Chart

如何使用 Chart.js？

Chart.js 很容易使用。

首先，添加指向提供 CDN（内容分发网络）的链接：

然后，将 添加到要绘制图表的位置：

canvas 元素必须有一个唯一的 id。

这是这样！

典型的散点图语法：

const myChart = new Chart("myChart", {
  type: "scatter",
  data: {},
  options: {}
});

典型的折线图语法：

const myChart = new Chart("myChart", {
  type: "line",
  data: {},
  options: {}
});

典型的条形图语法：

const myChart = new Chart("myChart", {
  type: "bar",
  data: {},
  options: {}
});

散点图

房价 vs. 面积

源代码

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:{...}
});

点击 "运行实例" 按钮查看在线实例

折线图

房价 vs. 面积

源代码

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:{...}
});

点击 "运行实例" 按钮查看在线实例

如果将 borderColor 设置为 0，则可以散点图绘制折线图：

borderColor: "rgba(0,0,0,0)",

点击 "运行实例" 按钮查看在线实例

多行

源代码

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}
  }
});

点击 "运行实例" 按钮查看在线实例

线性图

源代码

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);
  }
}

点击 "运行实例" 按钮查看在线实例

函数图

与线性图相同。只需更改 generateData 参数：

generateData("Math.sin(x)", 0, 10, 0.5);

点击 "运行实例" 按钮查看在线实例

条形图

源代码

var xValues = ["意大利", "法国", "西班牙", "美国", "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: {...}
});

点击 "运行实例" 按钮查看在线实例

只给一条上色：

var barColors = ["blue"];

点击 "运行实例" 按钮查看在线实例

所有条只有一种颜色：

var barColors ="red";

点击 "运行实例" 按钮查看在线实例

不同深浅的颜色：

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)",
];

点击 "运行实例" 按钮查看在线实例

水平条形图

只需将 type 由 "bar" 改为 "horizontalBar"：

type: "horizontalBar",

点击 "运行实例" 按钮查看在线实例

饼图

实例

new Chart("myChart", {
  type: "pie",
  data: {
    labels: xValues,
    datasets: [{
      backgroundColor: barColors,
      data: yValues
    }]
  },
  options: {
    title: {
      display: true,
      text: "全球葡萄酒生产"
    }
  }
});

点击 "运行实例" 按钮查看在线实例

甜甜圈图

只需将 type 由 "pie" 改为 "doughnut"：

type: "doughnut";

点击 "运行实例" 按钮查看在线实例