Chart.js
Chart.js 是一個免費的 JavaScript 庫，用於製作基於 HTML 的圖表。它是最簡單的 JavaScript 視覺化庫之一，並帶有以下內建圖表型別
- 散點圖
- 折線圖
- 柱狀圖
- 餅圖
- 甜甜圈圖
- 氣泡圖
- 面積圖
- 雷達圖
- 組合圖
如何使用 Chart.js？
Chart.js 易於使用。
首先，新增一個 CDN（內容分發網路）的連結
<script
src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js">
</script>
然後，新增一個 <canvas> 元素到你想要繪製圖表的位置
<canvas id="myChart" style="width:100%;max-width:700px"></canvas>
canvas 元素必須有一個唯一的 ID。
就是這樣！
典型的散點圖語法
const myChart = new Chart("myChart", {
type: "scatter",
data: {},
options: {}
});
典型的折線圖語法
const myChart = new Chart("myChart", {
type: "line",
data: {},
options: {}
});
典型的柱狀圖語法
const myChart = new Chart("myChart", {
type: "bar",
data: {},
options: {}
});
散點圖
房價 vs. 面積
原始碼
const xyValues = [
{x:50, y:7},
{x:60, y:8},
{x:70, y:8},
{x:80, y:9},
{x:90, y:9},
{x:100, y:9},
{x:110, y:10},
{x:120, y:11},
{x:130, y:14},
{x:140, y:14},
{x:150, y:15}
];
new Chart("myChart", {
type: "scatter",
data: {
datasets: [{
pointRadius: 4,
pointBackgroundColor: "rgba(0,0,255,1)",
data: xyValues
}]
},
options:{...}
});
折線圖
房價 vs. 面積
原始碼
const xValues = [50,60,70,80,90,100,110,120,130,140,150];
const yValues = [7,8,8,9,9,9,10,11,14,14,15];
new Chart("myChart", {
type: "line",
data: {
labels: xValues,
datasets: [{
backgroundColor:"rgba(0,0,255,1.0)",
borderColor: "rgba(0,0,255,0.1)",
data: yValues
}]
},
options:{...}
});
如果將 borderColor 設定為零，則可以將折線圖顯示為散點圖。
borderColor: "rgba(0,0,0,0)",
多行
原始碼
const xValues = [100,200,300,400,500,600,700,800,900,1000];
new Chart("myChart", {
type: "line",
data: {
labels: xValues,
datasets: [{
data: [860,1140,1060,1060,1070,1110,1330,2210,7830,2478],
borderColor: "red",
fill: false
},{
data: [1600,1700,1700,1900,2000,2700,4000,5000,6000,7000],
borderColor: "green",
fill: false
},{
data: [300,700,2000,5000,6000,4000,2000,1000,200,100],
borderColor: "blue",
fill: false
}]
},
options: {
legend: {display: false}
}
});
線性圖
原始碼
const xValues = [];
const yValues = [];
generateData("x * 2 + 7", 0, 10, 0.5);
new Chart("myChart", {
type: "line",
data: {
labels: xValues,
datasets: [{
fill: false,
pointRadius: 1,
borderColor: "rgba(255,0,0,0.5)",
data: yValues
}]
},
options: {...}
});
function generateData(value, i1, i2, step = 1) {
for (let x = i1; x <= i2; x += step) {
yValues.push(eval(value));
xValues.push(x);
}
}
函式圖
柱狀圖
原始碼
var xValues = ["義大利", "法國", "西班牙", "美國", "阿根廷"];
var yValues = [55, 49, 44, 24, 15];
var barColors = ["red", "green","blue","orange","brown"];
new Chart("myChart", {
type: "bar",
data: {
labels: xValues,
datasets: [{
backgroundColor: barColors,
data: yValues
}]
},
options: {...}
});
顏色漸變
var barColors = [
"rgba(0,0,255,1.0)",
"rgba(0,0,255,0.8)",
"rgba(0,0,255,0.6)",
"rgba(0,0,255,0.4)",
"rgba(0,0,255,0.2)",
];
餅圖
示例
new Chart("myChart", {
type: "pie",
data: {
labels: xValues,
datasets: [{
backgroundColor: barColors,
data: yValues
}]
},
options: {
title: {
display: true,
text: "世界葡萄酒產量"
}
}
});
