D3.js介绍
D3.js是一个流行的JavaScript数据可视化库，全称为Data-Driven Documents，即数据驱动文档。它以数据为核心，通过数据来驱动文档的展示和操作。D3.js提供了丰富的API和工具，使得开发者能够创建出各种交互式和动态的数据可视化效果。
官方介绍网站：What is D3? | D3 by Observable
D3.js导入方式介绍
在JavaScript中导入D3.js通常使用ESM+CDN、UMD+CDN和UMD+local这三种方式，其中：ESM (ES Modules) :ESM是ECMAScript模块（ECMAScript Modules）的缩写，也被称为ES6模块，是JavaScript官方的模块化方案。它使用import和export语句进行模块的导入和导出，支持静态导入和动态导入。
CDN (Content Delivery Network):CDN即内容分发网络，是一种通过分布在多个地理位置的服务器来快速、有效地向用户分发内容的网络服务。使用CDN可以加快资源的加载速度，提高用户体验。
UMD (Universal Module Definition):UMD是一种通用的模块定义方式，旨在使JavaScript库或模块能够在多种环境中使用，包括浏览器全局变量方式、AMD环境和CommonJS环境（如Node.js）。UMD允许库或模块在各种不同的JavaScript模块加载器和环境中运行。
local:将JavaScript库或模块直接保存在本地项目中，而不是从外部CDN或其他远程位置加载。
D3.js导入方式1：ESM+CDN
html
<!DOCTYPE html>
<div id="container"></div>
<script type="module">
import * as d3 from "https://cdn.jsdelivr.net/npm/d3@7/+esm";
// 一大堆代码
</script>D3.js导入方式2：UMD+CDN
html
<!DOCTYPE html>
<div id="container"></div>
<script src="https://cdn.jsdelivr.net/npm/d3@7"></script>
<script type="module">
// 一大堆代码
</script>D3.js导入方式3：UMD+local
html
<!DOCTYPE html>
<div id="container"></div>
<script src="/d3.v7.js"></script>
<script type="module">
// 一大堆代码
</script>D3.js文件官方下载地址：Getting started | D3 by Observable
使用D3.js绘制柱形图
html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>GGBoy</title>
<script src="/d3.v7.js"></script>
</head>
<body>
<script>
const width = 640;
const height = 400;
const marginTop = 20;
const marginRight = 20;
const marginBottom = 30;
const marginLeft = 40;
const innerWidth = width - marginLeft - marginRight;
const innerHeight = height - marginTop - marginBottom;
const svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
const plotArea = svg.append("g")
.attr("transform", `translate(${marginLeft},${marginTop})`);
const x = d3.scaleBand()
.domain(["Category1", "Category2", "Category3"])
.padding(0.1);
const y = d3.scaleLinear()
.domain([0, 100])
.range([innerHeight, 0]);
// Add the x-axis.
plotArea.append("g")
.attr("transform", `translate(0,${innerHeight})`)
.call(d3.axisBottom(x));
// Add the y-axis.
plotArea.append("g")
.call(d3.axisLeft(y));
const data = [
{ category: "Category1", value: 50 },
{ category: "Category2", value: 75 },
{ category: "Category3", value: 30 }
];
plotArea.selectAll(".bar")
.data(data)
.enter().append("rect")
.attr("class", "bar")
.attr("x", d => x(d.category))
.attr("width", x.bandwidth())
.attr("y", d => y(d.value))
.attr("height", d => innerHeight - y(d.value))
.attr("fill", "steelblue");
</script>
</body>
</html>
使用D3.js绘制曲线图
html
<!DOCTYPE html>
<html>
<head>
<title>GGBoy</title>
</head>
<body>
<div id="container" style="width: 600px; height: 400px;"></div>
<script type="module">
import * as d3 from "https://cdn.jsdelivr.net/npm/d3@7/+esm";
var data = [
{date: '2024-05-01', close: 100},
{date: '2024-05-02', close: 110},
{date: '2024-05-03', close: 95},
{date: '2024-05-04', close: 120},
{date: '2024-05-05', close: 105}
];
var parseDate = d3.timeParse("%Y-%m-%d");
data.forEach(function(d) {
d.date = parseDate(d.date);
});
const width = 600;
const height = 400;
const marginTop = 20;
const marginRight = 20;
const marginBottom = 30;
const marginLeft = 40;
var x = d3.scaleTime()
.range([marginLeft, width - marginRight])
.domain(d3.extent(data, function(d) { return d.date; }));
var y = d3.scaleLinear()
.range([height - marginBottom, marginTop])
.domain(d3.extent(data, function(d) { return d.close; }));
var svg = d3.select("#container").append("svg")
.attr("width", width)
.attr("height", height);
svg.append("g")
.attr("transform", `translate(0,${height - marginBottom})`)
.call(d3.axisBottom(x));
svg.append("g")
.attr("transform", `translate(${marginLeft},0)`)
.call(d3.axisLeft(y));
var line = d3.line()
.x(function(d) { return x(d.date); })
.y(function(d) { return y(d.close); })
.curve(d3.curveBasis);
svg.append("path")
.datum(data)
.attr("class", "line")
.attr("d", line)
.attr("stroke", "blue")
.attr("stroke-width", 2)
.attr("fill", "none");
</script>
</body>
</html>
使用D3.js实现网页时钟
html
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>GGBoy</title>
<script src="https://cdn.jsdelivr.net/npm/d3@7"></script>
<style>
.time {
font-family: Cursive;
font-size: 40px;
stroke: black;
stroke-width: 2;
fill: none;
}
</style>
</head>
<body>
<svg width="600" height="400"></svg>
<script>
function getTime() {
var time = new Date();
var hour = time.getHours();
var minute = time.getMinutes();
var second = time.getSeconds();
hour = hour < 10 ? '0' + hour : hour;
minute = minute < 10 ? '0' + minute : minute;
second = second < 10 ? '0' + second : second;
return hour + ':' + minute + ':' + second;
}
var svg = d3.select("svg"); // 选择SVG元素
var timeText = svg.append("text")
.attr("x", 100)
.attr("y", 100)
.attr("class", "time")
.text(getTime());
function updateTime() {
timeText.text(getTime());
}
setInterval(updateTime, 1000);
</script>
</body>
</html>