如何用Chart.js生成PDF

<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/2.4.0/jspdf.umd.min.js"></script>

<canvas id="myChart"></canvas>

<script>
  var ctx = document.getElementById('myChart').getContext('2d');
  var chart = new Chart(ctx, {
    type: 'bar',
    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: {
        y: {
          beginAtZero: true
        }
      }
    }
  });
</script>

<script>
  var canvas = document.getElementById('myChart');
  var imgData = canvas.toDataURL('image/png');
  var pdf = new jsPDF();
  pdf.addImage(imgData, 'PNG', 10, 10);
  pdf.save('chart.pdf');
</script>