chart = {
const svg = d3.select(DOM.svg(width, height));
const { id, href } = DOM.uid();
const mask = svg.append("mask").attr("id", id);
const pctOffset = y(0)/height
svg.append("linearGradient")
.attr("id", "area-gradient")
.attr("gradientUnits", "userSpaceOnUse")
.attr("x1", 0).attr("y1", 0)
.attr("x2", 0).attr("y2", height)
.selectAll("stop")
.data([
{offset: "0%", color: topColor},
{offset: pctOffset, color: topColor},
{offset: pctOffset, color: bottomColor},
{offset: "100%", color: bottomColor}
])
.enter().append("stop")
.attr("offset", function(d) { return d.offset; })
.attr("stop-color", function(d) { return d.color; });
svg
.append("path")
.datum(data)
.attr("fill", "url(#area-gradient)")
.attr("d", area);
svg.append("g").call(xAxis);
svg.append("g").call(yAxis);
return svg.node();
}
height = 500
margin = ({top: 20, right: 20, bottom: 30, left: 30})
x = d3.scaleTime()
.domain(d3.extent(data, d => d.date))
.range([margin.left, width - margin.right])
y = d3
.scaleLinear()
.domain([-300, d3.max(data, d => d.value)])
.nice()
.range([height - margin.bottom, margin.top])
xAxis = g => g
.attr("transform", `translate(0,${height - margin.bottom})`)
.call(d3.axisBottom(x).ticks(width / 80).tickSizeOuter(0))
yAxis = g => g
.attr("transform", `translate(${margin.left},0)`)
.call(d3.axisLeft(y))
.call(g => g.select(".domain").remove())
.call(g => g.select(".tick:last-of-type text").clone()
.attr("x", 3)
.attr("text-anchor", "start")
.attr("font-weight", "bold")
.text(data.y))
area = d3.area()
.x(d => x(d.date))
.y0(y(0))
.y1(d => y(d.value))
data = Object.assign(
(await require("@observablehq/aapl")).map(({ date, close }) => ({
date,
value: close - 300
})),
{ y: "$ Close" }
)
d3 = require("d3@5")
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