContext	data is (re)processed
michi-vz:datawarning	DataWarning[]	input warnings are detected

getContext()

mountTreemapChart(el, props).getContext() returns a renderer-agnostic TreemapChartContext: the flat leaves (value / partial / remainder / percent / path), the resolved layout, splitLabels, nesting depth, summary stats (grand total, totals per part, largest leaf, largest remainder), a deterministic natural-language summary, and an a11y table. See LLM context.

Source

Props are typed as TreemapChartProps in @michi-vz/core.