A viewBox with width: 100% scales everything, text included (Front-End Web Development, SVG in Responsive Design). Redrawing keeps text sizes: a ResizeObserver reports each container's width and the chart rebuilds its scales. The same code in a 250 px and a 420 px box:
<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>
<div class="box" style="width:250px"></div><div class="box" style="width:420px"></div>
<style>.box { display: inline-block; margin-right: 12px; font: 11px Arial }</style>
<script>
const { months } = prepareSales(SALES);
function draw(box, width) {
const svg = d3.select(box).selectAll('svg').data([null]).join('svg')
.attr('width', width).attr('height', 150);
const x = d3.scaleUtc(d3.extent(months, d => d.date), [15, width - 15]);
const y = d3.scaleLinear([0, 400], [130, 10]);
svg.selectAll('g.x').data([null]).join('g').attr('class', 'x')
.attr('transform', 'translate(0,130)').call(d3.axisBottom(x).ticks(width / 80));
svg.selectAll('path.line').data([months]).join('path').attr('class', 'line')
.attr('fill', 'none').attr('stroke', '#1f5f8b').attr('stroke-width', 2)
.attr('d', d3.line(d => x(d.date), d => y(d.units)));
}
const observer = new ResizeObserver(entries => entries.forEach(e =>
draw(e.target, e.contentRect.width))); // runs on observe and on every resize
document.querySelectorAll('.box').forEach(box => observer.observe(box));
</script>
ticks(width / 80) gives about one tick per 80 pixels, and the data([null]).join() idiom creates each element once and updates it afterward. Callbacks run after layout, before paint.
<!doctype html>
<style>
body { margin: 0; padding: 8px; background: #fafaf7; font: 11px system-ui, sans-serif; color: #263238; max-width: 600px; }
.box { display: inline-block; vertical-align: top; margin: 0 8px 8px 0; background: #fff; border: 1px dashed #b0a898; }
.redraw { height: 124px; } /* a fixed height: redrawing never resizes the box */
.box svg { display: block; }
#resizable { resize: horizontal; overflow: hidden; width: 330px; min-width: 150px; max-width: 580px; }
h4 { margin: 4px 0; font-size: 12px; }
</style>
<script src="https://cdn.jsdelivr.net/npm/d3@7.9.0/dist/d3.min.js"></script>
<h4>Redrawn on resize (text stays 11 px): drag the right box's corner</h4>
<div class="box redraw" style="width:230px"></div><div class="box redraw" id="resizable"></div>
<h4>Scaled with viewBox (everything shrinks, text included)</h4>
<div class="box" style="width:230px" id="scaled"></div>
<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 };
}
const { months } = prepareSales(SALES);
function draw(box, width) {
// data([null]).join(): create each element once, update it on later calls
const svg = d3.select(box).selectAll('svg').data([null]).join('svg').attr('width', width).attr('height', 120);
const x = d3.scaleUtc(d3.extent(months, d => d.date), [15, width - 15]);
const y = d3.scaleLinear([0, 500], [100, 10]);
svg.selectAll('g.x').data([null]).join('g').attr('class', 'x')
.attr('transform', 'translate(0,100)').call(d3.axisBottom(x).ticks(width / 80)); // ~1 tick per 80 px
svg.selectAll('path.line').data([months]).join('path').attr('class', 'line')
.attr('fill', 'none').attr('stroke', '#1f5f8b').attr('stroke-width', 2)
.attr('d', d3.line(d => x(d.date), d => y(d.units)));
svg.selectAll('text.w').data([width]).join('text').attr('class', 'w').attr('x', 15).attr('y', 12)
.text(w => `${Math.round(w)} px wide`);
}
// Runs once on observe() and again after every size change, before paint
const observer = new ResizeObserver(entries => entries.forEach(e => draw(e.target, e.contentRect.width)));
document.querySelectorAll('.redraw').forEach(box => observer.observe(box));
// For contrast: draw once at 420 px, then let a viewBox scale it into 230 px
draw(document.getElementById('scaled'), 420);
d3.select('#scaled svg').attr('viewBox', '0 0 420 120').attr('width', '100%').attr('height', null);
</script>