如何在Node.js中使用Chart.js？

Question

如何使用带有chartjs的NodeJ创建饼图？想使用chartjs创建不同类型的图表，但是当我尝试运行代码时显示“无法设置宽度属性”

TypeError: Cannot set property 'width' of undefined
    at ni.resize (node_modules\chart.js\dist\Chart.min.js:7:93312)
    at ni.initialize (node_modules\chart.js\dist\Chart.min.js:7:92818)
    at ni.construct (node_modules\chart.js\dist\Chart.min.js:7:92559)
    at new ni (node_modules\chart.js\dist\Chart.min.js:7:91964)
    at Object.<anonymous> (chartjs\chart.js:7:15)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)

我试图运行此代码以生成饼图图像，但发现此错误。

let Canvas = require("canvas"),
  canvas = Canvas.createCanvas(400, 400),
  ctx = canvas.getContext("2d"),
  Chart = require('chart.js'),
  fs = require("fs");

var myChart = new Chart(ctx, {
  type: "pie",
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [
      {
        label: "# of Votes",
        data: [12, 19, 3, 5, 2, 3],
        backgroundColor: [
          "rgba(255, 99, 132, 0.2)",
          "rgba(54, 162, 235, 0.2)",
          "rgba(255, 206, 86, 0.2)",
          "rgba(75, 192, 192, 0.2)",
          "rgba(153, 102, 255, 0.2)",
          "rgba(255, 159, 64, 0.2)"
        ],
        borderColor: [
          "rgba(255, 99, 132, 1)",
          "rgba(54, 162, 235, 1)",
          "rgba(255, 206, 86, 1)",
          "rgba(75, 192, 192, 1)",
          "rgba(153, 102, 255, 1)",
          "rgba(255, 159, 64, 1)"
        ],
        borderWidth: 1
      }
    ]
  },
  options: {
    scales: {
      yAxes: [
        {
          ticks: {
            beginAtZero: true
          }
        }
      ]
    }
  }
});

canvas.toBuffer(function(err, buf) {
  if (err) throw err;
  fs.writeFileSync("chart.png", buf);
});

应该是当前文件夹中的图像

Answer 1

如果要使用this创建图表，可以参考nodejs答案。

P.S。此问题重复到this