A treemap divides a rectangle so each leaf's area is proportional to its value, here copies on hand (sample numbers) times price. paddingTop leaves a header strip per shelf; the default treemapSquarify tiling keeps cells near the golden ratio:
<script src="https://cdn.jsdelivr.net/npm/d3@7.9.0/dist/d3.min.js"></script>
<script src="booknest-sales.js"></script><script src="booknest-prep.js"></script>
<script src="booknest-tree.js"></script>
<svg width="720" height="190" font-family="Arial" font-size="12"></svg>
<script>
const stock = { harbor: 64, deepweb: 22, saffron: 40, summit: 55, clock: 48, glass: 35 };
const root = d3.treemap().size([720, 190]).paddingInner(2) // paddingOuter sets all 4 sides
.paddingOuter(n => n.depth === 1 ? 3 : 0).paddingTop(n => n.depth === 1 ? 18 : 0)
(catalogTree(prepareSales(SALES), b => stock[b.key] * b.price));
const money = d3.format('$,.0f'), price = d3.format('$.2f');
const node = d3.select('svg').selectAll('g')
.data(root.descendants().filter(d => d.depth % 2)).join('g') // shelves, books
.attr('transform', d => `translate(${d.x0},${d.y0})`);
node.append('rect').attr('width', d => d.x1 - d.x0).attr('height', d => d.y1 - d.y0)
.attr('fill', d => d.children ? '#eceff1' : d.data.color);
node.append('text').attr('fill', d => d.children ? '#263238' : 'white').selectAll('tspan')
.data(d => d.children ? [`${nodeName(d)} ${money(d.value)}`] : [d.data.title,
`${stock[d.data.key]} x ${price(d.data.price)} = ${money(d.value)}`])
.join('tspan').attr('x', 5).attr('y', (t, i) => 13 + i * 15).text(t => t);
</script>
Plentiful Small Steps to Big Summits outweighs Patterns of the Deep Web at twice the price. Drawing depths 1 and 3 (depth % 2) skips the root and the one-book genres; treemapResquarify keeps cells stable in animations.
<!doctype html>
<style>
body { margin: 0; padding: 8px; background: #fafaf7; font: 12px system-ui, sans-serif; color: #263238; }
svg { width: 100%; max-width: 600px; display: block; }
</style>
<script src="https://cdn.jsdelivr.net/npm/d3@7.9.0/dist/d3.min.js"></script>
<p>Tiling: <select id="tile"><option>treemapSquarify</option><option>treemapBinary</option><option>treemapSlice</option><option>treemapDice</option><option>treemapSliceDice</option></select></p>
<svg viewBox="0 0 600 220" font-size="11"></svg>
<script>
// BookNest sample data, invented for these examples (not real sales)
const SALES = (() => {
const books = [
{ id: 1, key: 'harbor', title: 'The Quiet Harbor', author: 'Elena Marsh', genre: 'Fiction', color: '#1f5f8b', price: 18.99, rating: 4.6 },
{ id: 2, key: 'deepweb', title: 'Patterns of the Deep Web', author: 'Ravi Menon', genre: 'Technology', color: '#5b3f99', price: 39.5, rating: 4.3 },
{ id: 3, key: 'saffron', title: 'Salt and Saffron', author: 'Leila Haddad', genre: 'Cooking', color: '#e09a10', price: 24, rating: 4.8 },
{ id: 4, key: 'summit', title: 'Small Steps to Big Summits', author: 'Tom Okafor', genre: 'Self-Help', color: '#3f7d3a', price: 14.99, rating: 4.1 },
{ id: 5, key: 'clock', title: "The Clockmaker's Paradox", author: 'Iris Vale', genre: 'Science Fiction', color: '#b5452f', price: 16.2, rating: 4.5 },
{ id: 6, key: 'glass', title: 'Gardens in Glass', author: 'June Park', genre: 'Gardening', color: '#2a9d8f', price: 22.5, rating: 4.4 },
];
const units = { // units sold per month, January 2025 to August 2026
1: [40, 47, 46, 47, 57, 51, 46, 54, 60, 60, 71, 111, 52, 42, 49, 56, 59, 48, 53, 51],
2: [40, 37, 35, 41, 48, 43, 40, 42, 50, 53, 53, 84, 42, 35, 38, 41, 45, 41, 46, 46],
3: [46, 45, 41, 46, 53, 49, 46, 45, 60, 51, 63, 100, 48, 48, 49, 48, 53, 49, 48, 52],
4: [100, 80, 72, 70, 66, 66], // released March 2026
5: [48, 47, 54, 52, 65, 55, 57, 58, 64, 66, 75, 124, 58, 49, 59, 56, 63, 57, 54, 57],
6: [31, 30, 28, 35, 31, 32, 29, 30, 41, 36, 45, 64, 31, 30, 30, 38, 40, 38, 36, 38],
};
const months = d3.utcMonths(new Date('2025-01-01'), new Date('2026-09-01')).map(d3.utcFormat('%Y-%m'));
const sales = books.flatMap(b => units[b.id].map((n, i) =>
({ month: months[i + months.length - units[b.id].length], book: b.id, units: n })));
const ratings = [[4, 8, 20, 87, 293], [6, 10, 22, 95, 147], [2, 3, 8, 45, 342], [2, 3, 8, 24, 28],
[4, 8, 20, 90, 228], [4, 7, 20, 82, 147]].map((counts, i) => ({ book: i + 1, counts })); // 1 to 5 stars
const regions = [{ id: '826', name: 'United Kingdom', units: 1480 }, { id: '276', name: 'Germany', units: 1120 },
{ id: '250', name: 'France', units: 760 }, { id: '372', name: 'Ireland', units: 540 },
{ id: '528', name: 'Netherlands', units: 410 }, { id: '724', name: 'Spain', units: 320 }];
const links = [[5, 1, 38], [1, 3, 24], [2, 5, 18], [3, 6, 21], [4, 1, 12], [2, 6, 9], [4, 3, 15], [5, 6, 14]]
.map(([source, target, value]) => ({ source, target, value })); // customers who bought both
return { books, sales, ratings, regions, links };
})();
// prepareSales(raw): parsed dates, sales linked to book objects, revenue and totals
function prepareSales(raw) {
const parse = d3.utcParse('%Y-%m'), books = raw.books.map(b => ({ ...b }));
const byId = d3.index(books, b => b.id);
const sales = raw.sales.map(s => ({ date: parse(s.month), book: byId.get(s.book),
units: s.units, revenue: s.units * byId.get(s.book).price }));
for (const [book, rows] of d3.group(sales, s => s.book)) {
book.units = d3.sum(rows, s => s.units);
book.revenue = d3.sum(rows, s => s.revenue);
}
const months = d3.rollups(sales, v => ({ units: d3.sum(v, s => s.units),
revenue: d3.sum(v, s => s.revenue) }), s => +s.date).map(([t, v]) => ({ date: new Date(t), ...v }))
.sort((a, b) => a.date - b.date);
const ratings = raw.ratings.map(r => ({ ...r, book: byId.get(r.book) }));
return { ...raw, books, sales, months, ratings };
}
// catalogTree(data, value): shelf → genre → book, as a d3.hierarchy summed by value
const SHELF = { Fiction: 'Novels', 'Science Fiction': 'Novels' }; // the rest: Nonfiction
function catalogTree(data, value = b => b.revenue) {
const nest = d3.group(data.books, b => SHELF[b.genre] ?? 'Nonfiction', b => b.genre);
return d3.hierarchy(nest) // a Map becomes the entry [undefined, map]
.sum(d => d.id ? value(d) : 0) // only books (the leaves) carry a value
.sort((a, b) => b.height - a.height || b.value - a.value);
}
const nodeName = n => n.depth === 0 ? 'BookNest' : n.children ? n.data[0] : n.data.title;
const stock = { harbor: 64, deepweb: 22, saffron: 40, summit: 55, clock: 48, glass: 35 }; // copies on hand
const money = d3.format('$,.0f'), price = d3.format('$.2f'), svg = d3.select('svg');
const tree = catalogTree(prepareSales(SALES), b => stock[b.key] * b.price);
function draw(tile) {
const root = d3.treemap().size([600, 220]).tile(d3[tile]).paddingInner(2)
.paddingOuter(n => n.depth === 1 ? 3 : 0).paddingTop(n => n.depth === 1 ? 18 : 0)(tree.copy());
// Depths 1 and 3: the shelves and the books (skip the root and the one-book genres)
const node = svg.selectAll('g').data(root.descendants().filter(d => d.depth % 2), nodeName).join(enter => {
const g = enter.append('g');
g.append('rect');
g.append('text');
return g;
});
node.transition().duration(600).attr('transform', d => `translate(${d.x0},${d.y0})`);
node.select('rect').transition().duration(600).attr('width', d => d.x1 - d.x0).attr('height', d => d.y1 - d.y0);
node.select('rect').attr('fill', d => d.children ? '#eceff1' : d.data.color);
node.select('text').attr('fill', d => d.children ? '#263238' : 'white').selectAll('tspan')
.data(d => d.children ? [`${nodeName(d)} ${money(d.value)}`] : (d.x1 - d.x0 > 60 ? [d.data.title,
`${stock[d.data.key]} × ${price(d.data.price)}`, money(d.value)] : [d.data.key]))
.join('tspan').attr('x', 5).attr('y', (t, i) => 13 + i * 14).text(t => t);
}
d3.select('#tile').on('change', e => draw(e.target.value));
draw('treemapSquarify');
</script>