最近在学习 d3 brush 见官网有案例边下载调试但不成功
将function写在 <script> 标签内调用也没有出错，可是网页无显示任何图像，代码如下：
相关代码：
<!DOCTYPE html>
<html>
<head>
<script src = "https://d3js.org/d3.v7.min.js"></script>
</head>
<body>
<script>
var margin = ({top: 20, right: 20, bottom: 30, left: 40})
var width = 960 - margin.left - margin.right
var height = 440
var focusHeight = 100
var data = [{ "date":"0.1", "value":394.46},
{ "date":"0.2", "value":1366.42},
{ "date":"0.3", "value":1498.58},
{ "date":"0.4", "value":1452.43},
{ "date":"0.5", "value":20.6},
{ "date":"0.6", "value":1454.6},
{ "date":"0.7", "value":30.83},
{ "date":"0.8", "value":1217.68},
{ "date":"0.9", "value":1436.51},
{ "date":"1.0", "value":29.4}
];
var area = (x, y) => d3.area()
.defined(d => !isNaN(d.value))
.x(d => x(d.date))
.y0(y(0))
.y1(d => y(d.value))
var x = d3.scaleUtc()
.domain(d3.extent(data, d => d.date))
.range([margin.left, width - margin.right])
var y = d3.scaleLinear()
.domain([0, d3.max(data, d => d.value)])
.range([height - margin.bottom, margin.top])
var xAxis = (g, x, height) => g
.attr("transform", `translate(0,${height - margin.bottom})`)
.call(d3.axisBottom(x).ticks(width / 80).tickSizeOuter(0))
var yAxis = (g, y, title) => g
.attr("transform", `translate(${margin.left},0)`)
.call(d3.axisLeft(y))
.call(g => g.select(".domain").remove())
.call(g => g.selectAll(".title").data([title]).join("text")
.attr("class", "title")
.attr("x", -margin.left)
.attr("y", 10)
.attr("fill", "currentColor")
.attr("text-anchor", "start")
.text(title))
var chart = function(){
const svg = d3.create("svg")
.attr("viewBox", [0, 0, width, height])
.style("display", "block");
svg.append("clipPath")
.attr("id", "clip")
.append("rect")
.attr("x", margin.left)
.attr("y", 0)
.attr("height", height)
.attr("width", width - margin.left - margin.right);
const gx = svg.append("g");
const gy = svg.append("g");
const path = svg.append("path")
.datum(data)
.attr("clip-path", "clip")
.attr("fill", "steelblue");
return Object.assign(svg.node(), {
update(focusX, focusY) {
gx.call(xAxis, focusX, height);
gy.call(yAxis, focusY, data.y);
path.attr("d", area(focusX, focusY));
}
});
}
chart()
var focus = function(){
const svg = d3.create("svg")
.attr("viewBox", [0, 0, width, focusHeight])
.style("display", "block");
const brush = d3.brushX()
.extent([[margin.left, 0.5], [width - margin.right, focusHeight - margin.bottom + 0.5]])
.on("brush", brushed)
.on("end", brushended);
const defaultSelection = [x(d3.utcYear.offset(x.domain()[1], -1)), x.range()[1]];
svg.append("g")
.call(xAxis, x, focusHeight);
svg.append("path")
.datum(data)
.attr("fill", "steelblue")
.attr("d", area(x, y.copy().range([focusHeight - margin.bottom, 4])));
const gb = svg.append("g")
.call(brush)
.call(brush.move, defaultSelection);
function brushed({selection}) {
if (selection) {
svg.property("value", selection.map(x.invert, x).map(d3.utcDay.round));
svg.dispatch("input");
}
}
function brushended({selection}) {
if (!selection) {
gb.call(brush.move, defaultSelection);
}
}
return svg.node();
}
focus()
var update = function(){
const [minX, maxX] = focus;
const maxY = d3.max(data, d => minX <= d.date && d.date <= maxX ? d.value : NaN);
chart.update(x.copy().domain(focus), y.copy().domain([0, maxY]));
}
</script>
</body>
</html>
本人纯新手，还请帮忙看看如何在网页显示图像，谢谢。
极客观点
项目管理
HarmonyOS
你的问题是你创建了 chart 和 focus 函数，但没有把它们添加到 HTML 中